Five Prime Therapeutics Initiates Patient Dosing in Phase 1 Trial of Novel First-in-Class B7-H4 Antibody FPA150

Dual mechanism: blocks a T cell checkpoint pathway and delivers potent antibody-dependent cell-mediated cytotoxicity (ADCC) against B7-H4-expressing tumor cells

SOUTH SAN FRANCISCO, Calif.--(BUSINESS WIRE)-- Five Prime Therapeutics, Inc. (Nasdaq: FPRX), a biotechnology company discovering and developing innovative immuno-oncology protein therapeutics, today announced that it initiated patient dosing in its Phase 1 clinical trial of FPA150, a first-in-class immuno-oncology antibody that targets B7-H4.

"We're excited to advance into the clinic our targeted, first-in-class B7-H4 antibody, FPA150, which offers a differentiated approach to existing immunotherapies," said Helen Collins, M.D., Senior Vice President and Chief Medical Officer of Five Prime. "We're studying FPA150 in patients whose tumors overexpress B7-H4 and in which there is high unmet need for immuno-oncology treatments, such as in breast, ovarian and endometrial cancer. We're hopeful that a targeted therapy such as FPA150 may provide clinical benefit."

Five Prime designed the Phase 1 trial of monotherapy FPA150 with a dose-escalation phase in patients with solid tumors, followed by dose expansion in pre-specified cohorts in tumor types based on B7-H4 expression levels. The initial targeted tumors are advanced or metastatic breast, ovarian, endometrial and bladder cancers. Phase 1a dose escalation endpoints include identification of a maximum tolerated dose (MTD), safety, and pharmacokinetics (PK) of FPA150. Phase 1b dose expansion endpoints include objective response rate, as well as safety and PK.

About FPA150

FPA150 is a novel, fully human, afucosylated monoclonal antibody targeting B7-H4. B7-H4 expression is observed in multiple solid tumors, including breast, bladder and gynecologic cancers, and has been documented to correlate with poor prognosis. FPA150 is designed with a dual mechanism of action: blocking the T cell checkpoint activity of B7-H4 as well as delivering potent ADCC against tumor cells expressing B7-H4.

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 the 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 or follow us on LinkedIn, Twitter and Facebook.

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. Forward-looking statements contained in this press release include statements about (i) the progress and scope of the Phase 1 clinical trial of FPA150; (ii) the potential use of FPA150 to treat patients with cancer; and (iii) the extent of B7-H4 protein expression in patients with cancer. Many factors may cause differences between current expectations and actual results, including unexpected safety or efficacy data observed during non-clinical or clinical studies, clinical site activation rates or clinical trial enrollment rates that are lower than expected and changes in expected or existing competition. Other 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.


Five Prime Therapeutics, Inc.
Heather Rowe, 415-365-5737
Senior Director, Investor Relations and Corporate Communications


Source: Five Prime Therapeutics, Inc.

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