MLi-2, a Potent, Selective, and Centrally Active Compound for Exploring the Therapeutic Potential and Safety of LRRK2 Kinase Inhibition

J Pharmacol Exp Ther. 2015 Dec;355(3):397-409. doi: 10.1124/jpet.115.227587. Epub 2015 Sep 25.


Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene are the most common genetic cause of familial and sporadic Parkinson's disease (PD). That the most prevalent mutation, G2019S, leads to increased kinase activity has led to a concerted effort to identify LRRK2 kinase inhibitors as a potential disease-modifying therapy for PD. An internal medicinal chemistry effort identified several potent and highly selective compounds with favorable drug-like properties. Here, we characterize the pharmacological properties of cis-2,6-dimethyl-4-(6-(5-(1-methylcyclopropoxy)-1H-indazol-3-yl)pyrimidin-4-yl)morpholine (MLi-2), a structurally novel, highly potent, and selective LRRK2 kinase inhibitor with central nervous system activity. MLi-2 exhibits exceptional potency in a purified LRRK2 kinase assay in vitro (IC50 = 0.76 nM), a cellular assay monitoring dephosphorylation of LRRK2 pSer935 LRRK2 (IC50 = 1.4 nM), and a radioligand competition binding assay (IC50 = 3.4 nM). MLi-2 has greater than 295-fold selectivity for over 300 kinases in addition to a diverse panel of receptors and ion channels. Acute oral and subchronic dosing in MLi-2 mice resulted in dose-dependent central and peripheral target inhibition over a 24-hour period as measured by dephosphorylation of pSer935 LRRK2. Treatment of MitoPark mice with MLi-2 was well tolerated over a 15-week period at brain and plasma exposures >100× the in vivo plasma IC50 for LRRK2 kinase inhibition as measured by pSer935 dephosphorylation. Morphologic changes in the lung, consistent with enlarged type II pneumocytes, were observed in MLi-2-treated MitoPark mice. These data demonstrate the suitability of MLi-2 as a compound to explore LRRK2 biology in cellular and animal models.

MeSH terms

  • Alveolar Epithelial Cells / drug effects
  • Alveolar Epithelial Cells / pathology
  • Animals
  • Antiparkinson Agents / adverse effects*
  • Antiparkinson Agents / therapeutic use*
  • Behavior, Animal / drug effects
  • Binding, Competitive
  • Brain / metabolism
  • Brain Chemistry / drug effects
  • Cell Line
  • Cerebral Cortex / drug effects
  • Cerebral Cortex / metabolism
  • Dose-Response Relationship, Drug
  • Humans
  • Indazoles / pharmacology*
  • Leucine-Rich Repeat Serine-Threonine Protein Kinase-2
  • Lung / pathology
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mutation / genetics
  • Parkinson Disease / drug therapy
  • Parkinson Disease / pathology
  • Parkinson Disease / psychology
  • Phosphorylation
  • Protein Kinase Inhibitors / adverse effects*
  • Protein Kinase Inhibitors / therapeutic use*
  • Protein Serine-Threonine Kinases / antagonists & inhibitors*
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / metabolism
  • Pyrimidines / pharmacology*


  • 2,6-dimethyl-4-(6-(5-(1-methylcyclopropoxy)-1H-indazol-3-yl)pyrimidin-4-yl)morpholine
  • Antiparkinson Agents
  • Indazoles
  • Protein Kinase Inhibitors
  • Pyrimidines
  • Leucine-Rich Repeat Serine-Threonine Protein Kinase-2
  • Lrrk2 protein, mouse
  • Protein Serine-Threonine Kinases