Data from the second interim analysis of the ongoing Phase 2/3 FOCUS study has shown that Mateon Therapeutics’ CA4P (combretastatin a4-phosphate), also known as fosbretabulin, may prolong the time to disease progression or death, when added to the standard of care for platinum-resistant ovarian cancer.
“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,” William D. Schwieterman, MD, president and CEO of Mateon, said in a press release. “There is a large unmet medical need in the ovarian cancer market as patients with prOC have low survival rates and few treatment options.”
CA4P was designed to target blood vessels and the blood supply within tumors. This investigational drug is expected to deprive cancer cells of oxygen and nutrients, triggering their death.
The FOCUS trial (NCT02641639) was designed to assess the safety and efficacy of CA4P compared to placebo, when given in combination with Avastin (bevacizumab) and a physician’s choice chemotherapy to patients with platinum-resistant ovarian cancer. Eligible patients had received at least one, but no more than two, prior platinum-based regimens.
The trial’s primary objective was to determine the time to disease progression or death, a measure called progression-free survival (PFS). Other efficacy measures include objective response rate (ORR), overall survival (OS), and overall safety. Conducted in research centers in the United States, Belgium, and Germany, the study has enrolled a total of 91 participants in its Phase 2 part.
Results from the first interim analysis, which was conducted after the first 20 enrolled patients received two months of therapy or discontinued from the trial, showed that CA4P-treated patients had a better progression-free survival rate than those on placebo. Also, more patients had achieved partial responses with CA4P (22%) than with placebo (9%).
Now, the second interim analysis is based on data from the first 40 patients. At this point, 19 patients had received CA4P and 21 received placebo. All patients received Avastin plus physician’s choice chemotherapy.
Results showed that CA4P reduced risk of death or disease progression by 32% compared to placebo. The CA4P-treated group had a mean PFS of 6.64 months compared to the 4.96 months in the placebo arm.
Four of 16 patients (25%) treated with CA4P achieved a partial response, and nine (56%) had stable disease. In the placebo group, 31% had a partial response and 58% had stable disease.
Safety analysis continued to demonstrate that CA4P is well tolerated. About 57.9% of the patients receiving CA4P experienced a transient increase in blood pressure, compared to 9.5% in the control group. CA4P also induced mild to severe adverse effects more frequently than placebo, which included nausea, fatigue, cough, and hypertension. Only one case of serious grade 4 event of hypertensive crisis was reported in the treatment group.
“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,” Schwieterman said.
The next interim analysis is planned to be released after the first 60 participants have completed two months of treatment, or were discontinued from the study.