Development of BET inhibitors as potential treatments for cancer: A search for structural diversity.

We describe our efforts to identify structurally diverse leads in the triazole-containing N1-carboline series of bromodomain and extra-terminal inhibitors. Replacement of the N5 "cap" phenyl moiety with various heteroaryls, coupled with additional modifications to the carboline core, provided analogs with similar potency, improved pharmacokinetic properties, and increased solubility compared to our backup lead, BMS-986225 (2). Rapid SAR exploration was enabled by a convergent, synthetic route. These efforts provided a potent BET inhibitor, 3-fluoropyridyl 12, that demonstrated robust efficacy in a multiple myeloma mouse tumor model at 1 mg/kg.

BMS-871: a novel orally active pan-Notch inhibitor as an anticancer agent.

This Letter describes synthesis, SAR, and biological activity of (2-oxo-1,4-benzodiazepin-3-yl)-succinamides as inhibitors of γ-secretase mediated signaling of Notch receptors. Optimization of this series led to the identification of BMS-871 (compound 30) which displayed robust in vivo efficacy in Notch-dependent leukemia and solid tumor xenograft models.

Biochemical and transcriptional profiling to triage additional activities in a series of IGF-1R/IR inhibitors.

Therapeutic development of a targeted agent involves a series of decisions over additional activities that may be ignored, eliminated or pursued. This paper details the concurrent application of two methods that provide a spectrum of information about the biological activity of a compound: biochemical profiling on a large panel of kinase assays and transcriptional profiling of mRNA responses. Our mRNA profiling studies used a full dose range, identifying subsets of transcriptional responses with differing EC(50)s which may reflect distinct targets. Profiling data allowed prioritization for validation in xenograft models, generated testable hypotheses for active compounds, and informed decisions on the general utility of the series.

Development of BET Inhibitors as Potential Treatments for Cancer: Optimization of Pharmacokinetic Properties.

We describe the synthesis of triazole-containing carboline derivatives and their utility as bromodomain and extra-terminal (BET) inhibitors. A convergent synthetic route permitted the detailed investigation of deuteration and fluorination strategies to reduce clearance while maintaining a favorable in vitro profile. This work led to the identification of a potent BET inhibitor, 2-{8-fluoro-3-[4-(2H3)methyl-1-methyl-1H-1,2,3-triazol-5-yl]-5-[(S)-(oxan-4-yl)(phenyl)methyl]-5H-pyrido[3,2-b]indol-7-yl}propan-2-ol (15), which demonstrated reduced clearance and an improved pharmacokinetic (PK) profile across preclinical species. Importantly, no major metabolite was observed when 15 was incubated with human hepatocytes (hHEP) for 2 h. This study culminated with the evaluation of 15 in a mouse triple-negative breast cancer (TNBC) tumor model where it demonstrated robust efficacy at low doses.

Discovery and Preclinical Pharmacology of an Oral Bromodomain and Extra-Terminal (BET) Inhibitor Using Scaffold-Hopping and Structure-Guided Drug Design.

Inhibition of the bromodomain and extra-terminal (BET) family of adaptor proteins is an attractive strategy for targeting transcriptional regulation of key oncogenes, such as c-MYC. Starting with the screening hit 1, a combination of structure-activity relationship and protein structure-guided drug design led to the discovery of a differently oriented carbazole 9 with favorable binding to the tryptophan, proline, and phenylalanine (WPF) shelf conserved in the BET family. Identification of an additional lipophilic pocket and functional group optimization to optimize pharmacokinetic (PK) properties culminated in the discovery of 18 (BMS-986158) with excellent potency in binding and functional assays. On the basis of its favorable PK profile and robust in vivo activity in a panel of hematologic and solid tumor models, BMS-986158 was selected as a candidate for clinical evaluation.

Insulin-like growth factor-1 receptor (IGF-1R) kinase inhibitors: SAR of a series of 3-[6-(4-substituted-piperazin-1-yl)-4-methyl-1H-benzimidazol-2-yl]-1H-pyridine-2-one.

