Abstract 1795: Characterization of a novel series of potent, selective inhibitors of wild type and mutant/fusion anaplastic lymphoma kinase
Authors: Wilcoxen Keith M. , Brake Rachael L. , Saffran Doug , Teffera Yohannes , Choquette Deborah , Whittington Doug , Yu Violeta , Romero Karina , Bode Christiane , Stellwagen John , Potashman Michelle , Emkey Renee , Andrews Paul , Drew Allison E. , Xu Man , Szilvassy Stephen , Al-Assad Samer , Lewis Richard T. 
Published: August 2012

Abstract
Anaplastic lymphoma kinase (ALK) is a tyrosine kinase that has been implicated as a driving oncogene in a number of cancers, including non-small cell lung cancer (NSCLC), anaplastic large cell lymphoma (ALCL), neuroblastoma and inflammatory myofibroblastic tumors (IMT). Numerous genetic aberrations at the ALK locus are observed in cancer including point mutations, amplifications, translocations and inversions. Inversions are exemplified by inv(2)(p21;p23), which leads to the constitutively active oncogenic fusion protein EML4-ALK present in ∼5% of NSCLC. Crizotinib, a dual cMet/ALK kinase inhibitor, was recently approved by the FDA for locally advanced or metastatic NSCLC that is ALK-positive, thereby validating ALK as therapeutic target. Here we describe the pharmacological characterization of a novel series of potent, selective and orally bioavailable ALK kinase inhibitors. Members of this series inhibit wild type ALK, NPM-ALK fusion and crizotinib resistant ALK[L1196M] kinase activity at sub-nanomolar concentrations, displaying up to ∼200 fold increased inhibitory activity over crizotinib. Kinase profiling indicate that members of this series display increased selectivity scores relative crizotinib. In Karpas-299 cells, selected compounds inhibited both pY1604 ALK activation (IC50 = 2 nM) and cell proliferation (IC50 = 1 nM). Members of this series were also evaluated in the EML4-ALK expressing NSCLC cell line H3122, and displayed equipotent inhibition of pY1604 ALK activation and inhibition of cell proliferation (both IC50 = 1 nM). Members of this class did not inhibit growth of an ALK negative lymphoma cell line (HT). The in vivo activity of this series was examined in the Karpas-299 ALCL xenograft model. Compound was dosed daily (PO) at 10, 30 and 60 mg/kg. Tumor growth inhibition was observed at all dose levels, and the highest dose level resulted in significant tumor regression (96%, p&lt;0.0001) without weight loss. The inhibition of pY1604 ALK was evaluated in these tumors (8 hrs post dose); &gt;80% pALK inhibition was observed at the lowest doses tested, and complete inhibition was seen at doses of 30 mg/kg and above. In a direct comparison, members of this series achieved ALK inhibition in these tumors at a ∼15 fold lower plasma concentration than crizotinib. A PK/PD time course study was performed in the Karpas-299 model. A single 60 mg/kg dose of an inhibitor was able to maintain &gt;90% ALK inhibition in tumors up to 24 hours post-dose, indicating significant tumor penetration and sustained ALK kinase inhibition. In conclusion, the described compounds are potent and selective inhibitors of ALK kinase, possess an impressive efficacy profile and drug-like pharmacokinetic properties. These features together indicate the potential for significant advantages over crizotinib. There is a compelling case for their clinical evaluation in patients with ALK-driven cancers.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1795. doi:1538-7445.AM2012-1795