On 19 March, at the AD/PD 2026 International Conference on Alzheimer’s and Parkinson’s Diseases and Related Neurological Disorders, during a symposium on “Mechanisms and Therapeutics In The ALS-FTD Spectrum,” AL-S Pharma presented topline Phase II (NCT05039099) results for AP‑101. AL-S Pharma’s investigational therapy is an intravenous (IV) human monoclonal antibody (mAb) that selectively binds misfolded superoxide dismutase 1 (SOD1), in both sporadic and SOD1‑mutation amyotrophic lateral sclerosis (ALS), reinforcing misfolded SOD1 as a clinically actionable target beyond classic familial disease.
The Phase II trial was a multicenter, double‑blind study with two parallel cohorts enrolling 52 sporadic ALS patients and 21 SOD1‑mutation ALS patients. Each cohort was randomised 2:1 to AP‑101 or placebo for 24 weeks, followed by a 16‑week open‑label extension in which all patients could receive AP‑101. As per the data update, AP‑101 showed a reassuring safety and pharmacokinetic (PK) profile. Treatment-emergent adverse events (TEAEs) and serious adverse events (SAEs) were balanced between AP-101 and placebo groups, with no treatment‑related SAEs and no infusion‑related or allergic reactions reported. Only one patient developed anti‑drug antibodies, present at baseline, suggesting low immunogenicity of AP-101.
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The most impactful new data was around neurofilament biomarkers and survival‑linked outcomes. In the prespecified, per‑protocol sporadic cohort, AP‑101 achieved statistically significant reductions in cerebrospinal fluid (CSF) phosphorylated neurofilament heavy chain (pNfH) at six months, alongside favourable trends in serum neurofilament light chain (NfL). Six months was highlighted as the last time point with a clean placebo comparison, as patients on the placebo arm could cross over to the AP‑101 arm thereafter. Similar patterns of pNfH and NfL reduction were seen in the SOD1‑mutation cohort, indicating a consistent effect on axonal injury across genetic and sporadic, biomarker‑defined disease. These results directionally align with the regulator’s use of NfL in Biogen’s Qalsody (tofersen)’s SOD1‑ALS approval and with key opinion leader (KOL) expectations from interviews previously conducted by GlobalData indicating that robust biomarker effects are now “a de‑facto requirement for late‑stage ALS programs.”
Clinically, AP‑101 did not separate from placebo on the Revised Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS‑R) in the overall sporadic population but did demonstrate statistically significant benefit for prolonging survival or the need for non‑invasive ventilation at 12 months in both sporadic and SOD1‑mutation cohorts. In SOD1‑mutation ALS, AP‑101 stabilised disease progression measured using ALSFRS‑R scores and King’s clinical staging, while placebo patients saw disease progression, thus supporting a disease‑modifying signal despite baseline imbalances. Critically, a predefined analysis of sporadic patients in the highest tertile of baseline misfolded SOD1 levels showed outcomes that closely mirrored the SOD1‑mutation cohort: stabilisation of ALSFRS‑R, minimal disease progression by King’s staging, preservation of body weight, and corresponding reductions in pNfH and NfL.
Given that body weight is viewed by KOLs as one of the most objective markers of ALS progression, this convergence of clinical and biomarker effects in a biomarker‑enriched subgroup is highly compelling.
Overall, the data supports a Phase III program that can remain broad enough to satisfy regulators—enrolling both sporadic and SOD1‑mutation ALS—while prospectively stratifying by misfolded SOD1 levels and potentially powering key analyses in the “high‑misfolded‑SOD1” sporadic segment. AP‑101’s selective binding to misfolded rather than total SOD1 differentiates it from gene‑silencing approaches, and, if a Phase III trial confirms the signals, it could position AP‑101 as a first‑in‑class misfolded SOD1 mAb that extends SOD1‑pathway therapy well beyond the small mutation‑positive population.
