Filed pursuant to Rule 424(b)(5)
Registration No. 333-237319

The information in this preliminary prospectus supplement is not complete and may be changed. This preliminary prospectus supplement and the accompanying prospectus are part of an effective registration statement filed with the Securities and Exchange Commission. This preliminary prospectus supplement and the accompanying prospectus are not an offer to sell these securities and we are not soliciting offers to buy these securities in any jurisdiction where the offer or sale is not permitted.

SUBJECT TO COMPLETION, DATED JULY 29, 2020

PRELIMINARY PROSPECTUS SUPPLEMENT

(to prospectus dated May 8, 2020)

               Shares

Common Stock

We are offering                shares of our common stock, par value $0.001 per share, pursuant to this prospectus supplement and the accompanying prospectus.

Our common stock is traded on the Nasdaq Global Select Market under the symbol “SPPI.” On July 28, 2020, the last reported sale price of our common stock on the Nasdaq Global Select Market was $3.65 per share.

Investing in our common stock involves a high degree of risk. You should review carefully and consider the risks and uncertainties referenced under the heading “Risk Factors” beginning on page S-8 of this prospectus supplement and the risk factors contained in other documents incorporated by reference in this prospectus supplement.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the accuracy or adequacy of this prospectus supplement. Any representation to the contrary is a criminal offense.

	PER SHARE	TOTAL
Public offering price	$	$
Underwriting discounts and commissions (1)	$	$
Proceeds to Spectrum Pharmaceuticals, Inc., before expenses	$	$

⁽¹⁾  See “Underwriting” beginning on page S-25 for additional information regarding compensation payable to the underwriters.

Delivery of the shares of common stock is expected to be made on or about                     , 2020. We have granted the underwriters an option for a period of 30 days to purchase an additional              shares of our common stock. If the underwriters exercise the option in full, the total underwriting discounts and commissions payable by us will be $            , and the total proceeds to us, before expenses, will be $            .

Joint Book-Running Managers

Jefferies Cantor

Lead Manager

JMP Securities

Co-Managers

B. Riley FBR H.C. Wainwright & Co.

Prospectus Supplement Dated                     , 2020

TABLE OF CONTENTS

	PAGE
EXPLANATORY NOTE		S-1
ABOUT THIS PROSPECTUS SUPPLEMENT		S-1
PROSPECTUS SUPPLEMENT SUMMARY		S-3
THE OFFERING		S-7
RISK FACTORS		S-8
CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS		S-17
USE OF PROCEEDS		S-18
DIVIDEND POLICY		S-19
DILUTION		S-20
MATERIAL UNITED STATES FEDERAL INCOME TAX CONSIDERATIONS FOR NON-U.S. HOLDERS		S-21
CERTAIN ERISA CONSIDERATIONS		S-24
UNDERWRITING		S-25
LEGAL MATTERS		S-34
EXPERTS		S-34
WHERE YOU CAN FIND MORE INFORMATION		S-34
INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE		S-35

EXPLANATORY NOTE

We filed a shelf registration statement on Form S-3 on March 20, 2020, as amended, which was declared effective by the Securities and Exchange Commission (the “SEC”) on May 8, 2020. The registration statement contained a base prospectus covering the offering, issuance and sale by us of securities in an aggregate initial offering price not to exceed $150,000,000, as well as a sales agreement prospectus covering the offering, issuance and sale by us of up to a maximum aggregate offering price of $75,000,000 of our common stock pursuant to the terms of the Controlled Equity Offering^SM Sales Agreement, dated April 5, 2019, among us and Cantor Fitzgerald & Co., H.C. Wainwright & Co., LLC and B. Riley FBR, Inc. (which amount was included in the $150,000,000 aggregate offering price set forth in the base prospectus) in an at-the-market offering (the “ATM Offering”). On July 29, 2020, we filed a Form 8-K with the SEC terminating the ATM Offering. Prior to July 29, 2020, we sold an aggregate of 3,950,398 shares of common stock, for gross proceeds of approximately $15.2 million, pursuant to the ATM Offering since it commenced on May 8, 2020. The registration fees associated with the remaining approximately $134.8 million in shares of our common stock that remained unsold when the ATM Offering was terminated will be utilized in this offering.

ABOUT THIS PROSPECTUS SUPPLEMENT

This prospectus supplement and the accompanying prospectus are part of a registration statement on Form S-3 that we filed with the SEC, utilizing a “shelf” registration process. This document is in two parts. The first part is this prospectus supplement, including the documents incorporated by reference, which describes the specific terms of this offering. The second part, the accompanying prospectus, including the documents incorporated by reference, provides more general information. Generally, when we refer to this prospectus, we are referring to both parts of this document combined. We urge you to carefully read this prospectus supplement, the accompanying prospectus and the documents incorporated by reference herein and therein, before buying any of the securities being offered under this prospectus supplement. This prospectus supplement may add to or update information contained in the accompanying prospectus and the documents incorporated by reference therein. To the extent that any statement we make in this prospectus supplement is inconsistent with statements made in the accompanying prospectus or any documents incorporated by reference therein that were filed before the date of this prospectus supplement, the statements made in this prospectus supplement will be deemed to modify or supersede those made in the accompanying prospectus and such documents incorporated by reference therein.

We further note that the representations, warranties and covenants made by us in any agreement that is filed as an exhibit to any document that is incorporated by reference herein were made solely for the benefit of the parties to such agreement, including, in some cases, for the purpose of allocating risk among the parties to such agreement, and should not be deemed to be a representation, warranty or covenant to you. Moreover, such representations, warranties or covenants were accurate only as of the date when made. Accordingly such representations, warranties and covenants should not be relied on as accurately representing the current state of our affairs.

You should rely only on the information contained in this prospectus supplement and the accompanying prospectus, or incorporated by reference herein or therein. We have not, and the underwriters have not, authorized anyone to provide you with information that is in addition to or different from that contained or incorporated by reference into this prospectus supplement. We and the underwriters take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. Neither we nor the underwriters are offering to sell these securities in any jurisdiction where the offer or sale is not permitted. You should not assume that the information contained or incorporated by reference in this prospectus supplement is accurate as of any date other than as of the date of this prospectus supplement, or in the case of the documents incorporated by reference, the date of such documents, regardless of the time of delivery of this prospectus supplement or any sale of our common stock. Our business, financial condition, liquidity, results of operations and prospects may have changed since those dates. You should read this prospectus supplement, the accompanying prospectus, the documents incorporated by reference herein and therein and any free writing prospectus that we may authorize for use in connection with this

offering, in their entirety before making an investment decision. You should also read and consider the information

S-1

in the documents to which we have referred you in the sections of this prospectus supplement titled “Where You Can Find More Information” and “Incorporation of Certain Documents by Reference.”

Unless otherwise indicated or the context otherwise requires, the terms “Company,” “Spectrum Pharmaceuticals,” “we,” “us” and “our” refer to Spectrum Pharmaceuticals, Inc., a Delaware corporation, and its predecessors and consolidated subsidiaries.

S-2

PROSPECTUS SUPPLEMENT SUMMARY

The following is a summary of selected information contained elsewhere in this prospectus supplement or incorporated by reference into this prospectus supplement. It does not contain all of the information that you should consider before buying our securities. You should read this summary together with the entire prospectus supplement and the accompanying prospectus, including our consolidated financial statements, the notes to those consolidated financial statements, our Annual Report on Form 10-K for the fiscal year ended December 31, 2019, and the other documents that are incorporated by reference in this prospectus supplement and the accompanying prospectus, before deciding to buy shares of our common stock. See “Risk Factors” beginning on page S-8 of this prospectus supplement for a discussion of the risks involved in investing in our securities.

Spectrum Pharmaceuticals, Inc. Overview

We are a biopharma company, with a primary strategy comprised of acquiring, developing and commercializing novel and targeted oncology therapies. Our in-house development organization includes clinical development, regulatory, quality and data management. We plan to build out our commercial and marketing capabilities in the second half of 2020 to prepare for the launch of ROLONTIS.

We have three drugs in development:

∎ ROLONTIS, a novel long-acting granulocyte colony-stimulating factor (“G-CSF”) for chemotherapy-induced neutropenia, which has been accepted for review by the U.S. Food and Drug Administration (the “FDA”) and has a Prescription Drug User Fee Act (“PDUFA”) target action date of October 24, 2020;

∎ Poziotinib, a novel irreversible tyrosine kinase inhibitor under investigation for non-small cell lung cancer (“NSCLC”) tumors with various mutations; and

∎ Anti-CD20-IFNa, an antibody-interferon fusion molecule directed against CD20 that is in Phase 1 development for treating relapsed or refractory non-Hodgkin’s lymphoma (“NHL”) patients (including diffuse large B-cell lymphoma).

Our business strategy is the development of our late-stage assets through commercialization and the sourcing of additional assets that are synergistic with our existing portfolio (through purchase acquisitions, in-licensing transactions, or co-development and marketing arrangements).

During the six months ended June 30, 2020, we continued our strategic shift in our business following the completion of the sale of our legacy commercialized drug portfolio in March 2019. We also continued to make meaningful progress in the advancement of our product pipeline, as summarized below:

ROLONTIS, a novel long-acting G-CSF

ROLONTIS (eflapegrastim injection) is a novel long-acting G-CSF that employs a proprietary technology to enhance the duration of therapeutic effects and reduces the frequency of administration. ROLONTIS is being investigated for the treatment of chemotherapy-induced neutropenia. In January 2012, we entered into a co-development and commercialization agreement for ROLONTIS worldwide, except for Korea, China and Japan, with Hanmi, based on their proprietary LAPSCOVERY^™ technology.

Neutropenia, a common side effect of chemotherapy, is a condition where the number of neutrophils or white blood cells are too low, and can lead to infection, hospitalization and even death. G-CSF stimulates the production of white blood cells by the bone marrow. A recombinant form of G-CSF is used in appropriate cancer patients to accelerate recovery from neutropenia after chemotherapy, allowing higher-intensity treatment regimens to be given at full-dose and on schedule. The worldwide annual market opportunity for long-acting G-CSF-related drugs is over $3 billion, based on a 2019 revenue and sales analysis performed by Evaluate Pharma.

S-3

In October 2019, integrated results from our pivotal Phase 3 studies (ADVANCE Study, or SPI-GCF-301, and RECOVER Study, or SPI-GCF-302) were presented during a poster session at the 2019 Meeting of the American Society of Clinical Oncology (ASCO) Symposium in San Francisco. The integrated efficacy and safety data from both trials were consistent with results from the individual trials, demonstrating that ROLONTIS was non-inferior to pegfilgrastim in the reduction of duration of severe neutropenia in all four cycles of treatment. The integrated data also demonstrated that eflapegrastim provided an absolute risk reduction of severe neutropenia of 6.5% compared to pegfilgrastim in Cycle 1.

We submitted our updated Biologics License Application (“BLA”) for ROLONTIS with the FDA on October 24, 2019, which was accepted for review by the FDA on December 20, 2019. Our BLA is supported by data from two identically designed Phase 3 clinical trials, ADVANCE and RECOVER, which evaluated the safety and efficacy of ROLONTIS in 643 early-stage breast cancer patients for the treatment of neutropenia due to myelosuppressive chemotherapy. The FDA is actively reviewing the BLA for ROLONTIS with a PDUFA target action date set for October 24, 2020.

A company sponsored study has been initiated to evaluate the administration of ROLONTIS on the same day as chemotherapy. The first patient was dosed in April 2020. The trial will evaluate the duration of severe neutropenia when administered at three different time points on the same day following standard chemotherapy in patients with early stage breast cancer.

Poziotinib, an irreversible tyrosine kinase inhibitor

Poziotinib is a novel, pan-HER inhibitor that irreversibly blocks signaling through the Epidermal Growth Factor Receptor (“EGFR”) family of tyrosine-kinase receptors, including HER1 (erbB1; EGFR), HER2 (erbB2), HER4 (erbB4) and HER receptor mutations. This, in turn, leads to the inhibition of the proliferation of tumor cells that over-express these receptors. Mutations or over-expression/amplification of EGFR family receptors have been associated with a number of different cancers, including NSCLC, breast cancer and gastric cancer.

Our clinical development program for poziotinib is focused on previously treated NSCLC, first-line treatment of NSCLC and treatment of other solid tumors with EGFR or HER2 mutations. NSCLC tumors with EGFR or HER2 exon 20 insertion mutations are rare and have generally not been responsive to other tyrosine kinase inhibitors. Patients with these mutations have a poor prognosis, and available treatment options are limited. Poziotinib, due to its unique chemical structure and characteristics, is believed to inhibit cell growth of tumors with EGFR or HER2 exon 20 insertion mutations.

In collaboration with The University of Texas MD Anderson Cancer Center, an investigator-sponsored Phase 2 trial was initiated in NSCLC patients with EGFR or HER2 exon 20 mutations (the “MD Anderson Phase 2 Trial”) in March 2017. In September 2018, we announced preliminary poziotinib data from the MD Anderson Phase 2 Trial, which were released during an oral presentation at the IASLC 19th World Conference on Lung Cancer. This Phase 2 trial demonstrated anti-tumor activity for poziotinib in metastatic, heavily pretreated EGFR exon 20 mutant NSCLC. This data is summarized below:

∎ In 44 evaluable patients with EGFR exon 20 mutations, the confirmed overall response rate was 43% and disease control rate was 90%. Median progression free survival was 5.5 months.

∎ In evaluable patients with HER2 exon 20 mutations, the confirmed overall response rate was 42% and disease control rate was 83%. Median progression free survival was 5.1 months.

∎ EGFR-related toxicities (including rash, diarrhea and paronychia) were manageable and required dose reductions in 60% of patients. Discontinuation due to poor tolerance was rare (approximately 3% of patients).

In October 2017, we announced the start of a pivotal Phase 2 global study with active sites in the U.S., Canada and Europe (“ZENITH20”). The ZENITH20 study consists of seven cohorts of NSCLC patients. Cohorts 1 (EGFR) and 2 (HER2) have completed enrollment of previously treated NSCLC patients with exon 20 mutations. Cohort 3 (EGFR) recently completed enrollment and Cohort 4 (HER2) is currently enrolling first-line

S-4

NSCLC patients with exon 20 mutations. Cohorts 1- 4 are each independently powered for a pre-specified statistical hypothesis and the primary endpoint is objective response rate (“ORR”). Cohort 5 includes previously treated or treatment-naïve NSCLC patients with EGFR or HER2 exon 20 insertion mutations. Cohort 6 includes NSCLC patients with classical EGFR mutations who progressed while on treatment with first-line osimertinib and developed an additional EGFR mutation. Cohort 7 includes NSCLC patients with a variety of less common mutations in EGFR or HER2 exons 18-21 or the extracellular or transmembrane domains.

On December 26, 2019, we announced that the pre-specified primary endpoint in our Phase 2 clinical trial evaluating poziotinib in previously treated NSCLC patients with EGFR exon 20 insertion mutations was not met in Cohort 1 of the ZENITH20 trial. Cohort 1 enrolled a total of 115 patients who received 16 mg/day of poziotinib. The intent-to-treat analysis showed that 17 patients had a response (by RECIST) and 62 patients had stable disease for a 68.7% disease control rate (“DCR”). The confirmed ORR was 14.8% (95% Confidence Interval (“CI”) 8.9%-22.6%). Based on the FDA reviewed protocol, an observed ORR of 30%, with 17% as the lower bound for 95% CI was considered to be the clinically meaningful efficacy in our study. The median duration of response was 7.4 months and progression free survival was 4.2 months. The safety profile was in-line with the type of adverse events seen with other second-generation EGFR tyrosine kinase inhibitors.

We presented additional results for Cohort 1 from our Phase 2 clinical trial, ZENITH20, evaluating poziotinib in previously treated NSCLC patients with EGFR exon 20 insertion mutations, at a plenary session of the virtual American Association for Cancer Research (AACR) annual meeting on April 27, 2020. The podium presentation included additional safety and efficacy data. We also provided an update on our strategy for the ZENITH20 Phase 2 clinical trial evaluating poziotinib in NSCLC patients with EGFR and HER2 exon 20 insertion mutations. The protocol has been amended to explore additional dosing regimens and the earlier use of corticosteroids in an effort to increase drug compliance.

On July 27, 2020, we announced that we met the pre-specified primary endpoint in the ZENITH20 Phase 2 clinical trial evaluating poziotinib in Cohort 2.

Cohort 2 of the ZENITH20 clinical trial enrolled a total of 90 patients who received an oral, once daily dose of 16 mg of poziotinib. All the patients had failed at least one line of prior systemic therapy with 60 patients (67%) having failed two or more prior therapies, including chemotherapy and immunotherapy. All responses were read independently and confirmed by a central imaging laboratory using RECIST criteria. The intent-to-treat analysis demonstrated a confirmed ORR of 27.8% (95% CI 18.9%-38.2%). Based on the pre-specified statistical hypothesis for the primary endpoint, the observed lower bound of 18.9% exceeded the pre-specified lower bound of 17% in this heavily pre-treated population.

The median duration of response was 5.1 months (range 1 to >12.3), with a median follow up of 8.3 months. The DCR was 70% and the median progression free survival was 5.5 months. The safety profile was in-line with the type of adverse events seen with other second-generation EGFR tyrosine kinase inhibitors and similar to Cohort 1. Grade 3 treatment related rash was 30% and diarrhea was 26%. In Cohort 2, no pneumonitis was reported (0/90).

Cohort 2 was designed to be a registrational study. We are in the process of requesting a meeting with the FDA to discuss the data and our plans for a New Drug Application (NDA) submission. We plan to present additional study results for Cohort 2 at an upcoming medical meeting.

We expect to announce topline results for Cohort 3 in the second half of 2020.

Anti-CD20-IFNa

On April 15, 2019, we executed a license agreement with ImmunGene, Inc. for an antibody-interferon fusion molecule directed against CD20 (“Anti-CD20-IFNa”) and it is in Phase 1 development for treating relapsed or refractory NHL, including diffuse large B-cell lymphoma patients (representing a considerable unmet medical need). Under the terms of this agreement, we received the exclusive rights to commercialize this drug for any indication, and are financially responsible for the clinical and regulatory development programs.

S-5

You can find more information about us in our filings with the SEC referenced in the sections in this document titled “Where You Can Find More Information” and “Incorporation of Certain Documents by Reference.”

Update on Shareholder Litigation

Olutayo Ayeni v. Spectrum Pharmaceuticals, Inc., et al. (Filed September 21, 2016 in the United States District Court, Central District of California; Case No. 2:16-cv-07074) (the “Ayeni Action”) and Glen Hartsock v. Spectrum Pharmaceuticals, Inc., et al. (Filed September 28, 2016 in the United States District Court, District Court of Nevada Case; No. 2:16-cv-02279-RFB-GWF) (the “Hartsock Action”). As previously disclosed, we entered into a memorandum of understanding with these plaintiffs for a class action settlement on July 23, 2019. Plaintiffs filed an unopposed motion for preliminary approval of the class action settlement on December 27, 2019, which was granted on February 19, 2020. Following notice of the settlement to the class, the Court granted final approval of the class action settlement on July 28, 2020.

Corporate Information

Spectrum Pharmaceuticals, Inc. is a Delaware corporation that was originally incorporated in Colorado as Americus Funding Corporation in December 1987, became NeoTherapeutics, Inc. in August 1996, was reincorporated in Delaware in June 1997, and was renamed Spectrum Pharmaceuticals, Inc. in December 2002. More comprehensive information about our products and us is available through our website at www.sppirx.com. The information on our website is not incorporated by reference into this prospectus. Our principal executive offices are located at 11500 South Eastern Avenue, Suite 240, Henderson, Nevada 89052, and our telephone number is (702) 835-6300.

S-6

THE OFFERING

Common stock offered by us              shares.

Common stock to be outstanding after this offering              shares (or              shares if the underwriters exercise their option to purchase additional shares in full).

Option to purchase additional shares We have granted the underwriters an option for a period of 30 days from the date of this prospectus supplement to purchase up to              additional shares of common stock.

Use of proceeds We intend to use the net proceeds from this offering for general corporate purposes, including, without limitation, the continued development of our pipeline assets, sales and marketing activities, pre-launch activities associated with ROLONTIS and potential business development initiatives. See “Use of Proceeds” beginning on page S-18 of this prospectus supplement.