A series of 3-[6-(4-substituted-piperazin-1-yl)-4-methyl-1H-benzimidazol-2-yl]-1H-pyridine-2-one were synthesized to modulate CYP3A4 inhibition and improve aqueous solubility of our prototypical compound BMS-536924 (1), while maintaining potent IGF-1R inhibitory activity. Structure-activity and structure-solubility studies led to the identification of BMS-577098 (27), which demonstrates oral in vivo efficacy in animal models. The improvement was achieved by replacing morpholine with more polar bio-isoster piperazine and modulating the basicity of distal nitrogen with appropriate substitutions.

Targeting DDR2 enhances tumor response to anti-PD-1 immunotherapy.

While a fraction of cancer patients treated with anti-PD-1 show durable therapeutic responses, most remain unresponsive, highlighting the need to better understand and improve these therapies. Using an in vivo screening approach with a customized shRNA pooled library, we identified DDR2 as a leading target for the enhancement of response to anti-PD-1 immunotherapy. Using isogenic in vivo murine models across five different tumor histologies-bladder, breast, colon, sarcoma, and melanoma-we show that DDR2 depletion increases sensitivity to anti-PD-1 treatment compared to monotherapy. Combination treatment of tumor-bearing mice with anti-PD-1 and dasatinib, a tyrosine kinase inhibitor of DDR2, led to tumor load reduction. RNA-seq and CyTOF analysis revealed higher CD8+ T cell populations in tumors with DDR2 depletion and those treated with dasatinib when either was combined with anti-PD-1 treatment. Our work provides strong scientific rationale for targeting DDR2 in combination with PD-1 inhibitors.

Tissue distribution and tumor uptake of folate receptor-targeted epothilone folate conjugate, BMS-753493, in CD2F1 mice after systemic administration.

To assess targeting of an epothilone folate conjugate (BMS-753493) to the folate receptor (FR)-overexpressed tumor in mice bearing both FR+ and FR- tumors, a series of experiments were conducted by quantitative whole-body autoradiography (QWBA) and LC-MS/MS following i.v. administration of BMS-753493 or its active moiety, BMS-748285 in mice bearing FR+ (98M109) and FR- (M109) tumors. QWBA showed [3H]BMS-753493-derived radioactivity was extensively distributed to various tissues. The FR over-expressing 98M109 tumors showed consistently higher level of radioactivity than FR-negative tumors (i.e., M109 tumors) up to 48 h post dose of [3H]BMS-753493, despite the magnitude of difference between the tumors is relatively small (generally 3~5-fold). The radioactivity level in 98M109 tumors was 2~12-fold of normal tissues except intestine/content at 48 h post dose. No selective radioactivity uptake into 98M109 tumors over M109 or normal tissues was observed after i.v. administration of the active epothilone, [3H]BMS-748285. LC-MS/MS measurements demonstrated that the concentrations of BMS-748285, presumably from hydrolysis of the folate conjugate, in 98M109 tumors were greater than those in M109 tumors after i.v. administration of BMS-753493 (2-3-fold) whereas no differential uptake in the tumors following BMS-748285 administration. Those data were consistent with radioactivity determinations. Those results demonstrated that the folate conjugation in BMS-753493 enabled moderately preferential distribution of the active epothilone to FR over-expressing 98M109 tumors, thereby supporting targeted delivery of cytotoxics through the folate receptor.

Discovery of Clinical Candidate BMS-906024: A Potent Pan-Notch Inhibitor for the Treatment of Leukemia and Solid Tumors.

Structure-activity relationships in a series of (2-oxo-1,4-benzodiazepin-3-yl)-succinamides identified highly potent inhibitors of γ-secretase mediated signaling of Notch1/2/3/4 receptors. On the basis of its robust in vivo efficacy at tolerated doses in Notch driven leukemia and solid tumor xenograft models, 12 (BMS-906024) was selected as a candidate for clinical evaluation.

