RESUMEN
BACKGROUND: Covalent (irreversible) Bruton's tyrosine kinase (BTK) inhibitors have transformed the treatment of multiple B-cell cancers, especially chronic lymphocytic leukemia (CLL). However, resistance can arise through multiple mechanisms, including acquired mutations in BTK at residue C481, the binding site of covalent BTK inhibitors. Noncovalent (reversible) BTK inhibitors overcome this mechanism and other sources of resistance, but the mechanisms of resistance to these therapies are currently not well understood. METHODS: We performed genomic analyses of pretreatment specimens as well as specimens obtained at the time of disease progression from patients with CLL who had been treated with the noncovalent BTK inhibitor pirtobrutinib. Structural modeling, BTK-binding assays, and cell-based assays were conducted to study mutations that confer resistance to noncovalent BTK inhibitors. RESULTS: Among 55 treated patients, we identified 9 patients with relapsed or refractory CLL and acquired mechanisms of genetic resistance to pirtobrutinib. We found mutations (V416L, A428D, M437R, T474I, and L528W) that were clustered in the kinase domain of BTK and that conferred resistance to both noncovalent BTK inhibitors and certain covalent BTK inhibitors. Mutations in BTK or phospholipase C gamma 2 (PLCγ2), a signaling molecule and downstream substrate of BTK, were found in all 9 patients. Transcriptional activation reflecting B-cell-receptor signaling persisted despite continued therapy with noncovalent BTK inhibitors. CONCLUSIONS: Resistance to noncovalent BTK inhibitors arose through on-target BTK mutations and downstream PLCγ2 mutations that allowed escape from BTK inhibition. A proportion of these mutations also conferred resistance across clinically approved covalent BTK inhibitors. These data suggested new mechanisms of genomic escape from established covalent and novel noncovalent BTK inhibitors. (Funded by the American Society of Hematology and others.).
Asunto(s)
Agammaglobulinemia Tirosina Quinasa , Resistencia a Antineoplásicos , Leucemia Linfocítica Crónica de Células B , Mutación , Fosfolipasa C gamma , Inhibidores de Proteínas Quinasas , Humanos , Persona de Mediana Edad , Adenina/análogos & derivados , Adenina/farmacología , Agammaglobulinemia Tirosina Quinasa/antagonistas & inhibidores , Agammaglobulinemia Tirosina Quinasa/genética , Agammaglobulinemia Tirosina Quinasa/ultraestructura , Resistencia a Antineoplásicos/genética , Leucemia Linfocítica Crónica de Células B/tratamiento farmacológico , Fosfolipasa C gamma/genética , Piperidinas/farmacología , Inhibidores de Proteínas Quinasas/farmacología , Inhibidores de Proteínas Quinasas/uso terapéutico , Receptores de Antígenos de Linfocitos B/metabolismo , Análisis de Secuencia de ARN , Transducción de Señal/efectos de los fármacosRESUMEN
Bruton tyrosine kinase (BTK), a nonreceptor tyrosine kinase, is a major therapeutic target for B-cell-driven malignancies. However, approved covalent BTK inhibitors (cBTKis) are associated with treatment limitations because of off-target side effects, suboptimal oral pharmacology, and development of resistance mutations (eg, C481) that prevent inhibitor binding. Here, we describe the preclinical profile of pirtobrutinib, a potent, highly selective, noncovalent (reversible) BTK inhibitor. Pirtobrutinib binds BTK with an extensive network of interactions to BTK and water molecules in the adenosine triphosphate binding region and shows no direct interaction with C481. Consequently, pirtobrutinib inhibits both BTK and BTK C481 substitution mutants in enzymatic and cell-based assays with similar potencies. In differential scanning fluorimetry studies, BTK bound to pirtobrutinib exhibited a higher melting temperature than cBTKi-bound BTK. Pirtobrutinib, but not cBTKis, prevented Y551 phosphorylation in the activation loop. These data suggest that pirtobrutinib uniquely stabilizes BTK in a closed, inactive conformation. Pirtobrutinib inhibits BTK signaling and cell proliferation in multiple B-cell lymphoma cell lines, and significantly inhibits tumor growth in human lymphoma xenografts in vivo. Enzymatic profiling showed that pirtobrutinib was highly selective for BTK in >98% of the human kinome, and in follow-up cellular studies pirtobrutinib retained >100-fold selectivity over other tested kinases. Collectively, these findings suggest that pirtobrutinib represents a novel BTK inhibitor with improved selectivity and unique pharmacologic, biophysical, and structural attributes with the potential to treat B-cell-driven cancers with improved precision and tolerability. Pirtobrutinib is being tested in phase 3 clinical studies for a variety of B-cell malignancies.
