The discovery of BMS-737 as a potent, CYP17 lyase-selective inhibitor for the treatment of castration-resistant prostate cancer.

We report herein, the discovery of BMS-737 (compound 33) as a potent, non-steroidal, reversible small molecule inhibitor demonstrating 11-fold selectivity for CYP17 lyase over CYP17 hydroxylase, as well as a clean xenobiotic CYP profile for the treatment of castration-resistant prostate cancer (CRPC). Extensive SAR studies on the initial lead 1 at three different regions of the molecule resulted in the identification of BMS-737, which demonstrated a robust 83% lowering of testosterone without any significant perturbation of the mineralocorticoid and glucocorticoid levels in cynomologous monkeys in a 1-day PK/PD study.

Discovery of BMS-986202: A Clinical Tyk2 Inhibitor that Binds to Tyk2 JH2.

A search for structurally diversified Tyk2 JH2 ligands from 6 (BMS-986165), a pyridazine carboxamide-derived Tyk2 JH2 ligand as a clinical Tyk2 inhibitor currently in late development for the treatment of psoriasis, began with a survey of six-membered heteroaryl groups in place of the N-methyl triazolyl moiety in 6. The X-ray co-crystal structure of an early lead (12) revealed a potential new binding pocket. Exploration of the new pocket resulted in two frontrunners for a clinical candidate. The potential hydrogen bonding interaction with Thr599 in the pocket was achieved with a tertiary amide moiety, confirmed by the X-ray co-crystal structure of 29. When the diversity search was extended to nicotinamides, a single fluorine atom addition was found to significantly enhance the permeability, which directly led to the discovery of 7 (BMS-986202) as a clinical Tyk2 inhibitor that binds to Tyk2 JH2. The preclinical studies of 7, including efficacy studies in mouse models of IL-23-driven acanthosis, anti-CD40-induced colitis, and spontaneous lupus, will also be presented.

Optimization of Nicotinamides as Potent and Selective IRAK4 Inhibitors with Efficacy in a Murine Model of Psoriasis.

IRAK4 is an attractive therapeutic target for the treatment of inflammatory conditions. Structure guided optimization of a nicotinamide series of inhibitors has been expanded to explore the IRAK4 front pocket. This has resulted in the identification of compounds such as 12 with improved potency and selectivity. Additionally 12 demonstrated activity in a pharmacokinetics/pharmacodynamics (PK/PD) model. Further optimization efforts led to the identification of the highly kinome selective 21, which demonstrated a robust PD effect and efficacy in a TLR7 driven model of murine psoriasis.

Identification of Imidazo[1,2-b]pyridazine Derivatives as Potent, Selective, and Orally Active Tyk2 JH2 Inhibitors.

In sharp contrast to a previously reported series of 6-anilino imidazopyridazine based Tyk2 JH2 ligands, 6-((2-oxo-N1-substituted-1,2-dihydropyridin-3-yl)amino)imidazo[1,2-b]pyridazine analogs were found to display dramatically improved metabolic stability. The N1-substituent on 2-oxo-1,2-dihydropyridine ring can be a variety of alkyl, aryl, and heteroaryl groups, but among them, 2-pyridyl provided much enhanced Caco-2 permeability, attributed to its ability to form intramolecular hydrogen bonds. Further structure-activity relationship studies at the C3 position led to the identification of highly potent and selective Tyk2 JH2 inhibitor 6, which proved to be highly effective in inhibiting IFNγ production in a rat pharmacodynamics model and fully efficacious in a rat adjuvant arthritis model.

Discovery of Branebrutinib (BMS-986195): A Strategy for Identifying a Highly Potent and Selective Covalent Inhibitor Providing Rapid in Vivo Inactivation of Bruton's Tyrosine Kinase (BTK).

Bruton's tyrosine kinase (BTK), a non-receptor tyrosine kinase, is a member of the Tec family of kinases and is essential for B cell receptor (BCR) mediated signaling. BTK also plays a critical role in the downstream signaling pathways for the Fcγ receptor in monocytes, the Fcε receptor in granulocytes, and the RANK receptor in osteoclasts. As a result, pharmacological inhibition of BTK is anticipated to provide an effective strategy for the clinical treatment of autoimmune diseases such as rheumatoid arthritis and lupus. This article will outline the evolution of our strategy to identify a covalent, irreversible inhibitor of BTK that has the intrinsic potency, selectivity, and pharmacokinetic properties necessary to provide a rapid rate of inactivation systemically following a very low dose. With excellent in vivo efficacy and a very desirable tolerability profile, 5a (branebrutinib, BMS-986195) has advanced into clinical studies.

A polychromatic turbidity microplate assay to distinguish discovery stage drug molecules with beneficial precipitation properties.

