S-1

(Address, Including Zip Code, and Telephone Number, Including Area Code, of Registrant’s Principal Executive Offices)

(Name, Address, Including Zip Code, and Telephone Number, Including Area Code, of Agent For Service)

Approximate date of commencement of proposed sale to the public: As soon as practicable after the effective date of this registration statement.

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, check the following box. ☒

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ☐

The registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the registrant files a further amendment which specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933, as amended, or until the registration statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

The information in this prospectus is not complete and may be changed. These securities may not be sold until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities and it is not soliciting an offer to buy these securities in any state where the offer or sale is not permitted.

Up to 8,275,862 Shares of Common Stock or Common Stock Underlying Pre-Funded Warrants

This is a reasonable best efforts public offering of up to 8,275,862 shares (the “Shares”) of our common stock, par value $0.001 per share ("Common Stock") including shares of Common Stock underlying common warrants, and common stock purchase warrants (the “Common Warrants”) to purchase an aggregate of up to 8,275,862 shares of our Common Stock at an assumed combined public offering price of $1.45 per share of Common Stock and Common Warrant (assuming a public offering price equal to the last sale price of our Common Stock as reported by the Nasdaq Capital Market (“Nasdaq”) on June 29, 2023 of $1.45). Each Common Warrant is assumed to have an exercise price of $1.45 per Share (100% of the public offering price per Share and Common Warrant), will be exercisable upon issuance, and will expire five years from the date of issuance.

We are also offering to those purchasers, if any, whose purchase of Common Stock in this offering would otherwise result in any such purchaser, together with its affiliates, beneficially owning more than 4.99% (or, at the election of such purchaser, 9.99%) of our outstanding Common Stock immediately following the consummation of this offering, the opportunity to purchase pre-funded warrants (the “Pre-Funded Warrants”) in lieu of shares of our Common Stock that would otherwise result in such purchaser’s beneficial ownership exceeding 4.99% (or, at the election of such purchaser, 9.99%) of our outstanding Common Stock. The purchase price for each Pre-Funded Warrant will equal the per share public offering price for the Common Stock in this offering less the $0.001 per share exercise price of each such Pre-Funded Warrant. Each Pre-Funded Warrant will be exercisable upon issuance and will not expire prior to exercise. For each Pre-Funded Warrant we sell, the number of shares of Common Stock we are offering will be decreased on a one-for-one basis.

For purposes of clarity, each share of Common Stock or Pre-Funded Warrant to purchase one share of Common Stock is being sold together with a Common Warrant to purchase one share of Common Stock.

These securities are being sold in this offering to certain purchasers under a securities purchase agreement dated , 2023 between us and such purchasers. Pursuant to this prospectus, we are also offering the shares of Common Stock issuable upon the exercise of Pre-Funded Warrants and Common Warrants offered hereby.

The shares issuable upon exercise of the Pre-Funded Warrants or Common Warrants will be issued upon the exercise thereof. Because there is no minimum number of securities or minimum aggregate amount of proceeds for this offering to close, we may sell fewer than all of the securities offered hereby, and investors in this offering will not receive a refund in the event that we do not sell an amount of securities sufficient to pursue the business goals outlined in this prospectus. Because there is no escrow account and there is no minimum offering amount, investors could be

in a position where they have invested in our company, but we are unable to fulfill our objectives due to a lack of interest in this offering. Also, any proceeds from the sale of securities offered by us will be available for our immediate use, despite uncertainty about whether we would be able to use such funds to effectively implement our business plan.

The offering of the Shares, Pre-Funded Warrants and Common Warrants will terminate no later than , 2023; however, the shares of our Common Stock underlying the Pre-Funded Warrants and the Common Warrants will be offered on a continuous basis pursuant to Rule 415 under the Securities Act of 1933, as amended (the “Securities Act”).

Our Common Stock trades on Nasdaq, under the symbol “APVO.” On June 29, 2023, the last reported sale price of our Common Stock on Nasdaq was $1.45 per share. The combined public offering prices per Share and accompanying Common Warrant or per Pre-Funded Warrant and accompanying Common Warrant will be determined between us and investors based on market conditions at the time of pricing and may be at a discount to the current market price of our Common Stock. Therefore, the recent market price and resulting assumed price used throughout this prospectus may differ substantially from the actual offering price. None of the Common Warrants or Pre-Funded Warrants are listed on a national securities exchange. We do not intend to apply to list the Common Warrants or Pre-Funded Warrants on any national securities exchange. Without an active trading market, the liquidity of the Common Warrants and Pre-Funded Warrants may be limited.

We expect this offering to be completed within two business days following the commencement of this offering and we will deliver all securities to be issued in connection with this offering delivery versus payment upon receipt of investor funds received by us.

INVESTING IN OUR SECURITIES INVOLVES A HIGH DEGREE OF RISK. YOU SHOULD CAREFULLY READ AND CONSIDER THE RISKS AND UNCERTAINTIES DESCRIBED UNDER THE HEADING “RISK FACTORS” BEGINNING ON PAGE 12 OF THIS PROSPECTUS AND UNDER SIMILAR HEADINGS IN ANY AMENDMENTS OR SUPPLEMENTS TO THIS PROSPECTUS, INCLUDING OUR MOST RECENT ANNUAL REPORT ON FORM 10-K AND ANY SIMILAR SECTION CONTAINED IN ANY DOCUMENTS THAT ARE INCORPORATED BY REFERENCE INTO THIS PROSPECTUS.

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

We have engaged A.G.P./Alliance Global Partners as our exclusive placement agent (“A.G.P.” or the “Placement Agent”) to use its reasonable best efforts to solicit offers to purchase our securities in this offering. The Placement Agent has no obligation to purchase any of the securities from us or to arrange for the purchase or sale of any specific number or dollar amount of the securities. Because there is no minimum offering amount required as a condition to closing in this offering the actual public offering amount, placement agent’s fee, and proceeds to us, if any, are not presently determinable and may be substantially less than the total maximum offering amounts set forth above and throughout this prospectus. We have agreed to pay the Placement Agent the placement agent fees set forth in the table below and to provide certain other compensation to the Placement Agent. See “Plan of Distribution” beginning on page of this prospectus for more information regarding these arrangements.

(1) We have agreed to pay the Placement Agent a cash placement commission equal to 7.0% of the aggregate proceeds from this offering subject to a partial adjustment in the event certain investors participate. We have also agreed to reimburse the Placement Agent for certain expenses incurred in connection with this offering. See “Plan of Distribution” beginning on page 26 for additional information regarding the compensation to be paid to the Placement Agent.

(2) The above summary of offering proceeds does not give effect to any proceeds from the exercise of the Common Warrants or Pre-Funded Warrant being issued in this offering.

Delivery of the Shares and Pre-Funded Warrants, together with accompanying Common Warrants, is expected to be made on or about , 2023, subject to customary closing conditions.

This prospectus is part of a registration statement on Form S-1 that we filed with the Securities and Exchange Commission (“SEC”) to register the securities offered hereby under the Securities Act. We may also file a prospectus supplement or post-effective amendment to the registration statement of which this prospectus forms a part that may contain material information relating to these offerings. The prospectus supplement or post-effective amendment may also add, update or change information contained in this prospectus with respect to that offering. If there is any inconsistency between the information in this prospectus and the applicable prospectus supplement or post-effective amendment, you should rely on the prospectus supplement or post-effective amendment, as applicable. Before purchasing any securities, you should carefully read this prospectus, any post-effective amendment, and any applicable prospectus supplement, together with the additional information incorporated by reference into this prospectus and described under the heading “Where You Can Find More Information.” You may obtain the information incorporated by reference without charge by following the instructions under “Where You Can Find More Information.” You should carefully read this prospectus as well as additional information described under “Information Incorporated by Reference,” before deciding to invest in our securities.

You should rely only on the information contained in this prospectus. We have not, and the Placement Agent has not, authorized anyone to provide you with any information other than that contained in this prospectus. We take no responsibility for and can provide no assurance as to the reliability of, any other information that others may give you. This prospectus may only be used where it is legal to offer and sell our securities. The information in this prospectus is accurate only as of the date of this prospectus, regardless of the time of delivery of this prospectus or any sale of our securities. Our business, financial condition, results of operations and prospects may have changed since that date. We are not, and the Placement Agent is not, making an offer of these securities in any jurisdiction where the offer is not permitted.

For investors outside the United States: We have not, and the Placement Agent has not, done anything that would permit this offering or possession or distribution of this prospectus in any jurisdiction where action for that purpose is required, other than in the United States. Persons outside the United States must inform themselves about, and observe any restrictions relating to, the offering of securities and the distribution of this prospectus outside the United States.

For purposes of this prospectus, references to the terms “APVO,” “the Company,” “we,” “us” and “our” refer to Aptevo Therapeutics Inc., together with its subsidiaries, unless the context otherwise requires. This prospectus and the information incorporated herein by reference include trademarks, service marks and trade names owned by us or other companies. All trademarks, service marks and trade names included or incorporated by reference into this prospectus and the information incorporated herein by reference are the property of their respective owners.

We urge you to read carefully this prospectus, as supplemented and amended, before deciding whether to invest in any of the securities being offered.

This prospectus, the applicable prospectus supplement and any free writing prospectus, including the documents we incorporate by reference herein and therein, contain forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 and involve substantial risks and uncertainties. All statements other than statements of historical fact are forward-looking statements. These statements include, but are not limited to, statements regarding our intentions, beliefs, projections, outlook, analyses or current expectations concerning, among other things, our ongoing and planned preclinical development and clinical trials, the timing of and our ability to make regulatory filings and obtain and maintain regulatory approvals for our product candidates and any future product candidates, our intellectual property position, the degree of clinical utility of our product candidates, particularly in specific patient populations, our ability to develop and commercialize any product candidates, expectations regarding clinical trial data, statements regarding potential milestone payments, potential partnerships and collaborations, the advancement of our clinical and pre-clinical trials, our goals and milestones, our expectations regarding the size of the patient populations for our product candidates if approved for commercial use, our expectations regarding the effectiveness of our ADAPTIR and ADAPTIR-FLEX platforms, our ability to utilize any net operating losses, our results of operations, cash needs, spending of the proceeds from the offering described in this prospectus, financial condition, liquidity, prospects, growth and strategies, the industry in which we operate and the trends that may affect the industry or us. In some cases, you can identify forward-looking statements by terminology such as “believe,” “will,” “may,” “estimate,” “continue,” “anticipate,” “intend,” “should,” “plan,” “might,” “approximately,” “expect,” “predict,” “could,” “potentially” or the negative of these terms or other similar expressions, but the absence of these words does not mean that a statement is not forward looking.

