RESUMO
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.
Assuntos
Inibidores Enzimáticos , Proteína-Arginina N-Metiltransferases , Proteína-Arginina N-Metiltransferases/antagonistas & inibidores , Proteína-Arginina N-Metiltransferases/metabolismo , Humanos , Animais , Inibidores Enzimáticos/farmacologia , Inibidores Enzimáticos/química , Inibidores Enzimáticos/síntese química , Relação Estrutura-Atividade , Camundongos , Descoberta de Drogas , Linhagem Celular Tumoral , Antineoplásicos/farmacologia , Antineoplásicos/química , Antineoplásicos/síntese químicaRESUMO
Targeting the estrogen receptor alpha (ERα) pathway is validated in the clinic as an effective means to treat ER+ breast cancers. Here we present the development of a VHL-targeting and orally bioavailable proteolysis-targeting chimera (PROTAC) degrader of ERα. In vitro studies with this PROTAC demonstrate excellent ERα degradation and ER antagonism in ER+ breast cancer cell lines. However, upon dosing the compound in vivo we observe an in vitro-in vivo disconnect. ERα degradation is lower in vivo than expected based on the in vitro data. Investigation into potential causes for the reduced maximal degradation reveals that metabolic instability of the PROTAC linker generates metabolites that compete for binding to ERα with the full PROTAC, limiting degradation. This observation highlights the requirement for metabolically stable PROTACs to ensure maximal efficacy and thus optimisation of the linker should be a key consideration when designing PROTACs.
Assuntos
Receptor alfa de Estrogênio , Proteólise , Proteína Supressora de Tumor Von Hippel-Lindau , Humanos , Receptor alfa de Estrogênio/metabolismo , Proteína Supressora de Tumor Von Hippel-Lindau/metabolismo , Proteína Supressora de Tumor Von Hippel-Lindau/genética , Feminino , Proteólise/efeitos dos fármacos , Animais , Administração Oral , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Camundongos , Antineoplásicos/farmacologia , Antineoplásicos/administração & dosagemRESUMO
BACKGROUND: SP140 is a bromodomain-containing protein expressed predominantly in immune cells. Genetic polymorphisms and epigenetic modifications in the SP140 locus have been linked to Crohn's disease (CD), suggesting a role in inflammation. RESULTS: We report the development of the first small molecule SP140 inhibitor (GSK761) and utilize this to elucidate SP140 function in macrophages. We show that SP140 is highly expressed in CD mucosal macrophages and in in vitro-generated inflammatory macrophages. SP140 inhibition through GSK761 reduced monocyte-to-inflammatory macrophage differentiation and lipopolysaccharide (LPS)-induced inflammatory activation, while inducing the generation of CD206+ regulatory macrophages that were shown to associate with a therapeutic response to anti-TNF in CD patients. SP140 preferentially occupies transcriptional start sites in inflammatory macrophages, with enrichment at gene loci encoding pro-inflammatory cytokines/chemokines and inflammatory pathways. GSK761 specifically reduces SP140 chromatin binding and thereby expression of SP140-regulated genes. GSK761 inhibits the expression of cytokines, including TNF, by CD14+ macrophages isolated from CD intestinal mucosa. CONCLUSIONS: This study identifies SP140 as a druggable epigenetic therapeutic target for CD.
Assuntos
Doença de Crohn , Inibidores do Fator de Necrose Tumoral , Antígenos Nucleares/genética , Antígenos Nucleares/metabolismo , Doença de Crohn/genética , Doença de Crohn/metabolismo , Citocinas/genética , Citocinas/metabolismo , Epigênese Genética , Humanos , Macrófagos , Fatores de Transcrição/genéticaRESUMO
Through regulation of the epigenome, the bromodomain and extra terminal (BET) family of proteins represent important therapeutic targets for the treatment of human disease. Through mimicking the endogenous N-acetyl-lysine group and disrupting the protein-protein interaction between histone tails and the bromodomain, several small molecule pan-BET inhibitors have progressed to oncology clinical trials. This work describes the medicinal chemistry strategy and execution to deliver an orally bioavailable tetrahydroquinoline (THQ) pan-BET candidate. Critical to the success of this endeavor was a potency agnostic analysis of a data set of 1999 THQ BET inhibitors within the GSK collection which enabled identification of appropriate lipophilicity space to deliver compounds with a higher probability of desired oral candidate quality properties. SAR knowledge was leveraged via Free-Wilson analysis within this design space to identify a small group of targets which ultimately delivered I-BET567 (27), a pan-BET candidate inhibitor that demonstrated efficacy in mouse models of oncology and inflammation.
Assuntos
Aminoquinolinas/química , Desenho de Fármacos , Proteínas/metabolismo , Administração Oral , Aminoquinolinas/metabolismo , Aminoquinolinas/farmacocinética , Aminoquinolinas/uso terapêutico , Animais , Benzoatos/química , Benzoatos/metabolismo , Sítios de Ligação , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Cristalografia por Raios X , Cães , Meia-Vida , Humanos , Masculino , Camundongos , Conformação Molecular , Simulação de Dinâmica Molecular , Neoplasias/tratamento farmacológico , Proteínas/antagonistas & inibidores , Ratos , Relação Estrutura-AtividadeRESUMO
p300/CREB binding protein associated factor (PCAF/KAT2B) and general control nonderepressible 5 (GCN5/KAT2A) are multidomain proteins that have been implicated in retroviral infection, inflammation pathways, and cancer development. However, outside of viral replication, little is known about the dependence of these effects on the C-terminal bromodomain. Herein, we report GSK4027 as a chemical probe for the PCAF/GCN5 bromodomain, together with GSK4028 as an enantiomeric negative control. The probe was optimized from a weakly potent, nonselective pyridazinone hit to deliver high potency for the PCAF/GCN5 bromodomain, high solubility, cellular target engagement, and ≥18000-fold selectivity over the BET family, together with ≥70-fold selectivity over the wider bromodomain families.