SOUTH SAN FRANCISCO, Calif.—Five Prime Therapeutics Inc., a clinical-stage biotechnology company focused on discovering and developing novel protein therapeutics for cancer and inflammatory diseases, announced recently the advancement of FPA008 into the Phase 2 dose expansion portion of the ongoing Phase 1/2 trial in pigmented villonodular synovitis (PVNS), a rare, locally aggressive tumor of the synovium.

 

“We are very pleased to progress to the Phase 2 portion of this trial evaluating FPA008 as a treatment for patients with PVNS, an orphan joint disease associated with significant morbidity,” said Dr. Robert Sikorski, senior vice president of global clinical development at Five Prime.  “Macrophages make up the bulk of PVNS tumors due to local over-expression of CSF-1, and we believe FPA008, a CSF-1 inhibitor, has the potential to impact the tumor by blocking the activation and survival of these cells. In the Phase 2 portion of the trial, we will evaluate clinical measures such as response rate, pain and mobility in patients with PVNS, for whom there are currently few options beyond surgery.”

 

Given that it is characterized by local over-expression of CSF-1, PVNS recruits macrophages into the joints, forming the non-malignant tumor mass. It is associated with high morbidity, and there are no approved therapies for the condition. FPA008 blocks the binding of CSF-1 and inhibits the activity and survival of the macrophages that form the bulk of the tumor.

 

Five Prime initiated patient dosing in this Phase 1/2 clinical trial of FPA008 in July 2015.  During the Phase 1 dose escalation part of the trial, Five Prime assessed the safety and pharmacodynamics of multiple ascending doses of FPA008 to determine the dose for expansion. During the Phase 2 expansion, the company will evaluate response rate and duration, as well as measures of pain and range of motion, in approximately 30 patients.

 

In January 2016, the U.S. Food and Drug Administration (FDA) granted Orphan Drug Designation for FPA008 for the treatment of PVNS, which is estimated to have a prevalence of 25,000 patients in the U.S.