Solid Biosciences' shares have taken a hit after early results from a study of SGT-001 microdystrophin gene transfer for the treatment of Duchenne muscular dystrophy (DMD) fell short.

Shares in the company dropped as much as 73% after it reported disappointing preliminary results from the Phase I/II study.

The first three patients given SGT-001 at the lowest dose outlined in the study protocol, microdystrophin was detected via Western blot, while in the other two patients, microdystrophin was detected via immunofluorescence at very low levels, but it was undetectable via Western blot.

The six patients in Solid Biosciences' early-phase trial showed low levels of microdystrophin even after being treated, something the company believes can be fixed with higher doses of the drug.

"We believe that SGT-001 will be a meaningful treatment for patients with DMD and are confident we have the right approach in place to evaluate its potential at higher doses. We have already begun working to expedite the planned dose escalation strategy outlined in our clinical trial protocol," said Ilan Ganot, co-founder, CEO and president of Solid Biosciences.

He also noted that the company has “already begun working to expedite the planned dose-escalation strategy outlined in our clinical trial protocol.”

The results come after the FDA halted the IGNITE DMD study last year after a patient who received the treatment was hospitalised with low red blood cell and platelet counts, as well as evidence of complement activation.

DMD is caused by mutations in the dystrophin gene - people with the mutation can't make dystrophin protein, which is usually present in skeletal and cardiac muscles and helps protect them from injury.