PF-06447475

PF-06447475 is a highly potent, selective and brain penetrant LRRK2 inhibitor with an IC50 of 3 nM.

In Vitro:PF-06447475 inhibits LRRK2 enzyme and LRRK2 in the whole cell assay with IC50s of 3 and 25 nM, respectively[1]. Cells incubated with PF-06447475 alone (0.5, 1, 3 μM) or in the presence of ROT significantly reduces (S935)-LRRK2 kinase phosphorylation to control. PF-06447475 significantly preserves the nucleus morphology and ΔΨm of NLCs exposed to ROT compared to untreated and control. PF-475 significantly diminishes ROT-induced ROS generation to a similar extent to cells exposed to PF-475 alone[2].

In Vivo:In G2019S+ rats treated with PF-06447475, a significant reduction in microgliosis to levels found in wild-type rats could be observed. The proinflammatory marker MHC-II expressed on myeloid cells but not neurons also appears to be less abundant in confocal sections in G2019S+ rats treated with PF-06447475. PF-06447475 treatment in G2019S+ rats significantly lowers the number of CD68 cells recruited to the SNpc. PF-06447475 successfully blocks the enhanced neuroinflammation associated with G2019S-LRRK2 expression. Treatment of G2019S+ rats with PF-06447475 preserves TH expression in the dorsal striatum, consistent with drug attenuating neurodegeneration in the SNpc[3]. PF-06447475 is well tolerated in rats[1].

References:
[1]. Henderson JL, et al. Discovery and preclinical profiling of 3-[4-(morpholin-4-yl)-7H-pyrrolo[2,3-d]pyrimidin-5-yl]benzonitrile (PF-06447475), a highly potent, selective, brain penetrant, and in vivo active LRRK2 kinase inhibitor. J Med Chem. 2015 Jan 8;58(1):419-32. [2]. Mendivil-Perez M, et al. Neuroprotective Effect of the LRRK2 Kinase Inhibitor PF-06447475 in Human Nerve-Like Differentiated Cells Exposed to Oxidative Stress Stimuli: Implications for Parkinson's Disease. Neurochem Res. 2016 Oct;41(10):2675-2692. [3]. Daher JP, et al. Leucine-rich Repeat Kinase 2 (LRRK2) Pharmacological Inhibition Abates α-Synuclein Gene-induced Neurodegeneration. J Biol Chem. 2015 Aug 7;290(32):19433-44.

Discovery and preclinical profiling of 3-[4-(morpholin-4-yl)-7H-pyrrolo[2,3-d]pyrimidin-5-yl]benzonitrile (PF-06447475), a highly potent, selective, brain penetrant, and in vivo active LRRK2 kinase inhibitor.[Pubmed:25353650]

J Med Chem. 2015 Jan 8;58(1):419-32.

Leucine rich repeat kinase 2 (LRRK2) has been genetically linked to Parkinson's disease (PD) by genome-wide association studies (GWAS). The most common LRRK2 mutation, G2019S, which is relatively rare in the total population, gives rise to increased kinase activity. As such, LRRK2 kinase inhibitors are potentially useful in the treatment of PD. We herein disclose the discovery and optimization of a novel series of potent LRRK2 inhibitors, focusing on improving kinome selectivity using a surrogate crystallography approach. This resulted in the identification of 14 (PF-06447475), a highly potent, brain penetrant and selective LRRK2 inhibitor which has been further profiled in in vivo safety and pharmacodynamic studies.

Neuroprotective Effect of the LRRK2 Kinase Inhibitor PF-06447475 in Human Nerve-Like Differentiated Cells Exposed to Oxidative Stress Stimuli: Implications for Parkinson's Disease.[Pubmed:27394417]

Neurochem Res. 2016 Oct;41(10):2675-2692.

Leucine-rich repeat kinase 2 (LRRK2) has been implicated in oxidative stress (OS) and neurodegeneration in Parkinson's disease (PD). However, the pathophysiological mechanism of the LRRK2 kinase in neurons under stress stimuli is not yet understood. We demonstrate that rotenone (ROT), a mitochondria complex I inhibitor frequently used to generate in vitro and in vivo experimental models of PD, induces LRRK2 phosphorylation at serine 935 p-(S935) concomitant with cell death in nerve-like differentiated cells (NLCs). Indeed, ROT (50 microM) at 6 h exposure significantly increased reactive oxygen species (ROS) (~100 %), p-(S935)-LRRK2 kinase [~2 f(old)-(i)ncrease] level, induced nuclei condensation/fragmentation (16 %), increased the expression of NF-kappaB (5.6 f-i), p53 (5.3 f-i), c-Jun (5.4 f-i) transcription factors, activated caspase-3 (8.0 f-i) and AIF (6.8 f-i) proteins; but significantly decreased mitochondrial membrane potential (Psim, ~21 %), indicative of apoptosis -a type of regulated cell death process- compared to untreated cells. Strikingly, the LRRK2 kinase inhibitor PF-06447475 (PF-475, 1 microM) protects NLCs against ROT induced noxious effect. The inhibitor not only blocked the p-(S935)-LRRK2 kinase phosphorylation but also completely abolished ROS, and significantly reversed all ROT-induced apoptosis signaling and OS associated markers to comparable control values. We conclude that wild-type LRRK2 may act as a pro-apoptotic factor under OS stimuli. Our findings suggest an association between OS and LRRK2 phosphorylation in the NLCs death process, as PD model. Therefore, the pharmacological inhibition of LRRK2 might help to understand the OS-mediated kinase activation in PD neurodegenerative disorder.

Leucine-rich Repeat Kinase 2 (LRRK2) Pharmacological Inhibition Abates alpha-Synuclein Gene-induced Neurodegeneration.[Pubmed:26078453]

J Biol Chem. 2015 Aug 7;290(32):19433-44.

Therapeutic approaches to slow or block the progression of Parkinson disease (PD) do not exist. Genetic and biochemical studies implicate alpha-synuclein and leucine-rich repeat kinase 2 (LRRK2) in late-onset PD. LRRK2 kinase activity has been linked to neurodegenerative pathways. However, the therapeutic potential of LRRK2 kinase inhibitors is not clear because significant toxicities have been associated with one class of LRRK2 kinase inhibitors. Furthermore, LRRK2 kinase inhibitors have not been tested previously for efficacy in models of alpha-synuclein-induced neurodegeneration. To better understand the therapeutic potential of LRRK2 kinase inhibition in PD, we evaluated the tolerability and efficacy of a LRRK2 kinase inhibitor, PF-06447475, in preventing alpha-synuclein-induced neurodegeneration in rats. Both wild-type rats as well as transgenic G2019S-LRRK2 rats were injected intracranially with adeno-associated viral vectors expressing human alpha-synuclein in the substantia nigra. Rats were treated with PF-06447475 or a control compound for 4 weeks post-viral transduction. We found that rats expressing G2019S-LRRK2 have exacerbated dopaminergic neurodegeneration and inflammation in response to the overexpression of alpha-synuclein. Both neurodegeneration and neuroinflammation associated with G2019S-LRRK2 expression were mitigated by LRRK2 kinase inhibition. Furthermore, PF-06447475 provided neuroprotection in wild-type rats. We could not detect adverse pathological indications in the lung, kidney, or liver of rats treated with PF-06447475. These results demonstrate that pharmacological inhibition of LRRK2 is well tolerated for a 4-week period of time in rats and can counteract dopaminergic neurodegeneration caused by acute alpha-synuclein overexpression.