Ultragenyx announces longer-term DXT401 study data

Ultragenyx announced longer-term top-line safety and efficacy data from the first, lowest dose cohort of the ongoing Phase 1/2 study of DTX401, an adeno-associated virus, or AAV, based gene therapy for the treatment of glycogen storage disease type Ia, or GSDIa. After 24 weeks of treatment, the three patients enrolled in Cohort 1 have either maintained or further increased their time to hypoglycemia during the controlled fasting challenge compared to baseline. All three patients continue to show a clinical response with additional improvements in glucose control reflected by prolonged time to hypoglycemia during a controlled fasting challenge and by reductions in the use of cornstarch to maintain normal glucose levels throughout the day and overnight. The first patient in Cohort 1 demonstrated sustained improvement in time to hypoglycemia of 6.8 hours at Week 24, from 3.8 hours at baseline and 7.7 hours at Week 12. This patient received a tapering course of steroids, which began during Week 8 and ended at Week 16, to manage a mild asymptomatic elevation in alanine aminotransferase, or ALT, levels due to a response to the vector administration. Patient 2 showed a further improvement in time to hypoglycemia to 13.1 hours at Week 24, from 4.1 hours at baseline and 9.0 hours at Week 12. At Week 24, the fasting challenge was terminated at the patient’s request due to hunger and at the time the test was terminated, the patient’s glucose level remained in the normal range. This patient received a tapering course of steroids, which began at Week 12 and ended at Week 18, to manage a mild asymptomatic elevation in ALT levels due to a response to the vector administration. Patient 3 continued to show a clinical response, and maintained the improvement in time to hypoglycemia of 6.5 hours at Week 24, from 5.4 hours at baseline and 6.5 hours at Week 12. As of February 20, there have been no infusion-related adverse events and no treatment-related serious adverse events reported. All adverse events have been Grade 1 or 2. Patients 1 and 2 had mild elevations in ALT, similar to what has been observed in other programs using AAV-based gene therapy, and were successfully treated with a tapering course of steroids.
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