ALS drug AP-101 heads toward Phase 3 with promising weight preservation data

AL-S Pharma is moving closer to a pivotal trial for AP-101, its investigational antibody targeting misfolded superoxide dismutase 1 (SOD1) protein in ALS patients. At the 2026 NEALS Annual Meeting, the company unveiled the design of AP101-03 — a global, double-blind, placebo-controlled Phase 3 trial planned to enroll roughly 300–450 participants with either sporadic or SOD1-associated ALS. Participants will receive AP-101 (2,500 mg IV every 3 weeks) or placebo for 12 months on top of standard care, with the primary endpoint combining functional decline scores and survival events like death or permanent ventilation.

Alongside the trial design, AL-S Pharma presented new post hoc Phase 2 data showing AP-101 was associated with meaningful body weight preservation — a clinically significant finding given that weight loss in ALS is closely tied to faster disease progression and worse outcomes.

By the Numbers:

• 2.25 kg — weight difference favoring AP-101 vs. placebo at week 24 in sporadic ALS patients
• 4.82 kg — weight difference in SOD1-associated ALS patients at follow-up (P = .0092)
• 4.59 kg — weight difference in sporadic ALS patients with highest baseline misfolded SOD1 levels (P = .0010)

Why it matters: ALS remains a devastating and largely untreatable disease. AP-101's Phase 2 safety profile and early signals of benefit — including biomarker reductions and weight preservation — make the upcoming Phase 3 trial a closely watched milestone for the ALS community.