Peregrine Reports Positive Results From Phase II Trial For Bavituximab

Peregrine Pharmaceuticals has reported positive results from its phase II trial evaluating bavituximab in combination with docetaxel, in patients with advanced breast cancer.

Bavituximab is a monoclonal antibody that targets the cellular membrane component phosphatidylserine (PS) that is usually located inside cells, but which becomes exposed on the outside of the cells that line the blood vessels of tumors, creating a specific target for anti-cancer treatments. Bavituximab acts by binding to externalized PS on tumor blood vessels and inducing immune cell-mediated destruction of the blood vessels.

Preliminary data at the end of the six planned treatment cycles in the phase II study showed that 28 of 46, or 61%, of all patients enrolled in the trial achieved an objective tumor response, according to RECIST criteria.

The data compares with data from a published study showing an objective tumor response rate of 41% in a similar patient population receiving the same dosing regimen of docetaxel administered as a single agent.

Steven King, president and CEO of Peregrine, said: “The data released today continues to reinforce the positive results seen across the five cancer trials to date assessing the potential of bavituximab in different treatment combinations across multiple tumor types. We believe this data in aggregate shows the broad potential of this novel therapeutic compound for the treatment of solid tumors.”

The primary objective of the multi-center, open-label phase II study is to assess the overall response rate to bavituximab and docetaxel. In this trial’s Simon two-stage design, 15 patients were initially enrolled in the study followed by an additional 31 patients after the pre-specified primary efficacy endpoint for expanding the study was met, bringing the total to 46 patients. Initial data from the first set of 15 patients in the study was reported in an oral presentation at the 2009 ASCO Annual Meeting.

Recent analysis showed that the median progression-free-survival (PFS) of patients enrolled in the initial 15-patient cohort of the study was 7.4 months, a promising early result. Patient follow-up in the trial is continuing.

Secondary objectives of the study include measuring time to tumor progression, duration of response, overall patient survival and safety parameters. Patients in the study are evaluated regularly for tumor response according to RECIST criteria. Patients may continue to receive bavituximab as monotherapy after completion of chemotherapy as long as the cancer does not progress and side effects are acceptable, said the company.