Asunto(s)
Agammaglobulinemia Tirosina Quinasa , Linfoma , Agammaglobulinemia Tirosina Quinasa/antagonistas & inhibidores , Humanos , Animales , Ensayos Antitumor por Modelo de Xenoinjerto , Linfoma/tratamiento farmacológico , Evaluación Preclínica de Medicamentos , Línea Celular Tumoral , Ratones Endogámicos NOD , Masculino , Ratones SCID , Conformación Molecular , RatonesRESUMEN
Patients with melanoma receiving drugs targeting BRAFV600E and mitogen-activated protein (MAP) kinase kinases 1 and 2 (MEK1/2) invariably develop resistance and face continued progression. Based on preclinical studies, intermittent treatment involving alternating periods of drug withdrawal and rechallenge has been proposed as a method to delay the onset of resistance. The beneficial effect of intermittent treatment has been attributed to drug addiction, where drug withdrawal reduces the viability of resistant cells due to MAP kinase pathway hyperactivation. However, the mechanistic basis of the intermittent effect is incompletely understood. We show that intermittent treatment with the BRAFV600E inhibitor, LGX818/encorafenib, suppresses growth compared with continuous treatment in human melanoma cells engineered to express BRAFV600E, p61-BRAFV600E, or MEK2C125 oncogenes. Analysis of the BRAFV600E-overexpressing cells shows that, while drug addiction clearly occurs, it fails to account for the advantageous effect of intermittent treatment. Instead, growth suppression is best explained by resensitization during periods of drug removal, followed by cell death after drug readdition. Continuous treatment leads to transcriptional responses prominently associated with chemoresistance in melanoma. By contrast, cells treated intermittently reveal a subset of transcripts that reverse expression between successive cycles of drug removal and rechallenge and include mediators of cell invasiveness and the epithelial-to-mesenchymal transition. These transcripts change during periods of drug removal by adaptive switching, rather than selection pressure. Resensitization occurs against a background of sustained expression of melanoma resistance genes, producing a transcriptome distinct from that of the initial drug-naive cell state. We conclude that phenotypic plasticity leading to drug resensitization can underlie the beneficial effect of intermittent treatment.
Asunto(s)
Melanoma , Proteínas Proto-Oncogénicas B-raf , Línea Celular Tumoral , Resistencia a Antineoplásicos/genética , Humanos , Sistema de Señalización de MAP Quinasas , Melanoma/tratamiento farmacológico , Melanoma/genética , Melanoma/patología , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Mutación , Inhibidores de Proteínas Quinasas/farmacología , Inhibidores de Proteínas Quinasas/uso terapéutico , Proteínas Proto-Oncogénicas B-raf/genética , Proteínas Proto-Oncogénicas B-raf/metabolismoRESUMEN
Activating mutations in KRAS and BRAF are found in more than 30% of all human tumours and 40% of melanoma, respectively, thus targeting this pathway could have broad therapeutic effects. Small molecule ATP-competitive RAF kinase inhibitors have potent antitumour effects on mutant BRAF(V600E) tumours but, in contrast to mitogen-activated protein kinase kinase (MEK) inhibitors, are not potent against RAS mutant tumour models, despite RAF functioning as a key effector downstream of RAS and upstream of MEK. Here we show that ATP-competitive RAF inhibitors have two opposing mechanisms of action depending on the cellular context. In BRAF(V600E) tumours, RAF inhibitors effectively block the mitogen-activated protein kinase (MAPK) signalling pathway and decrease tumour growth. Notably, in KRAS mutant and RAS/RAF wild-type tumours, RAF inhibitors activate the RAF-MEK-ERK pathway in a RAS-dependent manner, thus enhancing tumour growth in some xenograft models. Inhibitor binding activates wild-type RAF isoforms by inducing dimerization, membrane localization and interaction with RAS-GTP. These events occur independently of kinase inhibition and are, instead, linked to direct conformational effects of inhibitors on the RAF kinase domain. On the basis of these findings, we demonstrate that ATP-competitive kinase inhibitors can have opposing functions as inhibitors or activators of signalling pathways, depending on the cellular context. Furthermore, this work provides new insights into the therapeutic use of ATP-competitive RAF inhibitors.
