After the U.S. FDA granted clearance in March 2023, sales began promptly of Acadia Pharmaceuticals Inc.’s new Rett syndrome therapy, Daybue (trofinetide), and questions during the recent J.P. Morgan Healthcare Conference in San Francisco had to do with – among other matters – sales guidance from the firm, which is hardly alone in seeking treatments for the disease. Other players include Anavex Life Sciences Corp., Neurogene Inc. and Taysha Gene Therapies Inc.