AB Science announced the publication of a new preprint article on MedRxiv presenting a post-hoc subgroup analysis from its phase 2b/3 AB10015 study of masitinib in amyotrophic lateral sclerosis (ALS) patients who had not yet experienced any complete loss of function on the ALS Functional Rating Scale (ALSFRS-R). The analysis focuses on this early-stage subgroup to better understand masitinib’s potential benefit-risk profile when administered before irreversible functional decline.
According to the MedRxiv report, patients given masitinib showed significant improvements in key clinical outcomes compared with placebo. In this subgroup, the difference in ALSFRS-R score—a measure of functional ability—favored masitinib by 4.04 points (p = 0.0065), indicating slower decline in daily functioning. The analysis also reported a 20.2 % relative benefit on the Combined Assessment of Function and Survival (CAFS) endpoint (p = 0.029), longer median progression-free survival (PFS) by 9 months (p = 0.0057), and median overall survival (OS extended by 12 months (p = 0.0192) compared with placebo in this specific subgroup.
Safety outcomes in the subgroup were reportedly improved, with a lower rate of serious adverse events in masitinib-treated patients compared with placebo. The authors of the analysis state that selecting patients earlier in the disease course—before complete loss of function—may optimize the balance between clinical benefit and risk, aligning with masitinib’s proposed mechanism of action targeting neuroinflammation and mast cell activity.
These findings have been incorporated into the design of AB23005, a confirmatory Phase 3 study aimed at ALS patients with preserved function and normal disease progression, which is expected to further evaluate masitinib’s effectiveness and safety in a more targeted population.