Risk factors Your investment in our common stock involves substantial risks. You should read carefully the “Risk Factors” beginning on page S-8 of this prospectus supplement, on page 4 of the accompanying prospectus and in the documents incorporated by reference into this prospectus supplement for a discussion of factors you should consider carefully before deciding to invest in our common stock.

Nasdaq Global Select Market symbol “SPPI”

The number of shares of our common stock to be outstanding immediately after the closing of this offering is based on 114,774,079 shares of common stock outstanding as of March 31, 2020 and excludes, as of that date:

∎ 7,987,421 shares of our common stock issuable upon the exercise of options outstanding, having a weighted average exercise price of $8.11 per share;

∎ 512,585 shares of common stock issuable upon the vesting and settlement of outstanding restricted stock units, having a weighted average grant date fair value of $25.21 per share; and

∎ an aggregate of 11,335,783 shares of our common stock reserved for future issuance under our 2018 Long-Term Incentive Plan and 2009 Employee Stock Purchase Plan.

In addition, we have sold 3,950,398 shares of common stock, for gross proceeds of approximately $15.2 million, pursuant to the ATM Offering since it commenced on May 8, 2020.

Unless otherwise indicated, all information in this prospectus supplement assumes:

∎ no exercise of the outstanding options or settlement of the restricted stock units described above; and

∎ no exercise by the underwriters of their option to purchase up to              additional shares of our common stock.

S-7

RISK FACTORS

Investment in our securities involves risks. Prior to making a decision about investing in our securities, you should consider carefully all of the information included and incorporated by reference or deemed to be incorporated by reference into this prospectus supplement, including the risk factors incorporated by reference herein from our Annual Report on Form 10-K for the year ended December 31, 2019, filed with the SEC on March 2, 2020, as updated by annual, quarterly and other reports and documents we file with the SEC after the date of this prospectus supplement and that are incorporated by reference herein or in any free writing prospectus. Each of these risk factors could have a material adverse effect on our business, results of operations, financial position or cash flows, which may result in the loss of all or part of your investment. The risks and uncertainties we have described are not the only ones we face. Additional risks and uncertainties not presently known to us or that we currently consider immaterial may also impair our business operations. If any of these risks actually occur, our business and financial results could be harmed. In that case, the trading price of our common stock or other securities could decline. Please also read carefully the section below titled “Cautionary Note Regarding Forward-Looking Statements.”

Risks Related to This Offering

We may allocate the net proceeds from this offering in ways that you and other stockholders may not approve.

We expect to use the net proceeds from this offering for general corporate purposes, including, without limitation, the continued development of our pipeline assets, sales and marketing activities, pre-launch activities associated with ROLONTIS and potential business development initiatives. In general, our management will have broad discretion in the application of the net proceeds from this offering and could spend the net proceeds in ways that do not necessarily improve our operating results or enhance the value of our common stock.

You will incur immediate and substantial dilution in the net tangible book value of the shares you purchase in this offering.

The price at which we are offering shares of our common stock in this offering is higher than the net tangible book value per share of outstanding common stock prior to completion of the offering. Based on our net tangible book value as of March 31, 2020 and upon the issuance and sale of                      shares of common stock by us (which assumes the underwriters do not exercise their option to purchase additional shares), you will suffer immediate dilution of approximately $                     per share in net tangible book value. Dilution is the amount by which the offering price paid by purchasers of our common stock in this offering will exceed the as adjusted net tangible book value per share of our common stock upon completion of this offering. If the underwriters exercise their option to purchase additional shares, or if outstanding options to purchase our common stock are exercised, you will experience additional dilution. You may experience additional dilution upon future equity issuances or the exercise of stock options to purchase common stock granted to our employees, executive officers and directors under our equity incentive plan or our employee stock purchase plan. See “Dilution.”

Your percentage of ownership in us may be diluted in the future.

As with any publicly traded company, your percentage ownership in us may be diluted in the future because of equity issuances for acquisitions, capital market transactions or otherwise, including equity awards that we expect will be granted to our directors, officers and employees.

We believe that the future growth of our business will depend on our ability to successfully develop and acquire new drugs for the treatment of cancer and successfully bring these drugs to market. As of March 31, 2020, we had $177.8 million in aggregate cash and equivalents and marketable securities. We will require additional liquidity as we continue to execute our business strategy, and in connection with opportunistic acquisitions or licensing arrangements. We anticipate that to the extent that we require additional liquidity, it will be funded through additional equity or debt financings, including this offering.

We do not expect to pay any cash dividends for the foreseeable future.

We currently intend to retain any future earnings, if any, for use in the expansion of our business and do not anticipate paying any dividends in the foreseeable future. However, the payment of dividends, if any, will be at the discretion of the board of directors and subject to compliance at such time with any applicable restrictions contained in our various agreements and applicable law. Accordingly, if you purchase shares in this offering, realization of a

S-8

gain on your investment will depend on the appreciation of the price of our common stock, which may never occur. Investors seeking cash dividends in the foreseeable future should not purchase our common stock.

Sales of substantial amounts of our common stock in the public markets, or the perception that such sales might occur, could cause the market price of our common stock to drop significantly, even if our business is doing well.

Sales of a substantial number of shares of our common stock in the public market could occur at any time. If our stockholders sell, or the market perceives that our stockholders intend to sell, substantial amounts of our common stock in the public market following this offering, the market price of our common stock could decline significantly.

Substantially all of our outstanding common stock is eligible for immediate resale in the public market. In connection with this offering, we and all of our directors and executive officers, have agreed not to sell, dispose of or hedge any common stock or securities convertible into or exchangeable for shares of common stock during the period from the date of this prospectus supplement continuing through and including the date 90  days after the date of this prospectus supplement, subject to certain exceptions as described in further detail under the section of this prospectus supplement titled “Underwriting.”

The market price and trading volume of our common stock fluctuate significantly and could result in substantial losses for individual investors.

The stock market from time to time experiences significant price and trading volume fluctuations that are unrelated to the operating performance of particular companies. These broad market fluctuations may cause the market price and trading volume of our common stock to decrease. In addition, the market price and trading volume of our common stock is often highly volatile, and you may not be able to resell your shares at or above the price at which you purchased your shares.

Factors that may cause the market price and volume of our common stock to decrease include, among other things:

∎ the impact of the novel coronavirus (“COVID-19”) on the U.S. and global economies;

∎ adverse results or delays in our clinical trials, including as a result of COVID-19;

∎ fluctuations in our results of operations;

∎ timing and announcements of our technological innovations or new products or those of our competitors;

∎ developments concerning any strategic alliances or acquisitions we may enter into;

∎ announcements of FDA non-approval of our products, or delays in the FDA or other foreign regulatory review processes or actions;

∎ changes in recommendations or guidelines of government agencies or other third parties regarding the use of our products;

∎ adverse actions taken by regulatory agencies with respect to our drug products, clinical trials, manufacturing processes or sales and marketing activities;

∎ concerns about our in-development products being reimbursed at requisite levels in the future;

∎ any lawsuit involving us or our products;

∎ developments with respect to our patents and proprietary rights;

∎ public concern as to the safety of products developed by us or others;

∎ regulatory developments in the U.S. and in foreign countries;

∎ changes in stock market analyst recommendations regarding our common stock or lack of analyst coverage;

∎ failure of our results of operations to meet the expectations of stock market analysts and investors;

∎ sales of our common stock by our executive officers, directors and significant stockholders or sales of substantial amounts of our common stock generally; and

∎ loss of any of our key scientific or management personnel.

Also, certain dilutive securities such as warrants can be used as hedging tools which may increase volatility in our stock and cause a price decline. While a decrease in market price could result in direct economic loss for an individual investor, low trading volume could limit an individual investor’s ability to sell our common stock, which could result in substantial economic loss as well. From January 1, 2020 through July 28, 2020, the closing price of our common stock ranged between $1.83 and $3.69, and the daily trading volume was as high as 31,122,530 shares and as low as 507,507 shares.

S-9

Following periods of volatility in the market price of a company’s securities, a securities class action litigation may be instituted against that company. Regardless of their merit, these types of lawsuits generally result in substantial legal fees and management’s attention and resources being diverted from the operations of a business.

The COVID-19 outbreak could adversely impact our business.

In December 2019, it was first reported that there had been an outbreak of COVID-19 in China. Since then, COVID-19 has continued to spread outside of China, including throughout the United States and other parts of the world, becoming a global pandemic. The COVID-19 pandemic has impacted our business and will likely continue to impact our business directly and/or indirectly for the foreseeable future. We are unable to accurately predict the full impact that the COVID-19 pandemic will have on our results from operations, financial condition and clinical studies due to numerous factors that are not within our control, including the duration and severity of the outbreak.

Governments in affected regions have implemented and may continue to implement safety precautions, including stay-at-home orders, travel restrictions, business closures, cancellations of public gatherings and other measures. These measures are disrupting normal business operations both in and outside of affected areas. We continue to monitor our operations and government recommendations and have made appropriate modifications to our operations because of COVID-19, including transitioning to a remote work environment and substantial modifications to employee travel. We are also unable to make site visits at this time due to social distancing guidelines. Over time, these factors could reduce our overall productivity and collaboration. In addition, we have recently seen a lower enrollment rate, with great variability by geographic location, in our on-going trials, which could result in a delay in enrollment in such trials. We anticipate the potential for delays in the initiation and enrollment of planned clinical trials until the pandemic resolves.

Despite travel restrictions and the remote work environment, the ROLONTIS BLA remains under active review by the FDA. The PDUFA target action date for the ROLONTIS BLA is October 24, 2020. In advance of the PDUFA date, the FDA will need to complete a pre-approval inspection of our third-party manufacturing facility in South Korea. To the extent that travel restrictions persist into the fall, the FDA may not be able to complete the pre-approval inspection prior to the scheduled PDUFA date, which could result in a delay in obtaining FDA approval for ROLONTIS, which could adversely impact our results of operations and financial projections.

As the COVID-19 pandemic continues to evolve, we may experience these and other disruptions that could severely impact our business and regulatory filings, including, but not limited to:

∎ disruption in our ability to manufacture our Active Pharmaceutical Ingredient (“API”) and future drug products;

∎ disruption in our ability to source materials;

∎ delays or difficulties in obtaining FDA approval for ROLONTIS and completing other regulatory work;

∎ fewer individuals undertaking or completing cancer treatments, whether due to contracting COVID-19, self-isolating or quarantining to lower the risk of contracting COVID-19 or being unable to access care as a result of healthcare providers tending to COVID-19 patients;

∎ impact to the financial markets which could impact our ability to raise capital;

∎ limitations on our employees’ ability to work, due to potential sickness of employees or their families;

∎ disruption in our ability to sell our future commercialized products including in foreign markets; and

∎ additional repercussions on our ability to operate our business.

While the long-term economic impact and the duration of the COVID-19 pandemic may be difficult to assess or predict, the widespread pandemic has resulted in, and may continue to result in, significant disruption of global financial markets, which could reduce our ability to access capital and could negatively affect our liquidity and the liquidity and stability of markets for our common stock. In addition, a recession, further market correction or depression resulting from the spread of COVID-19 could materially affect our business and the value our common stock.

S-10

Risks Relating to Our Intellectual Property

From time to time we may need to in-license patents and proprietary technologies from third parties, which may be difficult or expensive to obtain.

We may need to obtain licenses to patents and other proprietary rights held by third parties to successfully develop, manufacture and market our drug products. As an example, it may be necessary to use a third party’s proprietary technology to reformulate one of our drug products in order to improve upon the capabilities of the drug product. If we are unable to timely obtain these licenses on reasonable terms, or at all, our ability to commercially exploit our drug products may be inhibited or prevented.

If we are unable to adequately protect our technology or enforce our patent rights, our business could suffer.

Our success with the drug products that we develop will depend, in part, on our ability and the ability of our licensors to obtain and maintain patent protection for these products. We currently have a number of U.S. and foreign patents issued and pending, however, we primarily rely on patent rights licensed from others. Our license agreements generally give us the right and/or obligation to maintain and enforce the subject patents. We may not receive patents for any of our pending patent applications or any patent applications we may file in the future. If our pending and future patent applications are not allowed or, if allowed and issued into patents, if such patents and the patents we have licensed are not upheld in a court of law, our ability to competitively exploit our drug products would be substantially harmed. Also, such patents may or may not provide competitive advantages for their respective products or they may be challenged or circumvented by our competitors, in which case our ability to commercially exploit these products may be diminished.

The patent positions of pharmaceutical and biotechnology companies can be highly uncertain and involve complex legal and factual questions. No consistent policy regarding the breadth of claims allowed in pharmaceutical and biotechnology patents has emerged to date in the U.S. The laws of many countries may not protect intellectual property rights to the same extent as U.S. laws, and those countries may lack adequate rules and procedures for defending our intellectual property rights. Filing, prosecuting and defending patents on all our products or product candidates throughout the world would be prohibitively expensive. Competitors may use our technologies in jurisdictions not covered by any of our patent claims or other intellectual property rights.

Changes in either patent laws or in interpretations of patent laws in the U.S. and other countries may diminish the value of our intellectual property. We do not know whether any of our patent applications will result in the issuance of any patents, and we cannot predict the breadth of claims that may be allowed in our patent applications or in the patent applications we license from others.

Intellectual property rights do not necessarily address all potential threats.

The degree of future protection for our proprietary rights is uncertain because legal means afford only limited protection and may not adequately protect our rights or permit us to gain or keep our competitive advantage. For example:

∎ in certain jurisdictions, we or our licensors might not have been the first to make the inventions covered by each of our or our licensors’ pending patent applications and issued patents, and we may have to participate in expensive and protracted interference proceedings to determine priority of invention;

∎ we or our licensors might not have been the first to file patent applications for these inventions;

∎ others may independently develop similar or alternative product candidates or duplicate any of our or our licensors’ product candidates;

∎ our or our licensors’ pending patent applications may not result in issued patents;

∎ our or our licensors’ issued patents may not provide a basis for commercially viable products or may not provide us with any competitive advantages or may be challenged by third parties;

∎ others may design around our or our licensors’ patent claims to produce competitive products that fall outside the scope of our or our licensors’ patents;

∎ we may not develop or in-license additional patentable proprietary technologies related to our product candidates; or

∎ the patents of others may prevent us from marketing one or more of our product candidates for one or more indications that may be valuable to our business strategy.

S-11

An issued patent does not guarantee us the right to practice the patented technology or commercialize the patented product. Third parties may have blocking patents that could be used to prevent us from commercializing our patented products and practicing our patented technology. Patents issued to us and our licensors and those that may be issued in the future to us and our licensors may be challenged, invalidated or circumvented, which could limit our ability to prevent competitors from marketing related product candidates or could limit the length of the term of patent protection of our product candidates. Our competitors may independently develop similar technologies. In addition, because of the extensive time required for development, testing and regulatory review of a potential product, it is possible that, before any of our product candidates can be commercialized, any related patent may expire or remain in force for only a short period following commercialization, thereby reducing any advantage of the patent.

If we fail to comply with our obligations in the agreements under which we license intellectual property rights from third parties or otherwise experience disruptions to our business relationships with our licensors, we could lose intellectual property rights that are important to our business.

We are a party to exclusive license agreements with our partners and may need to obtain additional licenses from others to advance our research and development activities or allow the commercialization of our current product candidates and future product candidates we may identify and pursue. Our license agreements may impose, and we expect that future license agreements could impose various requirements on us, such as obligations related to development, diligence and commercialization, among others. In spite of our efforts, our licensors might conclude that we have materially breached our obligations under such license agreements and might therefore terminate the license agreements, thereby removing or limiting our ability to develop and commercialize products and technology covered by these license agreements. If these in-licenses are terminated, or if the underlying patents fail to provide the intended exclusivity, competitors or other third parties would have the freedom to seek regulatory approval of, and to market, products identical to ours and we may be required to cease our development and commercialization of our current product candidates or other product candidates that we may identify. Any of the foregoing could have a material adverse effect on our competitive position, business, financial conditions, results of operations, and prospects.

Moreover, disputes may arise regarding intellectual property subject to a licensing agreement, including:

∎ the scope of rights granted under the license agreement and other interpretation-related issues;

∎ the extent to which our product candidates, technology and processes infringe on intellectual property of the licensor that is not subject to the licensing agreement;

∎ the sublicensing of patent and other rights under our collaborative development relationships;

∎ our diligence obligations under the license agreement and what activities satisfy those diligence obligations;

∎ the inventorship and ownership of inventions and know-how resulting from the joint creation or use of intellectual property by our licensors and us and our partners; and

∎ the priority of invention of patented technology.

In addition, the agreements under which we currently license intellectual property or technology from third parties are complex, and certain provisions in such agreements may be susceptible to multiple interpretations. The resolution of any contract interpretation disagreement that may arise could narrow what we believe to be the scope of our rights to the relevant intellectual property or technology, or increase what we believe to be our financial or other obligations under the relevant agreement, either of which could have a material adverse effect on our business, financial condition, results of operations, and prospects. Moreover, if disputes over intellectual property that we have licensed prevent or impair our ability to maintain our current licensing arrangements on commercially acceptable terms, we may be unable to successfully develop and commercialize the affected product candidates, which could have a material adverse effect on our business, financial conditions, results of operations, and prospects.

If we are unable to protect the confidentiality of our trade secrets, the value of our technology could be materially adversely affected and our business would be harmed.

We also rely on trade secret protection and contractual protections for our unpatented and proprietary drug compounds. Trade secrets are difficult to protect. While we enter into confidentiality agreements with our employees, consultants and others, these agreements may not successfully protect our trade secrets or other confidential and proprietary information. It is possible that these agreements will be breached, or that they will not be enforceable in every instance, and that we will not have adequate remedies for any such breach. Likewise,

S-12

although we conduct periodic trade secret audits of certain partners, vendors and contract manufacturers, these trade secret audits may not protect our trade secrets or other confidential and proprietary information. It is possible that despite having certain trade secret audit security measures in place, trade secrets or other confidential and proprietary information may still be leaked or disclosed to a third party. It is also possible that our trade secrets will become known or independently developed by our competitors.

We also rely on trademarks to protect the names of our products. These trademarks may be challenged by others. If we enforce our trademarks against third parties, such enforcement proceedings may be expensive. Some of our trademarks are owned by, or assignable to, our licensors and, upon expiration or termination of the applicable license agreements, we may no longer be able to use these trademarks. If we are unable to adequately protect our technology, trade secrets or proprietary know-how, or enforce our patents and trademarks, our business, financial condition and prospects could suffer.

We may not be able to protect our intellectual property rights throughout the world.

Filing, prosecuting and defending patents on our product candidates in all countries throughout the world would be prohibitively expensive, and our intellectual property rights in some countries outside the United States can be less extensive than those in the United States.

In addition, the laws of some foreign countries do not protect intellectual property rights to the same extent as federal and state laws in the United States. Consequently, we may not be able to prevent third parties from practicing our inventions in all countries outside the United States, or from selling or importing products made using our inventions in and into the United States or other jurisdictions. Competitors may use our technologies in jurisdictions where we have not obtained patent protection to develop their own products and may also export infringing products to territories where we have patent protection, but enforcement is not as strong as that in the United States. These products may compete with our products and our patents or other intellectual property rights may not be effective or sufficient to prevent them from competing.

Many companies have encountered significant problems in protecting and defending intellectual property rights in foreign jurisdictions. The legal systems of certain countries, particularly certain developing countries, do not favor the enforcement of patents, trade secrets, and other intellectual property protection, particularly those relating to biotechnology products, which could make it difficult for us to stop the infringement of our patents or marketing of competing products in violation of our proprietary rights generally. Proceedings to enforce our patent rights in foreign jurisdictions, whether or not successful, could result in substantial costs and divert our efforts and attention from other aspects of our business, could put our patents at risk of being invalidated or interpreted narrowly and our patent applications at risk of not issuing and could provoke third parties to assert claims against us. We may not prevail in any lawsuits that we initiate and the damages or other remedies awarded, if any, may not be commercially meaningful. Accordingly, our efforts to enforce our intellectual property rights around the world may be inadequate to obtain a significant commercial advantage from the intellectual property that we develop or license.

Patent terms may be inadequate to protect our competitive position on our product candidates for an adequate amount of time.

