Amylyx axes ALS drug from market after Phase III failure
Last month, Amylyx announced that the Phase III confirmatory trial of ALS drug Relyvrio failed to meet its primary and secondary endpoints. Amylyx Pharmaceuticals has formally announced the removal of its amyloid lateral sclerosis (ALS) drug Relyvrio (AMX0035, sodium phenylbutyrate/ursodoxicoltaurine, also known as sodium phenylbutyrate/taurursodiol) from the market following disappointing Phase III results.
The drug is no longer available to patients as of 4 April, following several discussions between Amylyx, the US Food and Drug Administration (FDA), and Health Canada. However patients currently on Relyvrio in the US and Canada have the option to continue taking it as part of a free drug program.
Relyvrio bagged approvals for the ALS drug from Health Canada in June 2022, and the FDA in September 2022, based on results from the Phase II CENTAUR clinical trial (NCT03127514). However the European Medicines Agency (EMA) rejected Amylyx Pharmaceuticals’ marketing authorisation in October 2023, citing concerns surrounding results from the same study. The drug had generated $381m in sales in 2023, according to the company’s financials.
In March, data from the 48-week Phase III trial (NCT05021536) involving 664 participants were announced, wherein researchers concluded that the drug didn’t have better results than the placebo after the trial failed to meet its endpoints. The news decimated the company’s stock by more than 85% with the company announcing that it would consider withdrawing the drug from the market.
In the Phase II CENTAUR trial, data showed a statistically significant slowing of disease progression using the revised Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS-R), compared to placebo in 177 patients. However, the PHOENIX Phase III trial, which enrolled a much larger group of 664 patients, did not meet its primary endpoint of reaching statistical significance using the same rating scale, including in the subset of participants who met the CENTAUR trial criteria.
Sparse ALS drug landscape
This leaves only two drugs on the market to treat ALS, a progressive neurodegenerative disorder that affects nerve cells in the brain and spinal cord, leading to the loss of voluntary muscle movement. Over time, patients with ALS may lose the ability to speak, eat, move, and breathe. Currently the only approved treatments are Sanofi’s riluzole and Mitsubishi’s Radicava (edaravone).
Riluzole works by blocking the release of glutamate, too much of which is believed to injure nerve cells. However, the drug only prolongs survival rate by roughly two to three months. In 2017, the FDA approved Radicava (edaravone) IV, a synthetic free radical scavenger. Like riluzole, Radicava only adds a modest benefit to patients by slowing disease progression.
However, it’s not the end of the road for Amylx and ALS. Its candidate AMX0114, an antisense oligonucleotide targeting calpain-2, is set to be evaluated in a first-in-human trial in the second half of 2024. Nonetheless, the company will reduce its workforce by 70% to focus on this and other upcoming clinical milestones, according to the 4 April press release.
April 8, 2024
