Sarepta shares surge after gene therapy leads to microdystrophin expression in DMD patients

This week, shares in Sarepta Therapeutics rocketed by 80% after the company released preliminary data from a Phase 1/2a trial showing that its experimental gene therapy – AAVrh74.MHCK7 ­– boosted production of a truncated form of a muscle-making protein in three young boys with Duchenne muscular dystrophy (DMD).

Sarepta reported that all post-treatment biopsies showed that at three months patients were producing a mean level of micro-dystrophin that was 38.2% compared to normal, when measured using Sarepta's Western blot method, or 53.7% compared to normal. 

Sarepta CEO Doug Ingram said: "Since the discovery of the dystrophin gene in 1986, scientists, clinicians, patient advocates and the biotech ecosystem have searched for ways to restore or replace dystrophin and rescue boys with DMD from the damage and early death." 

Four boys between the ages of four and seven years old have so far been given the single-infusion treatment, although data were available on three of the patients. Sarepta said other preliminary results from the trial showed that mean gene expression was 76.2% compared to normal control, while all patients showed significant decreases of serum creatine kinase (CK), with a mean CK reduction of over 87% at day 60.

Sarepta said no serious adverse events were observed in the study. The company noted that two patients saw their levels of gamma-glutamyl transferase rise, but the issue was resolved with increased steroids within a week and returned to baseline levels.

Sarepta plans to report more detailed data from all six patients enrolled in this part of the study at the World Muscle Society (WMS) conference in October. Ingram said the hope is for Sarepta to be able to file for FDA approval off of that data, but "we need to meet with the FDA and ensure it aligns with us on that process." He indicated that the drugmaker plans to meet with the agency within four months to discuss the path toward approval. "Since the discovery of the dystrophin gene in 1986, scientists […] have tirelessly searched for ways to restore or replace dystrophin and rescue boys with DMD from the damage and early death."

Dr Jerry Mendell said: "Although the data are preliminary, these results represent an unprecedented advancement in the treatment of DMD."

Commenting on the news, Baird analyst Brian Skorne, added: "It is hard to believe this study won't be positive, ushering in a new paradigm that we expect will transform outcomes for patients diagnosed with this disease."