MRK003 is a γ-secretase inhibitor exhibits promising in vitro pre-clinical activity in multiple myeloma and non-Hodgkin's lymphoma. MRK003 treatment induced caspase-dependent apoptosis and inhibited proliferation of MM and NHL cell lines and patient cells. Examination of signaling events after treatment showed time-dependent decrease in levels of the notch intracellular domain, Hes1 and c-Myc. MRK003 downregulated cyclin D1, Bcl-Xl and Xiap levels in NHL cells and p21, Bcl-2 and Bcl-Xl in MM cells. In addition, MRK003 caused an upregulation of pAkt, indicating crosstalk with the PI3K Akt pathway.
LGB-321 is a potent and selective ATP-competitive small molecule inhibitor of PIM kinases (Pan-PIM kinase inhibitor). LGB321 is unique relative to previously described PIM inhibitors, in that it is active in PIM2 dependent cell lines. , a kinase that has proven difficult to inhibit in the cellular context. Consistent with its activity on all three PIM kinases, LGB321 inhibits proliferation of a number of cell lines derived from diverse hematological malignancies, including MM, AML, CML and B-Cell NHL. In vivo, LGB-321 is orally available, demonstrates efficacy in tumor xenografts and is well-tolerated within the therapeutic exposure range in mice. (source: Clin Cancer Res. 2014 Apr 1;20(7):1834-45 )