These statements relate to future events or our future financial performance and involve known and unknown risks, uncertainties and other factors that could cause our actual results, levels of activity, performance or results of operations to differ materially from those expressed or implied by these forward-looking statements. These statements reflect our views with respect to future events as of the time they were made and are based on assumptions and subject to risks and uncertainties. You should read the matters described in “Risk Factors” in this prospectus, in our Annual Report on Form 10-K and in our Quarterly Report on Form 10-Q which is incorporated by reference into this prospectus and the other cautionary statements made in this prospectus as being applicable to all related forward-looking statements wherever they appear in this prospectus or the documents incorporated by reference into this prospectus. In addition to factors identified under the section titled “Risk Factors” in this prospectus, factors that may impact such forward-looking statements include:

Should one or more of the risks or uncertainties described in this prospectus occur, additional material risks and uncertainties not currently known to us arise or should our underlying assumptions prove incorrect, actual results and plans could differ materially from those expressed in any forward-looking statements. Given these uncertainties, you should not place undue reliance on these forward-looking statements. Except as required by law, we undertake no obligation to update or revise publicly any forward-looking statements, whether as a result of new information, future events or otherwise.

PROSPECTUS SUMMARY

This summary highlights information contained elsewhere in this prospectus. This summary does not contain all of the information that you should consider before deciding to invest in our securities. You should read this entire prospectus carefully, including the “Risk Factors” section in this prospectus, in our most recent Annual Report on Form 10-K, in any subsequent Quarterly Reports on Form 10-Q and in our other reports filed from time to time with the SEC, as well as our historical financial statements and the notes thereto and the other documents that are incorporated by reference in this prospectus.

Business Overview

We are a clinical-stage, research and development biotechnology company focused on developing novel immunotherapy candidates for the treatment of different forms of cancer. We have developed two versatile and enabling platform technologies for rational design of precision immune modulatory drugs. Our lead clinical candidates, APVO436 and ALG.APV-527, and preclinical candidates, APVO603 and APVO711, were developed using our ADAPTIR™ modular protein technology platform. Our preclinical candidate APVO442 was developed using our ADAPTIR-FLEX™ modular protein technology platform.

Our ADAPTIR and ADAPTIR-FLEX platforms are designed to generate monospecific, bispecific, and multi-specific antibody candidates capable of enhancing the human immune system against cancer cells. ADAPTIR and ADAPTIR-FLEX are both modular platforms, which gives us the flexibility to potentially generate immunotherapeutic candidates with a variety of mechanisms of action. This flexibility in design allows us to generate novel therapeutic candidates that may provide effective strategies against difficult to treat, as well as advanced forms of cancer. We have successfully designed and constructed numerous investigational-stage product candidates based on our ADAPTIR platform. The ADAPTIR platform technology is designed to generate monospecific and bispecific immunotherapeutic proteins that specifically bind to one or more targets, for example, bispecific therapeutic molecules, which may have structural and functional advantages over monoclonal antibodies. The structural differences of ADAPTIR molecules over monoclonal antibodies allow for the development of ADAPTIR immunotherapeutics that are designed to engage immune effector cells and disease targets to produce signaling responses that modulate the immune system to kill tumor cells.

We believe we are skilled at candidate generation, validation, and subsequent preclinical and clinical development using the ADAPTIR platform and the ADAPTIR-FLEX platform to generate multi-specific candidates or other candidates to our platform capabilities. We have developed a preclinical candidate based on the ADAPTIR-FLEX platform which is advancing in our pipeline. We are developing our ADAPTIR and ADAPTIR-FLEX molecules using our protein engineering, preclinical development, process development, and clinical development capabilities.

Our Strategy

We seek to grow our business by, among other things:

Advancing our lead clinical stage candidate, APVO436, through clinical development to evaluate its therapeutic potential alone and in combination with other therapies. Based on the positive results from our Phase 1 dose escalation and dose expansion study, we plan to initiate a Phase 2 clinical trial in the second half of 2023 to continue to assess efficacy of APVO436 in combination with Venetoclax and Azacitidine for the treatment of acute myelogenous leukemia (AML).

Advancing our solid tumor candidate, ALG.APV-527, developed in partnership with Alligator Bioscience AB (Alligator), further in the clinic. Aptevo and Alligator continue to investigate ALG.APV-527 for the treatment of multiple 5T4-tumor expressing antigens in multiple solid tumor indications in a first-in-human Phase I clinical study that started in the first quarter of 2023. We are currently enrolling new patients. ALG.APV-527 targets the 4-1BB co-stimulatory receptor (on T lymphocytes and NK cells) and 5T4 (solid tumor antigen) and is designed to promote anti-tumor immunity.

Continued development and advancement our preclinical candidates, APVO603 (targeting 4-1BB (CD137) and OX40 (CD134), both members of the TNF-receptor family), APVO442 (targeting Prostate Specific Membrane Antigen (PSMA), a tumor antigen that is highly expressed on prostate cancer cells and CD3), and APVO711 (an anti-PD-L1 x anti-CD40 compound). We continue advance APVO603 and APVO442 through preclinical and IND-enabling studies. In January 2023, we filed a provisional patent with the U.S. Patent and Trademark Office (USPTO)

pertaining to APVO711, with the potential to treat a range of solid malignancies such as head and neck cancer. APVO711 is a dual mechanism bispecific antibody candidate that is designed to provide synergistic stimulation of CD40 on antigen presenting cells while simultaneously blocking the PD-1/PD-L1 inhibitory pathway to potentially promote a robust anti-tumor response. Preclinical studies are planned to further evaluate the mechanism of action and efficacy of APVO711.

Development of novel bispecific and multi-specific proteins for the treatment of cancer using our ADAPTIR and ADAPTIR-FLEX platforms. We have expertise in molecular and cellular biology, immunology, oncology, pharmacology, translational sciences, antibody engineering and the development of protein therapeutics. This includes target validation, preclinical proof of concept, cell line development, protein purification, bioassay and process development and analytical characterization. We focus on product development using our ADAPTIR and ADAPTIR-FLEX platforms. We plan to generate additional monospecific, bispecific, and multi-specific protein immunotherapies for development, potentially with other collaborative partners, to exploit the potential of the ADAPTIR and ADAPTIR-FLEX platforms. We will select novel candidates that have the potential to demonstrate proof of concept early in development. We expect to continue to expand the ADAPTIR and ADAPTIR-FLEX product pipelines to address areas of unmet medical need.

Establishing collaborative partnerships to broaden our pipeline and provide funding for research and development. We intend to pursue collaborations with other biotechnology and pharmaceutical companies, academia, and non-governmental organizations to advance our product portfolio.

Platform Technology and Product Candidates


Characteristics	Technology
Characteristics	ADAPTIR	ADAPTIR-FLEX
Drug Targeting	Bind up to two targets	Bind up to four targets
Genetic and Structural Format	Single gene that assembles into a homodimer based on an antibody backbone	Two genes that assemble into a heterodimer based on a mutated antibody backbone
Half-life	Contains Immunoglobulin Gamma 1 Fc Demonstrated antibody-like half-life in mice
Effector Function	Fc mutations may be utilized to eliminate binding to Fc Gamma Receptors or to enhance effector function
Manufacturing	Antibody-like manufacturing processes
Current Pipeline Candidates	APVO436 (CD123 x CD3) ALG.APV-527 (41BB x 5T4) APVO603 (41BB x OX40) APVO711 (PD-L1 x CD40)	APVO442 (PSMA x CD3)

Product Portfolio

Our current product candidate pipeline is summarized in the table below:

Smaller Reporting Company

Additionally, we are a “smaller reporting company” as defined in Rule 10(f)(1) of Regulation S-K. To the extent we qualify as a smaller reporting company, we may continue to take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not smaller reporting companies, including, among other things, providing only two years of audited financial statements and we are also permitted to elect to incorporate by reference information filed after the effective date of the S-1 registration statement of which this prospectus forms a part. We will remain a smaller reporting company until the last day of the fiscal year in which (1) the market value of our shares of Common Stock held by non-affiliates exceeds $250 million as of the prior June 30, or (2) our annual revenues exceeded $100 million during such completed fiscal year and the market value of our shares of Common Stock held by non-affiliates exceeds $700 million as of the prior June 30.

Corporate Information

On August 6, 2015, Emergent BioSolutions Inc. (“Emergent”), announced a plan to separate into two independent publicly traded companies. To accomplish this separation, Emergent created Aptevo Therapeutics Inc. (“Aptevo”), to be the parent company for the development-based biotechnology business focused on novel oncology and hematology therapeutics. Aptevo was incorporated in Delaware in February 2016 as a wholly owned subsidiary of Emergent. To effect the separation, Emergent made a pro rata distribution of Aptevo’s Common Stock to Emergent’s stockholders on August 1, 2016.

Our Common Stock currently trades on the Nasdaq under the symbol “APVO.” Our primary executive offices are located at 2401 4th Avenue, Suite 1050, Seattle, Washington and our telephone number is (206) 838-0500. Our website address is www.aptevotherapeutics.com. The information contained in, or that can be accessed through, our website is not a part of or incorporated by reference in this prospectus, and you should not consider it part of this prospectus or of any prospectus supplement. We have included our website address in this prospectus solely as an inactive textual reference.

