Ultragenyx Reports Positive Topline Cohort 2 Results From DTX301 Study

(RTTNews) - Ultragenyx Pharmaceutical Inc. (RARE) announced topline positive safety and efficacy data from the second dose cohort and positive longer-term data from the first dose cohort of the ongoing Phase 1/2 study of DTX301, an investigational adeno-associated virus gene therapy for the treatment of ornithine transcarbamylase deficiency.

"Data from the first two dose cohorts continue to demonstrate an acceptable initial safety profile and evidence of clinical activity, with one new patient achieving normalization of ureagenesis in Cohort 2 at 24 weeks," said Eric Crombez, Chief Medical Officer of the Ultragenyx Gene Therapy development unit.

The first patient in Cohort 2 (study patient 4) demonstrated normalization of ureagenesis to 104 percent at Week 24. After discontinuation of steroids, the rate of ureagenesis normalized at week 20 and remained normal at week 24, at which time a second course of steroids had been initiated due to mild asymptomatic alanine aminotransferase elevations, which were controlled. The second and third patients in Cohort 2 (study patients 5 and 6) did not show a clinically meaningful change in rate of ureagenesis at 12 weeks and did not have alanine aminotransferase elevations nor require steroid treatment.

The Data Monitoring Committee has completed its review of Week 12 data from Cohort 2 and recommended that Ultragenyx proceed to the third dose cohort of the study. In Cohort 3, three patients will be enrolled. The first patient is expected to be enrolled before the end of 2018, and data from the Cohort 3 are expected in mid-2019.