DNL151

Overview

Overview

DNL151 (also known as BIIB122) is a potent, selective, brain-penetrant small molecule inhibitor of leucine-rich repeat kinase 2 (LRRK2) developed by Denali Therapeutics Inc. in partnership with Biogen. DNL151 represents one of the most advanced [LRRK2](/entities/lrrk2) inhibitor programs in clinical development for Parkinson's disease (PD). The compound is a derivative of bosutinib, a known Src/Abl tyrosine kinase inhibitor, but was repurposed and optimized for selective LRRK2 inhibition with enhanced brain penetration["@biogen"][@lrrk].

DNL151/BIIB122 is currently in Phase 2 clinical development as a disease-modifying therapy for Parkinson's disease, targeting patients both with and without LRRK2 mutations. This makes it unique among LRRK2 inhibitors in development, as it aims to benefit the broader PD population rather than restricting to genetically-defined subgroups alone.

LRRK2 Biology and Parkinson's Disease

LRRK2 Structure and Function

LRRK2 (Leucine-Rich Repeat Kinase 2) is a large multi-domain protein (2527 amino acids) belonging to the ROCO family of kinases. It consists of multiple functional domains:

• Armadillo repeats: Located at the N-terminus, involved in protein-protein interactions
• Ankyrin repeats: Mediate interactions with cytoskeletal proteins
• Leucine-rich repeats (LRR): Protein-protein interaction domain
• Ras of complex (ROC) domain: GTPase domain that binds and hydrolyzes GTP
• COR domain: C-terminal of ROC, essential for kinase activity
• Kinase domain: Catalytic serine/threonine kinase activity
• WD40 repeats: C-terminal protein interaction domain

LRRK2 in Familial PD

Pathogenic mutations in the LRRK2 gene are among the most common genetic causes of Parkinson's disease:

• G2019S: The most common LRRK2 mutation, located in the kinase domain, increases kinase activity by ~2-3 fold. Accounts for 5-6% of familial PD cases and 1-2% of sporadic PD.
• R1441C/G/H: Located in the COR domain, affects GTPase activity
• Y1699C: COR domain mutation that increases kinase activity
• I2020T: Found in certain ethnic populations (e.g., Japanese)

LRRK2 in Sporadic PD

Beyond familial cases, LRRK2 plays a role in sporadic Parkinson's disease:

• LRRK2 expression: Elevated in PD brains, particularly in vulnerable regions
• Pathological phosphorylation: Increased pSer935 and pSer1292 in PD peripheral blood cells
• Protein aggregates: LRRK2 is found in Lewy bodies, a hallmark of PD neuropathology
• Microglial activation: LRRK2 regulates neuroinflammatory responses
• Lysosomal dysfunction: LRRK2 mutations impair [autophagy](/entities/autophagy)-lysosomal pathways

LRRK2 Pathogenic Mechanisms

The downstream effects of LRRK2 hyperactivity include:

Mechanism of Action

Kinase Inhibition

DNL151 is a selective ATP-competitive inhibitor of LRRK2 kinase activity:

• Target engagement: Dose-dependent reduction of LRRK2 phosphorylation at Ser935 (a biomarker of LRRK2 activity)
• Kinase selectivity: Designed to minimize off-target effects on other kinases
• Brain penetration: Demonstrated CSF exposure confirming central nervous system activity
• Reversible binding: Allows for controlled pharmacological effects

Pharmacodynamic Biomarkers

The development of DNL151 employs key pharmacodynamic markers:

| Biomarker | Site | Significance |
|-----------|------|--------------|
| pSer935 | LRRK2 | Primary biomarker, reduced by LRRK2 inhibition |
| pSer1292 | LRRK2 | Autophosphorylation site, activity marker |
| pThr73 | LRRK2 | Rab10 phosphorylation, downstream effector |
| LRRK2 expression | Peripheral blood mononuclear cells | Target engagement |

Reduction of pSer935 in peripheral blood cells serves as a proxy for central LRRK2 inhibition, as this biomarker is more readily measurable[@dnl].