THE OFFERING



Common Stock offered by us			Up to 8,275,862 Shares.
Common Warrants offered by us			Common Warrants to purchase up to 8,275,862 shares of our Common Stock, which will be exercisable during the period commencing on the date of their issuance and ending five years from such date at an exercise price of $1.45 per share of Common Stock (100% of the public offering price per Share and Common Warrant).
Pre-Funded Warrants offered by us			We are also offering to certain purchasers whose purchase of our Common Stock in this offering would otherwise result in the purchaser, together with its affiliates, beneficially owning more than 4.99% (or, at the election of the purchaser, 9.99%) of our outstanding shares of Common Stock immediately following the consummation of this offering, the opportunity to purchase Pre-Funded Warrants (together with the Common Warrants, the “Warrants”) in lieu of Common Stock that would otherwise result in any such purchaser’s beneficial ownership exceeding 4.99% (or, at the election of the purchaser, 9.99%) of our outstanding shares of Common Stock. Each Pre-Funded Warrant will be exercisable for one share of Common Stock. The purchase price of each Pre-Funded Warrant and the accompanying Common Warrant will equal the price at which the each Share and the accompanying Common Warrant are being sold to the public in this offering, minus $0.001, and the exercise price of each Pre-Funded Warrant will be $0.001 per share. The Pre-Funded Warrants will be exercisable immediately and may be exercised at any time until exercised in full. For each Pre-Funded Warrant we sell, the number of shares of Common Stock we are offering will be decreased on a one-for-one basis. Because we will issue Common Warrants to purchase one share of Common Stock for each share of Common Stock and for each Pre-Funded Warrant sold in this offering, the number of Common Warrants sold in this offering will not change as a result of a change in the mix of the shares of our Common Stock and Pre-Funded Warrants sold.
Assumed public offering price			$1.45 per Share and accompanying Common Warrant, or $1.45 per Pre-Funded Warrant and accompanying Common Warrant, as applicable, in each case assuming a public offering price equal to the last sale price of our Common Stock as reported by the Nasdaq on June 29, 2023, which was $1.45.
Common stock outstanding before this offering			7,543,440 shares.
Common stock to be outstanding immediately after this offering			15,819,302 shares (assuming we sell only shares of Common Stock and no Pre-Funded Warrants, and none of the Common Warrants issued in this offering are exercised).
Use of Proceeds			We estimate that the net proceeds from this offering will be approximately $12.0 million, based on an assumed


	combined public offering price of $1.45 per Share and accompanying Common Warrant, after deducting the Placement Agent fees and estimated offering expenses payable by us. We intend to use the net proceeds from this offering for the continued clinical development of our product candidates and for working capital, and other general corporate purposes. Because this is a reasonable best efforts offering with no minimum amount as a condition to closing, we may not sell all or any of the securities offered hereby. As a result, we may receive significantly less in net proceeds than we currently estimate. See “Use of Proceeds” on page 12.
Risk Factors	You should read the section entitled “Risk Factors” and other information appearing elsewhere in this prospectus and in the documents incorporated by reference for a discussion of the risk factors to consider carefully before deciding to invest in our securities.
Nasdaq Capital Market Symbol	"APVO"

Unless otherwise indicated, the number of shares of Common Stock to be outstanding after this offering is based on 7,543,440 shares of Common Stock outstanding as of June 27, 2023. The number of shares of Common Stock outstanding after this offering excludes:

•

259,166 shares of Common Stock issuable upon the exercise of stock options outstanding at a weighted average exercise price of $15.37 per share;

•

340,004 shares of Common Stock issuable upon the vesting of outstanding restricted stock units at a weighted average fair value per unit of $4.79 per share;

•

89,998 shares of Common Stock reserved for future grants of equity-based awards under our equity incentive plans; and

•

350,589 shares of Common Stock reserved for issuance upon exercise of warrants outstanding at a weighted average exercise price of $18.20 per share.

An investment in our securities involves a significant degree of risk. You should carefully consider the risk factors and all of the other information included in this prospectus and the documents we have incorporated by reference into this prospectus, including those in “Item 1A. Risk Factors” in our Annual Report on Form 10-K for the fiscal year ended December 31, 2023 and our Quarterly Report on Form 10-Q for the period ended March 31, 2023, incorporated herein by reference, before making an investment decision. Any of these risks and uncertainties could have a material adverse effect on our business, financial condition, cash flows and results of operations. If that occurs, the trading price of our Common Stock could decline materially, and you could lose all or part of your investment.

The risks included in this prospectus and the documents we have incorporated by reference into this prospectus are not the only risks we face. We may experience additional risks and uncertainties not currently known to us, or as a result of developments occurring in the future. Conditions that we currently deem to be immaterial may also materially and adversely affect our business, financial condition, cash flows and results of operations, and our ability to pay distributions to stockholders.

You will experience immediate and substantial dilution in the net tangible book value per share of the Common Stock you purchase. You may also experience future dilution as a result of future equity offerings.

The price per share, together with the number of shares of our Common Stock we propose to issue and ultimately will issue if this offering is completed, may result in an immediate decrease in the market price of our Common Stock. Our historical net tangible book value as of March 31, 2023 was $20.1 million, or approximately $2.78 per share of our Common Stock. After giving effect to the 8,275,862 shares of our Common Stock or the exercise of the Pre-Funded Warrants to be sold in this offering at a public offering price of $1.45 per share (assuming a public offering price equal to the last sale price of our Common Stock as reported by Nasdaq on June 29, 2023, which was $1.45 per share), our as adjusted net tangible book value as of March 31, 2023 would have been $31.2, or approximately $2.01 per share of our Common Stock. This represents an immediate dilution in the net tangible book value of $0.77 per share of our Common Stock to our existing stockholders and an immediate increase in net tangible book value of approximately $0.56 per share of our Common Stock to new investors, representing the difference between the public offering price and our as adjusted net tangible book value as of March 31, 2023, after giving effect to this offering, and the public offering price per share.

In addition, in order to raise additional capital, we may in the future offer additional shares of our Common Stock or other securities convertible into or exchangeable for our Common Stock at prices that may not be the same as the price per share in this offering. In the event that the outstanding options or warrants are exercised or settled, or that we make additional issuances of Common Stock or other convertible or exchangeable securities, you could experience additional dilution. We cannot assure you that we will be able to sell shares or other securities in any other offering at a price per share that is equal to or greater than the price per share paid by investors in this offering, and investors purchasing shares or other securities in the future could have rights superior to existing stockholders, including investors who purchase shares of Common Stock in this offering. The price per share at which we sell additional shares of our Common Stock or securities convertible into Common Stock in future transactions, may be higher or lower than the price per share in this offering. As a result, purchasers of the shares we sell, as well as our existing stockholders, will experience significant dilution if we sell at prices significantly below the price at which they invested.

Resales of our Common Stock in the public market during this offering by our stockholders may cause the market price of our Common Stock to fall.

Sales of a substantial number of shares of our Common Stock could occur at any time. The issuance of new shares of our Common Stock could result in resales of our Common Stock by our current stockholders concerned about the potential ownership dilution of their holdings. In turn, these resales could have the effect of depressing the market price for our Common Stock.

In order to raise additional capital, we may in the future offer additional common shares or other securities convertible into or exchangeable for our common shares that could result in further dilution to the investors purchasing our common shares in this offering or result in downward pressure on the price of our common shares. We may sell our common shares or other securities in any other offering at prices that are higher or lower than the prices paid by the investors in this offering, and the investors purchasing shares or other securities in the future could have rights superior to existing shareholders. Moreover, to the extent that we issue options or warrants to purchase, or securities convertible into or exchangeable for, our common shares in the future and those options, warrants or other securities are exercised, converted or exchanged, stockholders may experience further dilution.

We will have broad discretion in the use of the net proceeds from this offering and may not use them effectively.

We currently intend to use the net proceeds from the offering of securities under this prospectus for the continued clinical development of our product candidates and for working capital, and other general corporate purposes, as described in the section of this prospectus entitled “Use of Proceeds.” We will have broad discretion in the application of the net proceeds in the category of general corporate purposes and investors will be relying on the judgment of our management regarding the application of the proceeds of this offering.

The precise amount and timing of the application of these proceeds, if any, will depend upon a number of factors, such as the timing and progress of our research and development efforts, our funding requirements and the availability and costs of other funds. As of the date of this prospectus, we cannot specify with certainty all of the particular uses for the net proceeds to us from this offering. Depending on the outcome of our efforts and other unforeseen events, our plans and priorities may change and we may apply the net proceeds of this offering in different manners than we currently anticipate.

The failure by our management to apply these funds effectively could harm our business, financial condition and results of operations. Pending their use, we may invest the net proceeds from this offering in short-term, interest-bearing instruments. These investments may not yield a favorable return to our stockholders.

The price per share, together with the number of shares of Common Stock we propose to issue and ultimately will issue if this offering is completed, may result in an immediate decrease in the market price of our Common Stock. This decrease may continue after the completion of this offering.

There is no public market for the Pre-Funded Warrants and Common Warrants being offered in this offering.

There is no established public trading market for the Pre-Funded Warrants and Common Warrants being offered in this offering, and we do not expect a market to develop. In addition, we do not intend to apply to list the Pre-Funded Warrants and Common Warrants on any securities exchange or nationally recognized trading system. Without an active market, the liquidity of the Pre-Funded Warrants and Common Warrants will be limited.

Holders of our Pre-Funded Warrants and Common Warrants will have no rights as common stockholders until they acquire our Common Stock.

Until you acquire shares of Common Stock upon exercise of your Pre-Funded Warrants or the Common Warrants, you will have no rights with respect to the shares of Common Stock issuable upon exercise of your Common Warrants. Upon exercise of your Pre-Funded Warrants or the Common Warrants, you will be entitled to exercise the rights of a holder of shares only as to matters for which the record date occurs after the issuance date for such shares of Common Stock.

The Pre-Funded Warrants and Common Warrants offered hereby do not confer any rights of Common Stock ownership on their holders, such as voting rights or the right to receive dividends, but rather merely represent the right to acquire shares of Common Stock at a fixed price. Specifically, commencing on the date of issuance, holders of the Pre-Funded Warrants may acquire the Common Stock issuable upon exercise of such warrants at an exercise price of $0.0001 per share and holders of the Common Warrants may acquire the Common Stock issuable upon exercise of such warrants at an exercise price per share equal to the public offering price of shares of Common Stock in this offering. Moreover, following this offering, the market value of the Pre-Funded Warrants and the Common Warrants

is uncertain, and there can be no assurance that the market value of the Pre-Funded Warrants or the Common Warrants will equal or exceed their public offering price.

Each Common Warrant has an exercise price per share equal to the public offering price of the Shares in this offering and expires on the fifth anniversary of its original issuance date. In the event the market price per share of Common Stock does not exceed the exercise price of the Common Warrants during the period when the Common Warrants are exercisable, the Common Warrants may not have any value.

This is a reasonable best efforts offering, in which no minimum number or dollar amount of securities is required to be sold, and we may not raise the amount of capital we believe is required for our business plans.

The Placement Agent has agreed to use its reasonable best efforts to solicit offers to purchase the securities in this offering. The Placement Agent has no obligation to buy any of the securities from us or to arrange for the purchase or sale of any specific number or dollar amount of the securities. There is no required minimum number of securities that must be sold as a condition to completion of this offering. Because there is no minimum offering amount required as a condition to the closing of this offering, the actual offering amount, placement agent fees and proceeds to us are not presently determinable and may be substantially less than the maximum amounts set forth herein. We may sell fewer than all of the securities offered hereby, which may significantly reduce the amount of proceeds received by us, and investors in this offering will not receive a refund. Thus, we may not raise the amount of capital we believe is required for our operations and may need to raise additional funds to complete such short-term operations. Such additional fundraises may not be available or available on terms acceptable to us.