Asunto(s)
Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Neoplasias/patología , Inhibidores de Proteínas Quinasas/farmacología , Quinasas raf/antagonistas & inhibidores , Quinasas raf/metabolismo , Adenosina Trifosfato/metabolismo , Animales , Benzamidas/farmacología , Línea Celular , Membrana Celular/efectos de los fármacos , Membrana Celular/metabolismo , Proliferación Celular/efectos de los fármacos , Difenilamina/análogos & derivados , Difenilamina/farmacología , Activación Enzimática/efectos de los fármacos , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Humanos , Indenos/farmacología , Indoles/farmacología , Ratones , Quinasas de Proteína Quinasa Activadas por Mitógenos/antagonistas & inhibidores , Quinasas de Proteína Quinasa Activadas por Mitógenos/metabolismo , Neoplasias/tratamiento farmacológico , Neoplasias/enzimología , Neoplasias/metabolismo , Inhibidores de Proteínas Quinasas/uso terapéutico , Multimerización de Proteína , Estructura Terciaria de Proteína , Transporte de Proteínas/efectos de los fármacos , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas/metabolismo , Proteínas Proto-Oncogénicas B-raf/antagonistas & inhibidores , Proteínas Proto-Oncogénicas B-raf/química , Proteínas Proto-Oncogénicas B-raf/genética , Proteínas Proto-Oncogénicas B-raf/metabolismo , Proteínas Proto-Oncogénicas c-raf/deficiencia , Proteínas Proto-Oncogénicas c-raf/genética , Proteínas Proto-Oncogénicas c-raf/metabolismo , Proteínas Proto-Oncogénicas p21(ras) , Pirazoles/farmacología , Sulfonamidas/farmacología , Ensayos Antitumor por Modelo de Xenoinjerto , Quinasas raf/química , Quinasas raf/genética , Proteínas ras/genética , Proteínas ras/metabolismoRESUMEN
The protein kinase v-akt murine thymoma viral oncogene homolog (AKT), a key regulator of cell survival and proliferation, is frequently hyperactivated in human cancers. Intramolecular pleckstrin homology (PH) domain-kinase domain (KD) interactions are important in maintaining AKT in an inactive state. AKT activation proceeds after a conformational change that dislodges the PH from the KD. To understand these autoinhibitory interactions, we generated mutations at the PH-KD interface and found that most of them lead to constitutive activation of AKT. Such mutations are likely another mechanism by which activation may occur in human cancers and other diseases. In support of this likelihood, we found somatic mutations in AKT1 at the PH-KD interface that have not been previously described in human cancers. Furthermore, we show that the AKT1 somatic mutants are constitutively active, leading to oncogenic signaling. Additionally, our studies show that the AKT1 mutants are not effectively inhibited by allosteric AKT inhibitors, consistent with the requirement for an intact PH-KD interface for allosteric inhibition. These results have important implications for therapeutic intervention in patients with AKT mutations at the PH-KD interface.