A material sparing microplate screening assay was developed to evaluate and compare the precipitation of discovery stage drug molecules as a function of time, concentration and media composition. Polychromatic turbidity time course profiles were collected for cinnarizine, probucol, dipyridamole as well as BMS-932481, and compared with turbidity profiles of monodisperse particle size standards. Precipitation for select sample conditions were further characterized at several time points by size, morphology, amount and form via laser diffraction, microscopy, size based particle counting and X-ray diffraction respectively. Wavelength dependent turbidity was found indicative of nanoprecipitate, while wavelength independent turbidity was consistent with larger microprecipitate formation. A transition from wavelength dependent to wavelength independent turbidity occurred for nanoparticle to microparticle growth, and a decrease in wavelength independent turbidity correlated with continued growth in size of microparticles. Other sudden changes in turbidity signal over time such as rapid fluctuation, a decrease in slope or a sharp inversion were correlated with very large or aggregated macro-precipitates exceeding 100µm in diameter, a change in the rate of precipitate formation or an amorphous to crystalline form conversion respectively. The assay provides an effective method to efficiently monitor and screen the precipitation fates of drug molecules, even during the early stages of discovery with limited amounts of available material. This capability highlights molecules with beneficial precipitation properties that are able to generate and maintain solubility enabling amorphous or nanoparticle precipitates.

Discovery of the Selective CYP17A1 Lyase Inhibitor BMS-351 for the Treatment of Prostate Cancer.

Efforts to identify a potent, reversible, nonsteroidal CYP17A1 lyase inhibitor with good selectivity over CYP17A1 hydroxylase and CYPs 11B1 and 21A2 for the treatment of castration-resistant prostate cancer (CRPC) culminated in the discovery of BMS-351 (compound 18), a pyridyl biaryl benzimidazole with an excellent in vivo profile. Biological evaluation of BMS-351 at a dose of 1.5 mg in castrated cynomolgus monkeys revealed a remarkable reduction in testosterone levels with minimal glucocorticoid and mineralcorticoid perturbation. Based on a favorable profile, BMS-351 was selected as a candidate for further preclinical evaluation.

Rapid throughput solubility screening method for BCS class II drugs in animal GI fluids and simulated human GI fluids using a 96-well format.

A rapid solubility-screening assay was developed with a focus on Biopharmaceutic Classification Scheme (BCS) class II drug solubility in animal and simulated human gastrointestinal (GI) fluids. The assay enables biologically promising drug leads to be evaluated for solubility limitations earlier in the drug development process, minimizes GI fluid needs, and produces in vitro solubility information with potential in vivo implications. A number of BCS II drugs were dissolved in DMSO at approximately 40 mM, and robotically distributed to a 96-well plate. The DMSO was evaporated and drugs were equilibrated with selected GI fluids, both fed and fasted states. After equilibration, precipitated wells were subjected to HPLC analysis. A spreadsheet calculated solubility automatically from HPLC output. Intra-day, inter-day, and inter-plate reproducibility were within 15% RSTD for the tested drugs with the primary source of variability being injection precision of our injector system. The reported solubility from screening assays was well correlated with literature data (r(2) = 0.80) with a slope of 0.86 and (r(2) = 0.99) with a slope of 0.89. This screening assay converts conventional solubility measurements to a 96-well format for increased throughput (>12 samples/h), reduces fluid needs, and minimizes drug consumption.

Rapid throughput screening of apparent KSP values for weakly basic drugs using 96-well format.

A rapid-throughput screening assay was developed to estimate the salt solubility parameter, K(SP), with a minimal quantity of drug. This assay allows for early evaluation of salt limited solubility with a large number of counter-ions and biologically promising drug leads. Drugs dissolved (typically 10 mM) in DMSO are robotically distributed to a 96-well plate. DMSO is evaporated, and drugs are equilibrated with various acids at different concentrations (typically <1 M) to yield final total drug concentrations around 2.5 mM. The plate is checked for precipitation. Filtrates from only those precipitated wells were subjected to rapid gradient HPLC analysis. An iterative procedure is employed to calculate all species concentrations based on mass and charge balance equations. The apparent K(SP) values assuming 1:1 stoichiometry are determined from counter-ion and ionized drug activities. A correlation coefficient >0.975 for eight drugs totaling 16 salts is reported. Intra-day and inter-day reproducibility was <10%. Conventional apparent K(SP) measurements were translated to 96-well format for increased throughput and minimal drug consumption (typically 10 mg) to evaluate at least eight different counter-ions. Although the current protocol estimates K(SP) from 10(-3) to 10(-7) M, the dynamic range of the assay could be expanded by adjusting drug and counter-ion concentrations.