Patents have a limited lifespan. In the United States, if all maintenance fees are timely paid, the natural expiration of a patent is generally 20 years from its earliest U.S. non-provisional filing date. Various extensions may be available, but the life of a patent, and the protection it affords, is limited. Even if patents covering our product candidates are obtained, once the patent life has expired, we may be open to competition from competitive products, including generics or biosimilars. Given the amount of time required for the development, testing and regulatory review of new product candidates, patents protecting such candidates might expire before or shortly after such candidates are commercialized. As a result, our owned and licensed patent portfolio may not provide us with sufficient rights to exclude others from commercializing products similar or identical to ours.

Changes in U.S. patent law could diminish the value of patents in general, thereby impairing our ability to protect our products.

Changes in either the patent laws or interpretation of the patent laws in the United States could increase the uncertainties and costs surrounding the prosecution of patent applications and the enforcement or defense of issued patents. Assuming that other requirements for patentability are met, prior to March 2013, in the United States, the first to invent the claimed invention was entitled to the patent, while outside the United States, the first to file a patent application was entitled to the patent. After March 2013, under the Leahy-Smith America Invents Act, or the

S-13

America Invents Act, enacted in September 2011, the United States transitioned to a first inventor to file system in which, assuming that other requirements for patentability are met, the first inventor to file a patent application will be entitled to the patent on an invention regardless of whether a third party was the first to invent the claimed invention. A third party that files a patent application in the USPTO after March 2013, but before us could therefore be awarded a patent covering an invention of ours even if we had made the invention before it was made by such third party. This will require us to be cognizant of the time from invention to filing of a patent application. Since patent applications in the United States and most other countries are confidential for a period of time after filing or until issuance, we cannot be certain that we or our licensors were the first to either (i) file any patent application related to our product candidates or (ii) invent any of the inventions claimed in our or our licensor’s patents or patent applications.

The America Invents Act also includes a number of significant changes that affect the way patent applications will be prosecuted and also may affect patent litigation. These include allowing third party submission of prior art to the USPTO during patent prosecution and additional procedures to attack the validity of a patent by USPTO administered post-grant proceedings, including post-grant review, inter partes review, and derivation proceedings. Because of a lower evidentiary standard in USPTO proceedings compared to the evidentiary standard in United States federal courts necessary to invalidate a patent claim, a third party could potentially provide evidence in a USPTO proceeding sufficient for the USPTO to hold a claim invalid even though the same evidence would be insufficient to invalidate the claim if first presented in a district court action. Accordingly, a third party may attempt to use the USPTO procedures to invalidate our patent claims that would not have been invalidated if first challenged by the third party as a defendant in a district court action. Therefore, the America Invents Act and its implementation could increase the uncertainties and costs surrounding the prosecution of our owned or in-licensed patent applications and the enforcement or defense of our owned or in-licensed issued patents, all of which could have a material adverse effect on our business, financial condition, results of operations, and prospects.

In addition, the patent positions of companies in the development and commercialization of pharmaceuticals are particularly uncertain. Recent U.S. Supreme Court rulings have narrowed the scope of patent protection available in certain circumstances and weakened the rights of patent owners in certain situations. This combination of events has created uncertainty with respect to the validity and enforceability of patents, once obtained. Depending on future actions by the U.S. Congress, the federal courts, and the USPTO, the laws and regulations governing patents could change in unpredictable ways that could have a material adverse effect on our existing patent portfolio and our ability to protect and enforce our intellectual property in the future.

Obtaining and maintaining our patent protection depends on compliance with various procedural, document submission, fee payment and other requirements imposed by governmental patent agencies, and our patent protection could be reduced or eliminated for non-compliance with these requirements.

Periodic maintenance fees, renewal fees, annuity fees and various other governmental fees on patents and/or applications will be due to be paid to the USPTO and various governmental patent agencies outside of the United States in several stages over the lifetime of the patents and/or applications. We have systems in place to remind us when the fees are due, and we employ an outside firm to automatically pay these fees to both US and non-U.S agencies and we rely on our outside counsel to verify and confirm payment of these fees. The USPTO and various non-U.S. governmental patent agencies require compliance with a number of procedural, documentary, fee payment, and other similar provisions during the patent application process. We employ reputable law firms and other professionals to help us comply, and in many cases, an inadvertent lapse can be cured by payment of a late fee or by other means in accordance with the applicable rules. However, there are situations in which non-compliance can result in abandonment or lapse of the patent or patent application, resulting in partial or complete loss of patent rights in the relevant jurisdiction. In such an event, our competitors might be able to enter the market and this circumstance would have a material adverse effect on our business.

Intellectual property rights are complex and uncertain and therefore may subject us to infringement claims.

The patent positions related to our drug products are inherently uncertain and involve complex legal and factual issues. We believe that there is significant litigation in the pharmaceutical and biotechnology industry regarding patent and other intellectual property rights. A patent does not provide the patent holder with freedom to operate in a way that infringes the patent rights of others. We may be accused of patent infringement at any time. The coverage of patents is subject to interpretation by the courts, and the interpretation is not always uniform. If we are sued for patent infringement, we would need to demonstrate that our products or methods do not infringe the patent claims

S-14

of the relevant patent and/or that the patent claims are invalid or unenforceable, and we may not be able to do this. Proving invalidity, in particular, is difficult since it requires a showing of clear and convincing evidence to overcome the presumption of validity enjoyed by issued patents in the U.S.

Although we are not aware of any infringement by any of our drug products of any valid patent rights of any third party, there may be third party patents or other intellectual property rights, including trademarks and copyrights, relevant to our drug products of which we are not aware. Third parties may assert patent or other intellectual property infringement claims against us, or our licensors and collaborators, with products. Any claims that might be brought against us relating to infringement of patents may cause us to incur significant expenses and, if successfully asserted against us, may cause us to pay substantial damages and result in the loss of our use of the intellectual property that is critical to our business strategy.

In the event that we or our partners are found to infringe any valid claim of a patent held by a third party, we may, among other things, be required to:

∎ pay damages, including up to treble damages and the other party’s attorneys’ fees, which may be substantial;

∎ cease the development, manufacture, use and sale of our products that infringe the patent rights of others through a court-imposed sanction such as an injunction;

∎ expend significant resources to redesign our products so they do not infringe others’ patent rights, which may not be possible;

∎ discontinue manufacturing or other processes incorporating infringing technology; or

∎ obtain licenses to the infringed intellectual property, which may not be available to us on acceptable terms, or at all.

We may be subject to claims that our employees, consultants or independent contractors have wrongfully used or disclosed confidential information of third parties or that our employees have wrongfully used or disclosed alleged trade secrets of their former employers.

As is common in the biotechnology and pharmaceutical industry, we employ individuals who were previously employed at universities or other biotechnology or pharmaceutical companies, including our competitors or potential competitors. Although we try to ensure that our employees, consultants and independent contractors do not use the proprietary information or know-how of others in their work for us, we may be subject to claims that we or our employees, consultants or independent contractors have inadvertently or otherwise used or disclosed intellectual property, including trade secrets or other proprietary information, of any of our employee’s former employer or other third parties. Litigation may be necessary to defend against these claims. If we fail in defending any such claims, in addition to paying monetary damages, we may lose valuable intellectual property rights or personnel, which could adversely impact our business. Even if we are successful in defending against such claims, litigation could result in substantial costs and be a distraction to management and other employees.

In addition, while we require our employees and contractors who may be involved in the conception or development of intellectual property to execute agreements assigning such intellectual property to us, we may be unsuccessful in executing such an agreement with each party who, in fact, conceives or develops intellectual property that we regard as our own. The assignment of intellectual property rights may not be self-executing or the assignment agreements may be breached, and we may be forced to bring claims against third parties, or defend claims that they may bring against us, to determine the ownership of what we regard as our intellectual property.

We may be involved in additional lawsuits to defend or enforce our patents, which could be expensive, time-consuming and unsuccessful.

Competitors may infringe upon our patents. To counter infringement or unauthorized use, we may be required to file infringement claims, which can be expensive and time-consuming. In addition, in an infringement proceeding, a court may decide that one or more of our patents is not valid or is unenforceable, or may refuse to stop the other party from using the technology at issue on the grounds that our patents do not cover the technology in question. An adverse result in any litigation or defense proceedings could put one or more of our patents at risk of being invalidated, held unenforceable, or interpreted narrowly and could put our patent applications at risk of not issuing. Defense of these claims, regardless of their merit, would involve substantial litigation expense and would be a substantial diversion of employee resources from our business.

S-15

Interference or derivation proceedings provoked by third parties or brought by the USPTO may be necessary to determine the priority of inventions with respect to our patents or patent applications. An unfavorable outcome could require us to cease using the related technology or to attempt to license rights to it from the prevailing party. Our business could be harmed if the prevailing party does not offer us a license on commercially reasonable terms. Litigation or interference proceedings may fail, even if successful, may result in substantial costs and distract our management and other employees. We may not be able to prevent misappropriation of our trade secrets or confidential information, particularly in countries where the laws may not protect those rights as fully as in the U.S. or in Europe.

Furthermore, because of the substantial amount of discovery that could be required in connection with intellectual property litigation, there is a risk that some of our confidential information could be compromised by disclosure during this type of litigation. In addition, there could be public announcements of the results of hearings, motions or other interim proceedings or developments. If securities analysts or investors perceive these results to be negative, it could have a substantial adverse effect on our stock price.

We may be subject to claims challenging the inventorship of our patents and other intellectual property.

We or our licensors may be subject to claims that former employees, collaborators or other third parties have an interest in our owned or in-licensed patents, trade secrets, or other intellectual property as an inventor or co-inventor. For example, we or our licensors may have inventorship disputes arise from conflicting obligations of employees, consultants or others who are involved in developing our product candidates. Litigation may be necessary to defend against these and other claims challenging inventorship or our or our licensors’ ownership of our owned or in-licensed patents, trade secrets or other intellectual property. If we or our licensors fail in defending any such claims, in addition to paying monetary damages, we may lose valuable intellectual property rights, such as exclusive ownership of, or right to use, intellectual property that is important to our product candidates. Even if we are successful in defending against such claims, litigation could result in substantial costs and be a distraction to management and other employees. Any of the foregoing could have a material adverse effect on our business, financial condition, results of operations and prospects.

Some intellectual property that we have in-licensed may have been discovered through government funded programs and thus may be subject to federal regulations such as “march-in” rights, certain reporting requirements and a preference for U.S.-based companies. Compliance with such regulations may limit our exclusive rights, and limit our ability to contract with non-U.S. manufacturers.

Some of the intellectual property rights we have licensed are generated through the use of U.S. government funding and are therefore subject to certain federal regulations. As a result, the U.S. government may have certain rights to intellectual property embodied in our current or future product candidates pursuant to the Bayh-Dole Act of 1980, or Bayh-Dole Act, and implementing regulations. These U.S. government rights in certain inventions developed under a government-funded program include a non-exclusive, non-transferable, irrevocable worldwide license to use inventions for any governmental purpose. In addition, the U.S. government has the right to require us or our licensors to grant exclusive, partially exclusive, or non-exclusive licenses to any of these inventions to a third party if it determines that: (i) adequate steps have not been taken to commercialize the invention; (ii) government action is necessary to meet public health or safety needs; or (iii) government action is necessary to meet requirements for public use under federal regulations (also referred to as “march-in rights”). The U.S. government also has the right to take title to these inventions if we, or the applicable licensor, fail to disclose the invention to the government and fail to file an application to register the intellectual property within specified time limits. These time limits have recently been changed by regulation, and may change in the future. Intellectual property generated under a government funded program is also subject to certain reporting requirements, compliance with which may require us or the applicable licensor to expend substantial resources. In addition, the U.S. government requires that any products embodying the subject invention or produced through the use of the subject invention be manufactured substantially in the United States. The manufacturing preference requirement can be waived if the owner of the intellectual property can show that reasonable but unsuccessful efforts have been made to grant licenses on similar terms to potential licensees that would be likely to manufacture substantially in the United States or that under the circumstances domestic manufacture is not commercially feasible. This preference for U.S. manufacturers may limit our ability to contract with non-U.S. product manufacturers for products covered by such intellectual property. To

the extent any of our current or future intellectual property is generated through the use of U.S. government funding, the provisions of the Bayh-Dole Act may similarly apply.

S-16

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus supplement, the accompanying prospectus and the documents incorporated by reference herein and therein contain certain forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended (the “Securities Act”), and Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), in reliance upon the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Forward-looking statements include, without limitation, statements regarding our future product development and commercialization activities and costs, the revenue potential (licensing, royalty and sales) of our products and product candidates, the impact of the COVID-19 global pandemic on our business, the success, safety and efficacy of our drug products, revenues, development and commercialization timelines, product acquisitions, accounting principles, litigation expenses, liquidity and capital resources and trends and other statements containing forward-looking words, such as, “believes,” “may,” “could,” “will,” “expects,” “intends,” “estimates,” “anticipates,” “plans,” “seeks,” “continues,” or the negative thereof or variation thereon or similar terminology (although not all forward-looking statements contain these words). Such forward-looking statements are based on the reasonable beliefs of our management as well as assumptions made by and information currently available to our management. Readers should not put undue reliance on these forward-looking statements. Forward-looking statements are inherently subject to risks and uncertainties, some of which cannot be predicted or quantified; therefore, our actual results may differ materially from those described in any forward-looking statements.

Factors that might cause these differences include, but are not limited to, those described in our periodic reports filed with the SEC, including our Annual Report on Form 10-K for the fiscal year ended December 31, 2019, as well as those discussed elsewhere in this prospectus supplement, and the following factors:

∎ our ability to successfully develop, obtain regulatory approval and market our products;

∎ the approval, or timing of approval, of our products or new indications for our products by the FDA and other international regulatory agencies;

∎ the overall impact of COVID-19 on our business;

∎ actions by the FDA and other regulatory agencies, including international agencies;

∎ the timing and/or results of pending or future clinical trials, and our reliance on contract research organizations;

∎ our ability to maintain sufficient cash resources to fund our business operations;

∎ our history of net losses;

∎ our ability to enter into strategic alliances with partners for manufacturing, development and commercialization;

∎ our competitors’ progress with their drug development programs, which could adversely impact the perceived or actual value of our in-development drugs;

∎ the ability of our manufacturing partners to meet our product demands and timelines;

∎ our ability to identify and acquire new product candidates and to successfully integrate those product candidates into our operations;

∎ our ability to protect our intellectual property rights;

∎ the impact of legislative or regulatory reform on the pricing for pharmaceutical products;

∎ the impact of any litigation to which we are, or may become a party;

∎ our ability, and that of our suppliers, development partners and manufacturing partners, to comply with laws, regulations and standards that govern or affect the pharmaceutical and biotechnology industries; and

∎ our ability to maintain the services of our key executives and other personnel.

We urge you to consider these factors carefully in evaluating the forward-looking statements contained in this prospectus supplement. All subsequent written or oral forward-looking statements attributable to our company or persons acting on our behalf are expressly qualified in their entirety by these cautionary statements. The forward-looking statements included in this prospectus supplement are made only as of the date of this prospectus supplement. We undertake no obligation to update publicly any forward-looking statements, whether as a result of new information, future events or otherwise, except to the extent that we are required to do so by law.

S-17

USE OF PROCEEDS

We expect the net proceeds from this offering to be approximately $                 million (or $                 million if the underwriters exercise their option to purchase additional shares in full), after deducting underwriting discounts and commissions, as described in “Underwriting,” and estimated offering expenses payable by us.

We intend to use the net proceeds from this offering for general corporate purposes, including, without limitation, the continued development of our pipeline assets, sales and marketing activities, pre-launch activities associated with ROLONTIS and potential business development initiatives. We have not determined the amount of net proceeds to be used specifically for such purposes. As a result, management will retain broad discretion over the allocation of net proceeds.

The amounts and timing of our actual expenditures will depend on numerous factors, including our development and commercialization efforts, as well as the amount of cash used in our operations. We therefore cannot estimate with certainty the amount of net proceeds to be used for the purposes described above. We may find it necessary or advisable to use the net proceeds for other purposes, and we will have broad discretion in the application of the net proceeds. Pending the uses described above, we plan to invest the net proceeds from this offering in short-term, investment-grade, interest-bearing securities.

S-18

DIVIDEND POLICY

We have not paid dividends on our common stock during the two most recent fiscal years. We currently intend to retain all earnings, if any, for use in the expansion of our business and do not anticipate paying any dividends in the foreseeable future. However, the payment of dividends, if any, will be at the discretion of the board of directors and subject to compliance at such time with any applicable restrictions contained in our various agreements and applicable law.

S-19

DILUTION

If you invest in our common stock, your ownership interest will be diluted to the extent of the difference between the public offering price per share and the as-adjusted net tangible book value per share after this offering.

Our net tangible book value as of March 31, 2020 was $150.3 million, or $1.31 per share of common stock. We calculate net tangible book value per share by dividing the net tangible book value, which is tangible assets less total liabilities, by the number of outstanding shares of our common stock. Dilution with respect to net tangible book value per share represents the difference between the amount per share paid by purchasers of shares of common stock in this offering and the net tangible book value per share of our common stock immediately after this offering.

After giving effect to the sale by us of              shares of our common stock (which assumes the underwriters do not exercise their option to purchase additional shares) in this offering at the offering price of $             per share, and after deducting underwriting discounts and commissions, and approximately $             of estimated offering expenses payable by us, our as adjusted net tangible book value as of March 31, 2020 would have been approximately $             million, or $             per share of common stock. This amount represents an immediate increase in net tangible book value of $             per share to existing stockholders and an immediate dilution of $             per share to purchasers in this offering.

The following table illustrates this per share dilution:

Assumed offering price per share			$
Net tangible book value per share as of March 31, 2020	$	1.31
Increase in net tangible book value per share after this offering	$
As-adjusted net tangible book value per share after this offering			$
Dilution per share to new investors in this offering			$

The above discussion and table are based on 114,774,079 shares of our common stock outstanding as of March 31, 2020 and excludes, as of that date:

∎ 7,987,421 shares of our common stock issuable upon the exercise of options outstanding, having a weighted average exercise price of $8.11 per share;

∎ 512,585 shares of common stock issuable upon the vesting and settlement of outstanding restricted stock units, having a weighted average grant date fair value of $25.21 per share; and

∎ an aggregate of 11,335,783 shares of our common stock reserved for future issuance under our 2018 Long-Term Incentive Plan and 2009 Employee Stock Purchase Plan.

In addition, we have sold 3,950,398 shares of common stock, for aggregate gross proceeds of approximately $15.2 million, pursuant to the ATM Offering since it commenced on May 8, 2020.

To the extent that any of these outstanding options are exercised or restricted stock units are settled, there will be further dilution to new investors.

S-20

MATERIAL UNITED STATES FEDERAL INCOME TAX CONSIDERATIONS FOR NON-U.S. HOLDERS

The following is a summary of the material U.S. federal income tax considerations relevant to the purchase, ownership and disposition of our common stock by a non-U.S. holder (as defined below) as of the date hereof. This summary deals only with non-U.S. holders that acquire our common stock in this offering and hold the common stock as a capital asset within the meaning of Section 1221 of the Internal Revenue Code of 1986, as amended (the “Code”) (generally, property held for investment).

For purposes of this summary, a “non-U.S. holder” means a beneficial owner of our common stock (other than an entity or arrangement treated as a partnership for U.S. federal income tax purposes) that is not any of the following for U.S. federal income tax purposes: (i) an individual citizen or resident of the U.S.; (ii) a corporation (or other entity treated as a corporation) created or organized in or under the laws of the U.S., any state thereof, or the District of Columbia; (iii) an estate the income of which is subject to U.S. federal income taxation regardless of its source; or (iv) a trust if (1) its administration is subject to the primary supervision of a court within the U.S. and one or more U.S. persons have the authority to control all of its substantial decisions, or (2) it has a valid election in effect under applicable U.S. Treasury regulations to be treated as a U.S. person.

This summary is based upon provisions of the Code and regulations, rulings and judicial decisions as of the date hereof. Those authorities may be changed, perhaps retroactively, or be subject to differing interpretations, so as to result in U.S. federal income tax considerations different from those summarized below. This summary does not represent a detailed description of the U.S. federal income tax considerations to you in light of your particular circumstances. In addition, it does not address the U.S. federal income tax considerations to you if you are subject to special treatment under the U.S. federal income tax laws (including if you are a bank or other financial institution, insurance company, broker or dealer in securities, tax-exempt organization, foreign government or agency, U.S. expatriate, “controlled foreign corporation,” “passive foreign investment company,” a person who is subject to the alternative minimum tax, a person who holds or received our common stock pursuant to the exercise of any employee stock option or otherwise as compensation, or a person who holds our common stock in a straddle or as part of a hedging, conversion or constructive sale transaction). Except where noted, this summary does not address any non-income federal tax consequences, such as estate or gift tax consequences, nor does it address the Medicare tax on net investment income or any state, local or non-U.S. tax considerations. We cannot assure you that a change in law will not alter significantly the tax considerations that we describe in this summary.

