LRRK2 (Leucine-Rich Repeat Kinase 2) is a large multi-domain protein with both GTPase and kinase activities that represents one of the most common genetic risk factors for Parkinson's disease. Pathogenic LRRK2 mutations lead to increased kinase activity, which impairs lysosomal function, autophagy, and neuronal survival. LRRK2 inhibitors represent one of the most advanced disease-modifying therapeutic approaches for Parkinson's disease, with multiple compounds in clinical development. [1]
LRRK2 is a 2527-amino acid protein encoded by the LRRK2 gene. Pathogenic mutations like G2019S (kinase domain, approximately 40% of familial PD) and R1441C/G/H (ROC GTPase domain) lead to increased kinase activity, which promotes: [2]
The G2019S mutation increases LRRK2 kinase activity approximately 2-fold, leading to the downstream pathogenic cascade observed in PD patients carrying this mutation. [3]
The primary approach is to develop selective LRRK2 kinase inhibitors to reduce pathological kinase activity. [4]
| Inhibitor | Company | Development Status |
|---|---|---|
| BIIB122 (DNL151) | Biogen/Denali | Phase II (LUMA/Novitude) |
| PF-06685360 | Pfizer | Phase I |
| PBT434 | Prima BioMed | Phase I (MSA) |
| GZ-161 | Pharma partners | Preclinical |
| LL-010 | Lexicon | Preclinical |
| MRC-4869 | Medical Research Council | Preclinical |
| ATA-221 | Astellas | Preclinical |
BIIB122 (also known as DNL151) has advanced furthest, with Phase II trials (LUMA in LRRK2-associated PD, Novitude in sporadic PD) investigating safety, tolerability, and target engagement. [5]
MDS 2026 highlighted significant advances in LRRK2-targeted gene therapy approaches:
AAV-Mediated LRRK2 Silencing
| Approach | Vector | Mechanism | Status |
|---|---|---|---|
| AAV-shRNA-LRRK2 | AAV9 | shRNA-mediated knockdown | Preclinical |
| AAV-ASO-LRRK2 | AAV9 | Antisense oligonucleotide delivery | Preclinical |
| CRISPR-LRRK2 | AAV | Allele-specific editing | Discovery |
Clinical Considerations
Key developments from MDS 2026:
LRRK2 Gene Therapy for Atypical Parkinsonism
MDS 2026 featured data on LRRK2-targeted approaches for:
Gene therapy approaches may benefit these populations by:
Targeting the GTPase domain to modulate LRRK2 activity through an alternative mechanism: [6]
| Compound | Mechanism | Status |
|---|---|---|
| Imatinib (Gleevec) | GTPase modulation | Phase I completed |
| LRRK2-IN-1 | GTPase inhibitor | Preclinical |
Using RNA interference to reduce LRRK2 mRNA expression:
| Approach | Delivery | Status |
|---|---|---|
| AAV-mediated RNAi | CNS delivery | Preclinical |
| Antisense oligonucleotides | Intrathecal | Preclinical |
| siRNA-lipid nanoparticles | Peripheral delivery | Preclinical |
BIIB122 (NCT06602193) — LRRK2-associated early Parkinson's disease:
Note: NCT05348789 (LUMA) does not exist in ClinicalTrials.gov
Novitude — Sporadic Parkinson's disease:
BIIB122 demonstrated: [5:1]
LRRK2 inhibitors represent the most advanced genetic-targeted approach in PD:
| Drug | Company | Mechanism | Stage |
|---|---|---|---|
| BIIB122 | Biogen/Denali | Kinase inhibitor | Phase II |
| PBT434 | Prima BioMed | Kinase inhibitor | Phase I (MSA) |
| PF-06685360 | Pfizer | Kinase inhibitor | Phase I |
| Imatinib | Novartis | Multi-kinase | Phase I complete |
Tolosa E, et al. LRRK2 in Parkinson disease: challenges and opportunities. Nature Reviews Neurology. 2020. ↩︎
Alessi DR, et al. The relevant physics of LRRK2 mutations causing Parkinson disease. Biochemical Society Transactions. 2015. ↩︎
Baptista MA, et al. Loss of leucine-rich repeat kinase 2 (LRRK2) leads to altered motor and non-motor features in a knock-out mouse model. Brain. 2020. ↩︎
Cook DA, et al. Discovery and optimization of pyrrolopyridine LRRK2 inhibitors. Journal of Medicinal Chemistry. 2020. ↩︎
Jennings D, et al. LRRK2 Inhibition by BIIB122 in Healthy Participants and Patients with Parkinson's Disease. Movement Disorders. 2023. ↩︎ ↩︎
Andersen MA, et al. PBT434 prevents vibration-induced loss of dopaminergic neurons in an alpha-synuclein Parkinson's disease model. Journal of Parkinson's Disease. 2020. ↩︎