uniQure N.V. announced that AMT-060, its proprietary, investigational gene therapy in patients with severe hemophilia B, has received Breakthrough Therapy designation by the U.S. Food and Drug Administration (FDA). This designation is based on results from the ongoing, dose-ranging Phase 1-2 study that show sustained increases in Factor IX (FIX), reductions in FIX replacement usage and a near cessation of spontaneous bleeding in patients with severe disease at up to 12 months follow-up.
“We are very pleased the FDA has designated AMT-060 a Breakthrough Therapy for patients with hemophilia B,” stated Matthew Kapusta, chief executive officer of uniQure. “The FDA’s decision to prioritize and expedite the review of AMT-060 is an important milestone for uniQure and we are committed to working closely with the FDA to rapidly advance our hemophilia B program into late-stage development.
Updated clinical data from the ongoing, two-cohort Phase 1-2 trial of AMT-060 were recently presented at the 58th American Society of Hematology (ASH) Annual Meeting. The data included up to 52 weeks of follow-up from the low-dose cohort and up to 31 weeks of follow-up from the second dose cohort.
Data from the second-dose cohort show a dose response with improvement in disease state in all five patients, including the discontinuation of precautionary FIX infusions in all four patients that previously required chronic replacement therapy. As of the data cutoff date for the ASH presentation, only one unconfirmed spontaneous bleed was reported during an aggregate of 94 weeks follow-up after discontinuation of prophylactic FIX replacement therapy.
All five patients in the low-dose cohort, whose bleedings were previously uncontrolled despite being managed with prophylactic therapy, continue to maintain, constant and clinically meaningful levels of FIX activity for up to 52 weeks post treatment, resulting in a complete cessation of spontaneous bleedings in the last 14 weeks of observation.
AMT-060 continues to be well-tolerated, and there have been no severe adverse events. Three out of the total of 10 patients (two in the second-dose cohort and one previously reported from the low-dose cohort) experienced mild, asymptomatic elevations of alanine aminotransferase (ALT) and received a tapering course of corticosteroids per protocol. Importantly, the temporary elevations in ALT were not associated with any loss of endogenous FIX activity or T-cell response to the AAV5 capsid. No patients across either cohort have developed inhibitory antibodies against FIX and no patients screened in the study tested positive for anti-AAV5 antibodies.
Hemophilia B is a serious and rare inherited disease in males characterized by insufficient blood clotting. The condition can lead to repeated and sometimes life-threatening episodes of external and internal bleeding following accidental trauma or medical interventions. Severe hemophilia is characterized by recurrent episodes of spontaneous joint bleeds, that cause long-term damage to the joints resulting in disabling arthropathy.
