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.