Abagovomab as maintenance drug for OVC (new research)

Interim Analysis Supports Abagovomab in Ovarian Cancer
Elsevier Global Medical News. 2010 Jun 7, R Hyer


CHICAGO —Only 19 serious adverse events potentially related to treatment have been reported from the MIMOSA trial of abagovomab maintenance therapy in 888 patients with epithelial ovarian cancer, after a mean exposure to study treatment of 12.8 months.

This was the preliminary report of the randomized (2:1), double-blind, placebo-controlled, multicenter phase III trial in patients with FIGO stage III/IV ovarian cancer in complete response after platinum-taxane based first-line chemotherapy. It was presented in a poster at the annual meeting of the American Society of Clinical Oncology.

"We've shown that the tolerability is very good, and that there really are no safety issues, just some minimal injection-site reactions, and we're just anxiously awaiting the data," said lead author Dr. Paul Sabbatini of Memorial Sloan-Kettering Cancer Center, New York. Final efficacy data are expected in December.

Abagovomab is a murine monoclonal anti-idiotype antibody that recognizes the tumor antigen CA125, expressed in ovarian cancer. The antibody mimics the body's original antigen, potentially inducing an immune response and eradicating the ovarian cancer cells that are expressing CA125.

In earlier phase I and phase II studies, the specific humoral and cellular-mediated immune response induced by abagovomab against the CA125 antigen was associated with increased survival.

"The idea is to have a nontoxic maintenance strategy for when they've completed chemotherapy, when they otherwise would be observed," said Dr. Sabbatini. He said that abagovomab was immunogenic and had approximately a 67-70% antibody production rate, as observed in phase I studies.

"In the phase I and phase II trials, patients who made antibody responses had a markedly prolonged progression-free survival compared to those who did not," Dr. Sabbatini said. "But the danger there is that you just select people who have a competent immune system, who can do that. And you need the randomized data to answer the question."

The Monoclonal antibody Immunotherapy for Malignancies of the Ovary by Subcutaneous Abagovomab (MIMOSA) trial's primary endpoint is recurrence-free survival, and secondary endpoints are overall survival and immunological response. The trial was begun in December 2006 and enrollment was completed in December 2008. Mean patient age is 56.8 years, and the majority (82%) showed a serous/papillary histology with a G3-G4 grade of differentiation (61.7%). More than 90% of patients had Eastern Cooperative Oncology Group Performance Status (ECOG PS) less than 1.

The most frequent adverse events were injection site reaction and fatigue. Only 2% of patients discontinued study treatment because of an adverse event that was "at least potentially treatment related," according to the poster. The trial's Data Safety Monitoring Board found no safety issues as of October 11, 2009, and recommended continuing the study to completion as planned.

The study is sponsored by the Menarini Group, of Florence, Italy. Dr. Sabbatini disclosed no relevant financial information.