The Placement Agent is offering the shares on a “reasonable best efforts” basis, and the Placement Agent is under no obligation to purchase any shares for its own account. The Placement Agent is not required to sell any specific number or dollar amount of shares of Common Stock in this offering but will use its reasonable best efforts to sell the securities offered in this prospectus. as a “reasonable best efforts” offering, there can be no assurance that the offering contemplated hereby will ultimately be consummated.

We estimate that we will receive net proceeds of approximately $12.0 million from the sale of the securities by us in this offering, based on an assumed combined public offering price of $1.45 per share and accompanying Common Warrant (assuming a public offering price equal to the last sale price of our Common Stock as reported by Nasdaq on June 29, 2023, which was $1.45), after deducting the Placement Agent fees and estimated offering expenses payable by us, and excluding the proceeds, if any, received from the exercise of warrants issued in this offering.

We intend to use the net proceeds we receive from this offering for the continued clinical development of our product candidates and for working capital, and other general corporate purposes. Our expected use of net proceeds from this offering represents our intentions based on our present plans and business conditions, which could change as our plans and business conditions evolve. The amount and timing of our actual expenditures will depend on numerous factors, including the timing and success of clinical studies or clinical studies we may commence in the future, the timing of regulatory submissions and the feedback from regulatory authorities. As a result, our management will have broad discretion over the use of the net proceeds from this offering. Pending our use of the net proceeds from this offering, we may temporarily invest the net proceeds in investment-grade, interest-bearing securities.

Predicting the cost necessary to develop product candidates can be difficult and we anticipate we will need additional funds to complete the development work generally required for obtaining regulatory approval to commercialize a drug. We have based these estimates on assumptions that may prove to be wrong, and we could use our available capital resources sooner than we currently expect.

Our Common Stock is traded on the Nasdaq under the symbol “APVO.” The last reported sale price of our Common Stock on June 29, 2023 on the Nasdaq was $1.45 per share. As of June 29, 2023, there were 114 stockholders of record of our Common Stock.

We have never declared or paid, and do not anticipate declaring, or paying in the foreseeable future, any cash dividends on our capital stock. Future determinations as to the declaration and payment of dividends, if any, will be at the discretion of our board of directors and will depend on then existing conditions, including our operating results, financial conditions, contractual restrictions, capital requirements, business prospects and other factors our board of directors may deem relevant.

The following table presents a summary of our cash and cash equivalents and capitalization as of March 31, 2023:

The unaudited as adjusted information below is prepared for illustrative purposes only and our capitalization following the completion of this offering will be adjusted based on the actual public offering price and other terms of this offering determined at pricing. You should read the following table in conjunction with Management’s Discussion and Analysis of Financial Condition and Results of Operations and the historical financial statements and related notes in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2023 and our Quarterly Report on Form 10-Q for the period ended March 31, 2023, incorporated herein by reference.

Each $ increase (decrease) in the assumed public offering price of $ per share would increase (decrease) each of cash and cash equivalents, additional paid-in capital and total shareholders’ equity by approximately $ million, assuming the number of shares of Common Stock and Common Warrants offered, as set forth on the cover page of this prospectus, remains the same, and after deducting estimated placement agent fees and estimated offering expenses. Similarly, each increase (decrease) of shares in the number of shares of Common Stock and Common Warrants offered would increase (decrease) cash and cash equivalents, additional paid-in capital and total shareholders’ equity by approximately $ , assuming the assumed public offering price remains the same, and after deducting estimated placement agent fees and estimated offering expenses payable by us. The pro forma as adjusted information discussed above is illustrative only and will be adjusted based on the actual public offering price and other terms of this offering determined at pricing.

The number of shares of our Common Stock outstanding before and after this offering is based on 7,239,471 shares of our Common Stock outstanding as of March 31, 2023:

If you purchase shares of our Common Stock, your interest will be diluted immediately to the extent of the difference between the offering price per share you will pay in this offering and the as adjusted net tangible book value per share of our Common Stock after this offering. Net tangible book value per share represents our total tangible assets less total liabilities, divided by the number of shares of our Common Stock outstanding.

As of March 31, 2023, our net tangible book value was $20.1 million, or $2.78 per share of Common Stock.

After giving effect to the foregoing pro forma adjustments and the sale by us of 8,275,862 shares of Common Stock and Pre-Funded Warrants at an assumed public offering price of $1.45 per share and accompanying Common Warrant and $1.45 per Pre-Funded Warrant and accompanying Common Warrant, and after deducting the placement agent fees and estimated offering expenses payable by us, our as adjusted net tangible book value as of March 31, 2023, would have been $31.2 million, or $2.01 per share. This represents an immediate dilution in as adjusted net tangible book value of approximately $0.77 per share to our existing stockholders, and an immediate increase of $0.56 per share to purchasers of shares in this offering, as illustrated in the following table:

The number of shares of our Common Stock outstanding before and after this offering is based on 7,239,471 shares of our Common Stock outstanding as of March 31, 2023:

The following description of our Common Stock, which is the only security of the Company registered under Section 12 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), is intended as a summary, and is qualified in its entirety by reference our amended and restated certificate of incorporation, our amended and restated bylaws, applicable provisions of the Delaware General Corporation Law (the “DGCL”) and pursuant to our rights plan, which are available in our filings with the SEC.

In this offering, we are offering 8,275,862 Shares and Common Warrants to purchase up to 8,275,862 shares of Common Stock at an exercise price of $1.45 per Share and related Common Warrants to purchase up to 8,275,862 shares of Common Stock at an exercise price of $1.45 per share. This prospectus supplement also relates to the offering of shares of our Common Stock upon the exercise, if any, of the warrants issued in this offering.

Our authorized Shares consists of 500,000,000 shares of Common Stock and 15,000,000 shares of preferred stock, $0.001 par value per share (the “Preferred Stock”). Our Common Stock is registered under Section 12(b) of the Exchange Act and is listed on the Nasdaq under the trading symbol “APVO.”

Each holder of our Common Stock is entitled to one vote for each share on all matters submitted to a vote of the stockholders, including the election of directors. Under our amended and restated certificate of incorporation and amended and restated bylaws, our stockholders do not have cumulative voting rights. Because of this, the holders of a majority of the shares of Common Stock entitled to vote in any election of directors can elect all of the directors standing for election, if they should so choose.

Subject to preferences that may be applicable to any then-outstanding shares of preferred stock, holders of Common Stock are entitled to receive ratably those dividends, if any, as may be declared from time to time by our board of directors out of legally available funds.

In the event of our liquidation, dissolution or winding up, holders of Common Stock will be entitled to share ratably in the net assets legally available for distribution to stockholders after the payment of all of our debts and other liabilities and the satisfaction of any liquidation preference granted to the holders of any then-outstanding shares of preferred stock.

Each share of Common Stock includes an associated right pursuant to and as set forth in the Rights Agreement that we entered into with Broadridge Corporate Issuer Solutions, Inc. on November 8, 2020 (the “rights agreement”). Each right initially represents the right to purchase from us one one-thousandth of a share of our Series A Junior Participating Preferred Stock, par value $0.001 per share. This right is not exercisable until the occurrence of certain events specified in such rights agreement. The value attributable to these rights, if any, is reflected in the value of our Common Stock. The rights agreement and the rights granted thereunder will expire upon the earliest to occur of (i) the date on which all of such rights are redeemed, (ii) the date on which such rights are exchanged, and (iii) the close of business on November 8, 2021.

As of June 27, 2023, there were warrants to purchase 350,589 shares of Common Stock outstanding. These warrants were issued on March 11, 2019 as part of our public offering of Common Stock and warrants.

The following summary of certain terms and provisions of Pre-Funded Warrants that are being offered hereby is not complete and is subject to, and qualified in its entirety by, the provisions of the Pre-Funded Warrant, the form of which is filed as an exhibit to the registration statement of which this prospectus forms a part. Prospective investors should carefully review the terms and provisions of the form of Pre-Funded Warrant for a complete description of the terms and conditions of the Pre-Funded Warrants.

Duration and Exercise Price. Each Pre-Funded Warrant offered hereby will have an initial exercise price per share equal to $0.001. The Pre-Funded Warrants will be immediately exercisable and may be exercised at any time until the Pre-Funded Warrants are exercised in full. The exercise price and number of shares of Common Stock issuable upon exercise is subject to appropriate adjustment in the event of stock dividends, stock splits, reorganizations or similar events affecting our Common Stock and the exercise price. The Pre-Funded Warrants will be issued separately from the accompanying Common Warrants and may be transferred separately immediately thereafter.

Exercisability. The Pre-Funded Warrants will be exercisable, at the option of each holder, in whole or in part, by delivering to us a duly executed exercise notice accompanied by payment in full for the number of shares of our Common Stock purchased upon such exercise (except in the case of a cashless exercise as discussed below). Purchasers of the Pre-Funded Warrants in this offering may elect to deliver their exercise notice following the pricing of the offering and prior to the issuance of the Pre-Funded Warrants at closing to have their Pre-Funded Warrants exercised immediately upon issuance and receive shares of Common Stock underlying the Pre-Funded Warrants upon closing of this offering. A holder (together with its affiliates) may not exercise any portion of the Pre-Funded Warrant to the extent that the holder would own more than 4.99% of the outstanding Common Stock immediately after exercise, except that upon at least 61 days’ prior notice from the holder to us, the holder may increase the amount of ownership of outstanding stock after exercising the holder’s Pre-Funded Warrants up to 9.99% of the number of shares of our Common Stock outstanding immediately after giving effect to the exercise, as such percentage ownership is determined in accordance with the terms of the Pre-Funded Warrants. Purchasers of Pre-Funded Warrants in this offering may also elect prior to the issuance of the Pre-Funded Warrants to have the initial exercise limitation set at 9.99% of our outstanding Common Stock. No fractional shares of Common Stock will be issued in connection with the exercise of a Pre-Funded Warrant. In lieu of fractional shares, we will round down to the next whole share.

Cashless Exercise. If, at the time a holder exercises its Pre-Funded Warrants, a registration statement registering the issuance of the shares of Common Stock underlying the Pre-Funded Warrants under the Securities Act is not then effective or available, then in lieu of making the cash payment otherwise contemplated to be made to us upon such exercise in payment of the aggregate exercise price, the holder may elect instead to receive upon such exercise (either in whole or in part) the net number of shares of Common Stock determined according to a formula set forth in the Pre-Funded Warrants.

