NEW YORKA monoclonal antibody with high affinity for an ovarian tumor-associated antigen has shown promising activity in preliminary results from a large phase III study, said Jonathan S. Berek, MD, chief of the Division of Gynecology and Oncology, UCLA School of Medicine.
The antibody, known as oregovomab (OvaRex, AltaRex Corp., Waltham, Massachusetts), was clinically active in multiple studies of stage III-IV ovarian cancer patient populations. "The clinical activity, even with second-line chemotherapy, suggests new strategies for combined modality treatment," Dr. Berek said at the Chemotherapy Foundation Symposium XIX (abstract 30).
Oregovomab, a murine monoclonal antibody, has a high affinity for cancer antigen 125 (CA 125). In clinical studies, bioactivity correlating with clinical benefit has been observed in more than half of treated patients.
The agent’s "benign safety profile" makes it practical for real-world application, Dr. Berek said. Data from six trials including more than 400 patients suggest a safety profile similar to placebo, with infrequent and easily managed allergic responses (ie, pruritus) to the foreign protein.
A series of studies to date (prospective randomized and nonrandomized) show that this monoclonal antibody induces cellular and humoral responses across a wide range of ovarian cancer patients, notably in those with available circulating CA 125 and those who mount a potent immune response to treatment, defined as prolonged time to disease relapse.
More precise information on the clinical utility of oregovomab will be forthcoming from a large, double-blind, placebo-controlled trial including 345 stage III-IV ovarian cancer patients enrolled at 52 centers in Canada and the United States.
Antibody or placebo is given 4 to 10 weeks after successful primary surgery and platinum-based chemotherapy (normalized CA 125 and no residual disease).