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SGI-1776 is a novel ATP competitive inhibitor of Pim1 with IC50 of 7 nM, 50- and 10-fold selective versus Pim2 and Pim3, also potent to Flt3 and haspin. IC50 value: 7 nM [1] Target: Pim1 in vitro: In addition to Pim, SGI-1776 also potently targets FLT3 (IC50 = 44nM). Treatment of AML cells with SGI-1776 results in a concentration-dependent induction of apoptosis. Importantly, SGI-1776 is also cytotoxic in AML primary cells, irrespective of FLT3 mutation status and results in Mcl-1 protein decline [1]. Treatment of CLL cells with SGI-1776 results in a concentration-dependent induction of apoptosis. SGI-1776 induces apoptosis in CLL and that the mechanism involves Mcl-1 reduction. Apoptosis induction coupled with the inhibition of RNA synthesis is observed in CLL cells treated with SGI-1776 [2]. SGI-1776 exhibites cytotoxic activity in vitro with a median relative IC50 of 3.1 mM. SGI-1776 induces tumor growth inhibition meeting criteria for intermediate EFS T/C activity in 1 of 39 evaluable models. In contrast, SGI-1776 induces complete responses of subcutaneous MV4,11 [3]. in vivo: Consistent with cell line data, xenograft model studies with mice bearing MV-4-11 tumors shows efficacy with SGI-1776. [1] SGI-1776 has shown preclinical activity against leukemia and solid tumor cell line models with IC50 values of 0.005-11.68 mM. SGI-1776 induces significant differences in EFS distribution in vivo in 9 of 31 solid tumor xenografts and in 1 of 8 of the evaluable ALL xenografts [3].
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