Transferability. Subject to applicable laws, a Pre-Funded Warrant may be transferred at the option of the holder upon surrender of the Pre-Funded Warrant to us together with the appropriate instruments of transfer.

Exchange Listing. There is no trading market available for the Pre-Funded Warrants on any securities exchange or nationally recognized trading system. We do not intend to list the Pre-Funded Warrants on any securities exchange or nationally recognized trading system.

Right as a Stockholder. Except as otherwise provided in the Pre-Funded Warrants or by virtue of such holder’s ownership of shares of our Common Stock, the holders of the Pre-Funded Warrants do not have the rights or privileges of holders of our Common Stock, including any voting rights, until they exercise their Pre-Funded Warrants.

Fundamental Transaction. In the event of a fundamental transaction, as described in the Pre-Funded Warrants and generally including any reorganization, recapitalization or reclassification of our Common Stock, the sale, transfer or other disposition of all or substantially all of our properties or assets, our consolidation or merger with or into another person, the acquisition of more than 50% of our outstanding Common Stock, or any person or group becoming the beneficial owner of 50% of the voting power represented by our outstanding Common Stock, the holders of the Pre-Funded Warrants will be entitled to receive upon exercise of the Pre-Funded Warrants the kind and amount of

securities, cash or other property that the holders would have received had they exercised the Pre-Funded Warrants immediately prior to such fundamental transaction.

The following summary of certain terms and provisions of Common Warrants that are being offered hereby is not complete and is subject to, and qualified in its entirety by, the provisions of the Common Warrants, the form of which is filed as an exhibit to the registration statement of which this prospectus forms a part. Prospective investors should carefully review the terms and provisions of the form of Common Warrants for a complete description of the terms and conditions of the Common Warrants.

Duration and Exercise Price. Each Common Warrant offered hereby will have an initial exercise price per share equal to $ . The Common Warrants will be immediately exercisable and will expire on the fifth anniversary of the original issuance date. The exercise price and number of shares of Common Stock issuable upon exercise is subject to appropriate adjustment in the event of stock dividends, stock splits, reorganizations or similar events affecting our Common Stock and the exercise price. The exercise price is separately subject to reduction in the event of certain future dilutive issuances of shares of Common Stock by us, including pursuant to common stock equivalents and convertible or derivative securities. The Common Warrants will be issued separately from the Common Stock and will be held separately immediately thereafter. A Common Warrant to purchase one share of our Common Stock will be issued for every share of Common Stock or Pre-Funded Warrant to purchase one share purchased in this offering.

Exercisability. The Common Warrants will be exercisable, at the option of each holder, in whole or in part, by delivering to us a duly executed exercise notice accompanied by payment in full for the number of shares of our Common Stock purchased upon such exercise (except in the case of a cashless exercise as discussed below). A holder (together with its affiliates) may not exercise any portion of the Common Warrant to the extent that the holder would own more than 4.99% of the outstanding Common Stock immediately after exercise, except that upon at least 61 days’ prior notice from the holder to us, the holder may increase the amount of ownership of outstanding stock after exercising the holder’s Common Warrants up to 9.99% of the number of shares of our Common Stock outstanding immediately after giving effect to the exercise, as such percentage ownership is determined in accordance with the terms of the Common Warrants. No fractional shares of Common Stock will be issued in connection with the exercise of a Common Warrant. In lieu of fractional shares, we will round down to the next whole share.

Cashless Exercise. If, at the time a holder exercises its Common Warrants, a registration statement registering the issuance of the shares of Common Stock underlying the Common Warrants under the Securities Act is not then effective or available and an exemption from registration under the Securities Act is not available for the issuance of such shares, then in lieu of making the cash payment otherwise contemplated to be made to us upon such exercise in payment of the aggregate exercise price, the holder may elect instead to receive upon such exercise (either in whole or in part) the net number of shares of Common Stock determined according to a formula set forth in the Common Warrants.

Transferability. Subject to applicable laws, a Common Warrant in book entry form may be transferred at the option of the holder through the facilities of the Depository Trust Company and Common Warrants in physical form may be transferred upon surrender of the Common Warrant to the warrant agent together with the appropriate instruments of transfer. Pursuant to a warrant agency agreement between us and Broadridge, as warrant agent, the Common Warrants initially will be issued in book-entry form and will be represented by one or more global certificates deposited with The Depository Trust Company (“DTC”) and registered in the name of Cede & Co., a nominee of DTC , or as otherwise directed by DTC.

Exchange Listing. There is no established public trading market for the Common Warrants, and we do not expect a market to develop. In addition, we do not intend to list the Common Warrants on any securities exchange or nationally recognized trading system. Without an active trading market, the liquidity of the Common Warrants will be limited.

Right as a Stockholder. Except as otherwise provided in the Common Warrants or by virtue of such holder’s ownership of shares of our Common Stock, the holders of the Common Warrants do not have the rights or privileges of holders of our Common Stock, including any voting rights, until they exercise their Common Warrants.

Fundamental Transaction. In the event of a fundamental transaction, as described in the form of Common Warrant, and generally including any reorganization, recapitalization or reclassification of our Common Stock, the sale, transfer or other disposition of all or substantially all of our properties or assets, our consolidation or merger with or into another person, the acquisition of more than 50% of our outstanding Common Stock, or any person or group becoming the beneficial owner of 50% of the voting power represented by our outstanding Common Stock, the holders of the Common Warrants will be entitled to receive upon exercise of the Common Warrants the kind and amount of securities, cash or other property that the holders would have received had they exercised the Common Warrants immediately prior to such fundamental transaction.

The transfer agent and registrar for our Common Stock is Broadridge, which can be contacted at 51 Mercedes Way, Edgewood, NY 11717, shareholder@broadridge.com, or +1 (720) 378-5591.

Certain Anti-Takeover Provisions of Our Certificate of Incorporation, Our Bylaws, the DGCL and our Rights Plan

Delaware Law. We are subject to Section 203 of the DGCL, which prohibits a Delaware corporation from engaging in any business combination with any interested stockholder for a period of three years after the date that such stockholder became an interested stockholder, with the following exceptions:

In general, Section 203 defines a “business combination” to include the following:

In general, Section 203 defines an “interested stockholder” as an entity or person who, together with the person’s affiliates and associates, beneficially owns, or within three years prior to the time of determination of interested stockholder status did own, 15% or more of the outstanding voting stock of the corporation.

Staggered Board; Removal of Directors. Our amended and restated certificate of incorporation provides for our board of directors to be divided into three classes with staggered three-year terms. Only one class of directors is elected at each annual meeting of our stockholders, with the other classes continuing for the remainder of their respective three-year terms. Because our stockholders do not have cumulative voting rights, stockholders holding a majority of the shares of Common Stock outstanding are able to elect all of our directors. Our certificate of incorporation and our

bylaws also provide that directors may be removed by the stockholders only for cause upon the vote of 75% of our outstanding Common Stock. Furthermore, the authorized number of directors may be changed only by resolution of the board of directors, and vacancies and newly created directorships on the board of directors may, except as otherwise required by law or determined by the board, only be filled by a majority vote of the directors then serving on the board, even though less than a quorum.

Stockholder Action by Written Consent. Our amended and restated certificate of incorporation and amended and restated bylaws also provide that all stockholder actions must be effected at a duly called meeting of stockholders and eliminates the right of stockholders to act by written consent without a meeting. Our amended and restated bylaws also provide that only our chairman of the board, chief executive officer or the board of directors pursuant to a resolution adopted by a majority of the total number of authorized directors may call a special meeting of stockholders.

Requirements for Advance Notification of Stockholder Nominations, Proposals and Amendments. Our amended and restated bylaws also provide that stockholders seeking to present proposals before a meeting of stockholders to nominate candidates for election as directors at a meeting of stockholders must provide timely advance notice in writing, and specify requirements as to the form and content of a stockholder’s notice. Our certificate of incorporation and bylaws provide that the stockholders cannot amend many of the provisions described above except by a vote of 75% or more of our outstanding Common Stock.

Shareholder Rights Plan. On November 8, 2020, our board of directors adopted a rights plan pursuant to our rights agreement. The rights plan works by causing substantial dilution to any person or group that acquires beneficial ownership of ten percent (10%) or more of our Common Stock without the approval of our board of directors. As a result, the overall effect of the rights plan and the issuance of the rights pursuant to the rights plan may be to render more difficult or discourage a merger, tender or exchange offer or other business combination involving the Company that is not approved by our board of directors. The rights plan is not intended to interfere with any merger, tender or exchange offer or other business combination approved by our board of directors. The rights plan also does not prevent our board of directors from considering any offer that it considers to be in the best interest of our stockholders.

These provisions are intended to enhance the likelihood of continued stability in the composition of our board of directors and its policies and to discourage coercive takeover practices and inadequate takeover bids. These provisions are also designed to reduce our vulnerability to hostile takeovers and to discourage certain tactics that may be used in proxy fights. However, such provisions could have the effect of discouraging others from making tender offers for our shares and may have the effect of delaying changes in our control or management. As a consequence, these provisions may also inhibit fluctuations in the market price of our stock that could result from actual or rumored takeover attempts. We believe that the benefits of these provisions, including increased protection of our potential ability to negotiate with the proponent of an unfriendly or unsolicited proposal to acquire or restructure our company, outweigh the disadvantages of discouraging takeover proposals, because negotiation of takeover proposals could result in an improvement of their terms.

The following table sets forth information with respect to the beneficial ownership of shares of our Common Stock by (i) each director, (ii) each named executive officer, (iii) all directors and executive officers as a group, and (iv) each person who we know beneficially owns more than 5% of our Common Stock as of June 27, 2023, unless otherwise indicated below.

Beneficial ownership is determined in accordance with the rules of the SEC. These rules generally attribute beneficial ownership of securities to persons who possess sole or shared voting power or investment power with respect to those securities and include shares of Common Stock issuable upon the exercise of stock options that are immediately exercisable or exercisable and vesting restricted stock units (RSU) within 60 days after June 27, 2023 but excludes unvested stock options. Except as otherwise indicated, all of the shares reflected in the table are shares of Common Stock and all persons listed below have sole voting and investment power with respect to the shares beneficially owned by them, subject to applicable community property laws. The information is not necessarily indicative of beneficial ownership for any other purpose.

