An evaluation of the combination of sodium phenylbutyrate and taurursodiol for the treatment of amyotrophic lateral sclerosis

Introduction Amyotrophic lateral sclerosis (ALS) is a rapidly progressive, fatal neurodegenerative motor neuron disease. Despite the overwhelming need for effective therapeutics for ALS, riluzole and edaravone were the only two FDA-approved disease-modifying therapies prior to 2022. The randomized, double-blind, multicenter, placebo-controlled CENTAUR trial demonstrated the safety and efficacy of sodium phenylbutyrate-taurursodiol (PB-TURSO) in persons with ALS (PALS), leading to its conditional approval in Canada in June 2022 and full approval in the USA in September 2022.Areas covered Herein, the authors provide a review of the pharmacology and clinical trials evaluating sodium phenylbutyrate and/or taurursodiol in PALS.Expert opinion The safety and tolerability of both PB and TURSO were previously demonstrated in small PALS trials. The phase 2 CENTAUR study and its open-label extension demonstrated the safety and efficacy of AMX0035 (a sachet containing a fixed co-formulation of 3 g of PB and 1 g of TURSO given twice daily) in PALS. A phase 3 PHOENIX trial (NCT05021536) will offer more insight into safety and efficacy of AMX0035. AMX0035 currently costs $ 158,000 annually in the US, which may become a financial barrier for PALS to receive the medication.