Abstract Osimertinib is a third-generation, irreversible, oral EGFR tyrosine kinase inhibitor (TKI) recommended as first-line treatment for patients with locally advanced/metastatic EGFR mutation–positive (EGFRm) non–small cell lung cancer (NSCLC). However, MET amplification/overexpression is a common acquired osimertinib resistance mechanism. Savolitinib is an oral, potent, and highly selective MET-TKI; preliminary data suggest that combining osimertinib with savolitinib may overcome MET-driven resistance. A patient-derived xenograft (PDX) mouse model with EGFRm, MET-amplified NSCLC was tested with a fixed osimertinib dose [10 mg/kg for exposures equivalent to (≈)80 mg], combined with doses of savolitinib (0–15 mg/kg, ≈0–600 mg once daily), both with 1-aminobenzotriazole (to better match clinical half-life). After 20 days of oral dosing, samples were taken at various time points to follow the time course of drug exposure in addition to phosphorylated MET and EGFR (pMET and pEGFR) change. Population pharmacokinetics, savolitinib concentration versus percentage inhibition from baseline in pMET, and the relationship between pMET and tumor growth inhibition (TGI) were also modeled. As single agents, savolitinib (15 mg/kg) showed significant antitumor activity, reaching ∼84% TGI, and osimertinib (10 mg/kg) showed no significant antitumor activity (34% TGI, P > 0.05 vs. vehicle). Upon combination, at a fixed dose of osimertinib, significant savolitinib dose-related antitumor activity was shown, ranging from 81% TGI (0.3 mg/kg) to 84% tumor regression (15 mg/kg). Pharmacokinetic–pharmacodynamic modeling showed that the maximum inhibition of both pEGFR and pMET increased with increasing savolitinib doses. Savolitinib demonstrated exposure-related combination antitumor activity when combined with osimertinib in the EGFRm MET-amplified NSCLC PDX model.
Supplementary Figure 1. AZD5153 shows reduced BRD4 binding activity when BD2 function is abolished; Supplementary Figure 2. AZD5153 modulates MYC protein levels across hematologic cancer cell lines; Supplementary Figure 3. Gene Ontology (GO) analysis of the down-regulated transcripts by AZD5153 across all cell line types; Supplementary Figure 4. IC50 and percent maximal cell kill by AZD5153 and I-BET762 in five hematologic cell lines; Supplementary Figure 5. Tumor growth inhibition across six hematological xenograft Models
The design and synthesis of a novel series of 2,6-disubstituted pyrazine derivatives as CK2 kinase inhibitors is described. Structure-guided optimization of a 5-substituted-3-thiophene carboxylic acid screening hit (3a) led to the development of a lead compound (12b), which shows inhibition in both enzymatic and cellular assays. Subsequent design and hybridization efforts also led to the unexpected identification of analogs with potent PIM kinase activity (14f).
Abstract The bromodomain and extraterminal (BET) protein BRD4 regulates gene expression via recruitment of transcriptional regulatory complexes to acetylated chromatin. Pharmacological targeting of BRD4 bromodomains by small molecule inhibitors has proven to be an effective means to disrupt aberrant transcriptional programs critical for tumor growth and/or survival. Herein, we report AZD5153, a potent, selective, and orally available BET/BRD4 bromodomain inhibitor possessing a bivalent binding mode. Unlike previously described monovalent inhibitors, AZD5153 ligates two bromodomains in BRD4 simultaneously. The enhanced avidity afforded through bivalent binding translates into increased cellular and antitumor activity in preclinical hematologic tumor models. In vivo administration of AZD5153 led to tumor stasis or regression in multiple xenograft models of acute myeloid leukemia, multiple myeloma, and diffuse large B-cell lymphoma. The relationship between AZD5153 exposure and efficacy suggests that prolonged BRD4 target coverage is a primary efficacy driver. AZD5153 treatment markedly affects transcriptional programs of MYC, E2F, and mTOR. Of note, mTOR pathway modulation is associated with cell line sensitivity to AZD5153. Transcriptional modulation of MYC and HEXIM1 was confirmed in AZD5153-treated human whole blood, thus supporting their use as clinical pharmacodynamic biomarkers. This study establishes AZD5153 as a highly potent, orally available BET/BRD4 inhibitor and provides a rationale for clinical development in hematologic malignancies. Mol Cancer Ther; 15(11); 2563–74. ©2016 AACR.
The Wnt pathway is an evolutionarily conserved and tightly regulated signaling network with important roles in embryonic development and adult tissue regeneration. Impaired Wnt pathway regulation, arising from mutations in Wnt signaling components, such as Axin, APC, and β-catenin, results in uncontrolled cell growth and triggers oncogenesis. To explore the reported link between CK2 kinase activity and Wnt pathway signaling, we sought to identify a potent, selective inhibitor of CK2 suitable for proof of concept studies in vivo. Starting from a pyrazolo[1,5-a]pyrimidine lead (2), we identified compound 7h, a potent CK2 inhibitor with picomolar affinity that is highly selectivity against other kinase family enzymes and inhibits Wnt pathway signaling (IC50 = 50 nM) in DLD-1 cells. In addition, compound 7h has physicochemical properties that are suitable for formulation as an intravenous solution, has demonstrated good pharmacokinetics in preclinical species, and exhibits a high level of activity as a monotherapy in HCT-116 and SW-620 xenografts.