In computing the number of shares of Common Stock beneficially owned by a person and the percentage ownership of that person, we deemed outstanding shares of Common Stock subject to options or RSUs held by that person that are currently exercisable or exercisable within 60 days of June 27, 2023. We did not deem these shares outstanding, however, for the purpose of computing the percentage ownership of any other person.

Percentage ownership calculations for beneficial ownership for each person or entity are based on 7,543,440 shares outstanding as of June 27, 2023. Except as otherwise indicated in the table below, addresses of named beneficial owners are in care of Aptevo Therapeutics Inc., 2401 4th Avenue, Suite 1050, Seattle, Washington 98121.

A.G.P. has agreed to act as our Placement Agent in connection with this offering subject to the terms and conditions of the placement agency agreement dated , 2023. The Placement Agent is not purchasing or selling any of the securities offered by this prospectus, nor is it required to arrange the purchase or sale of any specific number or dollar amount of securities, but it has agreed to use its reasonable best efforts to arrange for the sale of all of the securities offered hereby. We may not sell the entire amount of securities offered pursuant to this prospectus.

We will enter into a securities purchase agreement directly with certain purchasers, at the purchaser’s option, who purchase our securities in this offering. Purchasers who do not enter into a securities purchase agreement shall rely solely on this prospectus in connection with the purchase of our securities in this offering.

We will deliver the securities being issued to purchasers upon receipt of purchaser funds for the purchase of the securities offered pursuant to this prospectus. We will deliver the securities being offered pursuant to this prospectus upon closing.

This offering will be completed no later than two business days following the commencement of this offering and the delivery of such securities will be made upon receipt of investor funds received by the Company. We expect to deliver the securities being offered pursuant to this prospectus on or about , 2023.

We have agreed to indemnify the Placement Agent and specified other persons against specified liabilities, including liabilities under the Securities Act, and to contribute to payments the Placement Agent may be required to make in respect thereof.

This offering is being conducted on a “reasonable best efforts” basis and the Placement Agent has no obligation to buy any of the securities from us or to arrange for the purchase or sale of any specific number or dollar amount of securities. We have agreed to pay the placement agent fees set forth in the table below (assuming the purchase of all of the securities we are offering).

We have agreed to pay to the Placement Agent a cash fee equal to 7.0% of the aggregate gross proceeds raised in this offering subject to a partial adjustment in the event certain investors participate. Because there is no minimum offering amount required as a condition to closing in this offering, the actual aggregate cash placement fee, if any, is not presently determinable and may be substantially less than the maximum amount set forth above.

We have also agreed to reimburse the Placement Agent at closing for legal and other expenses incurred by the placement agent in connection with this offering in an amount equal to $75,000 and for certain non-accountable expenses, up to $25,000. We estimate the total expenses payable by us for this offering, excluding the placement agent fees and expenses, will be approximately $ .

The Placement Agent may be deemed to be an underwriter within the meaning of Section 2(a)(ii) of the Securities Act. and any commissions received by it and any profit realized on the resale of the securities sold by it while acting as principal might be deemed to be underwriting discounts or commissions under the Securities Act. As an underwriter, the Placement Agent would be required to comply with the requirements of the Securities Act and the Exchange Act, including, without limitation, Rule 4l5(a)(4) under the Securities Act and Rule 10b-5 and Regulation M under the

Exchange Act. These rules and regulations may limit the timing of purchases and sales of securities by the Placement Agent acting as principal. Under these rules and regulations, the Placement Agent:

Our directors and executive officers have agreed to enter lock-up agreements. Under these agreements, these individuals have agreed, subject to specified exceptions, not to sell or transfer any shares of Common Stock or securities convertible into, or exchangeable or exercisable for, our shares of Common Stock during a period ending 90 days after the date of this prospectus, without first obtaining the written consent of the Placement Agent, subject to certain exceptions. Specifically, these individuals have agreed, in part, not to:

Notwithstanding these limitations, our securities may be transferred under limited circumstances, including, without limitation, by gift, will or intestate succession.

In addition, we have agreed that, subject to certain exceptions, (i) we will not conduct any issuances of our Common Stock for a period of 90 days following closing of this offering and that (ii) we will not enter into a variable rate transaction for a period of 90 days following the closing of this offering.

The public offering price of the securities we are offering was negotiated between us and the investors, in consultation with the Placement Agent based on the trading of our shares of Common Stock prior to the offering, among other things. Other factors considered in determining the public offering price of the securities we are offering include our history and prospects, the industry in which we operate, our past and present operating results, the stage of development of our business, our business plans for the future and the extent to which they have been implemented, the previous experience of our executive officers, general conditions of the securities markets at the time of the offering and such other factors as were deemed relevant.

Our Common Stock is listed on the Nasdaq under the symbol “APVO.” There is no established public trading market for the warrants or Pre-Funded Warrants, and we do not expect such a market to develop. We do not intend to apply to list the warrants or Pre-Funded Warrants on any securities exchange or other nationally recognized trading system. Without an active trading market, the liquidity of the warrants will be limited.

The Placement Agent does not intend to confirm sales of the securities offered hereby to any accounts over which it has discretionary authority.

The Placement Agent and certain of its 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 Placement Agent and certain of its affiliates have, from time to time, performed, and 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 addition, in the ordinary course of their various business activities, the Placement Agent and certain of its 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 Placement Agent or its affiliates enter into a lending relationship with us, they will routinely hedge their credit exposure to us consistent with their customary risk management policies. The Placement Agent and its affiliates may hedge such exposure by entering into transactions that 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 Placement Agent and certain of its 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.

The validity of the securities being offered by this prospectus will be passed upon by Goodwin Procter LLP, Washington, DC. The Placement Agent is being represented in connection with this offering by Sullivan & Worcester LLP, New York, New York. Additional legal matters may be passed upon for us or any underwriters, dealers or agents, by counsel that we will name in an applicable prospectus supplement.

Our consolidated financial statements as of December 31, 2022 and 2021, and for the years then ended, incorporated in this prospectus by reference and included in our Annual Report on Form 10-K for the year ended December 31, 2022, have been audited by Moss Adams LLP, an independent registered public accounting firm, as set forth in their report therein. Such consolidated financial statements are incorporated by reference in reliance upon the report of such firm given their authority as experts in accounting and auditing.

We have filed with the SEC a registration statement on Form S-1 under the Securities Act that registers the distribution of the securities offered under this prospectus. The registration statement, including the attached exhibits and schedules, contains additional relevant information about us and the securities. The rules and regulations of the SEC allow us to omit from this prospectus certain information included in the registration statement.

We are subject to the informational requirements of the Securities Exchange Act and are required to file annual, quarterly and current reports, proxy statements and other information with the SEC. Any information we file with the SEC, including the documents incorporated by reference into this prospectus, is also available on the SEC’s website at www.sec.gov. We also make these documents publicly available, free of charge, on our website at www.panbela.com as soon as reasonably practicable after filing such documents with the SEC. The information contained in, or that can be accessed through, our website is not part of this prospectus.

The SEC allows us to “incorporate by reference” the information we file with it, which means that we can disclose important information to you by referring you to those documents instead of having to repeat the information in this prospectus. The information incorporated by reference is considered to be part of this prospectus, and because we are a smaller reporting company, later information that we file with the SEC will automatically update and supersede this information. We incorporate by reference the documents listed below and any future filings (including those made after the initial filing of the registration statement of which this prospectus is a part and prior to the effectiveness of such registration statement) we will make with the SEC under Sections 13(a), 13(c), 14, or 15(d) of the Exchange Act until the termination of the offering of the shares covered by this prospectus (other than information furnished under Item 2.02 or Item 7.01 of Form 8-K):

As a smaller reporting company, we also are incorporating by reference any future information filed (rather than furnished) by us with the SEC under Section 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934, as amended, after the date of the initial filing of the registration statement of which this prospectus is a part and before the effective date of the registration statement and after the date of this prospectus until the termination of the offering. Any statements contained in a previously filed document incorporated by reference into this prospectus is deemed to be modified or superseded for purposes of this prospectus to the extent that a statement contained in this prospectus, or in a subsequently filed document also incorporated by reference herein, modifies or supersedes that statement.

We will provide to each person, including any beneficial owner, to whom a prospectus is delivered, at no cost, upon written or oral request, a copy of any or all of the reports or documents that have been incorporated by reference in the prospectus contained in the registration statement but not delivered with the prospectus. You should direct requests for documents to:

Up to 8,275,862 Shares of Common Stock or Common Stock Underlying Pre-Funded Warrants

The following table sets forth the costs and expenses payable by Aptevo Therapeutics Inc. (the “Company”) in connection with the offering and sale of the Common Stock being registered. All amounts shown are estimates, except the Securities and Exchange Commission (the “Commission”) registration fee.

Section 145 of the Delaware General Corporation Law (the “DGCL”), authorizes a court to award, or a corporation’s board of directors to grant, indemnity to directors and officers in terms sufficiently broad to permit such indemnification under certain circumstances for liabilities, including reimbursement for expenses incurred, arising under the Securities Act of 1933, as amended (the “Securities Act”).

The registrant’s certificate of incorporation and bylaws each provide for indemnification of the registrant’s directors, officers, employees and other agents to the maximum extent permitted by the DGCL.

The registrant has entered into indemnification agreements with its directors and officers whereby it has agreed to indemnify its directors and officers to the fullest extent permitted by law, including indemnification against expenses and liabilities incurred in legal proceedings to which the director or officer was, or is threatened to be made, a party by reason of the fact that such director or officer is or was a director, officer, employee or agent of the registrant, provided that such director or officer acted in good faith and in a manner that the director or officer reasonably believed to be in, or not opposed to, the best interest of the registrant. At present, there is no pending litigation or proceeding involving a director or officer of the registrant regarding which indemnification is sought, nor is the registrant aware of any threatened litigation that may result in claims for indemnification.

The registrant maintains insurance policies that indemnify its directors and officers against various liabilities arising under the Securities Act and the Exchange Act of 1934, as amended, that might be incurred by any director or officer in his or her capacity as such.

(1) To file, during any period in which offers or sales are being made, a post-effective amendment to this registration statement:

(i) To include any prospectus required by section 10(a)(3) of the Securities Act of 1933 (the “Securities Act”);

(ii) To reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities

offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the SEC pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than 20% change in the maximum aggregate offering price set forth in the “Calculation of Registration Fee” table in the effective registration statement; and

(iii) To include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such information in the registration statement;

provided, however, that paragraphs (1)(i), (l)(ii) and (l)(iii) of this section do not apply if the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the SEC by the registrant pursuant to Section 13 or Section 15(d) of the Exchange Act that are incorporated by reference in the registration statement or is contained in a form of prospectus filed pursuant to Rule 462(b) that is part of the registration statement.

