But on Wednesday, after hours of discussion, several advisers said that additional analyses submitted by the drug’s manufacturer, Cambridge-based Amylyx, bolstered the case for approval, even though uncertainties remain. Advisers were also affected by the disease’s severity and the lack of effective treatments. A vow by a top Amylyx official to pull the drug from the market if a larger study, with 600 patients, fails to show effectiveness was also a factor in the vote.
The FDA, which usually follows the recommendation of its outside advisers but is not required to, is expected to decide whether to approve the drug by Sept. 29.
The improved fortunes of the medicine came despite criticism from FDA staff as recently as last week about the treatment’s effectiveness, the conduct of its clinical trial and the researchers’ interpretation of the data.
But the medicine is considered safe, and the agency has been under intense pressure from ALS patients and physicians who say the treatment holds promise for a fatal disease that typically causes rapid deterioration and death.
Wednesday’s vote came after a dramatic moment featuring Billy Dunn, director of the FDA’s Office of Neuroscience, who stressed the agency may use broad flexibility to clear drugs for diseases like ALS that lack effective treatments.
Dunn also noted the large trial being conducted by the manufacturer will be completed late next year or in early 2024; that trial is expected to show definitively whether the drug works. In a highly unusual move, he asked company officials whether they would voluntarily withdraw the product if it was approved now but the larger trial failed to show effectiveness.
Justin Klee, co-chief executive of the Cambridge-based biotech company, agreed. If the larger trial is not successful, “we will do what is right for patients, which includes withdrawing the product from the market,” he said.
Other experts cautioned, however, that a voluntary commitment like Klee’s is not legally binding.
Still, the commitment from Amylyx and its new analyses convinced some panel members to change their votes from March. Liana G. Apostolova, a neurologist at Indiana University School of Medicine, said the new analyses left her “mildly to moderately” persuaded …
Read More: FDA advisers recommend approval of controversial ALS drug