Abstract C200: Second-generation PIM inhibitors exhibit improved activity in solid tumor models in vitro.

The proto-oncogene PIM kinase family (PIM-1, -2 and -3) comprises constitutively active serine/threonine kinases upregulated in multiple cancer indications, including lymphoma, leukemia, multiple myeloma, prostate, bladder, gastric and head & neck cancers. Overexpression of one or more PIM family members in patient tumors frequently correlates with poor prognosis. The PIM kinases function by inhibiting apoptosis in MYC-driven tumors, promoting tumor cell survival and proliferation. PIM-1 and PIM-2 overexpression models were obtained in the human prostate cancer cell lines PC-3M and 22RV-1 and the non-tumorigenic mouse NIH-3T3 background. Overexpression of PIM kinases led to enhanced cell growth and tumorigenicity in both NIH-3T3 and 22RV-1 cell lines. In the PC-3M cell line, enhanced phosphorylation of the PIM kinase substrate BAD (pBAD) was observed following PIM overexpression. Enhancement of pBAD was inhibited by SGI-1776, a well-described PIM inhibitor, as well as next generation PIM inhibitors exhibiting 4–10 fold improved potency against the PIM kinase family. The current PIM inhibitors display sub-μM activity in pharmacodynamic marker, proliferation and 2D colony formation assays using the PC-3M prostate cancer cell line, the UM-UC-3 bladder cancer cell line, and the HSC3 head & neck cancer cell line. The second generation PIM inhibitors possess favorable hERG and CYP inhibition profiles compared with SGI-1776, and demonstrate excellent oral bioavailability. In vivo xenograft studies using both PIM overexpression models and clinically relevant solid tumor models will facilitate identification of a clinical candidate. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C200.