Solid tanks as safety scare again rocks DMD gene therapy

A safety scare has rocked Solid Biosciences’ drive to get its Duchenne muscular dystrophy (DMD) gene therapy program back on track. The first patient treated with the higher dose of SGT-001 suffered a serious adverse event, reigniting concerns about the safety of the candidate and wiping 35% off Solid’s stock price. 

SGT-001 has run into multiple problems in its brief history as a clinical-phase asset. The FDA hit the program with two clinical holds relating to manufacturing problems and safety concerns, stymying its progress. And when SGT-001 reached a readout in February, the numbers disappointed, leading Solid to accelerate its dose escalation strategy in search of better results.

Now, Solid has accelerated straight into another safety scare. The first patient to receive the higher dose experienced an increase in transaminases and bilirubin, high levels of which can be indicative of liver damage. The bilirubin levels rose to twice the upper limit of normal. Solid reported the changes to the FDA as a serious adverse event linked to SGT-001. 

The increases in the levels of transaminases and bilirubin were transient and resolved rapidly with an increase in oral glucocorticoids, Solid said, and the patient has now resumed normal activities. 

Like other patients treated with SGT-001, the first person to receive the higher dose also suffered a transient decline in platelet count. That change was classified as a non-serious adverse event related to SGT-001. The patient was diagnosed with a gastrointestinal infection shortly after receiving SGT-001, too, but that was categorized as a serious adverse event unrelated to the study drug. 

That bundle of safety issues led investors to drive down Solid’s share price, which was already at a low ebb as a result of the clinical data released in February. But Solid continues to enroll patients in the trial per the study protocol, providing it with a shot at redemption when it releases further data later this year.

To bounce back, Solid will need to deliver data showing SGT-001 can trigger significant increases in microdystrophin protein expression. Armed with such data, Solid may have a chance at riding out the safety concerns and positioning SGT-001 as a rival to DMD gene therapies in development at Pfizer and Sarepta Therapeutics. But the data released to date offer scant encouragement that a turnaround is likely.