Clinical trials of a potential gene therapy treatment for Duchenne muscular dystrophy (DMD) have been put on hold after concerns emerged about the safety of the procedure, reports Genetic Engineering and Biotechnology News.
The first patient in the study to be given the therapy has been hospitalised, and the FDA has halted further patient treatment until its safety can be established. This has caused the stock of the company producing the treatment to plummet by 73%, and a company advisor has resigned, citing concerns over the safety of high-dosage gene therapy.
Duchenne muscular dystrophy is an inherited genetic disease that causes muscles to weaken over time, causing progressive disability. It is estimated to occur in one out of every 3,300 people, and usually in boys. Symptoms tend to be related to muscle weakness, and include frequent falling, difficulty walking or a waddling gait, large calf muscles, difficulty running, and learning disabilities. Unfortunately, DMD significantly shortens life expectancy and there is not currently an available cure. The potential gene therapy would therefore have a huge impact on patients with DMD if it were shown to meet safety standards.
The therapy, called SGT-001 and developed by the company Solid Biosciences, treats the genetic cause behind DMD. Patients with DMD lack a gene called the dystrophin gene, and because of this are unable to produce the corresponding dystrophin protein. This causes the symptoms of DMD. The gene therapy inserts a replacement copy of the dystrophin gene, which can then produce the missing dystrophin protein. Pre-clinical trials have shown that this therapy can reduce or even stop the progression of DMD at any stage of the disease.
However, the first patient to receive the therapy was taken to hospital after they showed signs of a serious adverse reaction. The patient exhibited a decreased platelet and red blood cell count, and signs of an immune system response. Although the patient has shown improvement, no further patients will receive the treatment until the FDA has granted approval.
This outcome has caused a huge drop of 73% in share prices for the Solid Biosciences, and multiple shareholders have reportedly filed lawsuits against the company. These shareholders are claiming that because the company failed to disclose the outcome of the medical trial when the shares were sold, the buyers were misinformed and the company therefore violated federal securities law.
The company also faces criticism from a gene therapy researcher, Dr James Wilson, who previously worked as an advisor for Solid Biosciences but resigned due to concerns about the safety of high-dosage gene therapy.