Published: August 22, 2011 r2011 American Chemical Society 6328 dx.doi.org/10.1021/jm200758k | J. Med. Chem. 2011, 54, 6328–6341 ARTICLE pubs.acs.org/jmc 2,7-Disubstituted-pyrrolo[2,1-f][1,2,4]triazines: New Variant of an Old Template and Application to the Discovery of Anaplastic Lymphoma Kinase (ALK) Inhibitors with in Vivo Antitumor Activity Gregory R. Ott,* Gregory J. Wells, Tho V. Thieu, Matthew R. Quail, Joseph G. Lisko, Eugen F. Mesaros, Diane E. Gingrich, Arup K. Ghose, Weihua Wan, Lihui Lu, Mangeng Cheng, Mark S. Albom, Thelma S. Angeles, Zeqi Huang, Lisa D. Aimone, Mark A. Ator, Bruce A. Ruggeri, and Bruce D. Dorsey Worldwide Discovery Research, Cephalon, Inc., 145 Brandywine Parkway, West Chester, Pennsylvania 19380, United States b S Supporting Information ABSTRACT: A novel 2,7-disubstituted-pyrrolo[2,1-f][1,2,4]triazine scaffold has been designed as a new kinase inhibitor platform mimicking the bioactive conformation of the well-known diaminopyrimidine motif. The design, synthesis, and validation of this new pyrrolo[2,1- f][1,2,4]triazine scaffold will be described for inhibitors of anaplastic lymphoma kinase (ALK). Importantly, incorporation of appropriate potency and selectivity determinants has led to the discovery of several advanced leads that were orally efficacious in animal models of anaplastic large cell lymphoma (ALCL). A lead inhibitor (30) displaying superior efficacy was identified and in depth in vitro/in vivo characterization will be presented. ’ INTRODUCTION Chromosomal translocations occur frequently in a select group of human cancers, including most lymphomas, leukemia, and sarcomas. 1 Individual translocations have shown a high degree of specificity for particular cancer types, and the presence of a particular translocation often correlates well with clinical behavior and outcome for specific types of cancer. Consequently, therapies directed at targets created by tumor- specific genetic aberrations may be more effective and less toxic than conventional chemotherapy. This has been best illustrated by imatinib, a small-molecule inhibitor of the fusion protein kinase BCR-ABL, which has been successfully used in the treatment of chronic myeloid leukemia (CML) associated with BCR-ABL mutations. 2,3 Anaplastic large cell lymphoma (ALCL) is associated with a t(2;5) (p23;q35) chromosome translocation in about 60% of cases. 4,5 The t(2;5) translocation contains the N-terminal portion of the nucleophosmin (NPM) gene, fused to the catalytic domain of anaplastic lymphoma kinase (ALK) gene. The NPM-ALK fusion gene encodes for an 80 kDa NPM-ALK chimeric oncoprotein with constitutively active ALK tyrosine kinase activity, which plays a key role in lymphomagenesis by aberrant phosphorylation of intracellular substrates. 5,6 The constitutively active ALK fusion protein is directly implicated in the pathogenesis of ALCL, and inhibition of ALK could markedly impair the growth of ALK-positive lymphoma cells. 612 The proclivity of ALK to form gene fusions is evident from the findings in non-small-cell lung cancer (NSCLC) cells, where a fused protein comprised of portions of the echinoderm micro- tubule-associated protein-like 4 (EML4) gene and the ALK gene was identified. 1315 The EML4-ALK fusion transcript was detected in approximately 37% of NSCLC patients examined, and these types of cancers were characterized with onset at a younger age and no or rare mutations in EGFR, KRAS, and TP53, all in agreement with the prevalence in non- or light smokers. 1618 The EML4-ALK fusion protein demonstrated oncogenic transforming activity when overexpressed in mouse fibroblasts and when tumor cells expressing EML4-ALK were inoculated in nude mice. Transgenic mice expressing EML4- ALK, specifically in lung alveolar epithelial cells, developed hundreds of adenocarcinoma nodules in both lungs within a few weeks of birth with the tumors undergoing progressive enlargement. 19 These data together reinforce the pivotal role of EML4-ALK in the pathogenesis of NSCLC. Recently, various mutations of the ALK gene have been implicated in both familial and sporadic cases of neuroblastoma. 2023 ALK muta- tions in neuroblastoma cells resulted in constitutive ALK phosphorylation and attenuation or inhibition of ALK by siRNA and small-molecule ALK inhibitors resulted in profound growth inhibition in those cell lines. Altogether, these data identify ALK as a critical player in neuroblastoma development Received: June 13, 2011