Comparison with Other LRRK2 Inhibitors

DNL151 differs from other LRRK2 inhibitors in development:

| Compound | Company | Status | Key Features |
|----------|---------|--------|--------------|
| DNL151/BIIB122 | Denali/Biogen | Phase 2 | Brain-penetrant, broad PD population |
| BML-284 | Denali (discontinued) | Preclinical | First-generation compound |
| MLi-2 | Merck | Preclinical | Highly potent, tool compound |
| DNL151 | Denali | Phase 2 | Current lead, once-daily oral |

The once-daily oral dosing of DNL151 represents an advantage over earlier compounds that required more frequent administration.

Clinical Development

Phase 1 Studies

NCT04056689 (First-in-Human)

This first-in-human study evaluated single and multiple ascending doses of DNL151 in healthy volunteers:

• Single ascending doses: 10-400 mg evaluated
• Multiple ascending doses: 7-14 day dosing at various levels
• Results: Safe and tolerable across all doses tested
• Target engagement: Dose-dependent reduction in pSer935
• CSF study: Demonstrated brain penetration in subset of participants[@biogendenali2020]

LUMINA Phase 1b Study

This study was specifically designed for dose selection for Phase 2:

• Objective: Identify optimal dose for Phase 2 based on target engagement
• Dose levels tested: Multiple doses ranging from 30-400 mg
• Biomarker results: Sustained pSer935 reduction at selected doses
• Safety profile: No dose-limiting toxicities observed

Phase 2 Clinical Program

NCT05129592 (LRRK2-PD)

A Phase 2 trial specifically enrolling patients with LRRK2-associated Parkinson's disease:

• Population: PD patients with confirmed LRRK2 mutations
• Design: Randomized, double-blind, placebo-controlled
• Primary endpoint: Safety and tolerability
• Secondary endpoints: Motor symptoms (MDS-UPDRS), biomarkers

NCT05785656 (Sporadic PD)

A Phase 2 trial in sporadic Parkinson's disease patients without LRRK2 mutations:

• Population: Idiopathic PD patients
• Rationale: LRRK2 pathway activation even without mutations
• Design: Multi-center, randomized, placebo-controlled
• Status: Currently recruiting

LRIK2-PD Study

Additional Phase 2 studies are evaluating DNL151 in various PD populations:

• Early-stage PD: Patients within 3 years of diagnosis
• Moderate PD: Patients on stable dopaminergic therapy
• Combination studies: Exploring adjunct to standard care

Pharmacokinetics and Pharmacodynamics

Absorption and Distribution

• Oral bioavailability: High (specific values proprietary)
• Time to peak: 2-4 hours post-dose
• Protein binding: Moderate, not extensively bound
• Volume of distribution: Moderate, indicating tissue distribution
• Brain penetration: Demonstrated in CSF studies (CSF:plasma ratio ~0.1-0.3)

Metabolism

• Primary metabolic pathway: Hepatic metabolism via CYP3A4
• Active metabolites: Bosutinib is the parent compound; DNL151 is an optimized derivative
• Drug-drug interactions: CYP3A4 inhibitors/inducers may affect exposure
• Elimination: Primarily fecal, with renal contribution

Dosing Regimen

• Route: Oral (tablet or capsule)
• Frequency: Once daily
• Dose range: Selected dose based on Phase 1b target engagement data
• Food effects: May be taken with or without food

Safety Profile

Phase 1 Safety Data

Based on completed Phase 1 studies:

• Generally well-tolerated across all dose levels tested
• No serious adverse events attributed to study drug
• Most common adverse events: Mild and transient
• Maximum tolerated dose: Not reached at highest tested dose (400 mg)
• Laboratory values: No clinically significant abnormalities

Expected Safety Considerations

Class considerations for LRRK2 inhibitors include:

• Liver function: Monitor transaminases (class effect seen with some kinase inhibitors)
• Lung function: Preclinical signals with some LRRK2 inhibitors (not observed with DNL151)
• Phototoxicity: Some kinase inhibitors cause photosensitivity
• Gastrointestinal: Monitor for diarrhea (common with bosutinib)

Contraindications and Warnings

• Hypersensitivity: To DNL151 or any excipients
• Pregnancy: Category not established; avoid in pregnancy
• Breastfeeding: Not recommended during treatment
• Drug interactions: CYP3A4 modulators require caution