Asunto(s)
Neoplasias/enzimología , Neoplasias/genética , Oncogenes/genética , Proteínas Proto-Oncogénicas c-akt/química , Proteínas Proto-Oncogénicas c-akt/genética , Regulación Alostérica/efectos de los fármacos , Regulación Alostérica/genética , Animales , Línea Celular Tumoral , Membrana Celular/efectos de los fármacos , Membrana Celular/enzimología , Transformación Celular Neoplásica/efectos de los fármacos , Transformación Celular Neoplásica/genética , Transformación Celular Neoplásica/patología , Activación Enzimática/efectos de los fármacos , Humanos , Ratones , Modelos Moleculares , Proteínas Mutantes/metabolismo , Mutación/genética , Células 3T3 NIH , Unión Proteica/efectos de los fármacos , Unión Proteica/genética , Inhibidores de Proteínas Quinasas/farmacología , Transporte de Proteínas/efectos de los fármacos , Proteínas Proto-Oncogénicas c-akt/metabolismo , Transducción de Señal/efectos de los fármacos , Transducción de Señal/genéticaRESUMEN
The efficacy of the highly selective RET inhibitor selpercatinib is now established in RET-driven cancers, and we sought to characterize the molecular determinants of response and resistance. We find that the pre-treatment genomic landscape does not shape the variability of treatment response except for rare instances of RAS-mediated primary resistance. By contrast, acquired selpercatinib resistance is driven by MAPK pathway reactivation by one of two distinct routes. In some patients, on- and off-target pathway reactivation via secondary RET solvent front mutations or MET amplifications are evident. In other patients, rare RET-wildtype tumor cell populations driven by an alternative mitogenic driver are selected for by treatment. Multiple distinct mechanisms are often observed in the same patient, suggesting polyclonal resistance may be common. Consequently, sequential RET-directed therapy may require combination treatment with inhibitors targeting alternative MAPK effectors, emphasizing the need for prospective characterization of selpercatinib-treated tumors at the time of monotherapy progression.
Asunto(s)
Neoplasias Pulmonares , Neoplasias de la Tiroides , Humanos , Pulmón , Neoplasias Pulmonares/tratamiento farmacológico , Neoplasias Pulmonares/genética , Mutación , Estudios Prospectivos , Proteínas Proto-Oncogénicas c-ret/genética , Neoplasias de la Tiroides/tratamiento farmacológico , Neoplasias de la Tiroides/genéticaRESUMEN
The development of inhibitors of B-Raf(V600E) serine-threonine kinase is described. Various head-groups were examined to optimize inhibitor activity and ADME properties. Several of the head-groups explored, including naphthol, phenol and hydroxyamidine, possessed good activity but had poor pharmacokinetic exposure in mice. Exposure was improved by incorporating more metabolically stable groups such as indazole and tricyclic pyrazole, while indazole could also be optimized for good cellular activity.
Asunto(s)
Inhibidores de Proteínas Quinasas/química , Proteínas Proto-Oncogénicas B-raf/antagonistas & inhibidores , Sustitución de Aminoácidos , Animales , Sitios de Unión , Línea Celular Tumoral , Cristalografía por Rayos X , Humanos , Indazoles/química , Ratones , Microsomas Hepáticos/metabolismo , Mutación , Oximas/química , Inhibidores de Proteínas Quinasas/síntesis química , Inhibidores de Proteínas Quinasas/farmacocinética , Proteínas Proto-Oncogénicas B-raf/genética , Proteínas Proto-Oncogénicas B-raf/metabolismo , Pirazoles/química , Relación Estructura-ActividadRESUMEN
Virtual and high-throughput screening identified imidazo[1,2-a]pyrazines as inhibitors of B-Raf. We describe the rationale, SAR, and evolution of the initial hits to a series of furo[2,3-c]pyridine indanone oximes as highly potent and selective inhibitors of B-Raf.
