The U.S. Food and Drug Administration (FDA) has granted fast-track designation to OXi4503, a vascular disrupting agent shown to cause tumor cell death and necrosis, for the treatment of relapsed/refractory acute myeloid leukemia (AML).
The decision was based on results from the phase IB dose-escalating OX1222 study, which was designed to establish the maximum tolerated dose for OXi4503 as a single agent or in combination with intermediate-dose cytarabine in patients with relapsed/refractory AML or myelodysplastic syndromes.
Results from the first two dose cohorts of OX1222, which were presented at the 2016 ASH Annual Meeting, demonstrated that OXi4503 (at doses of 3.75 and 4.68 mg/m2) was safe, and two of 10 patients achieved complete remission. In the third dose group, four patients received OXi4503 6.25 mg/m2 plus cytarabine 1g/m2 daily for 5 days; one patient achieved complete remission and no dose-limiting toxicities were observed. Two other patients saw a reduction in AML blasts.
OXi4503 had previously been granted orphan-drug designation by the FDA.
Sources: Mateon Therapeutics press releases, March 15, 2017 and June 7, 2017.