| Bioactivity | PLX5622 is a highly selective brain penetrant and orally active CSF1R inhibitor (IC50=0.016 µM; Ki=5.9 nM). PLX5622 allows for extended and specific microglial cells elimination, preceding and during pathology development. PLX5622 demonstrates desirable PK properties in varies animals[1][2]. | ||||||||||||
| Target | IC50: 0.016 µM (CSF1R); Ki: 5.9 nM (CSF1R) | ||||||||||||
| Invitro | PLX5622 (1-20 μM; 3 days) effectively depletes microglia without affecting oligodendrocytes or astrocytes in cerebellar slices. PLX5622 (4 μM; 3 days) causes a 30-40% reduction in NG2+ or PDGFRα+ cells, and this increased to 90-95% at 20 μM. No reduction of NG2+ or PDGFRα+ OPCs is observed in slices exposed to 1 μM or 2 μM PLX5622 despite robust (~95%) depletion of the microglial cells[3]. | ||||||||||||
| In Vivo | Pharmacodynamics of PLX5622 in preclinical studiesPLX5622 (1200 ppm; chow; for 3 weeks or 3 days; adult C57/Bl6 wild type mice) leads to around 80% of microglia lost after 3 days of treatment and a 99% microglia loss after 3 weeks of treatment. PLX5622 (adult C57/Bl6 wild type mice aged 3 months; diet for 3 weeks) decreases microglia in cortex, striatum, cerebellum and hippocampus[4].PLX5622 (50 mg/kg; intraperitoneal injection; once (neonatal rat) or twice (adult rat) a day; for a total of 14 days) depletes microglia by 80-90% within 3 days of treatment, which increases to > 90% by 7 days. After 14 days of PLX5622 treatment, microglia is depleted by > 96% in both neonates and adults while preserving baseline astrocyte quantity. (A single daily injection of 0.65% PLX5622 suspended in 5% dimethyl sulfoxide and 20% Kolliphor RH40 in 0.01 M PBS is sufficient for neonatal microglia depletion, adult depletion requires injections twice daily)[5].PLX5622 (formulated in AIN-76A standard chow at 1200 mg/kg; for 28 days) leads to reduction in microglia throughout the CNS in 14-month-old 5xfAD mice[6].Pharmacokinetics of PLX5622 in preclinical species[1]Species | ||||||||||||
| Name | PLX5622 | ||||||||||||
| CAS | 1303420-67-8 | ||||||||||||
| Formula | C21H19F2N5O | ||||||||||||
| Molar Mass | 395.41 | ||||||||||||
| Appearance | Solid | ||||||||||||
| Transport | Room temperature in continental US; may vary elsewhere. | ||||||||||||
| Storage |
|
||||||||||||
| Reference | [1]. Spangenberg E, et al. Sustained microglial depletion with CSF1R inhibitor impairs parenchymal plaque development in an Alzheimer's disease model. Nat Commun. 2019 Aug 21;10(1):3758. [2]. Lee S, et al. Targeting macrophage and microglia activation with colony stimulating factor 1 receptor inhibitor is an effective strategy to treat injury-triggered neuropathic pain. Mol Pain. 2018 Jan-Dec;14:1744806918764979. [3]. Liu Y, et al. Concentration-dependent effects of CSF1R inhibitors on oligodendrocyte progenitor cells ex vivo and in vivo. Exp Neurol. 2019;318:32-41. [4]. Badimon A, et al. Negative feedback control of neuronal activity by microglia. Nature. 2020;586(7829):417-423. [5]. Andrew J. Riquier, et al. Astrocytic response to neural injury is larger during development than in adulthood and is not predicated upon the presence of microglia, Brain, Behavior, & Immunity-Health, Volume 1, 2020, 100010, ISSN 2666-3546. [6]. Spangenberg EE, et al. Eliminating microglia in Alzheimer's mice prevents neuronal loss without modulating amyloid-β pathology. Brain. 2016;139(Pt 4):1265-1281. |