8-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): January 11, 2016

Five Prime Therapeutics, Inc.

(Exact name of registrant as specified in its charter)

Delaware	001-36070	26-0038620
(State or other jurisdiction of incorporation)	(Commission File Number)	(I.R.S. Employer Identification No.)
Two Corporate Drive South San Francisco, California		94080
(Address of principal executive offices)		(Zip Code)

Registrant’s telephone number, including area code: (415) 365-5600

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

¨ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

¨ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

¨ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

¨ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 2.02 Results of Operations and Financial Condition

Five Prime Therapeutics, Inc. (“FivePrime”) is in the process of finalizing its financial results for the fiscal year ended December 31, 2015. Set forth below is a preliminary estimate of FivePrime’s cash and cash equivalents and outstanding shares for the fiscal year ended December 31, 2015 and a forecast of FivePrime’s estimated net cash used in operations for fiscal year 2016, based on information currently available as of the date of this Current Report.

FivePrime estimates that its cash, cash equivalents and marketable securities as of December 31, 2015 was approximately $517 million. FivePrime estimates that it had 27.7 million shares of common stock outstanding as of December 31, 2015. FivePrime’s actual consolidated cash, cash equivalents and marketable securities balance and shares of common stock outstanding as of December 31, 2015 may differ from these estimates due to the completion of FivePrime’s year-end closing and auditing procedures.

FivePrime expects net cash used in operations for fiscal year 2016 will be less than $120.0 million, comprised of less than $90.0 million of net cash used in operations other than income tax payments and less than $30.0 million of income tax payments, which income tax payment amount could potentially be fully refunded to FivePrime in connection with FivePrime’s filing of its 2017 tax returns.

Item 8.01 Other Events

FivePrime and Human Genome Sciences, Inc. (“HGS”) entered into a License and Collaboration Agreement, effective March 16, 2011 (the “License Agreement”), pursuant to which FivePrime exclusively licensed to HGS rights to develop and commercialize FP-1039, FivePrime’s FGFR1 fusion protein, in the United States, the European Union and Canada. On August 2, 2012, GlaxoSmithKline (“GSK”) acquired HGS. In July 2013, GSK initiated a Phase 1b clinical trial of FP-1039, which GSK refers to as GSK3052230. GSK was conducting the Phase 1b clinical trial:

• in combination with paclitaxel and carboplatin in previously untreated metastatic squamous non-small cell lung cancer (NSCLC) (Arm A);

• in combination with docetaxel in metastatic squamous NSCLC that has progressed after previous therapy (Arm B); and

• in combination with pemetrexed and cisplatin in malignant pleural mesothelioma (Arm C).

On September 9, 2105, GSK presented preliminary clinical safety and efficacy data from the Phase 1b clinical trial at the World Conference on Lung Cancer, which, at that time, included efficacy and safety data through August 5, 2015 from Arm A in treatment-naïve squamous non-small cell lung cancer (sqNSCLC) patients, which were encouraging, from Arm B in 2nd line sqNSCLC and from Arm C, which Arm C data were immature because few mesothelioma patients were evaluable at August 5, 2015.

GSK and Five Prime have reviewed the data from the Phase 1b clinical trial as they have continued to mature and have agreed to continue to enroll up to 30 mesothelioma patients at the expansion dose of 15 mg/kg in Arm C of the trial and have agreed to stop enrolling sqNSCLC patients in Arm A and Arm B of the trial given the change in treatment paradigms following approvals of immuno-oncology agents and the increasingly competitive landscape.

A copy of the press release is filed herewith as Exhibit 99.1 and the information contained therein is incorporated by reference into this Current Report on Form 8-K.

Cautionary Note on Forward-looking Statements

This Current Report on Form 8-K contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Words such as “may,” “will,” “expect,” “plan,” “anticipate,” “estimate,” “intend” and similar expressions (as well as other words or expressions referencing future events, conditions or circumstances) are intended to identify forward-looking statements. These forward-looking statements are based on Five Prime’s expectations and assumptions as of the date of this Current Report. Each of these forward-looking statements involves risks and uncertainties. Actual results may differ materially from these forward-looking

2

statements. Forward-looking statements contained in this Current Report include statements about (i) FivePrime’s estimated net cash used in operating activities for fiscal year 2016, including the amount of net cash used for income tax payments, and (ii) the extent to which fiscal year 2016 income tax payments may be refunded in connection with FivePrime’s filing of its 2017 tax returns. Other factors that may cause Five Prime’s actual results to differ from those expressed or implied in the forward-looking statements in this Current Report are discussed in Five Prime’s filings with the U.S. Securities and Exchange Commission, including the “Risk Factors” sections contained therein. Except as required by law, Five Prime assumes no obligation to update any forward-looking statements contained herein to reflect any change in expectations, even as new information becomes available.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits.