(2) That, for the purpose of determining any liability under the Securities Act, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(3) To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering.

(4) That, for the purpose of determining liability under the Securities Act to any purchaser:

Each prospectus filed pursuant to Rule 424(b) as part of a registration statement relating to an offering, other than registration statements relying on Rule 430B or other than prospectuses filed in reliance on Rule 430A, shall be deemed to be part of and included in the registration statement as of the date it is first used after effectiveness.

Provided, however, that no statement made in a registration statement or prospectus that is part of the registration statement or made in a document incorporated or deemed incorporated by reference into the registration statement or prospectus that is part of the registration statement will, as to a purchaser with a time of contract of sale prior to such first use, supersede or modify any statement that was made in the registration statement or prospectus that was part of the registration statement or made in any such document immediately prior to such first use.

(5) That, for purposes of determining any liability under the Securities Act, each filing of the registrant’s annual report pursuant to Section 13(a) or Section 15(d) of the Exchange Act that is incorporated by reference in the registration statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(6) That, for the purpose of determining liability of the Registrant under the Securities Act to any purchaser in the initial distribution of the securities, the undersigned Registrant undertakes that in a primary offering of securities of the undersigned Registrant pursuant to this registration statement, regardless of the underwriting method used to sell the securities to the purchaser, if the securities are offered or sold to such purchaser by means of any of the following communications, the undersigned Registrant will be a seller to the purchaser and will be considered to offer or sell such securities to such purchaser: (i) any preliminary prospectus or prospectus of the undersigned Registrant relating to the offering required to be filed pursuant to Rule 424 of the Securities Act; (ii) any free writing prospectus relating to the offering prepared by or on behalf of the undersigned Registrant or used or referred to by the undersigned Registrant; (iii) the portion of any other free writing prospectus relating to the offering containing material information about the undersigned Registrant or its securities provided by or on behalf of the undersigned Registrant; and (iv) any other communication that is an offer in the offering made by the undersigned Registrant to the purchaser.

(7) Insofar as indemnification for liabilities arising under the Securities Act may be permitted to directors, officers, and controlling persons of the registrant pursuant to the foregoing provisions, or otherwise, the registrant has been advised that, in the opinion of the SEC, such indemnification is against public policy as expressed in

the Securities Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer or controlling person of the registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer, or controlling person in connection with the securities being registered, the registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities Act and will be governed by the final adjudication of such issue.

(a) For purposes of determining any liability under the Securities Act of 1933, the information omitted from the form of prospectus filed as part of this registration statement in reliance upon Rule 430A and contained in a form of prospectus filed by the registrant pursuant to Rule 424(b)(1) or (4) or 497(h) under the Securities Act shall be deemed to be part of this registration statement as of the time it was declared effective.

(b) For the purpose of determining any liability under the Securities Act of 1933, each post-effective amendment that contains a form of prospectus shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

Pursuant to the requirements of the Securities Act of 1933, as amended, Aptevo Therapeutics Inc. has duly caused this registration statement on Form S-1 to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Seattle, State of Washington, on the 30th day of June, 2023.

KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Marvin L. White, Jeffrey G. Lamothe, and SoYoung Kwon and each of them, either of whom may act without the joinder of the other, as his or her true and lawful attorneys-in-fact and agents with full power of substitution and re-substitution, for him or her and in his or her name, place and stead, in any and all capacities, to sign any and all amendments (including post-effective amendments) to this registration statement, and to sign any registration statement for the same offering covered by the registration statement that is to be effective upon filing pursuant to Rule 462(b) promulgated under the Securities Act, and all post-effective amendments thereto, and to file the same, with all exhibits thereto and all documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do and perform each and every act and thing requisite and necessary to be done in and about the premises, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorneys-in-fact and agents or any of them, or his or their substitute or substitutes, may lawfully do or cause to be done or by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, as amended this registration statement has been signed by the following persons in the capacities indicated on the 30th day of June, 2023.


	Per Share and Common Warrant	Per Pre-Funded Warrant and Common Warrant	Total
Public offering price	$	$	$
Placement Agent fees (1)	$	$	$
Proceeds to us, before expenses (2)	$	$	$


	As of March 31, 2023
(in thousands)	Actual			As adjusted
Cash and cash equivalents	$	25,328		$	36,388
Common stock: $0.001 par value; 500,000,000 shares authorized; 7,239,471 shares issued and outstanding, pro forma; 15,515,333 shares issued and outstanding, pro forma as adjusted		49			57
Additional paid-in capital		226,470			237,522
Accumulated deficit		(203,263	)		(203,263	)
Total stockholders' equity	$	23,256		$	34,316


	Beneficial Ownership (1)
Name of Beneficial Owners	Number of Shares		Percent of Total
Marvin L. White (Officer & Director) (2)		135,128	1.8%
Jeffrey G. Lamothe (Officer) (3)		71,822	1.0%
SoYoung Kwon (Officer) (4)		23,484	*
Daniel J. Abdun-Nabi (Director) (5)		15,782	*
John E. Niederhuber, M.D. (Director) (6)		13,125	*
Zsolt Harsanyi, Ph.D. (Director) (7)		15,918	*
Grady Grant, III (Director) (8)		12,323	*
Barbara Lopez Kunz (Director) (9)		12,323	*
All executive officers and directors as a group (9 persons) (10)		331,280	4.1%


	Per Share and Common Warrant	Per Pre-Funded Warrant and Common Warrant	Total
Public offering price	$	$	$
Placement Agent fees	$	$	$
Proceeds to us, before expenses(1)	$	$	$


SEC registration fee	$	1,322
Federal and state taxes and fees	*
FINRA filing fee	*
Accounting fees and expenses	*
Legal fees and expenses	*
Transfer agent and registrar fees	*
Printing expenses	*
Miscellaneous	*
Total	*


Large Accelerated filer	☐	Accelerated filer	☐

Non-accelerated filer	☒	Smaller reporting company	☒

		Emerging growth company	☐


	Page
ABOUT THIS PROSPECTUS	i
CAUTIONARY NOTE REGARDING FORWARD-LOOKING INFORMATION	ii
PROSPECTUS SUMMARY	1
THE OFFERING	10
RISK FACTORS	10
USE OF PROCEEDS	12
MARKET FOR COMMON STOCK AND DIVIDEND POLICY	13
CAPITALIZATION	14
DILUTION	15
DESCRIPTION OF SECURITIES	16
SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT	21
PLAN OF DISTRIBUTION	23
LEGAL MATTERS	25
EXPERTS	25
WHERE YOU CAN FIND MORE INFORMATION	25
INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE	26


Assumed public offering price per Share	$	1.45
Net tangible book value per share as of March 31, 2023	$	2.78
Net dilution in net tangible book value per share attributable to existing shareholders	$	0.77
As adjusted net tangible book value per share after this offering	$	2.01
Dilution in net tangible book value per share to new investors in the offering	$	0.56


Exhibit Number	Description	Form	Exhibit	Filing Date	File No.	Filed Herewith
1.1**	Form of Placement Agent Agreement

2.1	Contribution Agreement, dated July 29, 2016, by and among Emergent BioSolutions Inc., Aptevo Therapeutics Inc., Aptevo Research and Development LLC and Aptevo BioTherapeutics LLC	8-K	2.1	August 2, 2016	001-37746

+2.2	Separation and Distribution Agreement, dated July 29, 2016, by and between Emergent BioSolutions Inc. and Aptevo Therapeutics Inc.	8-K	2.2	August 2, 2016	001-37746

†+2.3	LLC Purchase Agreement, dated as of August 31, 2017, by and among Aptevo BioTherapeutics LLC, Aptevo Therapeutics Inc., Venus Bio Therapeutics Sub LLC, and Saol International Limited.	10-Q	2.1	November 13, 2017	001-37746

+2.4	LLC Purchase Agreement by and among Aptevo Therapeutics Inc. and Medexus Pharma, Inc. dated February 28, 2020.	8-K	2.1	March 2, 2020	001-37746

3.1	Amended and Restated Certificate of Incorporation of Aptevo Therapeutics Inc.	8-K	3.1	August 2, 2016	001-37746

3.2	Amended and Restated By-laws of the Company, as amended and restated on November 8, 2022.	10-Q	3.1	November 10, 2022	001-37746

3.3	Certificate of Amendment of Amended and Restated Certificate of Incorporation of Aptevo Therapeutics Inc.	8-K	3.1	March 27, 2020	001-37746

3.4	Certificate of Designation of Series A Junior Participating Preferred Stock of Aptevo Therapeutics Inc.	8-K	3.1	November 9, 2020	001-37746

3.5	Amended and Restated Bylaws of Aptevo Therapeutics Inc.	10-Q	3.1	November 10, 2022	001-37746

4.1	Form of Common Stock Certificate	10	4.1	June 29, 2016	001-37746

4.2	Registration Rights Agreement, dated as of August 1, 2016, by and among Aptevo Therapeutics Inc. and certain of its stockholders	8-K	4	August 2, 2016	001-37746

4.3	Registration Rights Agreement, dated December 20, 2018, by and between Aptevo Therapeutics Inc. and Lincoln Park Capital Fund, LLC.	8-K	10.2	December 24, 2018	001-37746

4.4	Rights Agreement, dated as of November 8, 2020, by and between Aptevo Therapeutics Inc. and Broadridge Corporate Issuer Solutions, Inc., as rights agent	8-K	4.1	November 9, 2020	001-37746

4.5	Amendment No. 1 to Right Agreement, dated as of November 5, 2021, between the Company and Broadridge Corporate Issuer Solutions, Inc., as Rights Agent	8-K	4.1	November 5, 2021	001-37746

4.6	Amendment No. 2 to Rights Agreement, dated as of November 4, 2022, between the Company and Broadridge Corporate Issuer Solutions, Inc., as Rights Agent.	8-K	4.1	November 4, 2022	001-37746

4.7	Description of Capital Stock of Aptevo Therapeutics		4.5	March 31, 2021	001-37746

4.8	Agreement to Terminate Registration Rights Agreement between the Company and Intervac L.L.C. and BioVac L.L.C.	10-K	4.7	March 24, 2022	001-37746

