ABSTRACT
TTK is an essential spindle assembly checkpoint enzyme in many organisms. It plays a central role in tumor cell proliferation and is aberrantly overexpressed in a wide range of tumor types. We recently reported on a series of potent and selective TTK inhibitors with strong antiproliferative activity in triple negative breast cancer (TNBC) cell lines (8: TTK IC50 = 3.0 nM; CAL-51 IC50 = 84.0 nM). Inspired by previously described potent tricyclic TTK inhibitor 6 (TTK IC50 = 0.9 nM), we embarked on a structure-enabled design and optimization campaign to identify an improved series with excellent potency, TTK selectivity, solubility, CYP inhibition profile, and in vivo efficacy in a TNBC xenograft model. These efforts culminated in the discovery of 25 (TTK IC50 = 3.0 nM; CAL-51 IC50 = 16.0 nM), which showed significant single-agent efficacy when dosed iv in a TNBC xenograft model without body weight loss.
Subject(s)
Cell Cycle Proteins/antagonists & inhibitors , Protein Serine-Threonine Kinases/antagonists & inhibitors , Protein-Tyrosine Kinases/antagonists & inhibitors , Antineoplastic Agents , Breast Neoplasms , Cell Line, Tumor , Female , Gene Expression Regulation, Enzymologic/drug effects , Gene Expression Regulation, Neoplastic/drug effects , Humans , Models, Molecular , Molecular Docking Simulation , Molecular Structure , Structure-Activity RelationshipABSTRACT
The PKC-θ isoform of protein kinase C is selectively expressed in T lymphocytes and plays an important role in the T cell antigen receptor (TCR)-triggered activation of mature T cells, T cell proliferation, and the subsequent release of cytokines such as interleukin-2 (IL-2). Herein, we report the synthesis and structure-activity relationship (SAR) of a novel series of PKC-θ inhibitors. Through a combination of structure-guided design and exploratory SAR, suitable replacements for the basic C4 amine of the original lead (3) were identified. Property-guided design enabled the identification of appropriately substituted C2 groups to afford potent analogs with metabolic stability and permeability to support in vivo testing. With exquisite general kinase selectivity, cellular inhibition of T cell activation as assessed by IL-2 expression, a favorable safety profile, and demonstrated in vivo efficacy in models of acute and chronic T cell activation with oral dosing, CC-90005 (57) was selected for clinical development.
Subject(s)
Cyclohexanols/therapeutic use , Graft vs Host Disease/drug therapy , Immunologic Factors/therapeutic use , Protein Kinase C-theta/antagonists & inhibitors , Protein Kinase Inhibitors/therapeutic use , Pyrimidines/therapeutic use , Animals , Caco-2 Cells , Cell Proliferation/drug effects , Cyclohexanols/chemical synthesis , Cyclohexanols/metabolism , Humans , Immunologic Factors/chemical synthesis , Immunologic Factors/metabolism , Lymphocyte Activation/drug effects , Male , Mice, Inbred C57BL , Molecular Docking Simulation , Molecular Structure , Protein Binding , Protein Kinase C-delta/antagonists & inhibitors , Protein Kinase C-delta/metabolism , Protein Kinase C-theta/metabolism , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/metabolism , Pyrimidines/chemical synthesis , Pyrimidines/metabolism , Structure-Activity Relationship , T-Lymphocytes/drug effectsABSTRACT
Triple negative breast cancer (TNBC) is an aggressive disease with high relapse rates and few treatment options. Outlined in previous publications, we identified a series of potent, dual TTK/CLK2 inhibitors with strong efficacy in TNBC xenograft models. Pharmacokinetic properties and kinome selectivity were optimized, resulting in the identification of a new series of potent, selective, and orally bioavailable TTK inhibitors. We describe here the structure-activity relationship of the 2,4-disubstituted-7 H-pyrrolo[2,3- d]pyrimidine series, leading to significant single agent efficacy in a TNBC xenograft model without body weight loss. The design effort evolving an iv-dosed TTK/CLK2 inhibitor to an orally bioavailable TTK inhibitor is described.
Subject(s)
Antineoplastic Agents/therapeutic use , Protein Kinase Inhibitors/therapeutic use , Protein Serine-Threonine Kinases/antagonists & inhibitors , Pyrimidines/therapeutic use , Pyrroles/therapeutic use , Triple Negative Breast Neoplasms/drug therapy , Animals , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/pharmacokinetics , Apoptosis/drug effects , Docetaxel/therapeutic use , Drug Design , Female , Mice, SCID , Microtubule-Associated Proteins/metabolism , Molecular Structure , Phosphorylation/drug effects , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/pharmacokinetics , Protein Serine-Threonine Kinases/metabolism , Pyrimidines/chemical synthesis , Pyrimidines/pharmacokinetics , Pyrroles/chemical synthesis , Pyrroles/pharmacokinetics , Rats , Structure-Activity Relationship , Xenograft Model Antitumor AssaysABSTRACT
Triple negative breast cancer (TNBC) remains a serious unmet medical need with discouragingly high relapse rates. We report here the synthesis and structure-activity relationship (SAR) of a novel series of 2,4,5-trisubstituted-7H-pyrrolo[2,3-d]pyrimidines with potent activity against TNBC tumor cell lines. These compounds were discovered from a TNBC phenotypic screen and possess a unique dual inhibition profile targeting TTK (mitotic exit) and CLK2 (mRNA splicing). Design and optimization, driven with a TNBC tumor cell assay, identified potent and selective compounds with favorable in vitro and in vivo activity profiles and good iv PK properties. This cell-based driven SAR produced compounds with strong single agent in vivo efficacy in multiple TNBC xenograft models without significant body weight loss. These data supported the nomination of CC-671 into IND-enabling studies as a single agent TNBC therapy.
