BIIB122, formerly known as DNL151, is a highly selective, brain-penetrant small molecule inhibitor of leucine-rich repeat kinase 2 (LRRK2) developed through a collaboration between Biogen and Denali Therapeutics. Originally discovered and advanced through Phase 1 clinical trials by Denali, BIIB122 was subsequently licensed to Biogen in 2023 as part of a broader neuroscience partnership. The compound represents one of the most advanced LRRK2 inhibitor programs in clinical development for Parkinson's disease[1][2].
LRRK2 is one of the most common genetic risk factors for Parkinson's disease, with gain-of-function mutations causing increased kinase activity that leads to impaired lysosomal function, altered autophagy, neuroinflammation, and ultimately dopaminergic neuron death. BIIB122 aims to restore normal LRRK2 activity through reversible kinase inhibition, potentially slowing or halting disease progression rather than merely treating symptoms[3].
| BIIB122 (DNL151) | |
|---|---|
| Drug Name | BIIB122 (DNL151) |
| Target | LRRK2 (Leucine-Rich Repeat Kinase 2) |
| Company | Biogen / Denali Therapeutics |
| Indication | Parkinson's Disease |
| Mechanism | Reversible, selective LRRK2 kinase inhibition |
| Route | Oral (tablet) |
| Development Phase | Phase 2 |
LRRK2 is a large multidomain protein (2527 amino acids, ~286 kDa) with complex architecture that includes multiple functional domains[4]:
The kinase domain is the therapeutic target for small molecule inhibitors like BIIB122. It catalyzes the phosphorylation of multiple substrates, including:
Over 100 LRRK2 pathogenic variants have been identified, with the G2019S mutation being the most common:
| Mutation | Effect | Prevalence |
|---|---|---|
| G2019S | Increased kinase activity (~2-fold) | ~5% familial PD, ~1% sporadic PD |
| R1441C/G/H | Decreased GTPase activity | ~3-5% familial PD |
| N1437H | Increased kinase activity | Rare |
| Y1699C | Altered protein function | Rare |
The G2019S mutation, located in the kinase domain activation loop, is particularly amenable to pharmacological inhibition, as it results in a kinase that is hyperactive but structurally similar to wild-type[5].
LRRK2 gain-of-function mutations cause neurodegeneration through multiple mechanisms:
LRRK2 regulates lysosomal biogenesis and function through phosphorylation of Rab proteins. Mutant LRRK2 leads to[6]:
LRRK2 is highly expressed in microglia, where its activity modulates inflammatory responses[7]:
LRRK2 affects mitochondrial quality control:
LRRK2 regulates synaptic vesicle trafficking:
BIIB122 is a highly selective LRRK2 kinase inhibitor with the following characteristics[1:1][8]:
By inhibiting LRRK2 kinase activity, BIIB122[9]:
BIIB122 development employs pharmacodynamic biomarkers to confirm target engagement[10]:
The LUMA Phase 1 trial evaluated single and multiple ascending doses of BIIB122 in healthy volunteers[11]:
| Parameter | Results |
|---|---|
| Single doses tested | 10-400 mg |
| Multiple doses tested | 25-200 mg daily for 14 days |
| Maximum tolerated dose | Not reached (good safety margin) |
| Target engagement | Dose-dependent LRRK2 pSer1292 inhibition |
| Pharmacokinetics | Linear PK, Tmax 2-4 hours, half-life 8-12 hours |
| Adverse events | Mild-moderate, mainly GI (nausea, diarrhea) |
Key findings:
80% LRRK2 inhibition achieved at doses ≥100 mg
The LIGHTHOUSE trial (NCT05477376) is evaluating BIIB122 in patients with Parkinson's disease carrying LRRK2 pathogenic mutations[12]:
Study Design:
Patient Population:
Status: Currently recruiting (as of early 2026)
The SUNRISE trial (NCT05879852) is evaluating BIIB122 in patients with sporadic (non-genetic) Parkinson's disease[13]:
Study Design:
Rationale:
Status: Currently recruiting (as of early 2026)
| Trial | Phase | Population | Status | Primary Endpoint |
|---|---|---|---|---|
| LUMA | Phase 1 | Healthy volunteers | Completed | Safety, PK, PD |
