Five Prime Therapeutics Presents Poster on FGFR2b Expression and Immune Signature in Urothelial Cancer at the Society for Immunotherapy of Cancer 32nd Annual Meeting

SOUTH SAN FRANCISCO, Calif., Nov. 10, 2017 -- Five Prime Therapeutics, Inc. (Nasdaq:FPRX), a clinical-stage biotechnology company focused on discovering and developing innovative immuno-oncology protein therapeutics, announced today that analyses of FGFR2b expression and baseline immune signature in urothelial cancer (UC) samples were featured in a poster presentation at the Society for Immunotherapy of Cancer (SITC) 32nd Annual Meeting, being held November 8-12, 2017 in National Harbor, Maryland. A PDF of the poster, "FGFR2b Expression and Baseline Immune Signature to Guide FPA144 Development in Urothelial Cancer," will be made available on the Publications page of the Five Prime website. Five Prime is developing FPA144, an isoform-selective antibody, as a targeted immunotherapy for tumors that overexpress FGFR2b. Five Prime continues to enroll patients in the Phase 1 trial cohort evaluating FPA144 as a treatment for patients with bladder cancer whose tumors overexpress FGFR2b.

“Profiling FGFR2b expression and baseline tumor-associated immune cells could help guide our clinical development strategy for FPA144 in bladder cancer," said Kevin Baker, Ph.D., Senior Vice President, Development Sciences at Five Prime. “Previously we showed in a pre-clinical model with moderate FGFR2b expression, that FPA144 can reprogram the tumor microenvironment making it more inflammatory. In the same studies, we also showed that FPA144 and PD-1 blockade have additive anti-tumor effects.”

Five Prime evaluated FGFR2b expression in 387 archival primary early stage UC samples and previously reported that >10% had overexpression of FGFR2b by immunohistochemistry (IHC) with intensity level of at least 1+. The research team selected 32 archival UC cases with a range of FGFR2b expression (62% were FGFR2b positive) and characterized baseline immune composition in the tumor microenvironment and the relationship with FGFR2b expression to potentially guide FPA144 development in combination with other therapies.

The results from the selected cases suggest that FGFR2b is expressed in all immune subtypes of UCs, but the expression level varies. The highest level of expression is in inflamed and more proliferative UCs. The Company plans to evaluate additional archival UC tissues from patients with more advanced metastatic disease to determine if there is an association of FGFR2b expression with baseline immune signature in late-stage patient tumors.

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 late 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: 
Derek Cole
Investor Relations Advisory Solutions
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