If an entity or arrangement classified as a partnership for U.S. federal income tax purposes holds our common stock, the tax treatment of a partner will generally depend on the status of the partner and the activities of the partnership. If you are a partnership holding our common stock, or a partner in such a partnership, you should consult your tax advisors.

If you are considering the purchase of our common stock, you should consult your own tax advisors concerning the particular U.S. federal tax consequences to you of the purchase, ownership and disposition of our common stock, as well as the consequences to you arising under the laws of any other taxing jurisdiction, including any state, local or foreign tax consequences.

Distributions

We do not anticipate paying any distributions on our common stock in the foreseeable future. If we were to pay distributions in the future on our common stock, a non-U.S. holder would be subject to U.S. federal income tax on such distributions in the manner described below.

Distributions on our common stock generally will constitute dividends for U.S. federal income tax purposes to the extent paid out of our current or accumulated earnings and profits, as determined under U.S. federal income tax principles. Distributions in excess of current and accumulated earnings and profits will be applied against and reduce a non-U.S. holder’s tax basis in our common stock, to the extent thereof, and any excess will be treated as capital gain realized on the sale or other disposition of the common stock and subject to tax in the manner described below under “—Gain on Disposition of Common Stock.”

S-21

Distributions paid to a non-U.S. holder that constitute dividends under the rules described above generally will be subject to U.S. federal income tax withholding at a 30% rate (on the gross amount of the dividend) or such lower rate as may be specified by an applicable income tax treaty. However, dividends that are effectively connected with the conduct of a trade or business by a non-U.S. holder within the U.S. and, where an income tax treaty applies, are attributable to a U.S. permanent establishment of the non-U.S. holder, are not subject to this withholding tax if the non-U.S. holder provides the required forms, including IRS Form W-8ECI, to us and/or our paying agent, as applicable, but instead are subject to U.S. federal income tax on a net income basis at applicable individual or corporate rates, in the same manner as if the non-U.S. holder were a resident of the United States. Any such effectively connected dividends received by a non-U.S. holder that is a corporation may be subject to an additional “branch profits tax” at a 30% rate or such lower rate as may be specified by an applicable income tax treaty.

A non-U.S. holder of our common stock who is entitled to and wishes to claim the benefits of an applicable treaty rate (and avoid backup withholding as discussed below) with respect to dividends received on our common stock generally will be required to (i) complete Internal Revenue Service (“IRS”) Form W-8BEN or W-8BEN-E (or an acceptable substitute form) and make certain certifications, under penalty of perjury, to establish its status as a non-U.S. person and its entitlement to treaty benefits or (ii) if the common stock is held through certain foreign intermediaries, satisfy the relevant certification requirements of applicable U.S. Treasury regulations. Such certificate must be provided before the payment of dividends and must be updated periodically.

A non-U.S. holder of our common stock eligible for a reduced rate of U.S. federal withholding tax pursuant to an income tax treaty may obtain a refund of any excess amounts withheld by timely filing an appropriate claim for refund with the IRS.

See the discussions below regarding backup withholding and the Foreign Account Tax Compliance Act, or FATCA, for additional withholding rules that may apply to distributions.

Gain on Disposition of Common Stock

Subject to the discussions below regarding backup withholding and FATCA, a non-U.S. holder generally will not be subject to U.S. federal income tax with respect to gain recognized on a sale or other disposition of our common stock unless (i) the gain is effectively connected with a trade or business of the non-U.S. holder in the U.S. and, where a tax treaty applies, is attributable to a U.S. permanent establishment of the non-U.S. holder, (ii) in the case of a non-U.S. holder who is an individual, such holder is present in the U.S. for 183 or more days in the taxable year of the sale or other disposition and certain other conditions are met, or (iii) subject to certain exceptions, we are or have been a “U.S. real property holding corporation” for U.S. federal income tax purposes.

In the case of a non-U.S. holder described in subsection (i) above, any net gain derived from the disposition generally will be subject to U.S. federal income tax under graduated U.S. federal income tax rates in generally the same manner as if the non-U.S. holder were a U.S. person as defined under the Code, unless an applicable income tax treaty provides otherwise. Additionally, a non-U.S. holder that is a corporation may be subject to a branch profits tax equal to 30% of its effectively connected earnings and profits attributable to such gain (or, if an income tax treaty applies, at such lower rate as may be specified by the treaty on its gains attributable to its U.S. permanent establishment), subject to adjustments. Except as otherwise provided by an applicable income tax treaty, an individual non-U.S. holder described in subsection (ii) above will be subject to a 30% tax on any gain derived from the disposition, which may be offset by certain U.S. source capital losses. With respect to subsection (iii) above, we believe we have not been and are not currently, and do not anticipate becoming, a “U.S. real property holding corporation” for U.S. federal income tax purposes.

Information Reporting and Backup Withholding

Payors must report annually to the IRS and to each non-U.S. holder the amount of dividends paid to such holder and the tax withheld (if any) with respect to such dividends, regardless of whether withholding was required. Copies of the information returns reporting such dividends and any withholding may also be made available to the tax authorities in the country in which the non-U.S. holder resides under the provisions of an applicable income tax treaty. In addition, dividends paid to a non-U.S. holder may be subject to backup withholding unless the non-U.S. holder certifies to the payor as to its status as an exempt recipient, such as by completing and providing the payor with an applicable IRS Form W-8.

S-22

Payment of the proceeds of a sale of our common stock within the U.S. or conducted through certain U.S. related financial intermediaries is subject to information reporting and, depending upon the circumstances, backup withholding unless the non-U.S. holder certifies under penalties of perjury that it is not a U.S. person (and the payor does not have actual knowledge or reason to know that the holder is a U.S. person) or the holder otherwise establishes an exemption.

Any amounts withheld under the backup withholding rules may be allowed as a refund or a credit against such holder’s U.S. federal income tax liability provided the required information is timely furnished to the IRS.

Foreign Account Tax Compliance Act

Legislation commonly referred to as FATCA generally imposes a 30% U.S. federal withholding tax on certain types of payments made to (i) a “foreign financial institution” (as specifically defined in the legislation), whether such foreign financial institution is the beneficial owner or an intermediary, unless such foreign financial institution agrees to verify, report and disclose its U.S. “account” holders (as specifically defined in the legislation) and meets certain other specified requirements, or (ii) a non-financial foreign entity, whether such non-financial foreign entity is the beneficial owner or an intermediary, unless such entity provides a certification that the beneficial owner of the payment does not have any substantial U.S. owners or provides the name, address and taxpayer identification number of each such substantial U.S. owner and certain other specified requirements are met. An intergovernmental agreement between the United States and an applicable foreign country may modify the FATCA requirements. In addition, in certain cases, the relevant foreign financial institution or non-financial foreign entity may qualify for an exemption from, or be deemed to be in compliance with, these rules. Under the applicable U.S. Treasury regulations and administrative guidance, withholding under FATCA generally applies to payments of dividends on our common stock. While withholding under FATCA would have applied also to payments of gross proceeds from the sale or other disposition of our common stock, proposed Treasury regulations eliminate FATCA withholding on payments of gross proceeds entirely. The preamble to such Treasury regulations provides that taxpayers generally may rely on these proposed Treasury regulations until final Treasury regulations are issued.

Investors are urged to consult with their own tax advisors regarding the possible application of these rules to their investment in our common stock.

S-23

CERTAIN ERISA CONSIDERATIONS

The offered securities may, subject to certain legal restrictions, be held by (i) an “employee benefit plan” (as defined in Section 3(3) of the Employee Retirement Security Act of 1974, as amended (“ERISA”)) that is subject to Title I of ERISA, (ii) a “plan” as defined in, and subject to, Section 4975 of the Code or (iii) a “benefit plan investor” within the meaning of Section 3(42) of ERISA. A fiduciary of any such employee benefit plan, plan, or benefit plan investor must determine that the purchase, holding and disposition of an interest in such offered security is consistent with its fiduciary duties and will not constitute or result in a non-exempt prohibited transaction under Section 406 of ERISA or Section 4975 of the Code.

S-24

UNDERWRITING

Subject to the terms and conditions set forth in the underwriting agreement, dated                 , 2020, between us and Jefferies LLC, as the representative of the underwriters named below, we have agreed to sell to the underwriters, and each of the underwriters has agreed, severally and not jointly, to purchase from us, the respective number of shares of common stock shown opposite its name below. Jefferies LLC and Cantor Fitzgerald & Co. are the joint book-running managers of this offering.

UNDERWRITER	NUMBER OF SHARES
Jefferies LLC
Cantor Fitzgerald & Co.
JMP Securities LLC
B. Riley FBR, Inc.
H.C. Wainwright & Co., LLC
Total

The underwriting agreement provides that the obligations of the several underwriters are subject to certain conditions precedent such as the receipt by the underwriters of officers’ certificates and legal opinions and approval of certain legal matters by their counsel. The underwriting agreement provides that the underwriters will purchase all of the shares of common stock if any of them are purchased. If an underwriter defaults, the underwriting agreement provides that the purchase commitments of the non-defaulting underwriters may be increased or the underwriting agreement may be terminated. We have agreed to indemnify the underwriters and certain of their controlling persons against certain liabilities, including liabilities under the Securities Act, and to contribute to payments that the underwriters may be required to make in respect of those liabilities.

The underwriters have advised us that, following the completion of this offering, they currently intend to make a market in the common stock as permitted by applicable laws and regulations. However, the underwriters are not obligated to do so, and the underwriters may discontinue any market-making activities at any time without notice in their sole discretion. Accordingly, no assurance can be given as to the liquidity of the trading market for the common stock, that you will be able to sell any of the common stock held by you at a particular time or that the prices that you receive when you sell will be favorable.

The underwriters are offering the shares of common stock subject to their acceptance of the shares of common stock from us and subject to prior sale. The underwriters reserve the right to withdraw, cancel or modify offers to the public and to reject orders in whole or in part.

Commission and Expenses

The underwriters have advised us that they propose to offer the shares of common stock to the public at the public offering price set forth on the cover page of this prospectus supplement and to certain dealers, which may include the underwriters, at that price less a concession not in excess of $             per share of common stock. The underwriters may allow, and certain dealers may reallow, a discount from the concession not in excess of $             per share of common stock to certain brokers and dealers. After the offering, the public offering price, concession and reallowance to dealers may be reduced by the representative. No such reduction will change the amount of proceeds to be received by us as set forth on the cover page of this prospectus supplement.

S-25

The following table shows the public offering price, the underwriting discounts and commissions that we are to pay the underwriters and the proceeds, before expenses, to us in connection with this offering. Such amounts are shown assuming both no exercise and full exercise of the underwriters’ option to purchase additional shares.

	PER SHARE		TOTAL
	WITHOUT OPTION TO PURCHASE ADDITIONAL SHARES	WITH OPTION TO PURCHASE ADDITIONAL SHARES	WITHOUT OPTION TO PURCHASE ADDITIONAL SHARES	WITH OPTION TO PURCHASE ADDITIONAL SHARES
Public offering price	$	$	$	$
Underwriting discounts and commissions paid by us	$	$	$	$
Proceeds to us, before expenses	$	$	$	$

We estimate expenses payable by us in connection with this offering, other than the underwriting discounts and commissions referred to above, will be approximately $            . We have also agreed to reimburse the underwriters for certain expenses incurred by them in connection with the offering.

Listing

Our common stock is listed on The Nasdaq Global Select Market under the symbol “SPPI.”

Option to Purchase Additional Shares

We have granted to the underwriters an option, exercisable for 30 days from the date of this prospectus supplement, to purchase, from time to time, in whole or in part, up to an aggregate of              additional shares from us at the public offering price set forth on the cover page of this prospectus supplement, less underwriting discounts and commissions. If the underwriters exercise this option, each underwriter will be obligated, subject to specified conditions, to purchase a number of additional shares proportionate to that underwriter’s initial purchase commitment as indicated in the table above.

No Sales of Similar Securities

We, our officers and our directors have agreed, subject to specified exceptions, not to directly or indirectly:

∎ sell, offer, contract or grant any option to sell (including any short sale), pledge, transfer or establish an open “put equivalent position” within the meaning of Rule 16a-1(h) under the Exchange Act;

∎ otherwise dispose of any shares of common stock, options or warrants to acquire shares of common stock, or securities exchangeable or exercisable for or convertible into shares of common stock, currently or hereafter owned either of record or beneficially;

∎ enter into any swap, hedge or similar arrangement or agreement that transfers, in whole or in part, the economic risk of ownership of shares of our common stock, or of options or warrants to shares of our common stock, or securities or rights exchangeable or exercisable for or convertible into shares of our common stock;

∎ make any demand for, or exercise any right with respect to, the registration under the Securities Act of the offer and sale of any shares of our common stock, or of options or warrants to purchase shares of our common stock, or securities or rights exchangeable or exercisable for or convertible into shares of our common stock, or cause to be filed a registration statement, prospectus or prospectus supplement (or an amendment or supplement thereto) with respect to any such registration;

∎ effect a reverse stock split, recapitalization, share consolidation, reclassification or similar transaction affecting the outstanding shares of common stock; or

∎ publicly announce an intention to do any of the foregoing, in each case for a period of 90 days after the date of this prospectus supplement without the prior written consent of Jefferies LLC.

This restriction terminates after the close of trading of the common stock on and including the 90th day after the date of this prospectus supplement.

S-26

Jefferies LLC may, in its sole discretion and at any time or from time to time before the termination of the 90-day period, release all or any portion of the securities subject to lock-up agreements. There are no existing agreements between the underwriters and any of our stockholders who will execute a lock-up agreement, providing consent to the sale of shares prior to the expiration of the lock-up period.

Stabilization

The underwriters have advised us that, pursuant to Regulation M under the Exchange Act, certain persons participating in the offering may engage in short sale transactions, stabilizing transactions, syndicate covering transactions or the imposition of penalty bids in connection with this offering. These activities may have the effect of stabilizing or maintaining the market price of the common stock at a level above that which might otherwise prevail in the open market. Establishing short sales positions may involve either “covered” short sales or “naked” short sales.

“Covered” short sales are sales made in an amount not greater than the underwriters’ option to purchase additional shares of our common stock in this offering. The underwriters may close out any covered short position by either exercising their option to purchase additional shares of our common stock or purchasing shares of our common stock in the open market. In determining the source of shares to close out the covered short position, the underwriters will consider, among other things, the price of shares available for purchase in the open market as compared to the price at which they may purchase shares through the option to purchase additional shares.

“Naked” short sales are sales in excess of the option to purchase additional shares of our common stock. The underwriters must close out any naked short position by purchasing shares in the open market. A naked short position is more likely to be created if the underwriters are concerned that there may be downward pressure on the price of the shares of our common stock in the open market after pricing that could adversely affect investors who purchase in this offering.

A stabilizing bid is a bid for the purchase of shares of common stock on behalf of the underwriters for the purpose of fixing or maintaining the price of the common stock. A syndicate covering transaction is the bid for or the purchase of shares of common stock on behalf of the underwriters to reduce a short position incurred by the underwriters in connection with the offering. Similar to other purchase transactions, the underwriter’s purchases to cover the syndicate short sales may have the effect of raising or maintaining the market price of our common stock or preventing or retarding a decline in the market price of our common stock. As a result, the price of our common stock may be higher than the price that might otherwise exist in the open market. A penalty bid is an arrangement permitting the underwriters to reclaim the selling concession otherwise accruing to a syndicate member in connection with the offering if the shares of common stock originally sold by such syndicate member are purchased in a syndicate covering transaction and therefore have not been effectively placed by such syndicate member.

Neither we nor any of the underwriters make any representation or prediction as to the direction or magnitude of any effect that the transactions described above may have on the price of our common stock. The underwriters are not obligated to engage in these activities and, if commenced, any of the activities may be discontinued at any time.

The underwriters may also engage in passive market making transactions in our common stock on The Nasdaq Global Select Market in accordance with Rule 103 of Regulation M during a period before the commencement of offers or sales of shares of our common stock in this offering and extending through the completion of distribution. A passive market maker must display its bid at a price not in excess of the highest independent bid of that security. However, if all independent bids are lowered below the passive market maker’s bid, that bid must then be lowered when specified purchase limits are exceeded.

S-27

Electronic Distribution

This prospectus supplement and the accompanying prospectus in electronic format may be made available by e-mail or on the web sites or through online services maintained by one or more of the underwriters or their affiliates. In those cases, prospective investors may view offering terms online and may be allowed to place orders online. The underwriters may agree with us to allocate a specific number of shares of common stock for sale to online brokerage account holders. Any such allocation for online distributions will be made by the underwriters on the same basis as other allocations. Other than this prospectus supplement and the accompanying prospectus in electronic format, the information on the underwriters’ web sites and any information contained in any other web site maintained by any of the underwriters is not part of this prospectus supplement or the accompanying prospectus, has not been approved and/or endorsed by us or the underwriters and should not be relied upon by investors.

Other Activities and Relationships

The underwriters and certain of their affiliates are full service financial institutions engaged in various activities, which may include securities trading, commercial and investment banking, financial advisory, investment management, investment research, principal investment, hedging, financing and brokerage activities. The underwriters and certain of their affiliates may in the future perform various commercial and investment banking and financial advisory services for us and our affiliates, for which they received or will receive customary fees and expenses.

In the ordinary course of their various business activities, the underwriters and certain of their affiliates may make or hold a broad array of investments and actively trade debt and equity securities (or related derivative securities) and financial instruments (including bank loans) for their own account and for the accounts of their customers, and such investment and securities activities may involve securities and/or instruments issued by us and our affiliates. If the underwriters or their respective affiliates have a lending relationship with us, they may routinely hedge their credit exposure to us consistent with their customary risk management policies. The underwriters and their respective affiliates may hedge such exposure by entering into transactions which consist of either the purchase of credit default swaps or the creation of short positions in our securities or the securities of our affiliates, including potentially the common stock offered hereby. Any such short positions could adversely affect future trading prices of the common stock offered hereby. The underwriters and certain of their respective affiliates may also communicate independent investment recommendations, market color or trading ideas and/or publish or express independent research views in respect of such securities or instruments and may at any time hold, or recommend to clients that they acquire, long and/or short positions in such securities and instruments.

Selling Restrictions

Canada

Resale Restrictions

The distribution of shares in Canada is being made only in the provinces of Ontario, Quebec, Alberta and British Columbia on a private placement basis exempt from the requirement that we prepare and file a prospectus with the securities regulatory authorities in each province where trades of these securities are made. Any resale of the shares in Canada must be made under applicable securities laws which may vary depending on the relevant jurisdiction, and which may require resales to be made under available statutory exemptions or under a discretionary exemption granted by the applicable Canadian securities regulatory authority. Purchasers are advised to seek legal advice prior to any resale of the securities.

Representations of Canadian Purchasers

By purchasing shares in Canada and accepting delivery of a purchase confirmation, a purchaser is representing to us and the dealer from whom the purchase confirmation is received that:

∎ the purchaser is entitled under applicable provincial securities laws to purchase the shares without the benefit of a prospectus qualified under those securities laws as it is an “accredited investor” as defined under National Instrument 45-106—Prospectus Exemptions;

∎ the purchaser is a “permitted client” as defined in National Instrument 31-103—Registration Requirements, Exemptions and Ongoing Registrant Obligations;

S-28

∎ where required by law, the purchaser is purchasing as principal and not as agent; and

∎ the purchaser has reviewed the text above under Resale Restrictions.

Conflicts of Interest

Canadian purchasers are hereby notified that certain of the underwriters are relying on the exemption set out in section 3A.3 or 3A.4, if applicable, of National Instrument 33-105—Underwriting Conflicts from having to provide certain conflict of interest disclosure in this document.

Statutory Rights of Action

Securities legislation in certain provinces or territories of Canada may provide a purchaser with remedies for rescission or damages if the offering memorandum (including any amendment thereto) such as this document contains a misrepresentation, provided that the remedies for rescission or damages are exercised by the purchaser within the time limit prescribed by the securities legislation of the purchaser’s province or territory. The purchaser of these securities in Canada should refer to any applicable provisions of the securities legislation of the purchaser’s province or territory for particulars of these rights or consult with a legal advisor.