In this letter, we describe the design, synthesis, and structure-activity relationship of 5-anilinopyrazolo[1,5-a]pyrimidine inhibitors of CK2 kinase. Property-based optimization of early leads using the 7-oxetan-3-yl amino group led to a series of matched molecular pairs with lower lipophilicity, decreased affinity for human plasma proteins, and reduced binding to the hERG ion channel. Agents in this study were shown to modulate pAKT(S129), a direct substrate of CK2, in vitro and in vivo, and exhibited tumor growth inhibition when administered orally in a murine DLD-1 xenograft.
Abstract Rituximab alone or in combination with chemotherapeutics is the first-line therapy for diffuse large B cell lymphomas (DLBCL). Although the complete response rate is quite impressive, vast majority of patient presents recurrent disease. The association between CD20 expression and clinical outcome in patients strongly suggests that reduced CD20 expression leads to inferior response to RCHOP (rituximab, cyclophosphamide, vincristine, doxorubicin and prednisone). In order to understand how loss of CD20 leads to development of RCHOP resistance, we developed rituximab resistant DoHH2 model in vivo by chronic exposure to rituximab. Characterization of several resistant in vivo xenografts revealed one model that maintained resistance to an acute dose of rituximab and demonstrated loss of CD20. Further characterization of the model demonstrated a loss of CD20 is associated with over expression of BCL2 and BIM. In vivo efficacy studies showed resistant line is insensitive to acute dose of RCHOP and treatment with an inhibitor of BCL2 (ABT199) in combination with chemotherapy resulted in better efficacy than RCHOP alone. We have identified an in vivo model of DLBCL where loss of CD20 and over expression of anti-apoptotic protein BCL2 leads to RCHOP resistance. These data suggest the addition of BCL2 inhibitor to chemotherapy might be effective in treating CD20 negative lymphomas. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A12. Citation Format: Chaitali Dutta, Michele Mayo, Mike Collins, Christopher Brueckner, Deborah Lawson, Zhongwu Lai, Larry Bao, Corinne Reimer. Small molecule inhibitor of BCL2 in combination with RCHOP is effective in CD20 negative DLBCL. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A12.
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.
Abstract Casein Kinase 2 (CK2) is a highly conserved and ubiquitously expressed serine/threonine kinase that regulates several key oncogenic signaling pathways, including PI3K/AKT, and NFkB and Wnt, and whose targeted overexpression in transgenic animal models results in neoplastic growth. Herein we describe the identification of AZ285, a potent pyrazolo[1,5-a]pyrimidine-derived inhibitor of CK2 with a high degree of kinase selectivity. AZ285 depletes levels of the CK2 substrates pAKTS129 and PTENS370 and induces apoptosis in cells in a concentration-dependent manner. Optimization of early leads was aided in part by cell wash-out experiments and X-ray cocrystallography with huCK2a and resulted in an agent with physical properties and DMPK characteristics suitable for evaluation in disease model studies. 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 3907. doi:1538-7445.AM2012-3907
Abstract 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
Abstract Deregulated Wnt signaling has been implicated in a wide range of cancer types, both through truncating mutations in the tumor suppressor protein Adenomatous Polyposis Coli (APC), most prevalent in colorectal cancer, as well as overexpression of Wnt ligands and receptors. Canonical Wnt signaling involves the regulated degradation of the beta catenin protein. In the absence of Wnt signaling, cytosolic beta catenin levels are maintained at low levels, as a result of its phosphorylation-dependent ubiquitination and subsequent proteasomal degradation. This degradation is mediated by the ‘destruction complex’, whose constituents include Glycogen Synthase Kinase 3 (GSK3β), Casein Kinase 1 (CK1) and the scaffolding proteins Axin and APC. The efficient assembly of this complex depends upon the steady state levels of its components, such as Axin, which when overexpressed has been shown to decrease beta catenin levels and inhibit Wnt signaling. Recent reports suggest that the poly-ADP-ribosylating Tankyrase enzymes can bind to and regulate Axin levels, hence providing promising targets for treating Wnt-dependent tumors. We have identified potent, low nM small molecule inhibitors of the Wnt pathway, which inhibit Tankyrases 1 and 2, stabilize Axin, deplete beta catenin protein levels and modulate a set of Wnt-regulated genes in colorectal cell lines in a similar manner as seen when using siRNA to beta catenin. Furthermore, using siRNAs to Tankyrase 1 and 2 we have shown that co-depletion of both enzymes is required for Axin stabilization and Wnt pathway inhibition. We have also successfully demonstrated that our lead molecules cause prolonged Axin stabilization and Wnt pathway inhibition in vivo following oral BID dosing in colon xenografts carrying APC mutations. However, in contrast to previous reports, using molecular tools and our lead compounds (e.g. inducible Axin cell lines, compound rescue experiments using siRNAs to Axin 1/2), we have shown that Axin stabilization has no effect on the viability/proliferation of APC mutant colorectal cell lines, under conditions where siRNA to beta catenin was able to cause significant growth inhibition. Some potential mechanistic rationales for this lack of phenotypic effect will be presented. Understanding the consequences of Tankyrase inhibition in vivo in relevant disease models will be important to establish the clinical utility of these molecules in colorectal cancer and beyond. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5196. doi:10.1158/1538-7445.AM2011-5196