Audentes Therapeutics Announces Dosing of First Patient in ASPIRO Trial

Audentes Therapeutics has commenced dosing of patients in ASPIRO, a Phase 1/2 clinical trial of AT132 for the treatment of X-Linked Myotubular Myopathy (XLMTM). ASPIRO is a multicenter, multinational, open-label, ascending dose study to evaluate the safety and preliminary efficacy of AT132 in approximately twelve XLMTM patients less than five years of age. Preliminary data from ASPIRO is expected to be available in the fourth quarter of 2017.

"XLMTM is a severe rare disease characterized by profound muscle weakness, respiratory failure and early death," said Suyash Prasad, M.D., Senior Vice President and Chief Medical Officer. "Over 50 percent of the boys affected by XLMTM do not live to celebrate their second birthday, and no currently approved treatment options exist for these patients, their families and care-givers."

In addition to ASPIRO, the clinical development program for AT132 includes RECENSUS, a retrospective medical chart review, for which Audentes has previously announced data from an initial analysis of 112 male subjects. This analysis confirmed and expanded upon the understanding of the significant disease burden of XLMTM on patients, families and the healthcare system. Audentes is also conducting INCEPTUS, a prospective natural history run-in study. The primary objectives of INCEPTUS are to characterize the clinical condition of children with XLMTM, identify subjects for potential enrollment in ASPIRO, and serve as a longitundinal baseline and within-patient control for ASPIRO. Audentes plans to announce preliminary data from INCEPTUS in the third quarter of 2017.

AT132 is the Audentes product candidate being developed to treat XLMTM, a rare monogenic disease characterized by extreme muscle weakness, respiratory failure and early death, with an estimated 50% mortality rate by 18 months of age. XLMTM is caused by mutations in the MTM1 gene, which encodes a protein called myotubularin. Myotubularin plays an important role in the development, maintenance and function of skeletal muscle cells. AT132 is comprised of an AAV8 vector containing a functional copy of the MTM1 gene. Multiple studies in animal models of XLMTM have demonstrated that a single administration of AT132 improved disease symptoms and survival rates, with no significant AT132-related adverse events or safety findings. In one study these effects have lasted more than four and a half years years. Audentes is developing AT132 in collaboration with Genethon.

ASPIRO is designed as a multicenter, multinational, open-label, ascending dose study to evaluate the safety and preliminary efficacy of AT132 in approximately 12 XLMTM patients less than five years of age. The study is expected to include nine AT132 treated subjects and three delayed-treatment concurrent control subjects. Primary endpoints include safety (adverse events and certain laboratory measures) and efficacy (assessments of neuromuscular and respiratory function). Secondary endpoints include the burden of disease and health related quality-of-life, and muscle tissue histology and biomarkers. The primary efficacy analysis is expected to be conducted at 12 months, with interim evaluations expected to be conducted at earlier time points. After the primary 12-month assessment, subjects are expected to be followed for another four years to assess long term safety, durability of effect and developmental progression.