Asunto(s)
Indanos/química , Oximas/química , Inhibidores de Proteínas Quinasas/química , Proteínas Proto-Oncogénicas B-raf/antagonistas & inhibidores , Piridinas/química , Animales , Sitios de Unión , Línea Celular Tumoral , Simulación por Computador , Evaluación Preclínica de Medicamentos , Humanos , Indanos/síntesis química , Indanos/farmacocinética , Microsomas Hepáticos/metabolismo , Modelos Químicos , Modelos Moleculares , Oximas/síntesis química , Oximas/farmacocinética , Inhibidores de Proteínas Quinasas/síntesis química , Inhibidores de Proteínas Quinasas/farmacocinética , Proteínas Proto-Oncogénicas B-raf/metabolismo , Ratas , Relación Estructura-ActividadRESUMEN
The synthesis and biological evaluation of non-oxime pyrazole based B-Raf inhibitors is reported. Several oxime replacements have been prepared and have shown excellent enzyme activity. Further optimization of fused pyrazole 2a led to compound 38, a selective and potent B-Raf inhibitor.
Asunto(s)
Inhibidores Enzimáticos/farmacología , Proteínas Proto-Oncogénicas B-raf/antagonistas & inhibidores , Pirazoles/síntesis química , Pirazoles/farmacología , Animales , Cristalografía por Rayos X , Relación Dosis-Respuesta a Droga , Activación Enzimática/efectos de los fármacos , Inhibidores Enzimáticos/síntesis química , Inhibidores Enzimáticos/química , Concentración 50 Inhibidora , Ratones , Estructura Molecular , Oximas/química , Pirazoles/químicaRESUMEN
A novel series of spirochromane pan-Akt inhibitors is reported. SAR optimization furnished compounds with improved enzyme potencies and excellent selectivity over the related AGC kinase PKA. Attempted replacement of the phenol hinge binder provided compounds with excellent Akt enzyme and cell activities but greatly diminished selectivity over PKA.
Asunto(s)
Inhibidores de Proteínas Quinasas/química , Proteínas Proto-Oncogénicas c-akt/antagonistas & inhibidores , Sitios de Unión , Cristalografía por Rayos X , Evaluación Preclínica de Medicamentos , Inhibidores de Proteínas Quinasas/síntesis química , Inhibidores de Proteínas Quinasas/farmacología , Proteínas Proto-Oncogénicas c-akt/metabolismo , Relación Estructura-ActividadRESUMEN
We describe the design and synthesis of novel bicyclic spiro sulfonamides as potent Akt inhibitors. Through structure-based rational design, we have successfully improved PKA selectivity of previously disclosed spirochromanes. Representative compounds showed favorable Akt potency while exhibiting up to 1000-fold selectivity against PKA.
Asunto(s)
Proteínas Quinasas Dependientes de AMP Cíclico/antagonistas & inhibidores , Inhibidores de Proteínas Quinasas/química , Proteínas Proto-Oncogénicas c-akt/antagonistas & inhibidores , Compuestos de Espiro/química , Sulfonamidas/química , Sitios de Unión , Simulación por Computador , Cristalografía por Rayos X , Proteínas Quinasas Dependientes de AMP Cíclico/metabolismo , Evaluación Preclínica de Medicamentos , Inhibidores de Proteínas Quinasas/síntesis química , Inhibidores de Proteínas Quinasas/farmacología , Proteínas Proto-Oncogénicas c-akt/metabolismo , Relación Estructura-Actividad , Sulfonamidas/síntesis química , Sulfonamidas/farmacologíaRESUMEN
The discovery and optimization of a series of pyrrolopyrimidine based protein kinase B (Pkb/Akt) inhibitors discovered via HTS and structure based drug design is reported. The compounds demonstrate potent inhibition of all three Akt isoforms and knockdown of phospho-PRAS40 levels in LNCaP cells and tumor xenografts.
