Five Prime Therapeutics Initiates Patient Dosing in Phase 1a/1b Trial Evaluating the Immunotherapy Combination of FPA008 and OPDIVO (nivolumab) in Six Tumor Types

SOUTH SAN FRANCISCO, Calif., Sept. 8, 2015 (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 announced that it has initiated patient dosing in the Phase 1a/1b clinical trial evaluating the immunotherapy combination of FPA008, Five Prime’s monoclonal antibody that inhibits colony stimulating factor-1 receptor (CSF1R), with OPDIVO® (nivolumab), Bristol-Myers Squibb’s PD-1 immune checkpoint inhibitor, in six tumor types.

FPA008 and OPDIVO are part of a new class of cancer treatments known as immunotherapies that are designed to harness the body’s own immune system to fight cancer. FPA008 targets macrophages and monocytes, which are activated or elevated in multiple disease settings. In cancer, tumor-associated macrophages suppress the immune system’s ability to kill cancer cells. OPDIVO is approved in the United States, Japan and the European Union for metastatic melanoma, and in the United States and European Union for squamous non-small cell lung cancer. OPDIVO is being evaluated as a mono therapy, as well as in combination with other agents, across multiple tumor types in more than 50 clinical trials. Preclinical data suggest that combining antibodies targeting PD-1 and CSF1R may lead to an enhanced anti-tumor immune response compared to either drug alone.

“We hope that targeting tumor suppressing macrophages in addition to a known immune checkpoint will allow us to harness more of the immune system’s anticancer activity, and will make durable responses a reality for more of our patients,” said Julie Brahmer, M.D., Associate Professor of Oncology and Interim Director at the Sidney Kimmel Comprehensive Cancer Center (Johns Hopkins Bayview campus) and a Principal Investigator for the trial. “We look forward to participating in this trial, which will generate important information about the potential of this immunotherapy combination across a number of tumor types, including many where patients have few effective treatments.”

“We are excited about the potential of FPA008 as a novel immuno-oncology therapeutic and about combining it with OPDIVO in this clinical collaboration with Bristol-Myers Squibb. We believe that targeting the CSF1R and PD-1 pathways in tandem may produce a synergistic treatment effect against a variety of tumors,” said Lewis T. “Rusty” Williams, M.D., Ph.D., president and chief executive officer of Five Prime. “Five Prime looks forward to enrolling this study, as it will provide us a wealth of information about this novel therapeutic combination and will further guide our development of FPA008 in oncology.”

During Phase 1a, Five Prime will evaluate the safety, pharmacokinetics and biomarkers of escalating doses of FPA008 as a monotherapy, as well as in combination with the approved 3 mg/kg dose of nivolumab. Approximately 30 patients with advanced cancers are expected to be enrolled during the Phase 1a part of the study and both drugs will be administered every two weeks. In the Phase 1b part of the study, Five Prime will evaluate the safety, tolerability and preliminary efficacy of the selected dose of FPA008 in combination with nivolumab in approximately 240 patients, as a front-line therapy for melanoma; as second-line therapy for squamous cell carcinoma of the head and neck, pancreatic cancer, and malignant glioma; as a second- or third-line therapy for non-small cell lung cancer (NSCLC); and as a third-line therapy for colorectal cancer. Tumor biopsies will be obtained both pre-treatment and one month post-treatment in a subset of patients to analyze the immune response within the tumor microenvironment, and Five Prime will use this analysis to further guide FPA008’s development in oncology.

Under the terms of the clinical collaboration, BMS made a one-time payment of $30 million to Five Prime and is responsible for external study costs, the costs for OPDIVO, and half of the costs for FPA008 used in the Phase 1b part of the trial. The study design will be described in further detail in a trial-in-progress presentation at the International Cancer Immunotherapy Conference, to be held September 16-19, 2015 in New York City. Five Prime expects to complete Phase 1a dose escalation and expand into Phase 1b with the selected dose of FPA008 in late 2015 or early 2016.

About FPA008

FPA008, Five Prime’s antibody that inhibits colony stimulating factor-1 receptor (CSF1R), targets macrophages and monocytes, which are activated or elevated in multiple disease settings. In cancer, tumor-associated macrophages suppress the immune system’s ability to kill cancer cells. In joint diseases, such as PVNS and RA, synovial macrophages play a central role in the disease process. Five Prime is evaluating the immunotherapy combination of FPA008 and OPDIVO (nivolumab), Bristol-Myers Squibb’s investigational PD-1 immune checkpoint inhibitor, in six tumor types in a Phase 1a/1b clinical trial. Five Prime is also conducting a Phase 1/2 trial of FPA008 in pigmented villonodular synovitis (PVNS), a joint tumor driven by the CSF1 pathway and an orphan disease, and a Phase 1 study in rheumatoid arthritis.

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

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 potential benefit of combining FPA008 and nivolumab to lead to an enhanced anti-tumor immune response; and (ii) the enrollment in and timing of the completion of the Phase 1a dose escalation and expansion into Phase 1b of the study of FPA008 in combination with nivolumab. Many factors may cause differences between current expectations and actual results including unexpected safety or efficacy data observed during the clinical study, clinical trial site activation or enrollment rates that are lower than expected, changes in expected or existing competition, changes in the regulatory environment, failure of BMS, Five Prime’s collaborator, to support or advance the clinical study of FPA008 in combination with nivolumab and unexpected litigation or other disputes. 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.

CONTACT: Amy Kendall,
         Corporate Communications

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