The FDA has stopped a clinical trial testing a Solid Biosciences gene therapy for Duchenne muscular dystrophy after a patient developed complications associated with the experimental treatment.
Cambridge, MA-based Solid Bio says the problems deemed to be related to the gene therapy included an immune system reaction, a decrease in red blood cells, kidney injury, and blood circulation difficulties. The problems disclosed Tuesday are similar to those reported in the study last year, leading to an earlier clinical hold. Later the FDA allowed the study to resume with additional measures to protect patients. The patient whose complications led to the current clinical hold is recovering and continues to improve, according to the company.
Shares of Solid Bio (NASDAQ: SLDB) sank more than 68 percent following the news of the clinical hold.
Duchenne muscular dystrophy is caused by a genetic mutation that leads to insufficient production of dystrophin, a key muscle protein. The disease leads to progressive muscle weakness, robbing patients of the ability to walk. Other complications include respiratory and heart failure. The Solid Bio gene therapy, SGT-001, uses an engineered virus to deliver genetic material intended to restore a patient’s ability to produce the level of dystrophin needed for proper muscle function.
Prior to its IPO last year, Solid Bio disclosed that the dosing requirements of its experimental therapy may increase the risk of side effects related to the virus used to deliver the treatment. Those concerns led gene therapy pioneer James Wilson to resign from Solid Bio’s scientific advisory board, according to regulatory filings.
Pfizer (NYSE: PFE) is also testing a gene therapy for Duchenne. In preliminary results from a Phase 1b study, the company reported that one patient in its study experienced an immune system reaction associated with kidney injury, destruction of red blood cells, and lower platelet counts.
To date, six patients have been dosed with Solid Bio’s experimental gene therapy—two groups of three patients, each group receiving a different dose. The patient who experienced complications was in the high-dose group and received the treatment in October. The clinical hold stops Solid Bio from enrolling new patients in the study or dosing patients already enrolled. In its quarterly report filed Tuesday, Solid Bio says it is still awaiting the formal clinical hold letter from the FDA.