MLi-2

Biological Activity

MLi-2 is a 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 dosedependent central and peripheral target inhibition over a 24-hour period as measured by dephosphorylation of pSer935 LRRK2. Treatment of MitoPark mice with MLi-2 is 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, are observed in MLi-2-treated MitoPark mice.

Protocol

Cell Experiment
Cell lines	SH-SY5Y cells
Preparation method	A human neuroblastoma cell line, SH-SY5Y, is used for the LRRK2 stable cell line construction. SH-SY5Y cells are cultured in Dulbecco’s modified Eagle’s medium/F-12 supplemented with GlutaMax, 10% tetracycline (Tet)-free fetal bovine serum, nonessential amino acids, pen-strep at 37°C and 5% carbon dioxide. Parental cells are transfected with plasmid constructs that overexpress full-length human LRRK2 wildtype or mutant (G2019S) under the control of a Tet-inducible promoter. Transfected cells are selected and maintained with hygromycin (2 mg/ml) and zeocin (100 mg/ml). Cells are seeded into six-well plates and induced with Tet (2 mg/ml) for 72 hours prior to treatment. After 90 minutes of MLi-2 incubation, cells were mechanically lifted, pelleted, and lysed with lysis buffer supplemented with protease, and phosphatase inhibitors. Pellets are further bead homogenized and then spun at 13,200 rpm for 20 minutes at 4°C. Supernatants are then removed for subsequent Western blot analyses.
Concentrations	10 serial 3-fold dilutions, top concentration 5 μM
Incubation time	90 min

Animal Experiment
Animal models	male C57Bl/6 mice weighing 20-25g
Formulation	suspended in 30% Captisol
Dosages	1-100 mg/kg; administered in a volume of 10 ml/kg
Administration	IV or PO administration

Conversion of different model animals based on BSA (Value based on data from FDA Draft Guidelines)

Species	Mouse	Rat	Rabbit	Guinea pig	Hamster	Dog
Weight (kg)	0.02	0.15	1.8	0.4	0.08	10
Body Surface Area (m2)	0.007	0.025	0.15	0.05	0.02	0.5
Km factor	3	6	12	8	5	20

Animal A (mg/kg) = Animal B (mg/kg) multiplied by	Animal B Km
	Animal A Km

For example, to modify the dose of Compound A used for a mouse (20 mg/kg) to a dose based on the BSA for a rat, multiply 20 mg/kg by the K_m factor for a mouse and then divide by the K_m factor for a rat. This calculation results in a rat equivalent dose for Compound A of 10 mg/kg.

Chemical Information

References

[1] Jack D Scott, et al. J Med Chem. Discovery of a 3-(4-Pyrimidinyl) Indazole (MLi-2), an Orally Available and Selective Leucine-Rich Repeat Kinase 2 (LRRK2) Inhibitor that Reduces Brain Kinase Activity

[2] Matthew J Fell, et al. J Pharmacol Exp Ther. MLi-2, a Potent, Selective, and Centrally Active Compound for Exploring the Therapeutic Potential and Safety of LRRK2 Kinase Inhibition