NASHVILLEIn a phase II study of an investigational
monoclonal antibody, OvaRex MAb, in advanced recurrent ovarian cancer, 6 of 13
patients survived 50 weeks or longer from entry into the trial, Thomas G.
Ehlen, MD, said at a poster session of the 32nd Annual Meeting of the Society
of Gynecologic Oncologists (SGO).
Dr. Ehlen was the lead investigator of the trial at the
Vancouver Cancer Center, British Columbia. The study was sponsored by AltaRex
Corp., Waltham, Massachusetts.
The study enrolled 13 patients with advanced ovarian cancer
that had relapsed after treatment failure of multiple standard therapies.
Patients received intravenous 2-mg infusions of OvaRex MAb on an outpatient
basis (five doses over a 12-week period, and then every 3 months until disease
Over half of the patients in the study showed a substantive
immune response following OvaRex MAb treatment, Dr. Ehlen said. Among these
immune responders, one patient survived more than 18 months, and two are still
alive almost 2 years after entry into the study.
In addition, Dr. Ehlen stated, OvaRex MAb was well tolerated,
and treatment was easily managed in the outpatient
Dr. Ehlen said that OvaRex MAb is antigen specific rather than
tumor specific. "It targets the antigen CA 125, which is produced by most
ovarian tumors but is not recognized by the patient’s immune system as a
threat since it is self-produced," he said. "OvaRex MAb binds to the
circulating CA 125, and because of its foreign nature, it fools the body’s
own immune system, including the T cells, into attacking the CA 125 and, in
turn, the associated ovarian tumor."
The frequent development of immune responses observed in the
study, which correlated with evidence of prolonged disease stabilization and
survival in some patients, provides further proof of principle for this
approach to cancer treatment, Dr. Ehlen commented.
The study is one of several prospective, controlled trials
sponsored by AltaRex in North America to evaluate the safety and efficacy of
OvaRex MAb. By the end of the year, AltaRex hopes to file a Biologics License
Application with the US Food and Drug Administration for regulatory approval of
OvaRex MAb for ovarian cancer indications. The agent has already received
Orphan Drug status and Fast Track designation from the FDA.