Gene Therapy Study for OTC Deficiency Has Begun

James Radke

A Phase 1/2 gene therapy study in patients with ornithine transcarbamylase (OTC) deficiency has begun.

Today, Dimension Therapeutics announced the initiation of patient dosing in the adeno-associated virus (AAV) gene therapy study that will, hopefully, deliver stable expression and activity of OTC following one infusion of their compound, DTX301.

OTC deficiency is a rare X-linked genetic disorder characterized by complete or partial lack of the enzyme OTC which leads to toxic levels of ammonia in the blood. Treatment of OTC deficiency consists of a very strict low protein diet as well as medications to stimulate the removal of nitrogen in the body.

 “OTC deficiency is an inherited metabolic disease (IMD) for which approved therapies are unable to eliminate the risk of metabolic crises from elevated ammonia. We believe that DTX301, based on our differentiated AAV8 platform in IMD, holds great promise for addressing the unmet need among patients, and we look forward to the continued advancement of the trial,” said Annalisa Jenkins, MBBS, FRCP, Chief Executive Officer of Dimension.

Dimension anticipates reporting initial clinical data from the Phase 1/2 DTX301 clinical trial later this year.

To evaluate DTX301’s efficacy, the trial will measure ammonia levels and other biomarkers, including 13C-acetate.

The trial will be conducted at numerous sites, including Additional information about the trial can be found at

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