4.9**	Form of Pre-Funded Warrant

4.10**	Form of Common Warrant

4.11**	Form of Warrant Agency Agreement

5.1**	Opinion of Goodwin Procter LLP


10.1	Transition Services Agreement, dated July 29, 2016, by and between Emergent BioSolutions Inc. and Aptevo Therapeutics Inc.	8-K	10.2	August 2, 2016	001-37746

10.2	Tax Matters Agreement, dated July 29, 2016, by and between Emergent BioSolutions Inc. and Aptevo Therapeutics Inc.	8-K	10.3	August 2, 2016	001-37746

10.3	Product License Agreement, dated July 29, 2016, by and between Emergent BioSolutions Inc. and Aptevo Therapeutics Inc.	8-K	10.8	August 2, 2016	001-37746

C 10.4	Aptevo Therapeutics Inc. Amended and Restated 2016 Stock Incentive Plan.	10-Q	4.1	August 10, 2017	001-37746

C 10.5	Aptevo Therapeutics Inc. Converted Equity Awards Incentive Plan	8-K	10.10	August 2, 2016	001-37746

C 10.6	Aptevo Therapeutics Inc. Amended and Restated Senior Management Severance Plan	10-K	10.6	March 24, 2022	001-37746

C 10.7	Form of Indemnity Agreement for directors and senior officers	10	10.9	April 15, 2016	001-37746

10.8	Fourth and Battery Office Lease, dated as of April 28, 2003, by and between Emergent Product Development Seattle, LLC (as successor-in-interest to Trubion Pharmaceuticals, Inc. and Genecraft, Inc.) and Selig Real Estate Holdings Eight L.L.C. , or the Seattle Office Lease	10	10.12	April 15, 2016	001-37746

10.9	Seattle Office Lease Amendment, dated December 8, 2004	10	10.13	April 15, 2016	001-37746

10.10	Seattle Office Lease Amendment, dated February 1, 2006	10	10.14	April 15, 2016	001-37746

10.11	Seattle Office Lease Amendment, dated February 2, 2007	10	10.15	April 15, 2016	001-37746

10.12	Seattle Office Lease Amendment, dated June 7, 2010	10	10.16	April 15, 2016	001-37746

10.13	Seattle Office Lease Amendment, dated December 21, 2010	10	10.17	April 15, 2016	001-37746

10.14	Seattle Office Lease Amendment, dated July 17, 2012	10	10.18	April 15, 2016	001-37746

10.15	Seventh Amendment to Seattle Office Lease, dated December 5, 2014	10	10.19	April 15, 2016	001-37746

†10.16	License and Co-Development Agreement, dated as of August 19, 2014, by and between Emergent Product Development Seattle, LLC and MorphoSys AG, or the MorphoSys Collaboration Agreement	10	10.20	June 29, 2016	001-37746

†10.17	First Amendment to MorphoSys Collaboration Agreement, dated June 19, 2015	10	10.21	April 15, 2016	001-37746

†10.18	Second Amendment to MorphoSys Collaboration Agreement, dated December 7, 2015	10	10.22	April 15, 2016	001-37746

10.19	Third Amendment to MorphoSys Collaboration Agreement, dated December 12, 2016	8-K	10.1	December 15, 2016	001-37746

10.20	Fourth Amendment MorphoSys Collaboration Agreement, dated June 19, 2017.	10	10.3	August 10, 2017	001-37746

10.21	Equity Distribution Agreement, dated November 9, 2017, between Aptevo Therapeutics, Inc. and Piper Jaffray and Company LLC.	8-K	1.1	November 9, 2017	001-37746

10.22	Collaboration and Option Agreement, dated as of July 20, 2017, by and between Aptevo Research and Development LLC, and Alligator Bioscience AB.	10-Q	10.2	November 13, 2017	001-37746

10.23	Amendment No. 3 to Credit and Security Agreement, dated as of February 23, 2018, by and among Aptevo Therapeutics Inc. and certain of its subsidiaries and Midcap Financial Trust.	10-K	10.38	March 13, 2018	001-37746



10.24	Third Amendment to Credit and Security Agreement dated August 30, 2022.	10-Q	3.1	November 10, 2022	001-37746

10.25	Aptevo Therapeutics Inc. 2018 Stock Incentive Plan.	10-Q	10.1	August 9, 2018	001-37746

10.26	Aptevo Therapeutics Inc. Non-Statutory Stock Option Agreement.	10-Q	10.2	August 9, 2018	001-37746

10.27	Eighth Amendment to Office Lease, dated as of March 19, 2019, by and between Aptevo Therapeutics Inc. and Selig Real Estate Holdings Eight L.L.C.	8-K	10.1	March 22, 2019	001-37746

10.28	Ninth Amendment to Office Lease, dated May 26, 2022, by and between Aptevo Therapeutics Inc. and Selig Real Estate Holdings Eight L.L.C.	10-K	10.3	August 11, 2022	001-37746

10.29	Amendment to LLC Purchase Agreement, dated as of August 31, 2017, by and among Aptevo BioTherapeutics LLC, Aptevo Therapeutics Inc., Venus Bio Therapeutics Sub LLC, and Saol International Limited.	10-Q	10.1	August 9, 2019	001-37746

10.30	Collaboration and License Agreement, dated as of December 19, 2005, by and among Wyeth Pharmaceuticals and Trubion Pharmaceuticals, Inc.	10-Q	10.1	August 14, 2020	001-37746

10.31	Amendment No. 1 to the Collaboration and License Agreement dated as of December 19, 2005 (the “Agreement”) by and between Trubion Pharmaceuticals, Inc. (“Trubion”) and Wyeth, acting through its Wyeth Pharmaceuticals Division (“Wyeth”).	10-Q	10.2	August 14, 2020	001-37746

10.32	Amendment No. 2 to the Collaboration and License Agreement dated as of December 19, 2005 (as previously amended, the “Agreement”) by and between Trubion Pharmaceuticals, Inc. (“Trubion”) and Wyeth LLC (formerly known as Wyeth), acting through its Wyeth Pharmaceuticals Division (“Wyeth”).	10-Q	10.3	August 14, 2020	001-37746

10.33	Amendment No. 3 to the Collaboration and License Agreement dated as of December 19, 2005 (as previously amended, the “Agreement”) by and between Emergent Product Development Seattle, LLC (successor to Trubion Pharmaceuticals, Inc. (“Trubion”)) (“EPDS”) and Wyeth LLC (formerly known as Wyeth), acting through its Wyeth Pharmaceuticals Division (“Wyeth”).	8-K	10.4	August 14, 2020	001-37746

10.34	Amendment No. 4 to the Collaboration and License Agreement dated as of December 19, 2005 (as previously amended, the “Agreement”) by and between Emergent Product Development Seattle, LLC (successor to Trubion Pharmaceuticals, Inc. (“Trubion”)) and Wyeth LLC (formerly known as Wyeth), acting through its Wyeth Pharmaceuticals Division (“Wyeth”).	10-Q	10.5	August 14, 2020	001-37746

10.35	Credit and Security Agreement, dated as of August 5, 2020, by and among Aptevo Therapeutics Inc., and MidCap Financial Trust.	10-Q	10.1	November 10, 2019	001-37746

10.36	Equity Distribution Agreement, dated December 14, 2020, between Aptevo Therapeutics Inc. and Piper Sandler & Co.	8-K	1.1	December 14, 2020	001-37746

10.37	Royalty Purchase Agreement by and among Aptevo Therapeutics Inc. and Healthcare Royalty Partners IV, LP. dated as of March 30, 2021.	10-Q	10.1	May 11, 2021	001-37746

10.38	Amendment to Royalty Purchase Agreement dated June 7, 2022.	10-Q	10.1	August 11, 2022	001-37746

10.39	First Amendment to Credit and Security Agreement dated March 30, 2021.	10-Q	10.2	May 11, 2021	001-37746



10.40	Limited Consent and Second Amendment to Credit and Security Agreement dated June 7, 2022.	10-Q	10.2	August 11, 2022	001-37746

10.41	Third Amendment to Credit and Security Agreement dated August 30, 2022.

10.42	Executive Transition Services Agreement.	10-Q	10.3	November 12, 2021	001-37746

10.43	Amendment to Executive Transition Services Agreement.	10-Q	10.4	November 12, 2021	001-37746

10.44	Purchase Agreement, dated February 16, 2022, by and between the Company and Lincoln Park.	8-K	10.1	February 17, 2022	001-37746

10.45	Registration Rights Agreement, dated February 16, 2022, by and between the Company and Lincoln Park.	8-K	10.2	February 17, 2022	001-37746

10.46	Payment Interest Purchase Agreement by and between Aptevo Therapeutics Inc. and XOMA (US) LLC, dated March 29, 2023.	10-Q	10.1	May 11, 2023	001-37746

10.47**	Form of Securities Purchase Agreement

21.1	Subsidiaries of Aptevo Therapeutics Inc.	10-K	21.1	March 24, 2022	001-37746

23.1	Consent of Independent Registered Public Accounting Firm.					X

23.2**	Consent of Goodwin Procter LLP (included in Exhibit 5.1)

24.1	Power of Attorney (included on signature page to this prospectus)					X

107	Filing Fee Table					X


*	Document has been furnished, is not deemed filed and is not to be incorporated by reference into any of the Company's filings under the Securities Act of 1933, as amended, or the Securities Exchange Act of 1934, as amended, irrespective of any general incorporation language contained in any such filing.


†	Confidential treatment granted from the Securities and Exchange Commission as to certain portions, which portions have been omitted and filed separately with the Securities and Exchange Commission.


+	Schedules have been omitted pursuant to Item 601(b)(2) of Regulation S-K. Aptevo will furnish copies of any such schedules to the Securities and Exchange Commission upon request.


**	To be filed by amendment.



Aptevo Therapeutics Inc.

By:						/s/Marvin L. White
Name:						Marvin L. White
Title:						President and Chief Executive Officer



SIGNATURE						TITLE

/s/Marvin L. White						President, Chief Executive Officer and Director (Principal Executive Officer)
Marvin L. White

/s/Daphne Taylor						Senior Vice President and Chief Financial Officer (Principal Financial Officer and Principal Accounting Officer)
Daphne Taylor

/s/John E. Niederhuber, M.D.						Chairman of the Board of Directors
John E. Niederhuber, M.D.

/s/Grady Grant, III						Director
Grady Grant, III

/s/Zsolt Harsanyi, Ph. D.						Director
Zsolt Harsanyi, Ph. D.

/s/Barbara Lopez Kunz						Director
Barbara Lopez Kunz

/s/Daniel J. Abdun-Nabi						Director
Daniel J. Abdun-Nabi