Amylyx Pharmaceuticals’ AMX0035 misses primary and secondary endpoints in ALS study

Cambridge, Massachusetts-based Amylyx Pharmaceuticals, Inc. (NASDAQ: AMLX), a key player in the pharmaceutical industry, announced today the top-line results of the PHOENIX study, a critical Phase 3 clinical trial investigating the efficacy of AMX0035 (sodium phenylbutyrate and taurursodiol) in treating amyotrophic lateral sclerosis (ALS). Despite the anticipation, the study did not meet its primary endpoint or secondary endpoints, casting uncertainty over the future of RELYVRIO in the U.S. and ALBRIOZA™ in Canada for ALS treatment.

The PHOENIX study, a 48-week, randomized, placebo-controlled trial, involved 664 participants diagnosed with ALS. The primary endpoint focused on the change from baseline in the Revised Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS-R) total score at Week 48. Unfortunately, the results did not demonstrate statistical significance (p=0.667) between the treatment group receiving AMX0035 and the placebo group, nor were significant differences observed in secondary endpoints.

Despite the setback in efficacy outcomes, the PHOENIX study reinforced AMX0035’s safety profile. The treatment was generally well-tolerated, with no new safety signals emerging, suggesting that AMX0035 maintains a manageable safety profile for patients.

In light of the PHOENIX study’s outcome, Amylyx Pharmaceuticals plans to engage in discussions with regulatory authorities and the ALS community within the next eight weeks. These conversations will inform the company’s forthcoming decisions regarding the future of RELYVRIO/ALBRIOZA in ALS treatment, which may involve voluntarily withdrawing the drug from the market. Despite this potential course of action, Amylyx has assured that RELYVRIO/ALBRIOZA will remain available for those living with ALS, and related patient support services will continue uninterrupted.

Amylyx is set to host an investor conference call to discuss these developments further. Co-CEOs Justin Klee and Joshua Cohen expressed their disappointment over the PHOENIX results but reaffirmed their dedication to the ALS community, emphasizing the importance of sharing this data with patients and healthcare providers.

Despite the PHOENIX study’s outcomes, Amylyx remains committed to exploring the potential of AMX0035 in other neurodegenerative diseases, including Wolfram syndrome (WS) and Progressive Supranuclear Palsy (PSP). Ongoing studies in these areas will continue, supported by data indicating AMX0035’s potential benefits.

The PHOENIX study results present a challenging moment for Amylyx Pharmaceuticals and the broader ALS community. While the drug’s safety profile remains a positive takeaway, the failure to meet primary and secondary efficacy endpoints necessitates a thoughtful reassessment of RELYVRIO/ALBRIOZA’s role in ALS treatment. Amylyx’s decision to pause promotion and consider withdrawing the drug underscores a commitment to patient safety and regulatory compliance. However, the continuation of AMX0035 studies in other neurodegenerative diseases highlights the potential for significant contributions to medical science and patient care in other contexts. As the conversation unfolds, the focus will remain on aligning with regulatory guidance and supporting the needs of the ALS community.