The FDA granted orphan drug designation to PTG-300 for the treatment of phlebotomy-requiring polycythemia vera (PV). PTG-300 is an injectable synthetic hepcidin mimetic in development for the treatment of PV and hereditary hemochromatosis.
The agency’s decision was based on data from a phase II, open-label, dose escalation study of adult patients with PV who had received at least three phlebotomies within a previous 24-week period.
Preliminary results showed that treatment with PTG-300, at doses ranging from 10 to 80 mg for up to 28 weeks, led to dose-related control of hematocrit levels and eliminated the need for phlebotomy in all 6 patients who received per-protocol treatment. The drug’s manufacturer reported that a seventh patient had an unintended dose interruption at 12 weeks, received a single phlebotomy, and resumed participation.
Injection-site reactions and bruising were reported as the most common adverse events, and the drug’s safety profile was found to be similar to that observed in prior studies. Enrollment in the study is ongoing and a total of 8 patients have enrolled to date.