Data Not Promising for CA4P to Treat Ovarian Cancer

James Radke

Interim analysis of a Phase 2/3 study testing Mateon Therapeutics’ vascular disrupting agent, CA4P, in platinum-resistant ovarian cancer patients is struggling to meet its primary endpoint.
CAP4 is a tubulin-binding vascular disrupting agent, and it is believed that the drug has an antitumor effect by targeting tumor blood vessels to deprive tumor cells of nutrients.
Ovarian cancer is rare and often difficult to detect in its early stages. By the time symptoms appear, it is often in its later stages where the tumor has already metastasized. Recurrent platinum-resistant/platinum-refractory ovarian cancer is especially difficult to treat and new agents and/or new combination therapies offer the best outlook for this condition.
The current analysis evaluated progression-free survival (PFS) in the first 40 patients (19 with CA4P, 21 with placebo), either treated for at least 2 months or discontinued from the trial. The results were not statistically significant.
In the study, 91 patients with platinum-resistant ovarian cancer have been enrolled and are receiving the current standard-of-care – bevacizumab and chemotherapy – and are randomized to also receive either CA4P or placebo. The interim analysis showed that in the CA4P group, PFS was 6.64 month compared to 4.96 month for the placebo group (HR=0.68; P = .456).  Further, 6 patients (31.6%) in the CA4P group and 10 (47.6%) patients in the control group progressed or died while in the study.
Partial response to treatment was observed in 4 patients in the CA4P group and 6 patients in the control group.
The final interim analysis is expected for the study when 3/4 of the patients complete 2 months of treatment.
While the interim results are not encouraging, the company remains optimistic. In a news release, William D. Schwieterman, M.D., President and Chief Executive Officer of mateon said, “We are encouraged that early data on the primary endpoint of the study continue to favor CA4P and that our investigational drug remains well tolerated.”
Dr. Schwieterman added, “There is a large unmet medical need in the ovarian cancer market as patients with prOC have low survival rates and few treatment options. We look forward to additional and more mature data from the 3rd interim analysis expected just over one month from now – in this upcoming analysis we will have more data on the current patients, who will have had additional time under treatment, as well as initial efficacy and safety information on approximately 25 additional patients.”
The National Cancer Institute estimates that 22,280 women will be diagnosed with ovarian cancer in 2016 and an estimated 14,240 will die of this disease.
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