BIIB122 (LRRK2 inhibitor)
Phase 3: large human trials
A pill targeting the LRRK2 enzyme, in large trials to test whether it can slow Parkinson's. Results are not yet available.
- Stage: Phase 2b / Phase 3
- Type: Disease-modifying
- Developer: Biogen and Denali Therapeutics
- Target: LRRK2 enzyme
- How it works: A pill that dials down an overactive enzyme called LRRK2, which is linked to some inherited and non-inherited Parkinson's.
- Who it's for: Two programs: one in people with a LRRK2 gene variant, one in people with early Parkinson's regardless of genetics.
- Key trials: NCT05348785, NCT05418673
- Last reviewed: 2026-06-01
What it is
Overactivity of the LRRK2 enzyme is one of the best-understood genetic contributors to Parkinson's, and may matter even in people without a LRRK2 mutation. BIIB122 is designed to reduce that overactivity, in the hope of protecting brain cells over time.
Where it stands
It is in two ongoing trials: LUMA (a large Phase 2b/3 study in early Parkinson's broadly) and LIGHTHOUSE (focused on people carrying a LRRK2 variant). Both are aimed at whether the drug slows progression. Top-line results are still pending.
What the data shows so far
Earlier studies established that the drug lowers markers of LRRK2 activity and was generally tolerated. Whether that translates into slower disease progression is exactly what the ongoing trials are designed to answer. There is no efficacy read-out yet.
What families should know
This is a leading test of the idea that targeting a known Parkinson's gene pathway can change the disease. If you have a family history or a known LRRK2 variant, the genetics-focused trial may be especially relevant, but enrollment criteria are specific.
Caveats
No results yet on whether it slows the disease. Some benefit may turn out to be limited to people with LRRK2 variants rather than all Parkinson's. Long-term safety of suppressing LRRK2 (including possible lung effects seen in early studies) is still being monitored.
Timeline
Most recent first.
- 2022, LUMA and LIGHTHOUSE Phase 2b/3 trials begin enrolling.
Sources
Last reviewed: 2026-06-01. Back to the Parkinson's drug pipeline