Two clinical studies for the treatment of late-onset Tay-Sachs with Zavesca, a drug used to treat Gaucher disease, produced neutral results — “a scientific way of saying that it didn’t work,” said Kim Crawford, director of member services for the National Tay-Sachs & Allied Diseases Association.
According to Crawford, Actelion, which produces Zavesca, will not seek FDA approval for the drug’s use on late-onset Tay-Sachs. Tay-Sachs is a lysosomal storage disorder that involves insufficient activity of the hexosaminidase A enzyme. Both Gaucher and late-onset Tay-Sachs disproportionately afflict Ashkenazic Jews.
Dr. Edwin Kolodny of New York University, who conducted one of the studies (the other was at Case Western Reserve University), was quick to emphasize that anecdotal evidence was far more promising. “Most of the patients who began the trial, and almost all the patients who remained at the end of the trial, want to continue taking the drug,” he said. “That means to me that they appreciate some positive benefits.”
Such benefits include improvement in speech patterns and articulation, reduction in psychotic episodes and general mental stabilization.
However, the hope was that Zavesca would stop or at least slow the decrease in muscle strength characteristic of such progressive neurodegenerative diseases as Tay-Sachs. “The data did not confirm that,” Kolodny said.
According to Kolodny, there are two other potential routes to treatment of late-onset Tay-Sachs. At least one biotechnology company, Genzyme, is developing a substrate synthesis inhibitor — the same type of drug as Zavesca — that would block production of the lipid that builds up in nerve cells of Tay-Sachs patients. It may soon be used in human trials.
The second option, known as the “chaperone molecule approach,” is currently in development. Here, doctors produce a small molecule in Tay-Sachs patients that can help correct the faulty hexosaminidase A enzyme.
Meanwhile, the jury is still out on trials currently being conducted for the use of Zavesca to treat juvenile and infantile (early-onset) Tay-Sachs. “The hope is that maybe in children and infants [Zavesca] is metabolized differently, and has an impact on the disease,” Crawford said.