Sigilon Therapeutics encountered a stumbling block in its first human test of its experimental hemophilia A cell therapy, and the FDA placed a Clinical reservation In the study after the patient has complications.
It is not clear whether serious adverse events are related to SIG-001 therapy. Sigilon, headquartered in Cambridge, Massachusetts, revealed on Friday that registration for the Phase 1/2 study has been suspended and an investigation is ongoing.
Sigilon’s drug candidate is a cell therapy wrapped in a biocompatible sphere. These spheres are designed to prevent the immune system from treating the internal cell therapy as foreign and triggering an immune response. Sigilon’s main disease target is hemophilia A, which is an inherited blood disease in which the patient lacks clotting factor VIII (a clotting protein). It is currently treated by long-term infusion of lacking protein. SIG-001 encapsulates cells designed to express high levels of factor VIII clotting protein that patients lack. This cell therapy is the most advanced product candidate in Sigilon’s drug pipeline.
The discontinued clinical trial is a phase 1/2 dose range study. The open label study aims to recruit up to 18 patients. The first two patients were given the drug in the fourth quarter of last year; the company stated in its annual report that the treatment was well tolerated and no serious adverse events occurred.
The company stated that the reported adverse event occurred in the third patient in the study, who received the highest dose of experimental Sigilon therapy. This patient developed inhibitors or antibodies against factor VIII. Inhibitors are well-known factor VIII treatment complications. The problem with Sigilon is that its cell therapy is designed to avoid this type of immune response. This concern frightened investors. The biotech company’s stock opened at $6.95 per share on Friday, a drop of nearly 25% from Thursday’s closing price.
Sigilon said that patients who had experienced adverse events responded well to drug treatments and their condition continued to improve. But the FDA has asked the company to provide more information on factors that may contribute to inhibitor development, such as family history and immune stimulation from recent vaccination. During Sigilon’s investigation of adverse events, the three patients who have been registered so far will continue to be followed.
“Patient safety is our top priority, and we are encouraged that patients are recovering,” Sigilon President and CEO Rogerio Vivaldi said in a prepared statement. “In cooperation with regulatory agencies and our consultants, we are conducting a thorough investigation of this incident to confirm whether there is a causal relationship between the development of the inhibitor and SIG-001. We are committed to working with the FDA to resolve the issue of clinical shelving.”
Sigilon is competing for better treatments for hemophilia A. BioMarin Pharmaceutical’s gene therapy is Rejected by the FDA last year, Because regulators require more data on treatment durability. Partners Pfizer and Sangamo Therapeutics are currently testing their experimental hemophilia A gene therapy in a phase 3 clinical trial. Spark Therapeutics, a subsidiary of Roche, is also conducting Phase 3 testing of its experimental gene therapy for the disease.
Photo: Streeter Lecka, Getty Images
