OvaRex Study Demonstrates Efficacy and Safety in Ovarian Cancer Patients

April 1, 2001

In a recently completed phase II study of the monoclonal antibody OvaRex, nearly half of the OvaRex-treated patients with advanced ovarian cancer survived 50 weeks or longer. The results of the trial were presented at the 32nd Annual Meeting of

In a recently completed phase II study of themonoclonal antibody OvaRex, nearly half of the OvaRex-treated patients with advanced ovarian cancer survived 50 weeks or longer. Theresults of the trial were presented at the 32nd Annual Meeting of the Society ofGynecologic Oncologists by Thomas G. Ehlen, MD, FRCSC, lead investigator of theclinical trial at the Vancouver Cancer Center in British Columbia. Patientsparticipating in this study had had a relapse of ovarian cancer after failure ofmultiple standard treatments.

The study enrolled 13 patients with advanced recurrent ovariancancer who received 2-mg intravenous infusions of OvaRex on an outpatient basis(five doses over a 12-week period and then every 3 months until diseaseprogression). Six patients survived 50 weeks or longer. Over half the patientsachieved immune responses following treatment. Among these immune responders,one patient survived more than 18 months and two are still alive almost 2 yearsafter entry into the study. In addition, OvaRex was well tolerated, andtreatment was easily managed in the outpatient setting.

New Treatments Needed

"For women with advanced ovarian cancer who have relapseddisease after treatment with standard chemotherapeutic agents, the responsebenefit from available drug treatment is commonly less than 1 year and is oftenassociated with significant toxicities," said Dr. Ehlen. "We need newtreatments that do not have the same side effects as currently usedchemotherapies, and so the clinical results from this and other completed orongoing trials with OvaRex are very encouraging."

Rather than being tumor specific, OvaRex is an antigen-specificproduct, Dr. Ehlen explained. "It targets the antigen CA-125, which isproduced by most ovarian tumors but not recognized by the patient’s immunesystem as a threat since it is self-produced," he continued. "OvaRexbinds to the circulating CA-125. And, because of its foreign nature, it foolsthe body’s own immune system, including the T cells, into attacking the CA-125and, in turn, the associated ovarian tumor. Among the patients followed in ourstudy, it was notable that two patients continue to survive years after startingthe protocol therapy."

Several Clinical Trials Underway

"We believe that the frequent development of immuneresponses observed in this study—correlated with evidence of prolongedstabilization of disease and survival in some patients—provides further proofof principle for this innovative approach to cancer treatment," commentedHoward Finger, MD, vice president of clinical operations and medical director ofAltaRex Corp, the manufacturer of OvaRex. "We are pleased with the outcomesof this completed study, one of several prospective, well-controlled trials inNorth America sponsored by AltaRex to evaluate the safety and efficacy of OvaRexMAb to support our upcoming US regulatory filing for ovarian cancerindications."

Currently, these late-stage clinical studies are underway at 64sites across North America. The studies involve patients in both the watchfulwaiting and recurrent ovarian cancer indications. Worldwide, OvaRex has beenstudied in more than 400 ovarian cancer patients.