Parkinson’s News TodayBiogen and Denali Halt BIIB122 Trial for Idiopathic Parkinson’s

📋 Regulatory Action / Label Change

BIIB122 (DNL151) was designed to restore lysosomal recycling via CNS-penetrant LRRK2 inhibition, a mechanism with biological rationale across both idiopathic and LRRK2-mutation Parkinson’s populations. Despite confirmed target engagement in Phase 1 and biomarker inhibition verified in LUMA exploratory endpoints, the drug produced no significant benefit on motor or nonmotor progression outcomes.

Clinical Considerations

• LUMA’s primary endpoint — time to confirmed worsening on MDS-UPDRS parts 2+3 — was not met; secondary nonmotor and motor endpoints also failed
• Exploratory biomarker endpoints confirmed LRRK2 inhibition in blood and CSF, dissociating target engagement from clinical benefit in the idiopathic population
• The trial enrolled patients with and without LRRK2 variants; whether mutation-carrier subgroup data show signal will be important to track when results are presented at conference
• Denali’s separate BEACON study continues in 50 adults with confirmed LRRK2 mutations at 225 mg daily for 3 months; data expected first half of 2027

Practice Applications

• Recognize that LRRK2 inhibition as a disease-modifying strategy for idiopathic Parkinson’s lacks clinical efficacy support at this stage
• Monitor BEACON results and forthcoming LUMA subgroup analyses for any mutation-specific signal before drawing conclusions about the broader LRRK2 target class
• Avoid characterizing BIIB122 as a closed chapter for LRRK2-mutation carriers; the idiopathic and genetic populations may behave differently
• Counsel patients enrolled in or awaiting LRRK2-targeted trials that this class remains under active investigation in genetically defined populations