Amylyx's Avexitide Hits Phase 3 Primary Endpoint; Stock Climbs 85%

Amylyx Pharmaceuticals (Nasdaq: AMLX) reported positive topline results from LUCIDITY, the Phase 3 trial of its first-in-class GLP-1 receptor antagonist avexitide in post-bariatric hypoglycemia (PBH). The stock closed at $39.66 on August 20, up about 85% from the $21.43 close on August 17, the session before the August 18 readout.

LUCIDITY met its FDA-agreed primary endpoint, showing a 55% reduction in the composite rate of Level 2 and Level 3 hypoglycemic events versus placebo through Week 16 (p=0.000003). The trial also met all secondary endpoints, with statistically significant reductions in Level 2 events measured by self-monitoring of blood glucose, Level 2 events measured by continuous glucose monitoring, and Level 3 events.

The 78-participant, double-blind, placebo-controlled trial randomized patients 3:2 to 90 mg of avexitide injected subcutaneously once daily or placebo across 21 U.S. sites. Avexitide was generally well-tolerated; the most common side effects were diarrhea, injection site redness, and injection site bruising, with no serious adverse events tied to the drug and no change in body weight over the 16-week double-blind period.

Why It Matters

PBH has no FDA-approved therapy. The condition affects an estimated 160,000 Americans who have undergone bariatric surgery, causing recurrent and sometimes disabling drops in blood sugar after eating. Level 2 and Level 3 hypoglycemic events can become medical emergencies, producing confusion, loss of consciousness, and seizures.

Avexitide’s mechanism is the inverse of the GLP-1 agonists that dominate metabolic medicine. Drugs like Ozempic and Wegovy activate the GLP-1 receptor to suppress appetite. Avexitide blocks it, curbing the exaggerated GLP-1-driven insulin surge that follows gastric bypass surgery and causes the dangerous blood-sugar crashes. The broader GLP-1 market dynamics are covered in our GLP-1 stocks analysis.

The win also matters for Amylyx itself. The company’s previous lead drug, the ALS therapy RELYVRIO, was withdrawn from the market in 2024 after its confirmatory trial failed. Avexitide is now the whole thesis, and the LUCIDITY result clears the path toward the first approved treatment for PBH.

What Happens Next

Amylyx plans to file a New Drug Application with the FDA by the end of 2026 and, if approved, launch avexitide commercially in 2027. The drug carries Breakthrough Therapy and Orphan Drug designations. The 32-week open-label extension of LUCIDITY remains ongoing, and detailed data will be presented at an upcoming medical meeting.

The near-term catalysts are the NDA submission timeline and the full data presentation, where investors will look for whether the 55% event reduction holds across the secondary measures and the open-label extension. For a plain-English walkthrough of how to read a topline release like this one, see our guide to clinical trial press releases.