The U.S. Food and Drug Administration (FDA) granted breakthrough therapy designation for the investigational gene therapy AMT-060 for severe hemophilia B.
The FDA’s decision was based on the results from an ongoing phase I/II study that included 10 patients with severe or moderately severe hemophilia at baseline, documented factor IX (FIX) levels <1 to 2 percent of normal, and who required chronic infusions of prophylactic or on-demand FIX therapy at the time of enrollment. Patients received a one-time, 30-minute intravenous dose of AMT-060 (5 patients received a dose of 5×1012 gc/kg and 5 received a dose of 2×1013 gc/kg).
After 52 weeks of follow-up, four patients in the low-dose cohort discontinued prophylactic therapy. All patients in this cohort continue to maintain “constant and clinically meaningful” levels of FIX activity, according to the researchers. No spontaneous bleeds were reported in this patient population in the last 14 weeks of observation.
Three patients (2 in the high-dose cohort and 1 in the low-dose cohort) experienced mild, asymptomatic elevations of alanine aminotransferase and received a tapering course of corticosteroids. No patients in either cohort developed inhibitory antibodies against FIX, and none of the patients screened tested positive for anti-AAV5 antibodies.
Source: Uniqure press release, January 31, 2017.