Mitochondrial DNA damage as a potential biomarker of LRRK2 kinase activity in LRRK2 Parkinson\u2019s disease

C P Gonzalez-Hunt,L H Sanders,S Deprets,E A Thacker,S Boularand,C M Toste,L Dubois

doi:10.1038/s41598-020-74195-6

C P Gonzalez-Hunt, L H Sanders + Show 5 more

Open Access

https://doi.org/10.1038/s41598-020-74195-6

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Abstract

Leucine-rich repeat kinase 2 (LRRK2) is a promising therapeutic target for the treatment of Parkinson’s disease (PD) and LRRK2 kinase inhibitors are currently being tested in early phase clinical trials. In order to ensure the highest chance of success, a biomarker-guided entry into clinical trials is key. LRRK2 phosphorylation, and phosphorylation of the LRRK2 substrate Rab10, have been proposed as target engagement biomarkers for LRRK2 kinase inhibition. However, a pharmacodynamic biomarker to demonstrate that a biological response has occurred is lacking. We previously discovered that the LRRK2 G2019S mutation causes mitochondrial DNA (mtDNA) damage and is LRRK2 kinase activity-dependent. Here, we have explored the possibility that measurement of mtDNA damage is a “surrogate” for LRRK2 kinase activity and consequently of kinase inhibitor activity. Mitochondrial DNA damage was robustly increased in PD patient-derived immune cells with LRRK2 G2019S mutations as compared with controls. Following treatment with multiple classes of LRRK2 kinase inhibitors, a full reversal of mtDNA damage to healthy control levels was observed and correlated with measures of LRRK2 dephosphorylation. Taken together, assessment of mtDNA damage levels may be a sensitive measure of altered kinase activity and provide an extended profile of LRRK2 kinase modulation in clinical studies.

Highlights

Mutations in leucine-rich repeat kinase 2 (LRRK2) are the most common genetic cause of autosomal-dominant Parkinson’s disease (PD), accounting for about 3–4% of all P D1,2
To evaluate mitochondrial DNA (mtDNA) damage for use as a pharmacodynamic biomarker of Leucine-rich repeat kinase 2 (LRRK2) kinase inhibitors in clinical trials and compare it to other candidate target engagement biomarkers, we examined healthy control and PD LRRK2 G2019S patient-derived Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines (LCL); detailed demographic information can be found in Supplemental Table S1
Given the strong link between LRRK2 and disease pathogenesis in familial and idiopathic PD, LRRK2 is a good candidate for small molecule kinase inhibitor development and highly specific inhibitors are being tested in clinical trials

Summary

Introduction

Mutations in leucine-rich repeat kinase 2 (LRRK2) are the most common genetic cause of autosomal-dominant Parkinson’s disease (PD), accounting for about 3–4% of all P D1,2. LRRK2 Ser[935] is an indirect readout and does not always reflect LRRK2 protein kinase activity and caution should be taken if used as a single measure of target engagement in clinical trials. Due to this complexity, additional distinct biomarkers including the bona fide LRRK2 substrates (e.g. LRRK2 Ser1292 and Rabs) have been pursued. Due to low levels measuring endogenous LRRK2 Ser1292 has been technically challenging and only robustly detected in overexpression models or in urine following exosome enrichment in PD patients carrying the G2019S mutation or idiopathic PD27,28. With drugs targeting LRRK2 already in clinical trials, it is of utmost importance that robust and sensitive biomarkers are developed, in particular, pharmacodynamic biomarkers for LRRK2 kinase inhibition

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