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.Non-clinical data of FPA150 featured in an oral poster presentation at the European Society for Medical Oncology (ESMO) 2017 Congress described potent ADCC and T cell checkpoint blockade activity in vitro and significant dose-dependent anti-tumor efficacy in vivo.

Five Prime initiated a Phase 1 clinical trial of FPA150 in March 2018. 

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.