Enforcement of Legal Rights

All of our directors and officers as well as the experts named herein may be located outside of Canada and, as a result, it may not be possible for Canadian purchasers to effect service of process within Canada upon us or those persons. All or a substantial portion of our assets and the assets of those persons may be located outside of Canada and, as a result, it may not be possible to satisfy a judgment against us or those persons in Canada or to enforce a judgment obtained in Canadian courts against us or those persons outside of Canada.

Taxation and Eligibility for Investment

Canadian purchasers of shares should consult their own legal and tax advisors with respect to the tax consequences of an investment in the shares in their particular circumstances and about the eligibility of the shares for investment by the purchaser under relevant Canadian legislation.

Australia

Neither this prospectus supplement nor the accompanying prospectus is a disclosure document for the purposes of the Corporations Act 2001 (Cth) of Australia, or Corporations Act, or has been lodged with the Australian Securities & Investments Commission, and each is only directed to the categories of exempt persons set out below. Accordingly, if you receive this prospectus supplement and the accompanying prospectus in Australia, you confirm and warrant that you are either:

∎ a “sophisticated investor” under section 708(8)(a) or (b) of the Corporations Act;

∎ a “sophisticated investor” under section 708(8)(c) or (d) of the Corporations Act and that you have provided an accountant’s certificate to the Company which complies with the requirements of section 708(8)(c)(i) or (ii) of the Corporations Act and related regulations before the offer has been made;

∎ a person associated with the Company under section 708(12) of the Corporations Act; or

∎ a “professional investor” within the meaning of section 708(11)(a) or (b) of the Corporations Act.

To the extent that you are unable to confirm or warrant that you are an exempt sophisticated investor, associated person or professional investor under the Corporations Act, any offer made to you under this prospectus supplement and the accompanying prospectus is void and incapable of acceptance.

You warrant and agree that you will not offer any of the shares issued to you pursuant to this prospectus supplement and the accompanying prospectus for resale in Australia within 12 months of those shares being issued unless any such resale offer is exempt from the requirement to issue a disclosure document under section 708 of the Corporations Act.

S-29

European Economic Area

In relation to each Member State of the European Economic Area (each a “Member State”), no shares have been offered or will be offered pursuant to the offering to the public in that Member State prior to the publication of a prospectus in relation to the shares which has been approved by the competent authority in that Member State or, where appropriate, approved in another Member State and notified to the competent authority in that Member State, all in accordance with the Prospectus Regulation, except that offers of shares may be made to the public in that Member State at any time under the following exemptions under the Prospectus Regulation:

∎ to any legal entity which is a qualified investor as defined under the Prospectus Regulation;

∎ to fewer than 150 natural or legal persons (other than qualified investors as defined under the Prospectus Regulation), subject to obtaining the prior consent of the underwriters; or

∎ in any other circumstances falling within Article 1(4) of the Prospectus Regulation;

provided that no such offer of shares shall require us or any underwriter to publish a prospectus pursuant to Article 3 of the Prospectus Regulation or supplement a prospectus pursuant to Article 23 of the Prospectus Regulation and each person who initially acquires any shares or to whom any offer is made will be deemed to have represented, acknowledged and agreed to and with each of the underwriters and the Company that it is a “qualified investor” within the meaning of Article 2(e) of the Prospectus Regulation. In the case of any shares being offered to a financial intermediary as that term is used in the Prospectus Regulation, each such financial intermediary will be deemed to have represented, acknowledged and agreed that the shares acquired by it in the offer have not been acquired on a non-discretionary basis on behalf of, nor have they been acquired with a view to their offer or resale to, persons in circumstances which may give rise to an offer of any shares to the public other than their offer or resale in a Member State to qualified investors as so defined or in circumstances in which the prior consent of the underwriters have been obtained to each such proposed offer or resale.

For the purposes of this provision, the expression an “offer to the public” in relation to shares in any Member State means the communication in any form and by any means of sufficient information on the terms of the offer and any shares to be offered so as to enable an investor to decide to purchase or subscribe for any shares, and the expression “Prospectus Regulation” means Regulation (EU) 2017/1129.

Hong Kong

No securities have been offered or sold, and no securities may be offered or sold, in Hong Kong, by means of any document, other than to persons whose ordinary business is to buy or sell shares or debentures, whether as principal or agent; or to “professional investors” as defined in the Securities and Futures Ordinance (Cap. 571) of Hong Kong, or SFO, and any rules made under that Ordinance; or in other circumstances which do not result in the document being a “prospectus” as defined in the Companies Ordinance (Cap. 32) of Hong Kong, or CO, or which do not constitute an offer or invitation to the public for the purpose of the CO or the SFO. No document, invitation or advertisement relating to the securities has been issued or may be issued or may be in the possession of any person for the purpose of issue (in each case whether in Hong Kong or elsewhere), which is directed at, or the contents of which are likely to be accessed or read by, the public of Hong Kong (except if permitted under the securities laws of Hong Kong) other than with respect to securities which are or are intended to be disposed of only to persons outside Hong Kong or only to “professional investors” as defined in the SFO and any rules made under that Ordinance.

Neither this prospectus supplement nor the accompanying prospectus have been registered with the Registrar of Companies in Hong Kong. Accordingly, this prospectus supplement and the accompanying prospectus may not be issued, circulated or distributed in Hong Kong, and the securities may not be offered for subscription to members of the public in Hong Kong. Each person acquiring the securities will be required, and is deemed by the acquisition of the securities, to confirm that he is aware of the restriction on offers of the securities described in this prospectus supplement and the accompanying prospectus and the relevant offering documents and that he is not acquiring, and has not been offered any securities in circumstances that contravene any such restrictions.

S-30

Israel

This document does not constitute a prospectus under the Israeli Securities Law, 5728-1968, or the Securities Law, and has not been filed with or approved by the Israel Securities Authority. In Israel, this prospectus supplement is being distributed only to, and is directed only at, and any offer of the shares is directed only at, (i) a limited number of persons in accordance with the Israeli Securities Law and (ii) investors listed in the first addendum, or the Addendum, to the Israeli Securities Law, consisting primarily of joint investment in trust funds, provident funds, insurance companies, banks, portfolio managers, investment advisors, members of the Tel Aviv Stock Exchange, underwriters, venture capital funds, entities with equity in excess of NIS 50 million and “qualified individuals,” each as defined in the Addendum (as it may be amended from time to time), collectively referred to as qualified investors (in each case, purchasing for their own account or, where permitted under the Addendum, for the accounts of their clients who are investors listed in the Addendum). Qualified investors are required to submit written confirmation that they fall within the scope of the Addendum, are aware of the meaning of same and agree to it.

France

Neither this prospectus supplement, the accompanying prospectus nor any other offering material relating to the shares described in this prospectus supplement or the accompanying prospectus has been submitted to the clearance procedures of the Autorité des Marchés Financiers or of the competent authority of another member state of the European Economic Area and notified to the Autorité des Marchés Financiers. The shares have not been offered or sold and will not be offered or sold, directly or indirectly, to the public in France. Neither this prospectus supplement nor any other offering material relating to the shares has been or will be:

∎ released, issued, distributed or caused to be released, issued or distributed to the public in France; or

∎ used in connection with any offer for subscription or sale of the shares to the public in France.

Such offers, sales and distributions will be made in France only:

∎ to qualified investors (investisseurs qualifiés) and/or to a restricted circle of investors (cercle restreint d’investisseurs), in each case investing for their own account, all as defined in, and in accordance with articles L.411-2, D.411-1, D.411-2, D.734-1, D.744-1, D.754-1 and D.764-1 of the French Code monétaire et financier;

∎ to investment services providers authorized to engage in portfolio management on behalf of third parties; or

∎ in a transaction that, in accordance with article L.411-2-II-1° -or-2° -or 3° of the French Code monétaire et financier and article 211-2 of the General Regulations (Règlement Général) of the Autorité des Marchés Financiers, does not constitute a public offer (appel public à l’épargne).

The shares may be resold directly or indirectly, only in compliance with articles L.411-1, L.411-2, L.412-1 and L.621-8 through L.621-8-3 of the French Code monétaire et financier.

Japan

The offering has not been and will not be registered under the Financial Instruments and Exchange Law of Japan (Law No. 25 of 1948 of Japan, as amended) (“FIEL”), and the underwriters will not offer or sell any securities, directly or indirectly, in Japan or to, or for the benefit of, any resident of Japan (which term as used herein means, unless otherwise provided herein, any person resident in Japan, including any corporation or other entity organized under the laws of Japan), or to others for re-offering or resale, directly or indirectly, in Japan or to a resident of Japan, except pursuant to an exemption from the registration requirements of, and otherwise in compliance with, the FIEL and any other applicable laws, regulations and ministerial guidelines of Japan.

Singapore

Neither this prospectus supplement nor the accompanying prospectus has been and neither will be lodged or registered as a prospectus with the Monetary Authority of Singapore. Accordingly, this prospectus supplement and the accompanying prospectus and any other document or material in connection with the offer or sale, or invitation for subscription or purchase, of the securities may not be circulated or distributed, nor may the securities be offered or sold, or be made the subject of an invitation for subscription or purchase, whether directly or indirectly, to persons in Singapore other than (i) to an institutional investor under Section 274 of the Securities and Futures Act, Chapter 289 of Singapore, or the SFA, (ii) to a relevant person pursuant to Section 275(1), or any person pursuant to

S-31

Section 275(1A), and in accordance with the conditions specified in Section 275, of the SFA, or (iii) otherwise pursuant to, and in accordance with the conditions of, any other applicable provision of the SFA.

Where the securities are subscribed or purchased under Section 275 of the SFA by a relevant person, which is:

∎ a corporation (which is not an accredited investor (as defined in Section 4A of the SFA)) the sole business of which is to hold investments and the entire share capital of which is owned by one or more individuals, each of whom is an accredited investor; or

∎ a trust (where the trustee is not an accredited investor) whose sole purpose is to hold investments and each beneficiary of the trust is an individual who is an accredited investor;

securities (as defined in Section 239(1) of the SFA) of that corporation or the beneficiaries’ rights and interest (howsoever described) in that trust shall not be transferred within six months after that corporation or that trust has acquired the shares pursuant to an offer made under Section 275 of the SFA except:

∎ to an institutional investor or to a relevant person defined in Section 275(2) of the SFA, or to any person arising from an offer referred to in Section 275(1A) or Section 276(4)(i)(B) of the SFA;

∎ where no consideration is or will be given for the transfer;

∎ where the transfer is by operation of law;

∎ as specified in Section 276(7) of the SFA; or

∎ as specified in Regulation 32 of the Securities and Futures (Offers of Investments) (Shares and Debentures) Regulations 2005 of Singapore.

Solely for the purposes of its obligations pursuant to Section 309B of the SFA, we have determined, and hereby notify all relevant persons (as defined in the CMP Regulations 2018), that the shares are “prescribed capital markets products” (as defined in the CMP Regulations 2018) and Excluded Investment Products (as defined in MAS Notice SFA 04-N12: Notice on the Sale of Investment Products and MAS Notice FAA-N16: Notice on Recommendations on Investment Products).

Switzerland

The securities may not be publicly offered in Switzerland and will not be listed on the SIX Swiss Exchange (“SIX”), or on any other stock exchange or regulated trading facility in Switzerland. This prospectus supplement and the accompanying prospectus have been prepared without regard to the disclosure standards for issuance prospectuses under art. 652a or art. 1156 of the Swiss Code of Obligations or the disclosure standards for listing prospectuses under art. 27 ff. of the SIX Listing Rules or the listing rules of any other stock exchange or regulated trading facility in Switzerland. Neither this prospectus supplement, the accompanying prospectus nor any other offering or marketing material relating to the securities or the offering may be publicly distributed or otherwise made publicly available in Switzerland.

Neither this prospectus supplement, the accompanying prospectus nor any other offering or marketing material relating to the offering, us or the securities have been or will be filed with or approved by any Swiss regulatory authority. In particular, this prospectus supplement and the accompanying prospectus will not be filed with, and the offer of securities will not be supervised by, the Swiss Financial Market Supervisory Authority (FINMA), and the offer of securities has not been and will not be authorized under the Swiss Federal Act on Collective Investment Schemes (“CISA”). The investor protection afforded to acquirers of interests in collective investment schemes under the CISA does not extend to acquirers of securities.

United Kingdom

This prospectus supplement and the accompanying prospectus are only being distributed to, and are only directed at, persons in the United Kingdom that are qualified investors within the meaning of Article 2(1)(e) of the Prospectus Directive that are also (i) investment professionals falling within Article 19(5) of the Financial Services and Markets Act 2000 (Financial Promotion) Order 2005, as amended (the “Order”), and/or (ii) high net worth entities falling within Article 49(2)(a) to (d) of the Order and other persons to whom it may lawfully be communicated (each, a “Relevant Person”).

S-32

This prospectus supplement, the accompanying prospectus and their contents are confidential and should not be distributed, published or reproduced (in whole or in part) or disclosed by recipients to any other persons in the United Kingdom. Any person in the United Kingdom that is not a Relevant Person should not act or rely on this document or any of its contents.

United Arab Emirates

The shares have not been, and are not being, publicly offered, sold, promoted or advertised in the United Arab Emirates (including the Dubai International Financial Centre) other than in compliance with the laws of the United Arab Emirates (and the Dubai International Financial Centre) governing the issue, offering and sale of securities. Further, this prospectus supplement does not constitute a public offer of securities in the United Arab Emirates (including the Dubai International Financial Centre) and is not intended to be a public offer. Neither this prospectus supplement nor the accompanying prospectus has been approved by or filed with the Central Bank of the United Arab Emirates, the Securities and Commodities Authority or the Dubai Financial Services Authority.

Dubai International Financial Centre.

This document relates to an “exempt offer” in accordance with the Markets Rules of the Dubai Financial Services Authority. This document is intended for distribution only to persons of a type specified in those rules to whom exempt offers can be made. It must not be delivered to, or relied on by, any other person. The Dubai Financial Services Authority has no responsibility for reviewing or verifying any documents in connection with exempt offers. The Dubai Financial Services Authority has not approved this document nor taken steps to verify the information set out in it, and has no responsibility for it. The shares of common stock to which this document relates may be illiquid and/or subject to restrictions on their resale. Prospective purchasers of the shares of common stock offered should conduct their own due diligence on the shares. If you do not understand the contents of this document you should consult an authorized financial adviser.

S-33

LEGAL MATTERS

The validity of the securities being offered hereby will be passed on by Paul Hastings, LLP, San Diego, California. Cooley LLP, New York, New York is acting as counsel for the underwriters in connection with this offering.

EXPERTS

The financial statements, and the related financial statement schedule, incorporated in this prospectus supplement by reference from the Company’s Annual Report on Form 10-K for the year ended December 31, 2019, and the effectiveness of Spectrum Pharmaceuticals, Inc.’s internal control over financial reporting have been audited by Deloitte & Touche LLP, an independent registered public accounting firm, as stated in their reports, which are incorporated herein by reference. Such financial statements and financial statement schedules have been so incorporated in reliance upon the reports of such firm given upon their authority as experts in accounting and auditing.

WHERE YOU CAN FIND MORE INFORMATION

We file annual, quarterly and special reports, proxy statements and other information with the SEC. The SEC maintains an Internet website at http://www.sec.gov that contains reports, proxy and information statements, and other information regarding issuers that file electronically with the SEC, including Spectrum Pharmaceuticals, Inc. You may also access our reports and proxy statements free of charge at our Internet website, www.spprix.com. The information contained in, or that can be accessed through, our website is not part of this prospectus supplement. The prospectus included in this filing is part of a registration statement filed by us with the SEC. The full registration statement can be obtained from the SEC, as indicated above, or from us.

S-34

INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

This prospectus supplement is part of a registration statement on Form S-3 filed by us with the SEC. This prospectus supplement does not contain all of the information set forth in the registration statement, certain parts of which are omitted in accordance with the rules and regulations of the SEC. For further information about us and the securities offered by this prospectus supplement, we refer you to the registration statement and its exhibits and schedules which may be obtained as described herein.

The SEC allows us to “incorporate by reference” information into this prospectus supplement. This means that we can disclose important information about us and our financial condition to you by referring you to another document filed separately with the SEC. The information incorporated by reference is considered to be part of this prospectus supplement. This prospectus supplement incorporates by reference the documents listed below that we have previously filed with the SEC:

∎ Our Annual Report on Form 10-K for the fiscal year ended December 31, 2019, as filed with the SEC on March 2, 2020;

∎ Our Definitive Proxy Statement on Schedule 14A, as filed with the SEC on April  22, 2020 (to the extent incorporated by reference into Part III of our Annual Report on Form 10-K for the fiscal year ended December 31, 2019);

∎ Our Quarterly Report on Form 10-Q for the three months ended March 31, 2020, as filed with the SEC on May 7, 2019;

∎ Our Current Reports on Form  8-K, as filed with the SEC on March  13, 2020, April  23, 2020, June  19, 2020, July 27, 2020 and July 29, 2020; and

∎ The description of our common stock contained in the Registration of Securities of Certain Successor Issuers filed pursuant to Section 12(g) of the Exchange Act on Form 8-B on June 27, 1997, including any amendments or reports filed for the purpose of updating such description.

We also incorporate by reference any future filings (other than information in current reports furnished under Item 2.02 or Item 7.01 of Form 8-K and exhibits filed on such form that are related to such items) made with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act, until we sell all of the securities offered by this prospectus supplement. Information in such future filings updates and supplements the information provided in this prospectus supplement. Any statements in any such future filings will automatically be deemed to modify and supersede any information in any document we previously filed with the SEC that is incorporated or deemed to be incorporated herein by reference to the extent that statements in the later filed document modify or replace such earlier statements.

Any information in any of the foregoing documents will automatically be deemed to be modified or superseded to the extent that information in this prospectus supplement or the accompanying prospectus or in a later filed document that is incorporated or deemed to be incorporated herein by reference modifies or replaces such information. Any statement so modified or superseded will not be deemed, except as so modified or superseded, to constitute a part of this prospectus supplement.

Upon written or oral request, we will provide to you, without charge, a written copy of any or all of the documents that are incorporated by reference into this prospectus supplement and the accompanying prospectus but not delivered with the prospectus, including exhibits which are specifically incorporated by reference into such documents. Requests should be directed to: Spectrum Pharmaceuticals, Inc., Attention: Investor Relations, 11500 South Eastern Avenue, Suite 240, Henderson, Nevada 89052, telephone (702) 835-6300.

Statements contained in this prospectus supplement as to the contents of any contract or other documents are not necessarily complete, and in each instance investors are referred to the copy of the contract or other document filed as an exhibit to the registration statement, each such statement being qualified in all respects by such reference and the exhibits and schedules thereto.

S-35

PROSPECTUS

$150,000,000

Common Stock

Preferred Stock

Debt Securities

Warrants

Units

This prospectus relates to common stock, preferred stock, debt securities, warrants for debt or equity securities and units consisting of the foregoing that we may sell from time to time in one or more transactions. We will provide the specific terms and conditions of these transactions and the securities we may sell in supplements to this prospectus prepared in connection with each transaction. The applicable prospectus supplement will contain information, where applicable, as to other listings, if any, on the Nasdaq Global Select Market, or the NASDAQ, or any securities exchange of the securities covered by the prospectus supplement. Any such prospectus supplement may also add, update or change information in this prospectus. We may also authorize one or more free writing prospectuses to be provided to you in connection with these offerings. You should carefully read this prospectus, any applicable prospectus supplement and any related free writing prospectuses, as well as the documents incorporated by reference or deemed to be incorporated by reference into this prospectus, carefully before you invest. This prospectus may not be used to offer or sell securities unless accompanied by a prospectus supplement.

Our common stock is traded on the NASDAQ under the symbol “SPPI.”

Investing in our securities involves a high degree of risk. You should review carefully the risks and uncertainties referenced under the heading “Risk Factors” on page 4 of this prospectus and contained in our filings made with the Securities and Exchange Commission and the applicable prospectus supplement.

