Five Prime Therapeutics Doses First Patient in Phase 1b Trial of FPA150
- First-in-class antibody targeting B7-H4
- Dual mechanism blocks a T cell checkpoint pathway and delivers potent antibody-dependent cell-mediated cytotoxicity (ADCC) against tumor cells that express B7-H4
- B7-H4 is over-expressed on hard-to-treat solid tumors with low response to checkpoint inhibition
- Phase 1b trial will test monotherapy FPA150 in patients with breast, ovarian, and endometrial tumors that over-express B7-H4
“We are very pleased with the progress of our FPA150 clinical program that began with a dose escalation study in solid tumors and rapidly proceeded to an exploratory basket cohort of tumors that over-express B7-H4,” said Helen Collins, Senior Vice President and Chief Medical Officer. “We have now dosed the first patient in the Phase 1b dose expansion portion of the trial. FPA150 specifically targets B7-H4, which is in the same family of checkpoint inhibitors as PD-L1 and is over-expressed in breast and gynecological cancers that are not well served by immunotherapy. We are hopeful that a targeted immunotherapy like FPA150 will provide clinical benefit to these patients who have limited treatment options.”
The objective of the Phase 1b dose expansion is to evaluate the safety, tolerability, pharmacokinetics (PK) and potential preliminary clinical benefit of FPA150 monotherapy in patients with breast, ovarian and endometrial cancers that over-express B7-H4. A subgroup of patients in the Phase 1b portion will undergo pre- and on-treatment biopsies to assess the pharmacodynamic effects of FPA150 on the tumor and the tumor microenvironment, including changes in markers of tumor immune infiltrates and cytokine levels. Endpoints for the Phase 1b portion include objective response rate (ORR), duration of response and progression-free survival (PFS).
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.
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