Solid Biosciences shares fell 3.93% to $9.54 in regular trading and dropped a further 1.99% to $9.35 after hours, extending a session that had opened near the company’s 52-week high of $11.45. The stock has gained 76% this year and nearly 99% over the past 12 months, pushing market capitalisation to $1.04 billion with a beta of 2.44. Management noted the firm was valued at roughly $38 million three years ago.
At the 12th Annual Cantor Fitzgerald Global Healthcare Conference, President and CEO Bo Cumbo detailed advancing clinical programmes for Duchenne muscular dystrophy and Friedreich’s ataxia. For the DMD candidate SGT-003, the Phase I/II INSPIRE trial has dosed 53 patients and is now full, having turned away more than 100 prospective enrollees. The company plans to administer three to four additional paediatric doses later this year using commercial-grade manufacturing material to bridge safety and efficacy data ahead of a Phase III programme. Eligible patients are defined as children aged zero to 12 who are pre-ambulatory to ambulatory; roughly half of ambulatory children qualify after excluding those with antibodies or ineligible mutations, yielding a target population of 2,000 to 3,000 patients. A 30-day steroid protocol is permitted during treatment.
The capsid vector AAV-SLB101 carries 60 RGD peptides per particle to enhance integrin binding, and about 90% of the construct clears from whole blood by day four. Preclinical biodistribution studies showed three to five times greater expression than AAV9 across several muscle groups, with some sites reaching five to ten times, and diaphragm expression reported as substantially higher. At a dose of 1×10¹⁴, the vector produced expression comparable to or better than Sarepta’s ELEVIDYS at 1.33×10¹⁴ and REGENXBIO’s candidate at 2×10¹⁴. In human cardiomyocytes, expression was 19 to 20 times greater than AAV9, and mouse heart expression reached 75% by day four.
No cases of drug-induced liver injury, myocarditis, thrombotic microangiopathy or atypical haemolytic uraemic syndrome have been reported in the DMD programme. The company submitted an updated statistical analysis plan to regulators in late July 2024 and expects a formal briefing-book meeting request to be scheduled within about 60 days, likely in late Q4. Preliminary data may be disclosed late this year or in early January, with no new dosing or data releases planned after 15 December.
For Friedreich’s ataxia, candidate SGT-212 targets the dentate nucleus in the brain alongside systemic cardiac delivery through an outpatient procedure that takes approximately four hours from start to finish. Three patients have been dosed with no serious adverse events; the third patient passed the 30-day safety window in early August. The firm aims to treat seven patients by year-end and hold an FDA meeting in the first half of 2025, with a registrational trial launching in the second half. Phase III efficacy could be assessed in as few as three to six months using seven to ten patients in a double-blind, sham-controlled design. Eligible patients would have baseline Modified Friedreich’s Ataxia Rating Scale scores between 40 and 80. In Europe, an estimated 15,000 to 20,000 patients could account for 40% to 50% of total gene-therapy revenue even after typical pricing adjustments.