The securities may be sold directly by us to investors, through agents designated from time to time or to or through underwriters or dealers. For additional information on the methods of sale, you should refer to the section entitled “Plan of Distribution” in this prospectus. If any underwriters are involved in the sale of these securities with respect to which this prospectus is being delivered, the names of such underwriters and any applicable commissions or discounts and over-allotment options will be set forth in a prospectus supplement. The price to the public of such securities and the net proceeds that we expect to receive from such sale will also be set forth in a prospectus supplement. No securities may be sold without delivery of this prospectus and the applicable prospectus supplement describing the method and terms of the offering of such securities.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the accuracy or adequacy of this prospectus. Any representation to the contrary is a criminal offense.

The date of this prospectus is May 8, 2020.

TABLE OF CONTENTS

	Page
ABOUT THIS PROSPECTUS		1
PROSPECTUS SUMMARY		2
RISK FACTORS		4
CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS		4
USE OF PROCEEDS		6
DESCRIPTIONS OF CAPITAL STOCK WE MAY OFFER		7
DESCRIPTION OF DEBT SECURITIES WE MAY OFFER		11
DESCRIPTION OF WARRANTS WE MAY OFFER		19
DESCRIPTION OF UNITS WE MAY OFFER		22
PLAN OF DISTRIBUTION		24
LEGAL MATTERS		27
EXPERTS		27
WHERE YOU CAN FIND MORE INFORMATION		27
INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE		28

ABOUT THIS PROSPECTUS

This prospectus is part of a shelf registration statement on Form S-3 that we filed with the Securities and Exchange Commission, or the SEC, under the Securities Act of 1933, as amended, or the Securities Act. utilizing a “shelf” registration process. Under this shelf registration process, we may, from time to time, offer and sell any combination of the securities described in this prospectus in one or more offerings for an aggregate offering amount of up to $150,000,000.

This prospectus only provides you with a general description of the securities we may sell in these transactions. Each time we sell any securities under this prospectus, we will provide a prospectus supplement that will contain specific information about the terms of that offering. The prospectus supplement also may add, update or change information contained in this prospectus. We may also authorize one or more free writing prospectuses to be provided to you that may contain material information relating to these offerings. This prospectus does not contain all of the information included in the Registration Statement we filed with the SEC. For further information about us or the securities offered hereby, you should carefully read this prospectus, any applicable prospectus supplement, any related free writing prospectuses, the information and documents incorporated herein by reference and the additional information under the heading “Where You Can Find More Information” before making an investment decision.

You should rely only on the information contained or incorporated by reference in this prospectus, any applicable prospectus supplement and any related free writing prospectuses that we may authorize to be provided to you. We have not authorized any other person to provide you with different information. If anyone provides you with different or inconsistent information, you should not rely on it. This prospectus and any accompanying supplement to this prospectus are not an offer to sell these securities and are not soliciting an offer to buy these securities in any jurisdiction where the offer or sale is not permitted. You should assume that the information appearing in this prospectus, any applicable prospectus supplement or any related free writing prospectuses, as well as information we have previously filed with the SEC and incorporated by reference, is accurate only as of the date on the cover of those documents. If any statement in one of these documents is inconsistent with a statement in another document having a later date-for example, a document incorporated by reference in this prospectus-the statement in the document having the later date modifies or supersedes the earlier statement as our business, financial condition, results of operations and prospects may have changed since the earlier dates.

This prospectus may not be used to consummate sales of any of these securities unless it is accompanied by a prospectus supplement. To the extent there are inconsistencies between any prospectus supplement, this prospectus and/or any documents incorporated by reference, the document with the most recent date will control.

1

PROSPECTUS SUMMARY

Unless otherwise indicated or the context otherwise requires, the terms “Company,” “Spectrum Pharmaceuticals,” “we,” “us” and “our” refer to Spectrum Pharmaceuticals, Inc., a Delaware corporation, and its predecessors and consolidated subsidiaries.

Business Overview of Spectrum Pharmaceuticals, Inc.

We are a biopharma company, with a primary strategy comprised of acquiring, developing, and commercializing novel and targeted oncology therapies. Our in-house development organization includes clinical development, regulatory, quality and data management. We plan to build out our commercial and marketing capabilities in the second half of 2020 to prepare for the launch of ROLONTIS.

We have three drugs in development:

• ROLONTIS, a novel long-acting granulocyte colony-stimulating for chemotherapy-induced neutropenia which has been filed with the FDA and has a Prescription Drug User Fee Act date of October 24, 2020;

• Poziotinib, a novel irreversible tyrosine kinase inhibitor under investigation for non-small cell lung cancer tumors with various mutations; and

• Anti-CD20-IFNá, an antibody-interferon fusion molecule directed against CD20 that is in Phase 1 development for treating relapsed or refractory non-Hodgkin’s lymphoma patients (including diffuse large B-cell lymphoma).

Our business strategy is the development of our late-stage assets through commercialization and the sourcing of additional assets that are synergistic with our existing portfolio (through purchase acquisitions, in-licensing transactions, or co-development and marketing arrangements).

On March 1, 2019, we completed the sale of our seven then-commercialized drugs, including FUSILEV, KHAPZORY, FOLOTYN, ZEVALIN, MARQIBO, BELEODAQ, and EVOMELA (the “Commercial Product Portfolio”) to Acrotech Biopharma LLC (“Acrotech”). Upon closing we received $158.8 million in an upfront cash payment of which $4 million was held in escrow until November 5, 2019. We are also entitled to receive up to an aggregate of $140 million upon Acrotech’s future achievement of certain regulatory milestones (totaling $40 million) and sales-based milestones (totaling $100 million) relating to the Commercial Product Portfolio.

Corporate Information

Spectrum Pharmaceuticals, Inc. is a Delaware corporation that was originally incorporated in Colorado as Americus Funding Corporation in December 1987, became NeoTherapeutics, Inc. in August 1996, was reincorporated in Delaware in June 1997, and was renamed Spectrum Pharmaceuticals, Inc. in December 2002. More comprehensive information about our products and us is available through our website at www.sppirx.com. The information on our website is not incorporated by reference into this prospectus. Our principal executive offices are located at 11500 South Eastern Avenue, Suite 240, Henderson, Nevada 89052, and our telephone number is (702) 835-6300.

Securities We May Offer

We may offer shares of our common stock and preferred stock, debt securities, warrants for debt or equity securities and units consisting of the foregoing, from time to time under this prospectus, together with any

2

applicable prospectus supplement and related free writing prospectus, at prices and on terms to be determined by market conditions at the time of offering. This prospectus provides you with a general description of the securities we may offer. Each time we offer a type or series of securities, we will provide a prospectus supplement that will describe the specific amounts, prices and other important terms of the securities, including, to the extent applicable:

• designation or classification;

• aggregate principal amount or aggregate offering price;

• maturity, if applicable;

• original issue discount, if any;

• rates and times of payment of interest or dividends, if any;

• redemption, conversion, exchange or sinking fund terms, if any;

• conversion or exchange prices or rates, if any, and, if applicable, any provisions for changes to or adjustments in the conversion or exchange prices or rates and in the securities or other property receivable upon conversion or exchange;

• ranking;

• restrictive covenants, if any;

• voting or other rights, if any; and

• important U.S. federal income tax considerations.

A prospectus supplement and any related free writing prospectus that we may authorize to be provided to you may also add, update or change information contained in this prospectus or in documents we have incorporated by reference. However, no prospectus supplement or free writing prospectus will offer a security that is not registered and described in this prospectus at the time of the effectiveness of the Registration Statement of which this prospectus is a part.

The securities may be offered directly by us or by any selling security holder from time to time, through agents designated by us or to or through underwriters, brokers or dealers. We will provide specific information about any selling security holders in one or more supplements to this prospectus. We, and our underwriters or agents, reserve the right to accept or reject all or part of any proposed purchase of securities. If we do offer securities through underwriters or agents, we will include in the applicable prospectus supplement:

• the names of those underwriters or agents;

• applicable fees, discounts and commissions to be paid to them;

• details regarding options to purchase additional securities, if any; and

• the net proceeds to us.

3

RISK FACTORS

Investment in our securities involves risks. Prior to making a decision about investing in our securities, you should consider carefully all of the information included in and incorporated by reference or deemed to be incorporated by reference in this prospectus or the applicable prospectus supplement, including the risk factors incorporated by reference herein from our Annual Report on Form 10-K for the year ended December 31, 2019, filed with the SEC on March 2, 2020, as updated by annual, quarterly and other reports and documents we file with the SEC after the date of this prospectus and that are incorporated by reference herein or in the applicable prospectus supplement or any free writing prospectus. Each of these risk factors could have a material adverse effect on our business, results of operations, financial position or cash flows, which may result in the loss of all or part of your investment. The risks and uncertainties we have described are not the only ones we face. Additional risks and uncertainties not presently known to us or that we currently consider immaterial may also impair our business operations. If any of these risks actually occur, our business and financial results could be harmed. In that case, the trading price of our common stock or other securities could decline. To the extent a particular offering implicates additional known material risks, we will include a discussion of those risks in the applicable prospectus supplement.

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus and the documents incorporated by reference into this prospectus contain certain forward-looking statements within the meaning of Section 27A of the Securities Act, and Section 21E of the Securities Exchange Act of 1934, as amended, or the Exchange Act, in reliance upon the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Forward-looking statements include, without limitation, statements regarding the success, safety and efficacy of our drug products, product approvals, product sales, revenues, development timelines, product acquisitions, liquidity and capital resources and trends, and other statements containing forward-looking words, such as, “believes,” “may,” “could,” “would,” “will,” “expects,” “intends,” “estimates,” “anticipates,” “plans,” “seeks,” or “continues” or the negative thereof or variation thereon or similar terminology (although not all forward-looking statements contain these words). Such forward-looking statements are based on the beliefs of our management as well as assumptions made by and information currently available to our management. Readers should not put undue reliance on these forward-looking statements because they involve known and unknown risks, uncertainties and other factors, some of which are beyond our control. These risks, uncertainties and other factors may cause our actual results, performance or achievements to be materially different from the anticipated future results, performance or achievements expressed or implied by the forward-looking statements.

Factors that might cause these differences include the following:

• our ability to successfully develop, obtain regulatory approval for, and market our products;

• the approval, or timing of approval, of our products or new indications for our products by the U.S. Food and Drug Administration (the “FDA”) and other international regulatory agencies;

• actions by the FDA and other regulatory agencies, including international agencies;

• the timing and/or results of pending or future clinical trials, and our reliance on contract research organizations;

• our ability to maintain sufficient cash resources to fund our business operations;

• our history of net losses;

• our ability to enter into strategic alliances with partners for manufacturing, development and commercialization;

• our competitors’ progress with their drug development programs, which could adversely impact the perceived or actual value of our in-development drugs;

4

• the ability of our manufacturing partners to meet our product demands and timelines;

• our ability to identify and acquire new product candidates and to successfully integrate those product candidates into our operations;

• our ability to protect our intellectual property rights;

• the impact of legislative or regulatory reform on the pricing for pharmaceutical products;

• the impact of any litigation to which we are, or may become a party;

• our ability, and that of our suppliers, development partners, and manufacturing partners, to comply with laws, regulations and standards that govern or affect the pharmaceutical and biotechnology industries; and

• our ability to maintain the services of our key executives and other personnel.

We urge you to consider these factors carefully in evaluating the forward-looking statements contained in this prospectus and any prospectus supplement. All subsequent written or oral forward-looking statements attributable to our company or persons acting on our behalf are expressly qualified in their entirety by these cautionary statements. The forward-looking statements included in this prospectus are made only as of the date of this prospectus. We undertake no obligation to update publicly any forward-looking statements, whether as a result of new information, future events or otherwise, except to the extent that we are required to do so by law.

5

USE OF PROCEEDS

Unless we indicate otherwise in the applicable prospectus supplement, we anticipate that the net proceeds from the sale of the securities offered from time to time hereby will be used for general corporate purposes, including, without limitation, research and development and clinical development costs to support the advancement of our in-development drug candidates, activities in connection with the launch of our in-development drug candidates, including hiring and building inventory supply, making acquisitions of assets, businesses, companies or securities, capital expenditures and for working capital. When a particular series of securities is offered, the related prospectus supplement will set forth our intended use of the net proceeds we receive from the sale of the securities. Pending the application of the net proceeds, we may invest the proceeds in short-term, interest-bearing instruments or other investment-grade securities.

6

DESCRIPTION OF CAPITAL STOCK WE MAY OFFER

General

Our authorized capital stock consists of 300,000,000 shares of common stock, par value $0.001 per share, and 5,000,000 shares of preferred stock, par value $0.001 per share.

The following description of our common stock and preferred stock, together with the additional information included in any applicable prospectus supplements or related free writing prospectuses, summarizes the material terms and provisions of these types of securities, but it is not complete. For the complete terms of our common stock and preferred stock, please refer to our restated certificate of incorporation and our third amended and restated bylaws that are incorporated by reference into the Registration Statement which includes this prospectus and, with respect to preferred stock, any certificate of designation that we may file with the SEC for a series of preferred stock we may designate, if any.

We will describe in a prospectus supplement or related free writing prospectuses, the specific terms of any common stock or preferred stock we may offer pursuant to this prospectus. If indicated in a prospectus supplement, the terms of such common stock or preferred stock may differ from the terms described below.

Common Stock

As of May 4, 2020, there were 116,468,472 shares of common stock outstanding. The holders of our common stock are entitled to one vote for each share held of record on all matters submitted to a vote of the stockholders. The holders of common stock are not entitled to cumulative voting rights with respect to the election of directors, and as a consequence, minority stockholders will not be able to elect directors on the basis of their votes alone.

Subject to preferences that may be applicable to any then outstanding shares of preferred stock, holders of common stock are entitled to receive ratably such dividends as may be declared by the board of directors out of funds legally available therefor. In the event of a liquidation, dissolution or winding up of us, holders of the common stock are entitled to share ratably in all assets remaining after payment of liabilities and the liquidation preferences of any then outstanding shares of preferred stock. Holders of common stock have no preemptive rights and no right to convert their common stock into any other securities. There are no redemption or sinking fund provisions applicable to our common stock. All outstanding shares of common stock are, and all shares of common stock to be issued under this prospectus will be, fully paid and non-assessable. The rights, preferences and privileges of holders of our common stock are subject to, and may be adversely affected by, the rights of the holders of shares of any of our outstanding preferred stock.

Listing

Our common stock is listed under the symbol “SPPI” on the NASDAQ.

Transfer Agent and Registrar

The transfer agent and registrar for our common stock is Computershare Trust Company, N.A.

Dividends

We have not declared any cash dividends on our common stock since 2012 and we do not anticipate paying any cash dividends on our common stock in the foreseeable future.

Stockholder Rights Agreement

On November 29, 2010, our board of directors approved a stockholder rights agreement, effective December 13, 2010, or the Stockholder Rights Agreement. A stockholder rights agreement is designed to deter

7

coercive, unfair, or inadequate takeovers and other abusive tactics that might be used in an attempt to gain control of our company. The Stockholder Rights Agreement will not prevent takeovers at a full and fair price, but rather is designed to deter coercive takeover tactics and to encourage anyone attempting to acquire our company to first negotiate with our board of directors.

On March 27, 2018, we entered into a Second Amendment to the Stockholder Rights Agreement which had the effect of suspending the Stockholders Rights Agreement as of March 30, 2018, though it will expire under its terms on December 13, 2020.

Preferred Stock

We are authorized to issue a total of 5,000,000 shares of preferred stock. As of May 4, 2020, there were no shares of preferred stock issued and outstanding.

Preferred stock may be issued from time to time, in one or more series, as authorized by the board of directors, without stockholder approval. The prospectus supplement relating to the preferred shares offered thereby will include specific terms of any preferred shares offered, including, if applicable:

• the title of the shares of preferred stock;

• the number of shares of preferred stock offered, the liquidation preference per share and the offering price of the shares of preferred stock;

• the dividend rate(s), period(s) and/or payment date(s) or method(s) of calculation thereof applicable to the shares of preferred stock;

• whether the shares of preferred stock are cumulative or not and, if cumulative, the date from which dividends on the shares of preferred stock shall accumulate;

• the procedures for any auction and remarketing, if any, for the shares of preferred stock;

• the provision for a sinking fund, if any, for the shares of preferred stock;

• the provision for redemption or repurchase, if applicable, and any restrictions on our ability to exercise those redemption and repurchase rights of the shares of preferred stock;

• any listing of the shares of preferred stock on any securities exchange;

• the terms and conditions, if applicable, upon which the shares of preferred stock will be convertible into common shares, including the conversion price (or manner of calculation thereof);

• discussion of federal income tax considerations applicable to the shares of preferred stock;

• the relative ranking and preferences of the shares of preferred stock as to dividend rights and rights upon liquidation, dissolution or winding up of our affairs;

• any limitations on issuance of any series or class of shares of preferred stock ranking senior to or on a parity with such series or class of shares of preferred stock as to dividend rights and rights upon liquidation, dissolution or winding up of our affairs;

• any other specific terms, preferences, rights, limitations or restrictions of the shares of preferred stock; and

• any voting rights of such preferred stock.

The transfer agent and registrar for any series or class of preferred stock will be set forth in the applicable prospectus supplement.

Possible Anti-Takeover Effects of Delaware Law and our Charter Documents

Provisions of the Delaware General Corporation Law, or DGCL, our restated certificate of incorporation, and our third amended and restated bylaws, could make it more difficult to acquire us by means of a tender offer,

8

a proxy contest or otherwise, or to remove incumbent officers and directors. These provisions, summarized below, are expected to discourage certain types of coercive takeover practices and takeover bids that our board of directors may consider inadequate and to encourage persons seeking to acquire control of us to first negotiate with our board of directors. We believe that the benefits of increased protection of our ability to negotiate with the proponent of an unfriendly or unsolicited proposal to acquire or restructure us outweigh the disadvantages of discouraging takeover or acquisition proposals because, among other things, negotiation of these proposals could result in an improvement of their terms.

Delaware Anti-Takeover Statute

We are subject to Section 203 of the DGCL, an anti-takeover statute. In general, Section 203 of the DGCL prohibits a publicly held Delaware corporation from engaging in a “business combination” with an “interested stockholder” for a period of three years following the time the person became an interested stockholder, unless the business combination or the acquisition of shares that resulted in a stockholder becoming an interested stockholder is approved in a prescribed manner. Generally, a “business combination” includes a merger, asset or stock sale, or other transaction resulting in a financial benefit to the interested stockholder. Generally, an “interested stockholder” is a person who, together with affiliates and associates, owns (or within three years prior to the determination of interested stockholder status did own) 15% or more of a corporation’s voting stock. The existence of this provision would be expected to have an anti-takeover effect with respect to transactions not approved in advance by our board of directors, including discouraging attempts that might result in a premium over the market price for the shares of common stock held by our stockholders.

Election and Removal of Directors

Our board of directors is elected annually by all holders of our capital stock. The stockholders may nominate one or more persons for election as directors at an annual meeting of stockholders, but only if written notice of such stockholder’s intent to make such nomination or nominations has been received by the Secretary of the Company not less than ninety (90) nor more than one hundred twenty (120) days prior to the first anniversary of the preceding year’s annual meeting of stockholders. Any vacancy on the board of directors resulting from death, resignation, removal or otherwise or newly created directorships may be filled by the vote of the majority of directors then in office, although less than a quorum, or by a sole remaining director.

Amendment

The affirmative vote of a majority of the entire board of directors may amend and repeal the bylaws. The bylaws may be altered, amended or repealed, and new bylaws may be adopted, at any annual meeting of the stockholders (or at any special meeting thereof duly called for that purpose) by a majority of the combined voting power of the then outstanding shares of capital stock of all classes and series of the Company entitled to vote generally in the election of directors, voting as a single class, provided that, in the notice of any such special meeting, notice of such purpose shall be given.

Size of Board and Vacancies

Pursuant to our restated certificate of incorporation, and our third amended and restated bylaws, our board of directors has the exclusive right to fix the size of the board and to fill any vacancies resulting from death, resignation, disqualification or removal as well as any newly created directorships arising from an increase in the size of the board.

Special Stockholder Meetings

Our third amended and restated bylaws provide that special meetings of stockholders can be called only by the board of directors, the chairman of the board of directors or the chief executive officer. Stockholders are not permitted to call a special meeting and cannot require the board of directors to call a special meeting. There is no right of stockholders to act by written consent without a meeting, unless the consent is unanimous.

