Biogen's ACTION 2 study does not meet primary, secondary efficacy endpoints
Biogen announced that in the Phase 2b dose-ranging ACTION 2 study in individuals with acute ischemic stroke, natalizumab did not demonstrate improvement in clinical outcomes compared to placebo. Both doses of natalizumab were generally well-tolerated and no new or important safety signals were observed. The results of the Phase 2b ACTION 2 study do not impact the benefit-risk profile of natalizumab in approved indications, including multiple sclerosis. In the middle of 2018, Biogen plans to initiate a global Phase 3 study of BIIB093 in individuals with large hemispheric infarction, where brain swelling often leads to high morbidity and mortality. Detailed Phase 2b ACTION 2 study findings will be made available in a future scientific forum. ACTION 2 was a Phase 2b multicenter, double-blind, placebo-controlled, randomized, dose-ranging study with a 90 day follow up to evaluate the safety and efficacy of natalizumab primarily in patients with moderate severity acute ischemic stroke. The study investigated natalizumab vs placebo in approximately 270 individuals who had a clinical diagnosis of AIS with last known normal less than or equal to 24 hours prior to treatment initiation. The study evaluated a 300 mg dose and a 600 mg dose versus placebo, both either within 9 hours of LKN or between 9-24 hours after LKN. The primary objective of ACTION 2 was to assess the effects of natalizumab compared to placebo on clinical measures of independence and activities of daily living. The primary endpoint was a composite global measure of functional disability based on a score of 0 to 1 on a modified Rankin scale and a score of greater than or equal to 95 on the Barthel Index at Day 90. The mRS measures independence with specific tasks pre- and post-stroke. BI is a scale that consists of 10 items that measure activities of daily living and mobility. Natalizumab was previously evaluated in AIS in the Phase 2a ACTION study. In this study, although natalizumab did not significantly decrease the primary endpoint of infarct volume at Day 5, secondary and exploratory endpoints suggested natalizumab treatment improved clinical outcomes compared with placebo which warranted further evaluation.