How flexible should the U.S. FDA evidentiary standards be for a therapy addressing a significant unmet need in a disease such as amyotrophic lateral sclerosis (ALS)? That’s the question the agency’s Cellular, Tissue and Gene Therapies Advisory Committee will ponder Sept. 27 as it looks at the data for Brainstorm Cell Therapuetics Inc.’s Nurown (debamestrocel), a mesenchymal stromal cell therapy targeting ALS. Nurown is going into the adcom with a bit of a checkered history that includes a refuse-to-file letter and a single phase III trial that failed to demonstrate efficacy for the primary endpoint and all key secondary efficacy endpoints, according to the FDA briefing document.