9

Stockholder Action by Unanimous Written Consent

Any action which may be taken at any annual or special meeting of stockholders, may be taken without a meeting and without prior notice, if a consent in writing or by electronic communication, setting forth the action so taken, is given by the holders of all of the outstanding shares entitled to vote thereon.

Requirements for Advance Notification of Stockholder Nominations and Proposals

Our third amended and restated bylaws establish advance notice procedures with respect to stockholder proposals and nomination of candidates for election as directors other than nominations made by or at the direction of our board of directors or a committee of our board of directors.

No Cumulative Voting

The DGCL provides that stockholders are denied the right to cumulate votes in the election of directors unless our certificate of incorporation provides otherwise. Our restated certificate of incorporation does not provide for cumulative voting.

Authorized but Unissued Shares

Our authorized but unissued shares of common stock and preferred stock will be available for future issuance without stockholder approval. We may use additional shares for a variety of purposes, including future public offerings to raise additional capital, to fund acquisitions and as employee compensation. The existence of authorized but unissued shares of undesignated preferred stock may enable our board of directors to render more difficult or to discourage an attempt to obtain control of us by means of a merger, tender offer, proxy contest or otherwise. For example, if in the due exercise of its fiduciary obligations, our board of directors were to determine that a takeover proposal is not in the best interests of us or our stockholders, our board of directors could cause shares of preferred stock to be issued without stockholder approval in one or more private offerings or other transactions that might dilute the voting or other rights of the proposed acquirer, stockholder or stockholder group. The rights of holders of our common stock described above will be subject to, and may be adversely affected by, the rights of any preferred stock that we may designate and issue in the future. The issuance of shares of undesignated preferred stock could decrease the amount of earnings and assets available for distribution to holders of shares of common stock. The issuance may also adversely affect the rights and powers, including voting rights, of these holders and may have the effect of delaying, deterring or preventing a change in control of us.

Director Liability

Our third amended and restated bylaws limit the extent to which our directors are personally liable to us and our stockholders, to the fullest extent permitted by the DGCL. The inclusion of this provision in our third amended and restated bylaws may reduce the likelihood of derivative litigation against directors and may discourage or deter stockholders or management from bringing a lawsuit against directors for breach of their duty of care.

10

DESCRIPTION OF DEBT SECURITIES WE MAY OFFER

The following description, together with the additional information we include in any applicable prospectus supplements or free writing prospectuses, summarizes the material terms and provisions of the debt securities that we may offer under this prospectus. We may issue debt securities, in one or more series, as either senior or subordinated debt or as senior or subordinated convertible debt. While the terms we have summarized below will apply generally to any future debt securities we may offer under this prospectus, we will describe the particular terms of any debt securities that we may offer in more detail in the applicable prospectus supplement or free writing prospectus. The terms of any debt securities we offer under a prospectus supplement may differ from the terms we describe below. Unless the context requires otherwise, whenever we refer to the “indentures,” we also are referring to any supplemental indentures that specify the terms of a particular series of debt securities.

We will issue any senior debt securities under the senior indenture that we will enter into with the trustee named in the senior indenture. We will issue any subordinated debt securities under the subordinated indenture and any supplemental indentures that we will enter into with the trustee named in the subordinated indenture. We have filed forms of these documents as exhibits to the Registration Statement, of which this prospectus is a part, and supplemental indentures and forms of debt securities containing the terms of the debt securities being offered will be filed as exhibits to the Registration Statement of which this prospectus is a part or will be incorporated by reference from reports that we file with the SEC.

The indentures will be qualified under the Trust Indenture Act of 1939, as amended, or the Trust Indenture Act. We use the term “trustee” to refer to either the trustee under the senior indenture or the trustee under the subordinated indenture, as applicable.

The following summaries of material provisions of the senior debt securities, the subordinated debt securities and the indentures are subject to, and qualified in their entirety by reference to, all of the provisions of the indenture and any supplemental indentures applicable to a particular series of debt securities. We urge you to read the applicable prospectus supplements and any related free writing prospectuses related to the debt securities that we may offer under this prospectus, as well as the complete indenture that contains the terms of the debt securities. Except as we may otherwise indicate, the terms of the senior indenture and the subordinated indenture are identical.

General

The terms of each series of debt securities will be established by or pursuant to a resolution of our board of directors and set forth or determined in the manner provided in an officers’ certificate or by a supplemental indenture. Debt securities may be issued in separate series without limitation as to aggregate principal amount. We may specify a maximum aggregate principal amount for the debt securities of any series. We will describe in the applicable prospectus supplement the terms of the series of debt securities being offered, including:

• the title;

• the principal amount being offered, and if a series, the total amount authorized and the total amount outstanding;

• any limit on the amount that may be issued;

• whether or not we will issue the series of debt securities in global form, and, if so, the terms and who the depositary will be;

• the maturity date;

• whether and under what circumstances, if any, we will pay additional amounts on any debt securities held by a person who is not a U.S. person for tax purposes, and whether we can redeem the debt securities if we have to pay such additional amounts;

11

• the annual interest rate, which may be fixed or variable, or the method for determining the rate and the date interest will begin to accrue, the dates interest will be payable and the regular record dates for interest payment dates or the method for determining such dates;

• whether or not the debt securities will be secured or unsecured, and the terms of any secured debt;

• the terms of the subordination of any series of subordinated debt;

• the place where payments will be payable;

• restrictions on transfer, sale or other assignment, if any;

• our right, if any, to defer payment of interest and the maximum length of any such deferral period;

• the date, if any, after which, and the price at which, we may, at our option, redeem the series of debt securities pursuant to any optional or provisional redemption provisions and the terms of those redemption provisions;

• provisions for a sinking fund purchase or other analogous fund, if any, including the date, if any, on which, and the price at which we are obligated, pursuant thereto or otherwise, to redeem, or at the holder’s option, to purchase, the series of debt securities and the currency or currency unit in which the debt securities are payable;

• provisions relating to modification of the terms of the security or the rights of the security holder;

• whether the indenture will restrict our ability or the ability of our subsidiaries to:

• incur additional indebtedness;

• issue additional securities;

• create liens;

• pay dividends or make distributions in respect of our capital stock or the capital stock of our subsidiaries;

• redeem capital stock;

• place restrictions on our subsidiaries’ ability to pay dividends, make distributions or transfer assets;

• make investments or other restricted payments;

• sell, transfer or otherwise dispose of assets;

• enter into sale-leaseback transactions;

• engage in transactions with stockholders or affiliates;

• issue or sell stock of our subsidiaries; or

• effect a consolidation or merger;

• whether the indenture will require us to maintain any interest coverage, fixed charge, cash flow-based, asset-based or other financial ratios;

• information describing any book-entry features;

• the applicability of the provisions in the indenture on discharge;

• whether the debt securities are to be offered at a price such that they will be deemed to be offered at an “original issue discount” as defined in paragraph (a) of Section 1273 of the Internal Revenue Code of 1986, as amended;

• the denominations in which we will issue the series of debt securities, if other than denominations of $1,000 and any integral multiple thereof;

12

• the currency of payment of debt securities if other than U.S. dollars and the manner of determining the equivalent amount in U.S. dollars; and

• any other specific terms, preferences, rights or limitations of, or restrictions on, the debt securities, including any additional events of default or covenants provided with respect to the debt securities, and any terms that may be required by us or advisable under applicable laws or regulations.

U.S. federal income tax consequences applicable to debt securities sold at an original issue discount will be described in the applicable prospectus supplement. In addition, U.S. federal income tax or other consequences applicable to any debt securities which are denominated in a currency or currency unit other than U.S. dollars may be described in the applicable prospectus supplement.

Conversion or Exchange Rights

We will set forth in the applicable prospectus supplement the terms under which a series of debt securities may be convertible into or exchangeable for our common stock, our preferred stock or other securities (including securities of a third party). We will include provisions as to whether conversion or exchange is mandatory, at the option of the holder or at our option. We may include provisions pursuant to which the number of shares of our common stock, our preferred stock or other securities (including securities of a third party) that the holders of the series of debt securities receive would be subject to adjustment.

Consolidation, Merger or Sale

Unless we provide otherwise in the prospectus supplement applicable to a particular series of debt securities, the indentures will not contain any covenant that restricts our ability to merge or consolidate, or sell, convey, transfer or otherwise dispose of all or substantially all of our assets. However, any successor to or acquiror of such assets must assume all of our obligations under the indentures or the debt securities, as appropriate. If the debt securities are convertible into or exchangeable for our other securities or securities of other entities, the person with whom we consolidate or merge or to whom we sell all of our property must make provisions for the conversion of the debt securities into securities that the holders of the debt securities would have received if they had converted the debt securities before the consolidation, merger or sale.

Events of Default under the Indenture

Unless we provide otherwise in the prospectus supplement applicable to a particular series of debt securities, the following are events of default under the indentures with respect to any series of debt securities that we may issue:

• if we fail to pay interest when due and payable and our failure continues for 90 days and the time for payment has not been extended;

• if we fail to pay the principal, premium or sinking fund payment, if any, when due and payable and the time for payment has not been extended;

• if we fail to observe or perform any other covenant contained in the debt securities or the indentures, other than a covenant specifically relating to another series of debt securities, and our failure continues for 90 days after we receive notice from the trustee or we and the trustee receive notice from the holders of at least 25% in aggregate principal amount of the outstanding debt securities of the applicable series; and

• if specified events of bankruptcy, insolvency or reorganization occur.

We will describe in each applicable prospectus supplement any additional events of default relating to the relevant series of debt securities. If an event of default with respect to debt securities of any series occurs and is continuing, other than an event of default specified in the last bullet point above, the trustee or the holders of at

13

least 25% in aggregate principal amount of the outstanding debt securities of that series, by notice to us in writing, and to the trustee if notice is given by such holders, may declare the unpaid principal, premium, if any, and accrued interest, if any, due and payable immediately. If an event of default arises due to the occurrence of certain specified bankruptcy, insolvency or reorganization events, the unpaid principal, premium, if any, and accrued interest, if any, of each issue of debt securities then outstanding shall be due and payable without any notice or other action on the part of the trustee or any holder.

The holders of a majority in principal amount of the outstanding debt securities of an affected series may waive any default or event of default with respect to the series and its consequences, except defaults or events of default regarding payment of principal, premium, if any, or interest, unless we have cured the default or event of default in accordance with the indenture. Any such waiver shall cure the default or event of default.

Subject to the terms of the applicable indenture, if an event of default under an indenture shall occur and be continuing, the trustee will be under no obligation to exercise any of its rights or powers under such indenture at the request or direction of any of the holders of the applicable series of debt securities, unless such holders have offered the trustee reasonable indemnity or security satisfactory to it against any loss, liability or expense. The holders of a majority in principal amount of the outstanding debt securities of any series will have the right to direct the time, method and place of conducting any proceeding for any remedy available to the trustee, or exercising any trust or power conferred on the trustee, with respect to the debt securities of that series, provided that:

• the direction so given by the holders is not in conflict with any law or the applicable indenture; and

• subject to its duties under the Trust Indenture Act, the trustee need not take any action that might involve it in personal liability or might be unduly prejudicial to the holders not involved in the proceeding.

The indentures provide that if an event of default has occurred and is continuing, the trustee will be required in the exercise of its powers to use the degree of care that a prudent person would use in the conduct of its own affairs. The trustee, however, may refuse to follow any direction that conflicts with law or the indenture, or that the trustee determines is unduly prejudicial to the rights of any other holder of the relevant series of debt securities, or that would involve the trustee in personal liability. Prior to taking any action under the indentures, the trustee will be entitled to indemnification against all costs, expenses and liabilities that would be incurred by taking or not taking such action.

A holder of the debt securities of any series will have the right to institute a proceeding under the indentures or to appoint a receiver or trustee, or to seek other remedies only if:

• the holder has given written notice to the trustee of a continuing event of default with respect to that series;

• the holders of at least 25% in aggregate principal amount of the outstanding debt securities of that series have made a written request and such holders have offered reasonable indemnity to the trustee or security satisfactory to it against any loss, liability or expense to be incurred in compliance with instituting the proceeding as trustee; and

• the trustee does not institute the proceeding, and does not receive from the holders of a majority in aggregate principal amount of the outstanding debt securities of that series other conflicting directions within 60 days after the notice, request and offer.

These limitations do not apply to a suit instituted by a holder of debt securities if we default in the payment of the principal, premium, if any, or interest on, the debt securities.

We will periodically file statements with the trustee regarding our compliance with specified covenants in the indentures.

The indentures provide that if a default occurs and is continuing and is actually known to a responsible officer of the trustee, the trustee must mail to each holder notice of the default within 45 days after it occurs,

14

unless such default has been cured. Except in the case of a default in the payment of principal or premium of, or interest on, any debt security or certain other defaults specified in an indenture, the trustee shall be protected in withholding such notice if and so long as the board of directors, the executive committee or a trust committee of directors, or responsible officers of the trustee, in good faith determine that withholding notice is in the best interests of holders of the relevant series of debt securities.

Modification of Indenture; Waiver

Subject to the terms of the indenture for any series of debt securities that we may issue, we and the trustee may change an indenture without the consent of any holders with respect to the following specific matters:

• to fix any ambiguity, defect or inconsistency in the indenture;

• to comply with the provisions described above under “—Consolidation, Merger or Sale”;

• to comply with any requirements of the SEC in connection with the qualification of any indenture under the Trust Indenture Act;

• to add to, delete from or revise the conditions, limitations and restrictions on the authorized amount, terms or purposes of issue, authentication and delivery of debt securities, as set forth in such indenture;

• to provide for the issuance of, and establish the form and terms and conditions of, the debt securities of any series as provided under “—General,” to establish the form of any certifications required to be furnished pursuant to the terms of the indenture or any series of debt securities, or to add to the rights of the holders of any series of debt securities;

• to evidence and provide for the acceptance of appointment hereunder by a successor trustee;

• to provide for uncertificated debt securities in addition to or in place of certificated debt securities and to make all appropriate changes for such purpose;

• to add such new covenants, restrictions, conditions or provisions for the protection of the holders, and to make the occurrence, or the occurrence and the continuance, of a default in any such additional covenants, restrictions, conditions or provisions an event of default or to surrender any right or power conferred to us in the indenture; or

• to change anything that does not materially adversely affect the interests of any holder of debt securities of any series in any material respect; provided that any amendment made solely to conform the provisions of the indenture to the corresponding description of the debt securities contained in the applicable prospectus or prospectus supplement shall be deemed not to adversely affect the interests of the holders of such debt securities; provided further, that in connection with any such amendment we will provide the trustee with an officers’ certificate certifying that such amendment will not adversely affect the rights or interests of the holders of such debt securities.

In addition, under the indentures, the rights of holders of a series of debt securities may be changed by us and the trustee with the written consent of the holders of at least a majority in aggregate principal amount of the outstanding debt securities of each series that is affected. However, unless we provide otherwise in the prospectus supplement applicable to a particular series of debt securities, we and the trustee may only make the following changes with the consent of each holder of any outstanding debt securities affected:

• extending the fixed maturity of the series of debt securities;

• reducing the principal amount, reducing the rate of or extending the time of payment of interest, or reducing any premium payable upon the redemption of any debt securities;

• reducing the percentage of debt securities, the holders of which are required to consent to any amendment, supplement, modification or waiver;

• changing any of our obligations to pay additional amounts;

15

• reducing the amount of principal of an original issue discount security or any other note payable upon acceleration of the maturity thereof;

• changing the currency in which any note or any premium or interest is payable;

• impairing the right to enforce any payment on or with respect to any note;

• adversely changing the right to convert or exchange, including decreasing the conversion rate or increasing the conversion price of, such note, if applicable;

• in the case of the subordinated indenture, modifying the subordination provisions in a manner adverse to the holders of the subordinated debt securities;

• if the debt securities are secured, changing the terms and conditions pursuant to which the debt securities are secured in a manner adverse to the holders of the secured debt securities;

• reducing the requirements contained in the applicable indenture for quorum or voting;

• changing any of our obligations to maintain an office or agency in the places and for the purposes required by the indentures; or

• modifying any of the above provisions set forth in this paragraph.

Discharge

Each indenture provides that, subject to the terms of the indenture and any limitation otherwise provided in the prospectus supplement applicable to a particular series of debt securities, we may elect to be discharged from our obligations with respect to one or more series of debt securities, except for specified obligations, including obligations to:

• register the transfer or exchange of debt securities of the series;

• replace stolen, lost or mutilated debt securities of the series;

• maintain paying agencies;

• hold monies for payment in trust;

• recover excess money held by the trustee;

• compensate and indemnify the trustee; and

• appoint any successor trustee.

In order to exercise our rights to be discharged, we must deposit with the trustee money or government obligations sufficient to pay all the principal of, and any premium and interest on, the debt securities of the series on the dates payments are due.

Form, Exchange and Transfer

We will issue the debt securities of each series only in fully registered form without coupons and, unless we otherwise specify in the applicable prospectus supplement, in denominations of $1,000 and any integral multiple thereof. The indentures provide that we may issue debt securities of a series in temporary or permanent global form and as book-entry securities that will be deposited with, or on behalf of, The Depository Trust Company or another depositary named by us and identified in a prospectus supplement with respect to that series.

At the option of the holder, subject to the terms of the indentures and the limitations applicable to global securities described in the applicable prospectus supplement, the holder of the debt securities of any series can exchange the debt securities for other debt securities of the same series, in any authorized denomination and of like tenor and aggregate principal amount.

16

Subject to the terms of the indentures and the limitations applicable to global securities set forth in the applicable prospectus supplement, holders of the debt securities may present the debt securities for exchange or for registration of transfer, duly endorsed or with the form of transfer endorsed thereon duly executed if so required by us or the security registrar, at the office of the security registrar or at the office of any transfer agent designated by us for this purpose. Unless otherwise provided in the debt securities that the holder presents for transfer or exchange, we will impose no service charge for any registration of transfer or exchange, but we may require payment of any taxes or other governmental charges.

We will name in the applicable prospectus supplement the security registrar, and any transfer agent in addition to the security registrar, that we initially designate for any debt securities. We may at any time designate additional transfer agents or rescind the designation of any transfer agent or approve a change in the office through which any transfer agent acts, except that we will be required to maintain a transfer agent in each place of payment for the debt securities of each series.

If we elect to redeem the debt securities of any series, we will not be required to:

• issue, register the transfer of, or exchange any debt securities of that series during a period beginning at the opening of business 15 days before the day of mailing of a notice of redemption of any debt securities that may be selected for redemption and ending at the close of business on the day of the mailing; or

• register the transfer of or exchange any debt securities so selected for redemption, in whole or in part, except the unredeemed portion of any debt securities we are redeeming in part.

Information Concerning the Trustee

The trustee, other than during the occurrence and continuance of an event of default under an indenture, undertakes to perform only those duties as are specifically set forth in the applicable indenture and is under no obligation to exercise any of the powers given it by the indentures at the request of any holder of debt securities unless it is offered reasonable security and indemnity against the costs, expenses and liabilities that it might incur. However, upon an event of default under an indenture, the trustee must use the same degree of care as a prudent person would exercise or use in the conduct of his or her own affairs.

Payment and Paying Agents

Unless we otherwise indicate in the applicable prospectus supplement, we will make payment of the interest on any debt securities on any interest payment date to the person in whose name the debt securities, or one or more predecessor securities, are registered at the close of business on the regular record date for the interest payment.

We will pay principal of and any premium and interest on the debt securities of a particular series at the office of the paying agents designated by us, except that unless we otherwise indicate in the applicable prospectus supplement, we will make interest payments by check that we will mail to the holder or by wire transfer to certain holders. Unless we otherwise indicate in the applicable prospectus supplement, we will designate the corporate trust office of the trustee in the City of New York as our sole paying agent for payments with respect to debt securities of each series. We will name in the applicable prospectus supplement any other paying agents that we initially designate for the debt securities of a particular series. We will maintain a paying agent in each place of payment for the debt securities of a particular series.

All money we pay to a paying agent or the trustee for the payment of the principal of or any premium or interest on any debt securities that remains unclaimed at the end of two years after such principal, premium or interest has become due and payable will be repaid to us, and the holder of the debt security thereafter may look only to us for payment thereof.

17

Governing Law

The indentures and the debt securities will be governed by and construed in accordance with the laws of the State of New York, except to the extent that the Trust Indenture Act is applicable.

Ranking Debt Securities

The subordinated debt securities will be unsecured and will be subordinate and junior in priority of payment to certain of our other indebtedness to the extent described in a prospectus supplement. The subordinated indenture does not limit the amount of subordinated debt securities that we may issue. It also does not limit us from issuing any other secured or unsecured debt.

