S63845

S63845 is a potent and selective myeloid cell leukemia 1 (MCL1) inhibitor with a K_d of 0.19 nM for human MCL1^[1]. IC50 & Target:Kd: 0.19 nM (MCL1)^[1] In Vitro: The pro-survival protein myeloid cell leukemia 1 (MCL1) is over expressed in many cancers. S63845 is a small molecule that specifically binds with high affinity to the BH3-binding groove of MCL1. S63845 potently kills MCL1-dependent cancer cells, including multiple myeloma, leukaemia and lymphoma cells, by activating the BAX/BAK-dependent mitochondrial apoptotic pathway. The activity of S63845 is next evaluated in a panel of eight AML cell lines: all lines are sensitive to S63845 (IC₅₀=4-233 nM)^[1]. In Vivo: S63845 shows potent anti-tumour activity with an acceptable safety margin as a single agent in several cancers. Intravenously injected (i.v.) S63845 exerts dose-dependent anti-tumour activity in human multiple myeloma (H929 and AMO1) xenografts in immunocompromised mice, with maximal tumour growth inhibition of 114% in the AMO1 model and 103% in the H929 model. At 25 mg/kg, S63845 induces complete regression in 7 out of 8 of the mice at 100 days after treatment in the AMO1 model^[1].