Rare Disease Report

Rare Pediatric Disease and Fast Track Designations Granted to Gene Therapy for Myotubular Myopathy

SEPTEMBER 27, 2017
Mathew Shanley
Audentes Therapeutics, Inc. has been granted both Rare Pediatric Disease and Fast Track Designation by the U.S. Food and Drug Administration (FDA) for its gene therapy product candidate AT132.

The drug, intended to treat X-Linked Myotubular Myopathy (XLMTM), had previously received Orphan Drug Designation from both the FDA and the European Medicines Agency (EMA).

XLMTM is usually evident at birth, as patients with it typically have decreased muscle tone and muscle weakness. The condition affects the muscles vital for movement, and is diagnosed almost exclusively in males. The XLMTM patient population commonly suffers from breathing issues, resulting in most patients living only into early childhood.

"The incentives provided by the Rare Pediatric Disease and Fast Track designations are significant and include opportunities to work with FDA to expedite the development of AT132, and the potential to obtain a valuable Rare Pediatric Disease Priority Review Voucher upon approval,” Matthew R. Patterson, President and Chief Executive Officer of Audentes said via press release. “We are eager to leverage these benefits and to work closely with the FDA and XLMTM patient community as we pursue our goal of developing AT132 to treat this devastating rare disease."

XLMTM is the result of mutations in the MTM1 gene, which encodes the myotubularin protein. The myotubularin protein plays a significant part in the development, maintenance and function of cells in the skeletal muscles. AT132 contains an AAV8 vector with a functional copy of the MTM1 gene.

Today’s news follows Thursday’s announcement that the company had dosed its first patient in the ASPIRO study (NCT03199469), a Phase 1/2 clinical trial that will evaluate the safety and preliminary efficacy of AT132 in approximately 12 patients with XLMTM, each under the age of 5 years. Previous studies in animal models of XLMTM have proven that a single dosage of the drug can improve disease symptoms and survival rates with no noteworthy related adverse events (AEs).

The clinical development program for AT132 includes RECENSUS, a retrospective medical chart review and INCEPTUS, a prospective natural history and run-in study. The former is intended to confirm and expound upon the understanding of the significant disease burden on patients with XLMTM, as well as their families and the healthcare system. The hope of the latter is that it will exemplify the condition of children with the disease, recognize potential subjects for ASPIRO, and provide a baseline for the study.

The FDA grants Rare Pediatric Disease designation to therapies that show the promise to treat uncommon conditions that are considered life-threatening, specifically in children under the age of 18 years. If approved, Audentes will be eligible to receive a rare pediatric disease priority review voucher, which can be worth upward of several millions of dollars. Earlier this year, Sarepta sold its voucher for $125 million.

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