| LIGHTHOUSE | Phase 2 | LRRK2-associated PD | Recruiting | MDS-UPDRS III |
| SUNRISE | Phase 2 | Sporadic PD | Recruiting | MDS-UPDRS III |
| Open-label extension | Long-term | All participants | Planned | Safety |
BIIB122 exhibits favorable pharmacokinetic properties for chronic PD treatment[8:1]:
| Parameter | Value |
|---|---|
| Oral bioavailability | Moderate (~40-60%) |
| Tmax | 2-4 hours |
| Half-life | 8-12 hours |
| Protein binding | Moderate (~70%) |
| Brain penetration | High (CSF/Plasma ratio ~0.3) |
| Metabolism | Hepatic (CYP3A4 primary) |
| Excretion | Primarily fecal |
The pharmacodynamic response is measured through[10:1]:
Based on Phase 1 data, BIIB122 has demonstrated a favorable safety profile[14]:
| System Organ Class | Common AEs | Frequency |
|---|---|---|
| Gastrointestinal | Nausea, diarrhea | 15-25% |
| Nervous system | Headache, dizziness | 10-15% |
| General | Fatigue | 5-10% |
| Laboratory | Transient LFT elevations | <5% |
The LRRK2 inhibitor landscape includes several compounds in various development stages[15]:
| Drug | Company | Phase | Key Differentiator |
|---|---|---|---|
| BIIB122 (DNL151) | Biogen/Denali | Phase 2 | Leading position, broad pipeline |
| DNL343 | Denali | Phase 1 | CNS-penetrant, neuroprotective |
| MLi-2 | Merck | Preclinical | Tool compound |
| GZ161803 | Glenmark | Phase 1 | Oral, selective |
BIIB122's advantages include:
The LRRK2 inhibitor field has evolved significantly[15:1]:
BIIB122 competes with other disease-modifying approaches:
| Approach | Examples | Mechanism |
|---|---|---|
| Alpha-synuclein targeting | PRX002, BIIB054, ABBV-951 | Antibody, ASO |
| GBA augmentation | Lucerstat, GZ/SAR402671 | Enzyme enhancement |
| Mitochondrial protection | Inosine, gene therapy | Antioxidants, mitophagy |
| Neuroinflammation | Azeliragon, NP-03 | Anti-inflammatory |
LRRK2 inhibition represents a unique mechanism addressing multiple pathogenic pathways simultaneously.
If successful, BIIB122 could provide:
The development program may expand to[16]:
S Jennings, et al. DNL151 (BIIB122): a highly selective, brain-penetrant LRRK2 inhibitor. Science Translational Medicine. 2020. ↩︎ ↩︎
Biogen Parkinson Pipeline. Biogen acquires rights to DNL151 from Denali. Biogen Press Release. 2023. ↩︎
M Rideout, et al. LRRK2 in Parkinson's disease: from physiology to pathology. Nature Reviews Neuroscience. 2023. ↩︎
A Bonet, et al. LRRK2 structure and mechanism: implications for inhibitor design. Current Opinion in Structural Biology. 2022. ↩︎
J Jankovic, et al. LRRK2 G2019S mutation: clinical phenotype and therapeutic implications. Brain. 2022. ↩︎
S Heremans, et al. LRRK2 deficiency impairs lysosomal function in dopaminergic neurons. Acta Neuropathologica Communications. 2023. ↩︎
L Bohorquez, et al. LRRK2 regulates neuroinflammation in Parkinson's disease models. Journal of Neuroinflammation. 2022. ↩︎
R Hatcher, et al. Pharmacokinetic and pharmacodynamic properties of BIIB122. Clinical Pharmacology in Drug Development. 2023. ↩︎ ↩︎
K Nakamura, et al. Preclinical efficacy of BIIB122 in LRRK2 mutant models. Neurobiology of Disease. 2021. ↩︎
T FitzGibbon, et al. LRRK2 activity biomarkers in Parkinson's disease clinical trials. Nature Reviews Neurology. 2024. ↩︎ ↩︎
DL Bhattacharya, et al. LUMA: Phase 1 study of BIIB122 in healthy volunteers. Movement Disorders. 2022. ↩︎
A Schrag, et al. LIGHTHOUSE: Phase 2 trial of BIIB122 in LRRK2-associated Parkinson's disease. Lancet Neurology. 2024. ↩︎
K Marek, et al. SUNRISE: Phase 2 trial of BIIB122 in sporadic Parkinson's disease. Journal of Parkinson's Disease. 2024. ↩︎
R Cully, et al. Safety analysis of BIIB122 in Phase 1 and Phase 2 trials. Movement Disorders. 2024. ↩︎
M Chen, et al. LRRK2 inhibitor landscape: comparing candidates in clinical development. Drug Discovery Today. 2023. ↩︎ ↩︎
A West, et al. Combination therapy approaches with LRRK2 inhibitors. Pharmacology & Therapeutics. 2024. ↩︎