Solid Biosciences Stock Surges on Promising Duchenne Muscular Dystrophy Gene Therapy Data

Solid Biosciences (NASDAQ: SLDB) shares surged on Tuesday, February 18, following the release of positive interim data from its Phase 1/2 INSPIRE DUCHENNE trial evaluating SGT-003, a next-generation gene therapy product candidate intended for the treatment of Duchenne muscular dystrophy (DMD). The biotech reported expectation-busting results, sending its stock spiraling upward by almost 90% in premarket trading to top $7.50.

The trial's first three participants showed an average microdystrophin expression of 110%, as measured by western blot, and improvements in multiple biomarkers that are indicators of muscle health and resilience. Between 70% and 88% of the participants' fibers were positive for dystrophin, resulting in a mean result of 78%. Solid Biosciences' CEO Bo Cumbo had previously stated that 40% dystrophin-positive fibers would be sufficient to achieve a clinical benefit for Duchenne patients.

SGT-003 was well-tolerated in the first six participants dosed as of the data cutoff date of February 11, 2025. No serious adverse events or suspected unexpected serious adverse reactions were observed, and there was no evidence of thrombotic microangiopathy, atypical hemolytic uremic syndrome, or hemolysis. None of the adverse events observed required the use of additional immunomodulatory agents such as eculizumab, sirolimus, or rituximab.

The company also reported reductions in markers of muscle injury and stress and an 8% mean increase in cardiac function in two patients with 180 days of follow-up. These early signals of potential cardiac benefit are encouraging, as cardiac involvement is a common complication in Duchenne patients.

Solid Biosciences expects to have dosed at least 10 patients by early in the second quarter and roughly double that figure by the fourth quarter. The expansion will support a planned chat with the FDA about an accelerated approval pathway for SGT-003.



Solid Biosciences' stock trade at around $5 each, with about $4 per share in cash providing some downside protection. Assuming SGT-003 follows a timeline similar to Sarepta's Elevidys, even a one-year delay would lower the price target to $11 per share (current price target of $16)—still above the current trading price. With other programs yet to be included in the valuation, the analyst sees strong potential and initiates with an Outperform rating.

In conclusion, Solid Biosciences' positive interim data from the INSPIRE DUCHENNE trial has sparked investor confidence in the company's next-generation gene therapy candidate, SGT-003. As the trial continues and more data becomes available, investors will be watching closely to see if the therapy can maintain its promise and potentially revolutionize the treatment of Duchenne muscular dystrophy.