Agenus Inc. announced results from a Phase 2 clinical trial testing the Prophage Series G-200 vaccine (HSPPC-96; vitespen) in deadly recurrent brain cancer, glioblastoma multiforme (GBM), at the 47th Annual Meeting of the American Society of Clinical Oncology (ASCO).
The key objectives of the Prophage Series G-200 Phase 2 trial were to evaluate the overall survival rate, safety and immunological activity consistent with a tumor-specific immune response. The primary objective of the trial was to assess the survival rate at 26 weeks, which represents the average survival time for patients experiencing recurrence of their GBM. Results from this trial showed that 93% of the patients were alive at ? 26 weeks after surgery and a median overall survival of 11 months (47.6 weeks).
Results from pre-defined exploratory analyses of disease progression showed a median progression free survival (PFS) of approximately 5 months (20 weeks). Importantly, measures of immune response post vaccination with Prophage Series G-200 demonstrated a significant tumor-specific CD8+ T-cell response as well as innate immune responses as marked by a significant increase in levels of circulating NK cells.
“The robust immune response coupled with improved survival relative to historical controls makes the data from this trial especially encouraging. The safety profile of HSPPC-96 offers a great opportunity for its use in combination with other approved treatments for GBM,” said Andrew T. Parsa, MD, PhD, associate professor in the department of neurological surgery at the University of California, San Francisco (UCSF) and lead investigator in the trial. “Taken together, the results clearly support advancement of Prophage Series G-200 into later stage randomized trials, and offer an opportunity to add a biologically active and highly well tolerated adjuvant therapy to surgical resection for recurrent GBM patients.”
Adverse events considered related to Prophage Series G-200 were grade 1 or 2 in nature and mainly associated with the injection, including skin reactions and stinging at the site of injection as well as reports of fatigue. No related grade 3 or 4 adverse events were reported in this trial.
“Based on the promising results from this Phase 2 study, Agenus has started working with the UCSF team, as well as other experts in the field, to design a randomized trial to confirm the efficacy of Prophage Series G-200 in the setting of recurrent GBM,” said Marcel Rozencweig, MD, Acting Chief Medical Officer of Agenus. “With the recent FDA approvals of Provenge and Yervoy, which both harness the power of the immune system to fight cancer and offer the potential for combination use with other immunological agents, I believe we are entering a new era in the treatment of cancer that could see substantially improved survival rates in patients fighting this disease.”
The Phase 2 trial was designed to enroll approximately 30 patients with recurrent high-grade GBM, the deadliest form of brain cancer. Patients underwent surgery to remove >90% of their tumors (also referred to as gross total resection), which were then used to manufacture Prophage Series G-200, a patient-specific heat shock protein based therapeutic vaccine. Eligible patients were treated after surgery with Prophage Series G-200 once weekly for four weeks, followed by biweekly injections until vaccine depletion or disease progression.
A total of 33 patients were enrolled (ITT population) and all received at least one dose of vaccine; 30 of the 33 patients were considered evaluable per-protocol as they received ? 4 doses of Prophage Series G-200. The median patient age was 53 years and all had an original diagnosis of GBM, which tends to carry a poor prognosis.
Results in the ITT population were similar to those reported on in the evaluable group (91% survival rate at ? 26 weeks; median survival rate of 42.6 weeks). Results from pre-defined exploratory analyses of disease progression showed a median progression free survival (PFS) of approximately 5 months (20 weeks) in the evaluable population, which were also similar in the ITT population (PFS of 17.1 weeks).
Release Date: June 6, 2011
Source: Agenus Inc.
Filed Under: Drug Discovery