Allan Wu

AZD1208, a potent and selective pan-Pim kinase inhibitor, demonstrates efficacy in preclinical models of acute myeloid leukemia

Upregulation of Pim kinases is observed in several types of leukemias and lymphomas. Pim-1, -2, and -3 promote cell proliferation and survival downstream of cytokine and growth factor signaling pathways. AZD1208 is a potent, highly selective, and orally available Pim kinase inhibitor that effectively inhibits all three isoforms at <5 nM or <150 nM in enzyme and cell assays, respectively. AZD1208 inhibited the growth of 5 of 14 acute myeloid leukemia (AML) cell lines tested, and sensitivity correlates with Pim-1 expression and STAT5 activation. AZD1208 causes cell cycle arrest and apoptosis in MOLM-16 cells, accompanied by a dose-dependent reduction in phosphorylation of Bcl-2 antagonist of cell death, 4EBP1, p70S6K, and S6, as well as increases in cleaved caspase 3 and p27. Inhibition of p4EBP1 and p-p70S6K and suppression of translation are the most representative effects of Pim inhibition in sensitive AML cell lines. AZD1208 inhibits the growth of MOLM-16 and KG-1a xenograft tumors in vivo with a clear pharmacodynamic-pharmacokinetic relationship. AZD1208 also potently inhibits colony growth and Pim signaling substrates in primary AML cells from bone marrow that are Flt3 wild-type or Flt3 internal tandem duplication mutant. These results underscore the therapeutic potential of Pim kinase inhibition for the treatment of AML.

Discovery of novel benzylidene-1,3-thiazolidine-2,4-diones as potent and selective inhibitors of the PIM-1, PIM-2, and PIM-3 protein kinases.

Novel substituted benzylidene-1,3-thiazolidine-2,4-diones (TZDs) have been identified as potent and highly selective inhibitors of the PIM kinases. The synthesis and SAR of these compounds are described, along with X-ray crystallographic, anti-proliferative, and selectivity data.

Discovery and Optimization of a Novel Series of Potent Mutant B-Raf V600E Selective Kinase Inhibitors.

B-Raf represents an attractive target for anticancer therapy and the development of small molecule B-Raf inhibitors has delivered new therapies for metastatic melanoma patients. We have discovered a novel class of small molecules that inhibit mutant B-Raf(V600E) kinase activity both in vitro and in vivo. Investigations into the structure-activity relationships of the series are presented along with efforts to improve upon the cellular potency, solubility, and pharmacokinetic profile. Compounds selectively inhibited B-Raf(V600E) in vitro and showed preferential antiproliferative activity in mutant B-Raf(V600E) cell lines and exhibited selectivity in a kinase panel against other kinases. Examples from this series inhibit growth of a B-Raf(V600E) A375 xenograft in vivo at a well-tolerated dose. In addition, aminoquinazolines described herein were shown to display pERK elevation in nonmutant B-Raf cell lines in vitro.

Potent and Selective Inhibitors of CK2 Kinase Identified through Structure-Guided Hybridization

In this paper we describe a series of 3-cyano-5-aryl-7-aminopyrazolo[1,5-a]pyrimidine hits identified by kinase-focused subset screening as starting points for the structure-based design of conformationally constrained 6-acetamido-indole inhibitors of CK2. The synthesis, SAR, and effects of this novel series on Akt signaling and cell proliferation in vitro are described.

Identification of amidoheteroaryls as potent inhibitors of mutant (V600E) B-Raf kinase with in vivo activity.

A series of amidoheteroaryl compounds were designed and synthesized as inhibitors of B-Raf kinase. Several compounds from the series show excellent potency in biochemical, phenotypic and mode of action cellular assays. Potent examples from the series have also demonstrated good plasma exposure following an oral dose in rodents and activity against the Ras-Raf pathway in tumor bearing mice.

Identification of azabenzimidazoles as potent JAK1 selective inhibitors.

