Biogen and Denali Therapeutics dropped BIIB122 in idiopathic Parkinson’s after a Phase 2b trial missed its primary endpoint, according to updated results reported to industry. The randomized study enrolled 648 adults with Parkinson’s, testing placebo versus BIIB122, a pill designed to target the LRRK2 protein. The readout deals a setback to a strategy that has been widely discussed since genetic evidence linked LRRK2 mutations to inherited Parkinson’s and since prior work suggested blocking LRRK2 could benefit broader patient populations. Denali plans to continue independently a separate study focused on a specific subset of Parkinson’s patients, keeping the broader question of whether patient enrichment or disease stage can restore clinical signal for LRRK2 inhibition.