The Pan-PIM Kinase Inhibitor LGH447 Shows Activity In PIM2-Dependent Multiple Myeloma and In AML Models

Background PIM1, PIM2, and PIM3 are a closely related family of constitutively active serine/threonine kinases. PIM kinases were first identified as common integration sites in MMLV-induced murine T-cell lymphomas, with these viral insertions resulting in transcriptional activation and expression of the kinase. Similar unbiased insertional mutagenesis screens were used to demonstrate that the three kinases could substitute for each other in this oncogenic process, indicating that inhibition of all three PIM kinases may be necessary to achieve a therapeutic benefit. In human cancers, increased expression and activity of PIM kinases has been detected in many hematopoietic malignancies and solid tumors (prostate, lung, liver) and it is thought that this contributes to cancer cell survival and proliferation in these malignancies. Methods & Results We have developed a potent and specific pan-PIM inhibitor, LGH447, and shown that it is active in PIM2-dependent Multiple Myeloma (MM) cell lines by inhibiting proliferation, mTOR-C1 signaling and phosphorylation of BAD. In addition, LGH447 inhibited proliferation of several AML cell lines. Furthermore, we demonstrated that LGH447 inhibits tumor growth in several mouse subcutaneous xenograft models of MM and AML, where modulation of the pharmacodynamic marker phospho-S6 Ribosomal Protein was used to predict efficacy. We have also determined that LGH447 significantly reduced the bone tumor burden in a disseminated orthotopic human xenograft model of MM. Finally, we have demonstrated increased activity of LGH447 in combination with the PI3K inhibitor BYL719 in a MM model and with Cytarabine in an AML model. Summary Our Results have supported the clinical development of LGH447, a Pan-PIM inhibitor, in relapsed, refractory MM, and further suggest that it may be effective in the treatment of AML and other hematological malignancies, either as a single agent or in combination with other select therapeutic agents. Disclosures: Garcia: Novartis Institutes for Biomedical Research: Employment, Equity Ownership. Langowski: Novartis Institutes for Biomedical Research: Employment. Holash: Novartis Institutes for Biomedical Research: Employment, Equity Ownership. Burger: Novartis Institutes for Biomedical Research: Employment, Equity Ownership. Zang: Novartis Institutes for Biomedical Research: Employment, Equity Ownership. Zavorotinskaya: Novartis Institutes for Biomedical Research: Employment, Equity Ownership. Fanton: Novartis Institutes for Biomedical Research: Employment, Equity Ownership. Saci: Novartis Institutes for Biomedical Research: Employment, Equity Ownership. Growney: Novartis Institutes for Biomedical Research: Employment, Equity Ownership. Vanasse: Novartis Pharmaceuticals Corporation: Employment.