Mateon discontinuing Zybrestat on Phase II/III ovarian cancer data

Mateon Therapeutics Inc. (OTCQX:MATN) discontinued development of Zybrestat fosbretabulin (combretastatin A4P, CA4P) after data from the first 70 platinum-resistant ovarian cancer patients enrolled in the Phase II/III FOCUS trial showed Zybrestat in combination with physician’s choice of chemotherapy and Avastin bevacizumab missed the primary endpoint of improving median progression-free survival (PFS) vs. placebo plus chemotherapy and Avastin. The Zybrestat combination also did not lead to a significant improvement on the secondary endpoint of improving objective response rate (ORR) vs. the placebo arm. The company said it will now focus on acute myelogenous leukemia (AML) candidate OXi4503 combretastatin A1 di-phosphate (CA1P) and reduce headcount.

In the double-blind, international FOCUS trial, 60 mg/m² Zybrestat every 2 weeks plus chemotherapy and Avastin led to a median PFS of 202 days vs. 170 days for placebo plus chemotherapy and Avastin (HR=0.844, p=0.688). Additional secondary endpoints include overall survival (OS), PFS at 6, 9 and 12 months and safety. Mateon previously reported a median PFS of 6.6 months for the Zybrestat arm vs. 5 months for the placebo arm (HR=0.68, p=0.456) (see BioCentury, Sept. 1)...