The senior debt securities will be unsecured and will rank equally in right of payment to all our other senior unsecured debt. The senior indenture does not limit the amount of senior debt securities that we may issue. It also does not limit us from issuing any other secured or unsecured debt.

18

DESCRIPTION OF WARRANTS WE MAY OFFER

As of May 4, 2020, we had no warrants to purchase shares of our common stock outstanding. We typically issue warrants to purchase shares of our common stock to investors as part of a financing transaction, or in connection with services rendered by placement agents and outside consultants.

We may issue warrants to purchase debt securities, preferred stock, common stock or any combination of the foregoing. We may issue warrants independently or together with any other securities we offer under a prospectus supplement. The warrants may be attached to or separate from the securities. We will issue each series of warrants under a separate warrant agreement to be entered into between a warrant agent and us. The warrant agent will act solely as our agent in connection with the warrants and will not have any obligations or relationship of agency or trust for or with holders or beneficial owners of warrants. The following outlines some of the general terms and provisions of the warrants that we may issue from time to time. When we issue warrants, we will provide the specific terms of the warrants and the applicable warrant agreement in a prospectus supplement and any related free writing prospectuses and such terms may differ from those described below. To the extent the information contained in the prospectus supplement differs from this summary description, you should rely on the information in the prospectus supplement. The following description, and any description of the warrants included in a prospectus supplement, may not be complete and is subject to and qualified in its entirety by reference to the terms and provisions of the applicable warrant agreement.

Debt Warrants

We will describe in the applicable prospectus supplement and any related free writing prospectuses the terms of the debt warrants being offered, the warrant agreement relating to the debt warrants and the debt warrant certificates representing the debt warrants, including, as applicable:

• the title of the debt warrants;

• the aggregate number of the debt warrants;

• the price or prices at which the debt warrants will be issued;

• the designation, aggregate principal amount and terms of the debt securities purchasable upon exercise of the debt warrants, and the procedures and conditions relating to the exercise of the debt warrants;

• the designation and terms of any related debt securities with which the debt warrants are issued, and the number of the debt warrants issued with each security;

• the date, if any, on and after which the debt warrants and the related debt securities will be separately transferable;

• the principal amount of debt securities purchasable upon exercise of each debt warrant, and the price at which the principal amount of the debt securities may be purchased upon exercise;

• the date on which the right to exercise the debt warrants will commence, and the date on which the right will expire;

• the maximum or minimum number of the debt warrants that may be exercised at any time;

• information with respect to book-entry procedures, if any;

• changes to or adjustments in the exercise price of the debt warrants;

• a discussion of the material U.S. federal income tax considerations applicable to the exercise of the debt warrants; and

• any other terms of the debt warrants and terms, procedures and limitations relating to the exercise of the debt warrants.

19

As may be permitted under the warrant agreement, holders may exchange debt warrant certificates for new debt warrant certificates of different denominations, and may exercise debt warrants at the corporate trust office of the warrant agent or any other office indicated in the applicable prospectus supplement and any related free writing prospectuses. Prior to the exercise of their debt warrants, holders of debt warrants will not have any of the rights of holders of the securities purchasable upon the exercise and will not be entitled to payments of principal, premium or interest on the securities purchasable upon the exercise of debt warrants.

Equity Warrants

We will describe in the applicable prospectus supplement and any related free writing prospectuses the terms of the preferred stock warrants or common stock warrants being offered, the warrant agreement relating to the preferred stock warrants or common stock warrants and the warrant certificates representing the preferred stock warrants or common stock warrants, including, as applicable:

• the title of the warrants;

• the securities for which the warrants are exercisable;

• the price or prices at which the warrants will be issued;

• if applicable, the number of warrants issued with each share of preferred stock or share of common stock;

• if applicable, the date on and after which the warrants and the related preferred stock or common stock will be separately transferable;

• the date on which the right to exercise the warrants will commence, and the date on which the right will expire;

• the maximum or minimum number of warrants which may be exercised at any time;

• information with respect to book-entry procedures, if any;

• a discussion of the material U.S. federal income tax considerations applicable to exercise of the warrants; and

• any other terms of the warrants, including terms, procedures and limitations relating to the exchange and exercise of the warrants.

Unless otherwise provided in the applicable warrant agreement and corresponding prospectus supplement or any related free writing prospectuses, holders of equity warrants will not be entitled, by virtue of being such holders, to vote, consent, receive dividends, receive notice as stockholders with respect to any meeting of stockholders for the election of our directors or any other matter, or to exercise any rights whatsoever as stockholders.

Except as provided in the applicable warrant agreement and corresponding prospectus supplement or any related free writing prospectuses, the exercise price payable and the number of shares of common stock or preferred stock purchasable upon the exercise of each warrant will be subject to adjustment in certain events, including the issuance of a stock dividend to holders of common stock or preferred stock or a stock split, reverse stock split, combination, subdivision or reclassification of common stock or preferred stock. In lieu of adjusting the number of shares of common stock or preferred stock purchasable upon exercise of each warrant, we may elect to adjust the number of warrants. Unless otherwise provided in the applicable warrant agreement and corresponding prospectus supplement or any related free writing prospectuses, no adjustments in the number of shares purchasable upon exercise of the warrants will be required until all cumulative adjustments require an adjustment of at least 1% thereof. No fractional shares will be issued upon exercise of warrants, but we will pay the cash value of any fractional shares otherwise issuable. Notwithstanding the foregoing, except as otherwise provided in the applicable warrant agreement and corresponding prospectus supplement or any related free writing prospectuses, in case of any consolidation, merger, or sale or conveyance of our property as an entirety or

20

substantially as an entirety, the holder of each outstanding warrant will have the right to the kind and amount of shares of stock and other securities and property, including cash, receivable by a holder of the number of shares of common stock or preferred stock into which each warrant was exercisable immediately prior to the particular triggering event.

Exercise of Warrants

Each warrant will entitle the holder of the warrant to purchase for cash at the exercise price provided in the applicable warrant agreement and corresponding prospectus supplement or any related free writing prospectuses the principal amount of debt securities or shares of preferred stock or shares of common stock being offered. Holders may exercise warrants at any time up to the close of business on the expiration date provided in the applicable warrant agreement and corresponding prospectus supplement or any related free writing prospectuses. After the close of business on the expiration date, unexercised warrants are void.

Holders may exercise warrants as described in the applicable warrant agreement and corresponding prospectus supplement or any free writing prospectuses relating to the warrants being offered. Upon receipt of payment and the warrant certificate properly completed and duly executed at the corporate trust office of the warrant agent or any other office indicated in the applicable warrant agreement and corresponding prospectus supplement or any related free writing prospectuses, we will, as soon as practicable, forward the debt securities, shares of preferred stock or shares of common stock purchasable upon the exercise of the warrant. If less than all of the warrants represented by the warrant certificate are exercised, we will issue a new warrant certificate for the remaining warrants.

21

DESCRIPTION OF UNITS WE MAY OFFER

The following description, together with the additional information we may include in any applicable prospectus supplements and free writing prospectuses, summarizes the material terms and provisions of the units that we may offer under this prospectus. While the terms we have summarized below will apply generally to any units that we may offer under this prospectus, we will describe the particular terms of any series of units in more detail in the applicable prospectus supplement. The terms of any units offered under a prospectus supplement may differ from the terms described below. However, no prospectus supplement will fundamentally change the terms that are set forth in this prospectus or offer a security that is not registered and described in this prospectus at the time of its effectiveness.

We will file as exhibits to the Registration Statement of which this prospectus is a part, or will incorporate by reference from a current report on Form 8-K that we file with the SEC, the form of unit agreement that describes the terms of the series of units we are offering, and any supplemental agreements, before the issuance of the related series of units. The following summaries of material terms and provisions of the units are subject to, and qualified in their entirety by reference to, all the provisions of the unit agreement and any supplemental agreements applicable to a particular series of units. We urge you to read the applicable prospectus supplements related to the particular series of units that we sell under this prospectus, as well as the complete unit agreement and any supplemental agreements that contain the terms of the units.

General

We may issue units comprised of one or more shares of common stock, shares of preferred stock, debt securities and warrants in any combination. Each unit will be issued so that the holder of the unit is also the holder of each security included in the unit. Thus, the holder of a unit will have the rights and obligations of a holder of each included security. The unit agreement under which a unit is issued may provide that the securities included in the unit may not be held or transferred separately, at any time or at any time before a specified date.

We will describe in the applicable prospectus supplement the terms of the series of units, including:

• the designation and terms of the units and of the securities comprising the units, including whether and under what circumstances those securities may be held or transferred separately;

• any provisions of the governing unit agreement that differ from those described below; and

• any provisions for the issuance, payment, settlement, transfer or exchange of the units or of the securities comprising the units.

The provisions described in this section, as well as those described under “Description of Capital Stock We May Offer,” “Description of Debt Securities We May Offer” and “Description of Warrants We May Offer” will apply to each unit and to any common stock, preferred stock, debt security or warrant included in each unit, respectively.

Issuance in Series

We may issue units in such amounts and in numerous distinct series as we determine.

Enforceability of Rights by Holders of Units

Each unit agent will act solely as our agent under the applicable unit agreement and will not assume any obligation or relationship of agency or trust with any holder of any unit. A single bank or trust company may act as unit agent for more than one series of units. A unit agent will have no duty or responsibility in case of any default by us under the applicable unit agreement or unit, including any duty or responsibility to initiate any

22

proceedings at law or otherwise, or to make any demand upon us. Any holder of a unit may, without the consent of the related unit agent or the holder of any other unit, enforce by appropriate legal action its rights as holder under any security included in the unit.

We, the unit agents and any of their agents may treat the registered holder of any unit certificate as an absolute owner of the units evidenced by that certificate for any purpose and as the person entitled to exercise the rights attaching to the units so registered, despite any notice to the contrary.

23

PLAN OF DISTRIBUTION

We may sell the offered securities from time to time.

• through agents;

• to or through underwriters;

• to or through broker-dealers (acting as agent or principal);

• in “at the market offerings” within the meaning of Rule 415(a)(4) of the Securities Act;

• directly to purchasers, through a specific bidding or auction process or otherwise; or

• through a combination of these methods of sale.

The applicable prospectus supplement (and any related free writing prospectus that we may authorize to be provided to you) will describe the terms of the offering of the securities, including:

• the name or names of any underwriters, if any, and if required, any dealers or agents and the amount of shares underwritten or purchased by each of them;

• the purchase price or other consideration to be paid in connection with the sale of the securities being offered and the proceeds we will receive from the sale;

• any underwriting discounts or agency fees and other items constituting underwriters’ or agents’ compensation;

• any over-allotment options under which underwriters may purchase additional securities from us;

• any discounts or concessions allowed or reallowed or paid to dealers; and

• any securities exchange or market on which the securities may be listed.

We may distribute the securities from time to time in one or more transactions at:

• fixed price or prices, which may be changed from time to time;

• market prices prevailing at the time of sale;

• prices related to such prevailing market prices; or

• negotiated prices.

Only underwriters named in the prospectus supplement are underwriters of the securities offered by the prospectus supplement.

If we utilize an underwriter in the sale of the securities being offered, we will execute an underwriting agreement with the underwriter at the time of sale. Any underwriters used in the sale will acquire the securities for their own account and may resell the securities from time to time in one or more transactions at a fixed public offering price or at varying prices determined at the time of sale. The obligations of the underwriters to purchase the securities will be subject to the conditions set forth in the applicable underwriting agreement. We may offer the securities to the public through underwriting syndicates represented by managing underwriters or by underwriters without a syndicate.

In connection with the sale of the securities, we, or the purchasers of the securities for whom the underwriter may act as agent, may compensate the underwriter in the form of underwriting discounts or commissions. The underwriter may sell the securities to or through dealers, and the underwriter may compensate those dealers in the form of discounts, concessions or commissions. Subject to certain conditions, the underwriters will be obligated to purchase all of the securities offered by the prospectus supplement. We may change from time to time the public offering price and any discounts or concessions allowed or reallowed or paid to dealers.

24

We may directly solicit offers to purchase the securities. We may also designate agents to solicit offers to purchase the securities from time to time. We will name in a prospectus supplement any agent involved in the offer or sale of our securities. Unless the prospectus supplement states otherwise, our agent will act on a best-efforts basis for the period of its appointment.

If we utilize a dealer in the sale of the securities being offered by this prospectus, we will sell the securities to the dealer, as principal. The dealer may then resell the securities to the public at varying prices to be determined by the dealer at the time of resale.

We may authorize agents or underwriters to solicit offers by institutional investors to purchase securities from us at the public offering price set forth in the prospectus supplement pursuant to delayed delivery contracts providing for payment and delivery on a specified date in the future. We will describe the conditions to these contracts and the commissions we must pay for solicitation of these contracts in the prospectus supplement.

Underwriters, dealers and agents participating in the distribution of the securities may be deemed to be underwriters within the meaning of the Securities Act, and any discounts and commissions received by them and any profit realized by them on resale of the securities may be deemed to be underwriting discounts and commissions. We may enter into agreements to indemnify underwriters, dealers and agents against civil liabilities, including liabilities under the Securities Act, or to contribute to payments they may be required to make in respect thereof.

In addition, we may enter into derivative transactions with third parties (including the writing of options), or sell securities not covered by this prospectus to third parties in privately negotiated transactions. If the applicable prospectus supplement indicates, in connection with such a transaction, the third parties may, pursuant to this prospectus and the applicable prospectus supplement, sell securities covered by this prospectus and the applicable prospectus supplement. If so, the third party may use securities borrowed from us or others to settle such sales and may use securities received from us to close out any related short positions. We may also loan or pledge securities covered by this prospectus and the applicable prospectus supplement to third parties, who may sell the loaned securities or, in an event of default in the case of a pledge, sell the pledged securities pursuant to this prospectus and the applicable prospectus supplement. The third party in such sale transactions will be an underwriter and will be identified in the applicable prospectus supplement or in a post-effective amendment.

All securities we offer, other than common stock, will be new issues of securities with no established trading market. Any underwriters may make a market in these securities, but will not be obligated to do so and may discontinue any market making at any time without notice. We cannot guarantee the liquidity of the trading markets for any securities. Shares of our common stock sold pursuant to the Registration Statement of which this prospectus is a part will be authorized for listing and trading on the NASDAQ. The applicable prospectus supplement will contain information, where applicable, as to any other listing, if any, on the NASDAQ or any securities market or other securities exchange of the securities covered by the prospectus supplement.

Underwriters may engage in stabilizing and syndicate covering transactions in accordance with Rule 104 under the Exchange Act. Rule 104 permits stabilizing bids to purchase the securities being offered as long as the stabilizing bids do not exceed a specified maximum. Underwriters may over-allot the offered securities in connection with the offering, thus creating a short position in their account. Syndicate covering transactions involve purchases of the offered securities by underwriters in the open market after the distribution has been completed in order to cover syndicate short positions. Underwriters may also cover an over-allotment or short position by exercising their over-allotment option, if any. Stabilizing and syndicate covering transactions may cause the price of the offered securities to be higher than it would otherwise be in the absence of these transactions. These transactions, if commenced, may be discontinued at any time.

Any underwriters who are qualified market makers on the NASDAQ may engage in passive market making transactions in the securities on the NASDAQ in accordance with Rule 103 of Regulation M, during the business

25

day prior to the pricing of the offering, before the commencement of offers or sales of the common stock. Passive market makers must comply with applicable volume and price limitations and must be identified as passive market makers. In general, a passive market maker must display its bid at a price not in excess of the highest independent bid for such security; if all independent bids are lowered below the passive market maker’s bid, however, the passive market maker’s bid must then be lowered when certain purchase limits are exceeded.

The underwriters, dealers and agents may engage in other transactions with us, or perform other services for us, in the ordinary course of their business. We will describe such relationships in the prospectus supplement naming the underwriter and the nature of any such relationship.

26

LEGAL MATTERS

The validity of the securities being offered hereby will be passed on by Paul Hastings, LLP, San Diego, California. Any underwriters, dealers or agents will also be advised about the validity of the securities and other legal matters by their own counsel, which will be named in the prospectus supplement.

EXPERTS

The financial statements, and the related financial statement schedule, incorporated in this prospectus by reference from the Company’s Annual Report on Form 10-K, and the effectiveness of Spectrum Pharmaceuticals, Inc.’s internal control over financial reporting have been audited by Deloitte & Touche LLP, an independent registered public accounting firm, as stated in their reports, which are incorporated herein by reference. Such financial statements and financial statement schedule have been so incorporated in reliance upon the reports of such firm given upon their authority as experts in accounting and auditing.

WHERE YOU CAN FIND MORE INFORMATION

We are a reporting company and file annual, quarterly and current reports, proxy and information statements and other information with the SEC. This prospectus is part of a Registration Statement that we have filed with the SEC relating to the securities to be offered under this prospectus. This prospectus does not contain all of the information set forth in the Registration Statement and the exhibits to the Registration Statement. For further information with respect to us and the securities to be offered under this prospectus, we refer you to the Registration Statement and the exhibits and schedules filed as a part of the Registration Statement. The SEC maintains an internet site that contains reports, proxy and information statements, and other information regarding issuers that file electronically with the SEC, where you may read and copy the Registration Statement, as well as our reports, proxy and information statements and other information. The address of the SEC’s web site is www.sec.gov. We maintain a website at www.spprix.com. Information contained in or accessible through our website does not constitute a part of this prospectus.

In addition, our common stock is listed on the NASDAQ and similar information concerning us can be inspected and copied at the offices of The Nasdaq Stock Market, One Liberty Plaza, 165 Broadway, New York, NY 10006.

27

INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

The SEC allows us to “incorporate by reference” information into this prospectus. This means that we can disclose important information about us and our financial condition to you by referring you to another document filed separately with the SEC. The information incorporated by reference is considered to be part of this prospectus. This prospectus incorporates by reference the documents listed below that we have previously filed with the SEC:

• Our Annual Report on Form 10-K for the fiscal year ended December 31, 2019, as filed with the SEC on March 2, 2020;

• Our Definitive Proxy Statement on Schedule 14A, as filed with the SEC on April  22, 2020 (to the extent incorporated by reference into Part III of our Annual Report on Form 10-K for the fiscal year ended December 31, 2019);

• Our Current Reports on Form 8-K, as filed with the SEC on March  13, 2020 and April 23, 2020; and

• The description of our common stock contained in the Registration of Securities of Certain Successor Issuers filed pursuant to Section 12(g) of the Exchange Act on Form 8-B on June 27, 1997, including any amendment or reports filed for the purpose of updating such description.

We also incorporate by reference into this prospectus all documents filed by us with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act, including any such documents filed after the date of the initial registration statement and prior to the effectiveness date of the registration statement, until we file a post-effective amendment which indicates that all securities offered hereby have been sold or which deregisters all securities then remaining unsold. Nothing in this prospectus shall be deemed to incorporate information furnished but not filed with the SEC (including without limitation, information furnished under Item 2.02 or Item 7.01 of Form 8-K, and any exhibits relating to such information).

Any statement contained in this prospectus or in a document incorporated or deemed to be incorporated by reference in this prospectus shall be deemed to be modified or superseded for purposes of this prospectus to the extent that a statement contained herein or in the applicable prospectus supplement or in any other subsequently filed document which also is or is deemed to be incorporated by reference modifies or supersedes the statement. Any statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this prospectus.

We will provide to each person, including any beneficial owner, to whom a prospectus is delivered, upon written or oral request, at no cost to the requestor, a copy of any or all of the information that is incorporated by reference in this prospectus. Requests for such documents should be directed to:

Spectrum Pharmaceuticals, Inc.

11500 South Eastern Avenue, Suite 240

Henderson, Nevada 89052

Telephone: (702) 835-6300

Attention: Investor Relations

Statements contained in this prospectus as to the contents of any contract or other documents are not necessarily complete, and in each instance investors are referred to the copy of the contract or other document filed as an exhibit to the Registration Statement, each such statement being qualified in all respects by such reference and the exhibits and schedules thereto.

28

               Shares

Common Stock

PROSPECTUS SUPPLEMENT

Joint Book-Running Managers

Jefferies Cantor

Lead Manager

JMP Securities

Co-Managers

B. Riley FBR H.C. Wainwright & Co.

                    , 2020