We have identified a class of azabenzimidazoles as potent and selective JAK1 inhibitors. Investigations into the SAR are presented along with the structural features required to achieve selectivity for JAK1 versus other JAK family members. An example from the series demonstrated highly selective inhibition of JAK1 versus JAK2 and JAK3, along with inhibition of pSTAT3 in vivo, enabling it to serve as a JAK1 selective tool compound to further probe the biology of JAK1 selective inhibitors.

Abstract 2796: Efficacy and biomarker modulation by AZD1208, a novel, potent and selective pan-Pim kinase inhibitor, in models of acute myeloid leukemia

The Pim serine/threonine kinase family is composed of three highly homologous members; Pim-1, Pim-2 and Pim-3, identified by the ability of the prototype member Pim-1 to drive lymphomagenesis in mice. Upregulation of Pim-1 and Pim-2 is observed in leukemias and lymphomas, including AML, NHL and CLL, highlighting the potential of these kinases as therapeutic targets in these indications. Overexpression of Pim-1 or Pim-3 has also been observed in prostate, pancreatic, gastric, bladder and hepatocellular cancers. Pim kinases are downstream effectors of many cytokine and growth factor signaling pathways and are direct transcriptional targets of STAT transcription factors activated by these pathways. Pims can phosphorylate multiple substrates to mediate cell proliferation and survival. Here we describe the activity of AZD1208, an orally available, potent and highly selective Pim inhibitor that effectively inhibits all three isoforms. AZD1208 inhibits the growth of several AML cell lines and sensitivity correlates with the level of Pim-1 expression, STAT5 activation and presence of protein tyrosine kinase mutation. AZD1208 causes cell cycle arrest and apoptosis in MOLM-16 cells in culture. This is accompanied by a dose-dependent reduction in phosphorylation of BAD, 4EBP1 and p70S6K. AZD1208 suppresses the growth of MOLM-16 and KG-1a xenograft tumors in vivo in a dose proportional manner. In addition, AZD1208 leads to potent inhibition of colony growth of primary AML cells from bone marrow aspirates and downregulates phosphorylation of Pim targets. These results underscore the therapeutic potential of Pim kinase inhibition by AZD1208 for the treatment of AML. They also further support investigation of this inhibitor in other hematological and solid tumor malignancies where PIM signaling may play a role in tumorigenesis and survival. 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 2796. doi:1538-7445.AM2012-2796

Structure-Based Design of Selective Noncovalent CDK12 Inhibitors

Cyclin‐dependent kinase (CDK) 12 knockdown via siRNA decreases the transcription of DNA‐damage‐response genes and sensitizes BRCA wild‐type cells to poly(ADP‐ribose) polymerase (PARP) inhibition. To recapitulate this effect with a small molecule, we sought a potent, selective CDK12 inhibitor. Crystal structures and modeling informed hybridization between dinaciclib and SR‐3029, resulting in lead compound 5 [(S)‐2‐(1‐(6‐(((6,7‐difluoro‐1H‐benzo[d]imidazol‐2‐yl)methyl)amino)‐9‐ethyl‐9H‐purin‐2‐yl)piperidin‐2‐yl)ethan‐1‐ol]. Further structure‐guided optimization delivered a series of selective CDK12 inhibitors, including compound 7 [(S)‐2‐(1‐(6‐(((6,7‐difluoro‐1H‐benzo[d]imidazol‐2‐yl)methyl)amino)‐9‐isopropyl‐9H‐purin‐2‐yl)piperidin‐2‐yl)ethan‐1‐ol]. Profiling of this compound across CDK9, 7, 2, and 1 at high ATP concentration, single‐point kinase panel screening against 352 targets at 0.1 μm, and proteomics via kinase affinity matrix technology demonstrated the selectivity. This series of compounds inhibits phosphorylation of Ser2 on the C‐terminal repeat domain of RNA polymerase II, consistent with CDK12 inhibition. These selective compounds were also acutely toxic to OV90 as well as THP1 cells.

