RESUMEN
PRMT5, a type 2 arginine methyltransferase, has a critical role in regulating cell growth and survival in cancer. With the aim of developing MTA-cooperative PRMT5 inhibitors suitable for MTAP-deficient cancers, herein we report our efforts to develop novel "MTA-cooperative" compounds identified through a high-throughput biochemical screening approach. Optimization of hits was achieved through structure-based design with a focus on improvement of oral drug-like properties. Bioisosteric replacement of the original thiazole guanidine headgroup, spirocyclization of the isoindolinone amide scaffold to both configurationally and conformationally lock the bioactive form, and fine-tuning of the potency, MTA cooperativity, and DMPK properties through specific substitutions of the azaindole headgroup were conducted. We have identified an orally available in vivo lead compound, 28 ("AZ-PRMT5i-1"), which shows sub-10 nM PRMT5 cell potency, >50-fold MTA cooperativity, suitable DMPK properties for oral dosing, and significant PRMT5-driven in vivo efficacy in several MTAP-deficient preclinical cancer models.
Asunto(s)
Inhibidores Enzimáticos , Proteína-Arginina N-Metiltransferasas , Proteína-Arginina N-Metiltransferasas/antagonistas & inhibidores , Proteína-Arginina N-Metiltransferasas/metabolismo , Humanos , Animales , Inhibidores Enzimáticos/farmacología , Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/síntesis química , Relación Estructura-Actividad , Ratones , Descubrimiento de Drogas , Línea Celular Tumoral , Antineoplásicos/farmacología , Antineoplásicos/química , Antineoplásicos/síntesis químicaRESUMEN
ATAD2 is an epigenetic bromodomain-containing target which is overexpressed in many cancers and has been suggested as a potential oncology target. While several small molecule inhibitors have been described in the literature, their cellular activity has proved to be underwhelming. In this work, we describe the identification of a novel series of ATAD2 inhibitors by high throughput screening, confirmation of the bromodomain region as the site of action, and the optimization campaign undertaken to improve the potency, selectivity, and permeability of the initial hit. The result is compound 5 (AZ13824374), a highly potent and selective ATAD2 inhibitor which shows cellular target engagement and antiproliferative activity in a range of breast cancer models.
Asunto(s)
ATPasas Asociadas con Actividades Celulares Diversas/antagonistas & inhibidores , Antineoplásicos/síntesis química , Antineoplásicos/farmacología , Neoplasias de la Mama/tratamiento farmacológico , Proteínas de Unión al ADN/antagonistas & inhibidores , Línea Celular Tumoral , Cristalografía por Rayos X , Descubrimiento de Drogas , Ensayos de Selección de Medicamentos Antitumorales , Femenino , Humanos , Modelos Moleculares , Bibliotecas de Moléculas Pequeñas , Relación Estructura-Actividad , Especificidad por Sustrato , Ensayo de Tumor de Célula MadreRESUMEN
When activated by amino acid starvation, the stress sensing protein kinase GCN2 phosphorylates the eukaryotic initiation factor 2 alpha, inhibiting translation to conserve energy and facilitate cell survival. Amino acid starvation, particularly of tryptophan and arginine, affects immune tolerance by suppressing differentiation and proliferation of T-cells via activation of GCN2 kinase. In addition, the GCN2 pathway mediates cancer survival directly within the context of metabolic stress. Here, we report the first crystal structures of the human GCN2 kinase domain (KD) in complex with two inhibitors of different size, shape, and chemical scaffold. Three novel activation loop conformations representative of different activation states of the kinase are described. In addition, a novel dimerization organization for GCN2 is observed. This arrangement is consistent with the hypothesis that the GCN2 KD forms an antiparallel inactive dimer until uncharged tRNA binds to it and triggers conformational changes that shift the equilibrium to the active parallel dimer.
Asunto(s)
Proteínas Serina-Treonina Quinasas/antagonistas & inhibidores , Proteínas Serina-Treonina Quinasas/química , Cristalografía por Rayos X , Factor 2 Eucariótico de Iniciación/metabolismo , Humanos , Unión Proteica , Dominios Proteicos , Multimerización de Proteína , ARN de Transferencia/metabolismoRESUMEN
Tumors have evolved a variety of methods to reprogram conventional metabolic pathways to favor their own nutritional needs, including glutaminolysis, the first step of which is the hydrolysis of glutamine to glutamate by the amidohydrolase glutaminase 1 (GLS1). A GLS1 inhibitor could potentially target certain cancers by blocking the tumor cell's ability to produce glutamine-derived nutrients. Starting from the known GLS1 inhibitor bis-2-(5-phenylacetamido-1,2,4-thiadiazol-2-yl)ethyl sulfide, we describe the medicinal chemistry evolution of a series from lipophilic inhibitors with suboptimal physicochemical and pharmacokinetic properties to cell potent examples with reduced molecular weight and lipophilicity, leading to compounds with greatly improved oral exposure that demonstrate in vivo target engagement accompanied by activity in relevant disease models.
Asunto(s)
Antineoplásicos/farmacología , Glutaminasa/antagonistas & inhibidores , Neoplasias/tratamiento farmacológico , Piridazinas/farmacología , Tiadiazoles/farmacología , Animales , Antineoplásicos/química , Antineoplásicos/farmacocinética , Antineoplásicos/uso terapéutico , Disponibilidad Biológica , Línea Celular Tumoral , Descubrimiento de Drogas , Glutaminasa/metabolismo , Humanos , Masculino , Ratones SCID , Simulación del Acoplamiento Molecular , Neoplasias/metabolismo , Neoplasias/patología , Piridazinas/química , Piridazinas/farmacocinética , Piridazinas/uso terapéutico , Tiadiazoles/química , Tiadiazoles/farmacocinética , Tiadiazoles/uso terapéuticoRESUMEN
MTH1 (NUDT1) is an oncologic target involved in the prevention of DNA damage. We investigate the way MTH1 recognises its substrates and present substrate-bound structures of MTH1 for 8-oxo-dGTP and 8-oxo-rATP as examples of novel strong and weak binding substrate motifs. Investigation of a small set of purine-like fragments using 2D NMR resulted in identification of a fragment with weak potency. The protein-ligand X-Ray structure of this fragment provides insight into the role of water molecules in substrate selectivity. Wider fragment screening by NMR resulted in three new protein structures exhibiting alternative binding configurations to the key Asp-Asp recognition element of the protein. These inhibitor binding modes demonstrate that MTH1 employs an intricate yet promiscuous mechanism of substrate anchoring through its Asp-Asp pharmacophore. The structures suggest that water-mediated interactions convey selectivity towards oxidized substrates over their non-oxidised counterparts, in particular by stabilization of a water molecule in a hydrophobic environment through hydrogen bonding. These findings may be useful in the design of inhibitors of MTH1.