Asunto(s)
Inhibidores de Proteínas Quinasas/química , Proteínas Proto-Oncogénicas c-akt/antagonistas & inhibidores , Pirimidinas/química , Pirroles/química , Proteínas Adaptadoras Transductoras de Señales , Animales , Sitios de Unión , Línea Celular , Cristalografía por Rayos X , Diseño de Fármacos , Evaluación Preclínica de Medicamentos , Ensayos Analíticos de Alto Rendimiento , Humanos , Ratones , Fosfoproteínas/deficiencia , Fosfoproteínas/genética , Fosfoproteínas/metabolismo , Isoformas de Proteínas/antagonistas & inhibidores , Isoformas de Proteínas/metabolismo , Inhibidores de Proteínas Quinasas/síntesis química , Inhibidores de Proteínas Quinasas/farmacología , Estructura Terciaria de Proteína , Proteínas Proto-Oncogénicas c-akt/metabolismo , Pirimidinas/síntesis química , Pirimidinas/farmacología , Pirroles/síntesis química , Pirroles/farmacología , Relación Estructura-Actividad , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Herein we report the discovery and synthesis of a novel series of dihydrothieno- and dihydrofuropyrimidines (2 and 3) as potent pan Akt inhibitors. Utilizing previous SAR and analysis of the amino acid sequences in the binding site we have designed inhibitors displaying increased PKA and general kinase selectivity with improved tolerability compared to the progenitor pyrrolopyrimidine (1). A representative dihydrothieno compound (34) was advanced into a PC3-NCI prostate mouse tumor model in which it demonstrated a dose-dependent reduction in tumor growth and stasis when dosed orally daily at 200 mg/kg.
Asunto(s)
Neoplasias de la Próstata/tratamiento farmacológico , Inhibidores de Proteínas Quinasas/química , Proteínas Proto-Oncogénicas c-akt/antagonistas & inhibidores , Pirimidinas/química , Animales , Sitios de Unión , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Masculino , Ratones , Inhibidores de Proteínas Quinasas/farmacología , Pirimidinas/farmacología , Relación Estructura-Actividad , Carga Tumoral/efectos de los fármacosRESUMEN
INTRODUCTION: Novel rearranged in transfection (RET)-specific tyrosine kinase inhibitors (TKIs) such as selpercatinib (LOXO-292) have shown unprecedented efficacy in tumors positive for RET fusions or mutations, notably RET fusion-positive NSCLC and RET-mutated medullary thyroid cancer (MTC). However, the mechanisms of resistance to these agents have not yet been described. METHODS: Analysis was performed of circulating tumor DNA and tissue in patients with RET fusion-positive NSCLC and RET-mutation positive MTC who developed disease progression after an initial response to selpercatinib. Acquired resistance was modeled preclinically using a CCDC6-RET fusion-positive NSCLC patient-derived xenograft. The inhibitory activity of anti-RET multikinase inhibitors and selective RET TKIs was evaluated in enzyme and cell-based assays. RESULTS: After a dramatic initial response to selpercatinib in a patient with KIF5B-RET NSCLC, analysis of circulating tumor DNA revealed emergence of RET G810R, G810S, and G810C mutations in the RET solvent front before the emergence of clinical resistance. Postmortem biopsy studies reported intratumor and intertumor heterogeneity with distinct disease subclones containing G810S, G810R, and G810C mutations in multiple disease sites indicative of convergent evolution on the G810 residue resulting in a common mechanism of resistance. Acquired mutations in RET G810 were identified in tumor tissue from a second patient with CCDC6-RET fusion-positive NSCLC and in plasma from patients with additional RET fusion-positive NSCLC and RET-mutant MTC progressing on an ongoing phase 1 and 2 trial of selpercatinib. Preclinical studies reported the presence of RET G810R mutations in a CCDC6-RET patient-derived xenograft (from a patient with NSCLC) model of acquired resistance to selpercatinib. Structural modeling predicted that these mutations sterically hinder the binding of selpercatinib, and in vitro assays confirmed loss of activity for both anti-RET multikinase inhibitors and selective RET TKIs. CONCLUSIONS: RET G810 solvent front mutations represent the first described recurrent mechanism of resistance to selective RET inhibition with selpercatinib. Development of potent inhibitor of these mutations and maintaining activity against RET gatekeeper mutations could be an effective strategy to target resistance to selective RET inhibitors.
