Tweaks made to the design of the phase III trial called Phoenix (vs. the narrowly positive phase II Centaur study) with Amylyx Pharmaceuticals Inc.’s amyotrophic lateral sclerosis (ALS) drug Relyvrio (sodium phenylbutyrate plus taurursodiol) didn’t work. Now, the Cambridge, Mass.-based firm is facing possible withdrawal of the treatment from the U.S. and Canada, where it’s known as Albrioza. Shares of Amylyx (NASDAQ: AMLX) closed March 8 at $3.36, down $15.61, or 82.3%, after the firm disclosed top-line results from Phoenix, a global, 48-week, randomized, placebo-controlled phase III effort with Relyvrio, also known as AMX-0035.