Abstract 919: AZD3463, a novel ALK/IGF1R inhibitor, overcomes multiple mechanisms of acquired resistance to crizotinib.

Genomic rearrangement of Anaplastic Lymphoma Kinase (ALK) has been observed in several tumor types including 60-80% anaplastic large cell lymphoma (ALCL) and 3-6% of non small cell lung cancer (NSCLC). Although the ALK inhibitor crizotinib has clinical efficacy in selected ALK positive NSCLC patients, the majority of patients who show initial responses eventually relapse. Various mechanisms leading to resistance have been proposed and include ALK amplification and resistance mutations, as well as alternative pathway drivers including EGFR, cKIT and, more recently, IGF1R. We have discovered a novel and potent inhibitor of ALK, AZD3463 with a Ki value of 0.75nM which also inhibits additional receptor tyrosine kinases including insulin growth factor receptor (IGF1R) with equivalent potency. AZD3463 inhibits ALK in cells as demonstrated by its ability to decrease ALK autophosphorylation in tumor cell lines containing ALK fusions including DEL (ALCL NPM-ALK), H3122 (NSCLC EML4-ALK) and H2228 (NSCLC EML4-ALK). Inhibition of ALK is associated with perturbations in downstream signaling including ERK, AKT and STAT3 pathways leading to preferential inhibition of proliferation in the ALK fusion containing cell lines in vitro. AZD3463 also demonstrates the ability to dose dependently inhibit pALK in xenograft tumors in vivo resulting in stasis (H3122) or regression (DEL, H2228). AZD3463 retains good activity against a number of clinically relevant crizotinib resistant mutations including the gatekeeper mutant L1196M where equivalent potency to wild type ALK is observed in vitro and in vivo in EML4-ALK containing BAF3 cell lines. To further assess the potential ability of AZD3463 to overcome additional resistance mechanisms, antiproliferative activity was assessed in multiple crizotinib resistant cell lines independently derived in vitro from H3122 cells as well as a patient derived crizotinib relapsed model. These resistant cell lines contain multiple resistance mechanisms including the L1196M gatekeeper and T115Ins mutations, ALK amplification and/or secondary drivers including EGFR and IGF1R. AZD3463 retains antiproliferative potency within 4 fold of parental H3122 cells for 10 out of 12 of these acquired resistance models in vitro. In summary, AZD3463 is a potent ALK inhibitor which inhibits additional kinases including IGF1R and has activity in a number of crizotinib resistant models driven by multiple resistance mechanisms. Citation Format: Lisa Drew, Jane Cheng, Jeffrey Engelman, Douglas Ferguson, Ryohei Katayama, Brenda McDermott, Jamal Saeh, Alice Shaw, Minhui Shen, Dan Widzowski, Allan Wu, Graeme Smith. AZD3463, a novel ALK/IGF1R inhibitor, overcomes multiple mechanisms of acquired resistance to crizotinib. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 919. doi:10.1158/1538-7445.AM2013-919

Discovery and Optimization of a Novel Series of Highly Selective JAK1 Kinase Inhibitors

Janus kinases (JAKs) have been demonstrated to be critical in cytokine signaling and have thus been implicated in both cancer and inflammatory diseases. The JAK family consists of four highly homologous members: JAK1-3 and TYK2. The development of small-molecule inhibitors that are selective for a specific family member would represent highly desirable tools for deconvoluting the intricacies of JAK family biology. Herein, we report the discovery of a potent JAK1 inhibitor, 24, which displays ∼1000-fold selectivity over the other highly homologous JAK family members (determined by biochemical assays), while also possessing good selectivity over other kinases (determined by panel screening). Moreover, this compound was demonstrated to be orally bioavailable and possesses acceptable pharmacokinetic parameters. In an in vivo study, the compound was observed to dose dependently modulate the phosphorylation of STAT3 (a downstream marker of JAK1 inhibition).