Higher doses of ipilimumab combined with the GVAX vaccine is showing a lot of success in increasing anti-tumor activity in these patients, said Saskia J.A.M. Santegoets, Ph.D., a researcher in the Department of Pathology and Division of Immunotherapy at the Vrije Universiteit Medical Center in the Netherlands. Were encouraged by the results of this phase I trial and expect ongoing analyses to yield more valuable data about the GVAX/ ipilimumab combination.
In this trial, the vaccine was administered with escalating doses of anti-CTLA-4 (cytotoxic T-lymphocyte antigen 4) antibody ipilimumab. Researchers believe that the combination of these two immunotherapies increases ones immunity to prostate cancer.
Twelve patients were enrolled in this study. All were given the same doses of GVAX (a 500 million cell first dose followed by bi-weekly 300 million-cell doses for 24 weeks), and, in groups of three, different quantities of ipilimumab administered every four weeks (.3mg, 1mg, 3mg, or 5 mg).
Anti-tumor activity was seen in five of the six patients who received the two highest doses of ipilimumab, including PSA-level declines of greater than 50 percent; these PSA declines were maintained in four of these patients for at least six months, and up to 16 months. Among the patients with PSA-level declines, researchers noted complete resolution of multiple lesions on bone scans in two patients, resolution of cancer spread to abdominal lymph nodes in one patient, and improvement in bone pain in one patient.
The ongoing phase I trial of this combination has enrolled an additional 16 patients with hormone-resistant prostate cancer into an expansion cohort.
Evidence of Efficacy of Antibody Directed Enzyme Prodrug Therapy (ADEPT) in a Phase I Tria
Contact: Staci Vernick Goldberg
American Association for Cancer Research