RK-24466 (KIN 001-51) (Synonyms: Lymphocyte-specific Protein Tyrosine Kinase, RK-24466)

RK-24466 (KIN 001-51) is a potent and selective Lck inhibitor; inhibits Lck (64-509) and LckCD isoforms with IC50s of less than 1 and 2 nM, respectively.

RK-24466 is selective for Lck over a range of receptor, non-receptor tyrosine kinases and seronine/threonine kinases. RK-24466 are potent inhibitors of IL2 production in Jurkat cells stimulated with anti-CD3 antibody, being at least 100-fold more potent than PP1. RK-24466 displays remarkable cellular selectivity[1]. RK-24466 significantly inhibits both VSMC proliferation and migration. RK-24466 suppresses VSMC proliferation and migration via down-regulating the protein kinase B (Akt) and extracellular signal regulated kinase (ERK) pathways, and it significantly decreases the expression of proliferating cell nuclear antigen (PCNA) and cyclin D1 and, the phosphorylation of retinoblastoma protein (pRb)[2].

RK-24466 inhibits T-cell receptor stimulated (a-CD3 mAb) IL-2 production in mice at low doses (ED50=4 mg/kg) after ip administration. However, efficacy is greatly reduced after oral administration (ED50=25 mg/kg) which is presumed to reflect poor intestinal absorption in the latter regimen. Inhibition of antigen specific T-cell immune responses is also seen for RK-24466. After administration of RK-24466 twice daily (100 mg/kg po) for 3 days during the in vivo priming phase, a 70% inhibition of IFNγ production is seen upon subsequent antigen-specific (KLH) challenge of lymphocytes from the draining lymph nodes in vitro[3]. RK-24466 suppresses the migration of VSMCs from endothelium-removed aortic rings, as well as neointima formation following rat carotid balloon injury[2].

[1]. Arnold LD, et al. Pyrrolo[2,3-d]pyrimidines containing an extended 5-substituent as potent and selective inhibitors of lck I. Bioorg Med Chem Lett. 2000 Oct 2;10(19):2167-70. [2]. Seo HH, et al. 7-cyclopentyl-5-(4-phenoxyphenyl)-7H-pyrrolo[2,3-d] pyrimidin-4-ylamine inhibits the proliferation and migration of vascular smooth muscle cells by suppressing ERK and Akt pathways. Eur J Pharmacol. 2017 Mar 5;798:35-42. [3]. Burchat AF, et al. Pyrrolo[2,3-d]pyrimidines containing an extended 5-substituent as potent and selective inhibitorsof lck II. Bioorg Med Chem Lett. 2000 Oct 2;10(19):2171-4.