Five Prime Therapeutics Announces FPA150 Poster Presentation at the 2019 ASCO Annual Meeting

– Phase 1a/1b Study of First-in-class B7-H4 Antibody as
Monotherapy in Patients with Advanced Solid Tumors –

SOUTH SAN FRANCISCO, Calif.–(BUSINESS WIRE)–Five
Prime Therapeutics, Inc. (NASDAQ: FPRX), a clinical-stage
biotechnology company focused on discovering and developing innovative
immuno-oncology protein therapeutics, today announced an upcoming poster
presentation at the 2019 ASCO Annual Meeting being held in Chicago, May
31 – June 4, 2019.

Data will be presented from the Phase 1a/1b study of FPA150, which is a
first-in-class B7-H4 antibody. The Phase 1a dose escalation portion of
the study is being conducted in patients with advanced solid tumors and
the Phase 1b expansion is enrolling patients with breast, ovarian and
endometrial tumors that overexpress B7-H4.

Here are the details of the upcoming poster presentation:

The poster abstracts will be available on May 15, 2019 at 5:00 PM EST at
the ASCO
Meeting Library and the posters can be found on Five
Prime Therapeutics’ Scientific Publications page after presentation
at the conference.

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 and gynecologic cancers. FPA150 is designed with a dual
mechanism of action: blocking the T cell checkpoint activity of B7-H4 as
well as enhanced ADCC against tumor cells expressing B7-H4.

About Five Prime Therapeutics

Five Prime Therapeutics, Inc. discovers and develops innovative protein
therapeutics to improve the lives of patients with serious diseases.
Five Prime’s product candidates have innovative mechanisms of action and
address patient populations in need of better therapies. The company
focuses on researching and developing immuno-oncology and targeted
cancer therapies paired with companion diagnostics to identify patients
who are most likely to benefit from treatment with Five Prime’s product
candidates. 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 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. 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.

Contacts

Media and Investor Contact
Martin Forrest
VP, Investor
Relations & Corporate Communications
Five Prime Therapeutics,
Inc.
415-365-5625
[email protected]