Therapeutic Potential

Disease-Modifying Mechanism

DNL151 aims to slow or halt PD progression through:

Advantages of LRRK2 Targeting

LRRK2 inhibition represents a promising therapeutic approach:

• Genetic validation: LRRK2 mutations cause PD, establishing causality
• Mechanistic rationale: Hyperactive kinase drives pathogenesis
• Peripheral biomarker: pSer935 allows easy target engagement monitoring
• Broad applicability: May benefit both genetic and sporadic PD
• Oral delivery: Patient-friendly administration

Challenges and Limitations

• Compensatory pathways: Other kinases may compensate for LRRK2 inhibition
• Timing of intervention: May need early intervention before extensive neuron loss
• Biomarker limitations: pSer935 reduction may not fully reflect central effects
• Long-term safety: Extended treatment effects not yet characterized

Partnership and Commercialization

Denali-Biogen Collaboration

In 2020, Denali Therapeutics entered a strategic partnership with Biogen for the co-development of LRRK2 inhibitors:

• Collaboration terms: Biogen received rights to develop and commercialize BIIB122 in North America
• Denali retained: Rights for certain international markets
• Development costs: Shared between both companies
• Regulatory responsibilities: Joint decision-making on development strategy

Competitive Landscape

DNL151 faces competition from other LRRK2 programs:

• Merck: MLi-2 (preclinical, highly potent tool compound)
• Genentech/Roche: Early-stage LRRK2 program
• Intracellular Therapeutics: LRRK2 targeting approaches
• Academic programs: Various preclinical compounds in development

Research and Development History

Preclinical Development

The path to clinical development included:

• Lead optimization: From initial bosutinib derivative to DNL151
• Selectivity profiling: Extensive kinase panel testing
• Efficacy models: Mouse and non-human primate studies
• Safety assessment: IND-enabling toxicology studies

Clinical Milestones

Key development timeline:

| Year | Milestone |
|------|-----------|
| 2018 | IND submission cleared by FDA |
| 2019 | Phase 1 initiated |
| 2020 | Phase 1 completed; partnership with Biogen announced |
| 2021 | Phase 1b (LUMINA) completed |
| 2022 | Phase 2 trials initiated |
| 2023 | Phase 2 enrollment ongoing |
| 2024 | Phase 2 results expected |

Future Directions

Potential future development areas:

• Combination therapy: With dopamine agonists or MAO-B inhibitors
• Early intervention: Trials in prodromal PD (LRRK2 carriers)
• Biomarker-driven: Enriching trials with biomarker-positive patients
• Neuroprotective endpoints: Imaging and fluid biomarkers of progression

Patient Perspectives

Potential Benefits for Patients

If approved, DNL151/BIIB122 could provide:

• Disease modification: Slowing progression rather than just treating symptoms
• Convenient dosing: Once-daily oral medication
• Targeted therapy: Based on individual disease biology
• Broad applicability: For both familial and sporadic PD

Ongoing Clinical Trials

Patients interested in participating can find information on:

• ClinicalTrials.gov: Search for DNL151, BIIB122, or LRRK2 inhibitor trials
• Michael J. Fox Foundation: LRRK2 consortium and trial information
• Parkinson's Foundation: Clinical trial resources
• Denali Therapeutics: Company trial announcement page
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [LRRK2 Gene](/genes/lrrk2)
• [LRRK2 Protein](/proteins/lrrk2-protein)
• [Leucine-Rich Repeat Kinase 2](/proteins/lrrk2-protein)
• [G2019S Mutation](/mutations/g2019s)
• [Kinase Inhibitors in Neurodegeneration](/therapeutics/kinase-inhibitors-neurodegeneration)
• [Autophagy in PD](/mechanisms/autophagy-lysosomal-pathway)
• [Neuroinflammation in Parkinson's](/mechanisms/neuroinflammation-parkinsons)
• [--](/proteins/n--cadherin-protein)

See Also

• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Parkinson's Disease](/diseases/parkinsons-disease)

External Links

• [PubMed](https://pubmed.ncbi.nlm.nih.gov/)
• [KEGG Pathways](https://www.genome.jp/kegg/pathway.html)
• [Allen Human Brain Atlas](https://brain-map.org/)

References