Promising interim results of a double-blind placebo-controlled trial of the monoclonal antibody OvaRex in 345 patients with ovarian cancer were presented at the 37th annual meeting of the American Society of Clinical Oncology (ASCO) in San Francisco. Dr. Jonathan Berek, MD, PhD, professor and vice chair at the University of California-Los Angeles Medical Center and coprincipal investigator of the study made the presentation.
High-Risk Patients Show Greatest Benefit
Among the highlights of Dr. Berek’s presentation was the recent breakthrough in the understanding of the correlation between circulating levels of the ovarian tumor marker CA-125 and the efficacy of OvaRex. Specifically:
At the initiation of the trial, the CA-125 levels of participants were assumed to be in the normal range for this patient population. One notable observation was that patients on the high end of this range are at significantly increased risk of relapsing. OvaRex is proving to be most beneficial in these patients.
The proportion of high-risk patients who achieved a disease-free survival of 6 months is significantly higher (P = .0397) among those treated with OvaRex (79%) than among those receiving placebo (39%).
Approximately 50% of patients developed a specific immune response to OvaRex that correlated directly with clinical benefit.
Results of Phase II Trials
In addition to the interim analysis, AltaRex Inc (manufacturer of OvaRex) has analyzed final data from two phase II trials. These results demonstrate that in late-stage ovarian cancer patients with recurrent disease, treatment with OvaRex can provide comparable efficacy to salvage chemotherapies but without the associated toxicities.
An analysis of the primary end point of time to disease relapse for all 345 patients in the lead trial is scheduled to begin in the third-quarter of this year. Clinical data from this trial and five other complementary and supporting trials will form the basis for a simultaneous filing for product approval with both the United States and Canadian regulatory authorities.