Exhibit No.	Description
99.1	Press Release, dated January 11, 2016

3

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Five Prime Therapeutics, Inc.
By:	/s/ Francis Sarena
	Francis Sarena
	Executive Vice President, General Counsel & Secretary

Dated: January 11, 2016

4

EXHIBIT INDEX

Exhibit No.	Description
99.1	Press Release, dated January 11, 2016

5

EX-99.1

Exhibit 99.1

Five Prime Therapeutics Provides Update on FP-1039 Clinical Program

SOUTH SAN FRANCISCO, Calif., January 11, 2016 (GLOBE NEWSWIRE) — Five Prime Therapeutics, Inc. (Nasdaq: FPRX), a clinical-stage biotechnology company focused on discovering and developing novel protein therapeutics for cancer and inflammatory diseases, today provided an update on GlaxoSmithKline’s (GSK) ongoing Phase 1b clinical trial of FP-1039/GSK3052230, an FGF ligand trap, in patients with squamous non small cell lung cancer (sqNSCLC) and mesothelioma.

GSK presented preliminary clinical safety and efficacy data from the Phase 1b trial at the World Conference on Lung Cancer on September 9, 2015. At the time, data from Arm A in treatment-naïve squamous sqNSCLC patients were encouraging, Arm B in second line sqNSCLC had few patients enrolled, and data from Arm C were immature because few mesothelioma patients were then evaluable. Based on preliminary data, GSK and Five Prime have agreed to continue to enroll up to 30 mesothelioma patients at the expansion dose of 15 mg/kg in Arm C of the trial. GSK plans to submit data for presentation at the American Society of Clinical Oncology (ASCO) 2016 Annual Meeting in June. The companies have also agreed to stop enrolling the sqNSCLC patient study cohorts given the change in treatment paradigms following approvals of immuno-oncology agents and the increasingly competitive landscape.

“We are encouraged by the preliminary data we have recently reviewed from the mesothelioma arm of the study and look forward to seeing the results as additional patients are enrolled and followed,” said Lewis T. “Rusty” Williams, M.D., Ph.D., president and chief executive officer of Five Prime. “The majority of mesothelioma tumors express high levels of FGF-2, so our FGF ligand trap represents a rational therapeutic approach, and patients currently have limited treatment options. If we see similar results once we have full, mature data for Arm C, we will seek to regain rights for FP-1039 in the U.S., Canada and the E.U. from GSK, as mesothelioma could represent a potentially attractive market opportunity for Five Prime.”

About the Phase 1b Trial

The Phase 1b clinical trial of FP-1039 is being conducted by GSK and is designed as a three-arm, multicenter, non-randomized, parallel-group, uncontrolled, open-label trial. This clinical trial was designed to evaluate the safety, tolerability, dosage, response rate and duration of response of FP-1039:

• in combination with paclitaxel and carboplatin in previously untreated metastatic sqNSCLC (Arm A);

• in combination with docetaxel in metastatic sqNSCLC that has progressed after previous therapy (Arm B); or

• in combination with front-line pemetrexed and cisplatin in mesothelioma (Arm C), a tumor in which the FGF-2 ligand is overexpressed.

About FP-1039

FP-1039 is a protein drug designed to intervene in FGF signaling. As a ligand trap, FP-1039 binds to FGF ligands circulating in the extracellular space (such as FGF-2), preventing these signaling proteins from reaching FGFR1 on the surface of tumor cells where they would otherwise stimulate cancer cell division and/or angiogenesis. However, FP-1039 does not bind to certain “hormonal” FGFs, including FGF-23, which regulates phosphate levels in the blood. As a result, treatment with FP-1039 treatment has not been shown to cause hyperphosphatemia, a side effect seen with small molecule inhibitors of FGF receptors, which block the activity of both cancer-associated FGFs and FGF-23.

About Mesothelioma

Mesothelioma is a disease with high unmet medical need and high mortality rate. A majority of mesothelioma patients have tumors with abnormally high levels of FGF-2. In preclinical testing, Five Prime observed inhibition of mesothelioma tumor growth with single-agent FP-1039. Mesothelioma is an orphan indication in the United States with a prevalence of about 4,000 patients and incidence of about 3,000 patients. Worldwide, there are a total of approximately 14,000 cases of mesothelioma diagnosed each year.

About Five Prime

Five Prime Therapeutics, Inc. discovers and develops innovative therapeutics to improve the lives of patients with serious diseases. Five Prime’s comprehensive discovery platform, which encompasses virtually every medically relevant extracellular protein, positions it to explore pathways in cancer, inflammation and their intersection in immuno-oncology, an area with significant therapeutic potential and a growing focus of the company’s R&D activities. Five Prime has entered into strategic collaborations with leading global pharmaceutical companies and has promising product candidates in clinical and preclinical development. For more information, please visit www.fiveprime.com.

Cautionary Note on Forward-looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Words such as “may,” “will,” “expect,” “plan,” “anticipate,” “estimate,” “intend” and similar expressions (as well as other words or expressions referencing future events, conditions or circumstances) are intended to identify forward-looking statements. These forward-looking statements are based on Five Prime’s expectations and assumptions as of the date of this press release. Each of these forward-looking statements involves risks and uncertainties. Actual results may differ materially from these forward-looking statements. Factors that may cause actual results to differ from those expressed or implied in the forward-looking statements in this press release are discussed in Five Prime’s filings with the U.S. Securities and Exchange Commission, including the “Risk Factors” contained therein. Except as required by law, Five Prime assumes no obligation to update any forward- looking statements contained herein to reflect any change in expectations, even as new information becomes available.

CONTACT:

Heather Rowe

Investor Relations

415-365-5737

heather.rowe@fiveprime.com

Amy Kendall,

Corporate Communications

415-365-5776

amy.kendall@fiveprime.com