Five Prime Therapeutics Initiates Patient Dosing in The Dose Exploration Cohort of Its Phase 1 Trial of Novel First-in-Class B7-H4 Antibody FPA150
- The exploratory cohort will test FPA150 in patients whose tumors overexpress B7-H4
- B7-H4 is in the same family of checkpoint molecules as PD-L1 and is expressed in tumors that are not currently well served by immunotherapy
“We’re excited to be ahead of schedule in opening up our dose exploration basket cohort for FPA150, our first-in-class B7-H4 antibody, in patients whose tumors overexpress B7-H4,” said Helen Collins, M.D., Senior Vice President and Chief Medical Officer of Five Prime. “B7-H4 is generating excitement in investigators because it's expressed in tumor types that are currently not well served by immunotherapy, including breast and gynecologic cancers. We’re hopeful that a targeted therapy like FPA150 will provide clinical benefit in these patients who have limited treatment options.”
B7-H4 is in the same family of checkpoint molecules as PD-L1 and, like PD-L1, appears to inhibit T-cells in preclinical models. FPA150 has a dual mechanism of action: it blocks a T cell checkpoint pathway and delivers antibody-dependent cell-mediated cytotoxicity (ADCC) against B7-H4-expressing tumor cells.
FPA150-001 is an ongoing Phase 1a/1b dose escalation and expansion clinical trial of FPA150 monotherapy in patients with advanced solid tumors. The exploratory basket cohort is a part of that trial and will include up to 10 patients whose tumors overexpress B7-H4, as assessed by an immunohistochemistry (IHC) assay. The objective of this cohort is to evaluate a range of FPA150 doses to gain additional data on safety, pharmacokinetics (PK) and potential preliminary clinical activity. All patients will undergo pre- and on-treatment biopsies to assess the pharmacodynamic effects of FPA150 on the tumor and the tumor microenvironment.
The Phase 1a dose-escalation portion of FPA150-001 in unselected patients with any solid tumor is currently ongoing. The primary objective of this portion of the trial is to identify a maximum tolerated dose (MTD) or recommended dose (RD) for FPA150 monotherapy.
Once the MTD/RTD has been identified, the company will initiate a Phase 1b dose-expansion portion of the trial in B7-H4 positive tumors, including in breast cancer, ovarian cancer and endometrial cancer. The Phase 1b dose expansion endpoints include objective response rate, as well as safety and PK.
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 delivering ADCC against tumor cells expressing B7-H4.
About Five Prime
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
Five Prime Therapeutics, Inc.
Heather Rowe, 415-365-5737
Senior Director, Investor Relations and Corporate Communications