Preclinical efficacy spectrum and pharmacokinetics of ixabepilone.

PURPOSE: Ixabepilone, a semisynthetic analog of natural epothilone B, was developed for use in cancer treatment. This study extends previous findings regarding the efficacy of ixabepilone and its low susceptibility to tumor resistance mechanisms and describes the pharmacokinetics of this new antineoplastic agent. METHODS: The cytotoxicity of ixabepilone was assessed in vitro in breast, lung, and colon tumor cell lines and in vivo in human xenografts in mice. Antitumor activities of ixabepilone and taxanes were compared in multidrug-resistant models in vivo. Differential drug uptake of ixabepilone and paclitaxel was assessed in a P-glycoprotein (P-gp)-resistant colon cancer model in vitro. The pharmacokinetic profile of ixabepilone was established in mice and humans. RESULTS: Ixabepilone demonstrated potent cytotoxicity in a broad range of human cancer cell lines in vitro and in a wide range of xenografts in vivo. Ixabepilone was *3-fold more potent than docetaxel in the paclitaxel-resistant Pat-21 xenograft model (resistant due to overexpression of betaIII-tubulin and a lack of betaII-tubulin). Ixabepilone activity against P-gp-overexpressing breast and colon cancer was confirmed in in vivo models. Cellular uptake of ixabepilone, but not paclitaxel, was established in a P-gp-overexpressing model. The pharmacokinetics of ixabepilone was characterized by rapid tissue distribution and extensive tissue binding. CONCLUSIONS: Cytotoxicity studies against a range of tumor types in vitro and in vivo demonstrate that ixabepilone has potent and broad-spectrum antineoplastic activity. This is accompanied by favorable pharmacokinetics. Ixabepilone has reduced susceptibility to resistance due to P-gp overexpression, tubulin mutations, and alterations in beta-tubulin isotype expression.

BMS-754807, a small molecule inhibitor of insulin-like growth factor-1R/IR.

BMS-754807 is a potent and reversible inhibitor of the insulin-like growth factor 1 receptor/insulin receptor family kinases (Ki, <2 nmol/L). It is currently in phase I development for the treatment of a variety of human cancers. BMS-754807 effectively inhibits the growth of a broad range of human tumor types in vitro, including mesenchymal (Ewing's, rhabdomyosarcoma, neuroblastoma, and liposarcoma), epithelial (breast, lung, pancreatic, colon, gastric), and hematopoietic (multiple myeloma and leukemia) tumor cell lines (IC50, 5-365 nmol/L); the compound caused apoptosis in a human rhabdomyosarcoma cell line, Rh41, as shown by an accumulation of the sub-G1 fraction, as well as by an increase in poly ADP ribose polymerase and Caspase 3 cleavage. BMS-754807 is active in vivo in multiple (epithelial, mesenchymal, and hematopoietic) xenograft tumor models with tumor growth inhibition ranging from 53% to 115% and at a minimum effective dose of as low as 6.25 mg/kg dosed orally daily. Combination studies with BMS-754807 have been done on multiple human tumor cell types and showed in vitro synergies (combination index, <1.0) when combined with cytotoxic, hormonal, and targeted agents. The combination of cetuximab and BMS-754807 in vivo, at multiple dose levels, resulted in improved clinical outcome over single agent treatment. These data show that BMS-754807 is an efficacious, orally active growth factor 1 receptor/insulin receptor family-targeted kinase inhibitor that may act in combination with a wide array of established anticancer agents.

Discovery of a 2,4-disubstituted pyrrolo[1,2-f][1,2,4]triazine inhibitor (BMS-754807) of insulin-like growth factor receptor (IGF-1R) kinase in clinical development.

This report describes the biological activity, characterization, and SAR leading to 9d (BMS-754807) a small molecule IGF-1R kinase inhibitor in clinical development.