Bettina Cockcroft, MD, Chief Medical Officer at Sangamo Therapeutics, recently talked to CheckRare about the gene therapy that the company has in development to treat people with Fabry disease.
Fabry disease is a rare lysosomal storage disorder involving mutations of the GLA gene that leads to the accumulation of globotriaosylceramide (Gb3) in the body’s cells that result in a plethora of symptoms.
What is the STAAR study?
ST-920 is our investigational gene therapy for Fabry disease. Fabry is a rare X-linked lysosomal storage disorder and it’s caused by a gene mutation in the alpha-Gal A enzyme which is responsible for breaking down fatty substances. Build-up of these substances in the absence of that enzyme in cells leads to dysfunction in many organs such as the skin, eyes, kidney, heart, brain, and peripheral nervous system. I’m happy to say that we’ve successfully screened and enrolled the first few patients in the Phase 1/2 STAAR study evaluating ST-920 gene therapy for the treatment of Fabry disease and we expect to initiate patient dosing at the earliest appropriate and safe opportunity in light of the COVID-19 pandemic.
What is the current standard of care for Fabry disease?
Current standard of care is enzyme replacement therapy and that involves regular blood infusions at the hospital usually once every two weeks, so [very] frequently. What’s unique about treating Fabry with ST-920 is that it’s a single intravenous infusion. We are looking to provide with this a stable, potentially long-term production of the alpha-Gal A enzyme at therapeutic levels, therefore aiming to reduce the need for enzyme replacement therapy infusions. In our gene therapy, the corrective gene is delivered through a deactivated AAV6 virus and that targets the liver. This technology is proprietary to Sangamo and, indeed, ST-920 actually uses the same AAV6 capsid as our investigational gene therapy SB 525 for Hemophilia A.
Is it difficult to enrol patients for clinical trials due to the COVID-19 pandemic?
I think that clinical trials in rare diseases have a challenge of finding patients for their studies and that has been compounded by the pandemic. We want to make sure that when we treat and dose those patients with that single intravenous infusion that it is done at a time when the patients are in a safe environment and they are not at risk of potentially being infected with COVID-19. So yes, there is going to be a slight delay in our dosing but this is because the patient’s safety is a priority at this stage.