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
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
Antibody or placebo is given 4 to 10 weeks after successful primary surgery
and platinum-based chemotherapy (normalized CA 125 and no residual disease).