Biogen and Denali Therapeutics said their experimental Parkinson’s therapy targeting LRRK2 failed to slow disease progression in a randomized trial. The study randomized 648 adults with Parkinson’s to placebo or the LRRK2-directed pill. The approach followed earlier scientific interest in LRRK2 biology, including genetic evidence that LRRK2 mutations can cause a rare inherited form of Parkinson’s and later findings suggesting LRRK2 blockade might benefit broader patient populations. Thursday’s results represent a setback for that translational hypothesis. The outcome will likely affect how investors and investigators prioritize LRRK2-based drug development and may shift attention toward alternative mechanisms and biomarkers for Parkinson’s progression.