Asunto(s)
Neoplasias Pulmonares , Proteínas Proto-Oncogénicas c-ret , Humanos , Neoplasias Pulmonares/tratamiento farmacológico , Neoplasias Pulmonares/genética , Mutación , Inhibidores de Proteínas Quinasas/farmacología , Inhibidores de Proteínas Quinasas/uso terapéutico , Proteínas Proto-Oncogénicas c-ret/genética , Pirazoles , Piridinas , Solventes , TransfecciónRESUMEN
The protease activity of hepatitis C virus nonstructural protein 3 (NS3) is essential for viral replication. ITMN-191, a macrocyclic inhibitor of the NS3 protease active site, promotes rapid, multilog viral load reductions in chronic HCV patients. Here, ITMN-191 is shown to be a potent inhibitor of NS3 with a two-step binding mechanism. Progress curves are consistent with the formation of an initial collision complex (EI) that isomerizes to a highly stable complex (EI*) from which ITMN-191 dissociates very slowly. K(i), the dissociation constant of EI, is 100 nM, and the rate constant for conversion of EI to EI* is 6.2 x 10(-2) s(-1). Binding experiments using protein fluorescence confirm this isomerization rate. From progress curve analysis, the rate constant for dissociation of ITMN-191 from the EI* complex is 3.8 x 10(-5) s(-1) with a calculated complex half-life of approximately 5 h and a true biochemical potency (K(i)*) of approximately 62 pM. Surface plasmon resonance studies and assessment of enzyme reactivation following dilution of the EI* complex confirm slow dissociation and suggest that the half-life may be considerably longer. Abrogation of the tight binding and slow dissociative properties of ITMN-191 is observed with proteases that carry the R155K or D168A substitution, each of which is likely in drug resistant mutants. Slow dissociation is not observed with closely related macrocyclic inhibitors of NS3, suggesting that members of this class may display distinct binding kinetics.
Asunto(s)
Hepacivirus/enzimología , Inhibidores de Proteasas/química , Proteínas no Estructurales Virales/antagonistas & inhibidores , Proteínas no Estructurales Virales/química , Sustitución de Aminoácidos , Hepacivirus/química , Hepacivirus/genética , Cinética , Inhibidores de Proteasas/síntesis química , Unión Proteica , Proteínas no Estructurales Virales/genética , Proteínas no Estructurales Virales/metabolismoRESUMEN
Herein we describe a novel pyrazole-based class of ATP competitive B-Raf inhibitors. These inhibitors exhibit both excellent cellular potency and striking B-Raf selectivity. A subset of these inhibitors has demonstrated the ability to inhibit downstream ERK phosphorylation in LOX tumors from mouse xenograft studies.
Asunto(s)
Química Farmacéutica/métodos , Inhibidores de Proteínas Quinasas/síntesis química , Inhibidores de Proteínas Quinasas/farmacología , Proteínas Proto-Oncogénicas B-raf/antagonistas & inhibidores , Proteínas Proto-Oncogénicas B-raf/química , Pirazoles/química , Quinasas raf/antagonistas & inhibidores , Quinasas raf/química , Animales , Línea Celular Tumoral , Cristalografía por Rayos X/métodos , Diseño de Fármacos , Humanos , Concentración 50 Inhibidora , Ratones , Modelos Químicos , Trasplante de Neoplasias , FosforilaciónRESUMEN
PURPOSE: The Ras-Raf-mitogen-activated protein kinase kinase (MEK) pathway is overactive in many human cancers and is thus a target for novel therapeutics. We have developed a highly potent and selective inhibitor of MEK1/2. The purpose of these studies has been to show the biological efficacy of ARRY-142886 (AZD6244) in enzymatic, cellular, and animal models. EXPERIMENTAL DESIGN: The ability of ARRY-142886 to inhibit purified MEK1 as well as other kinases was evaluated. Its effects on extracellular signal-regulated kinase (ERK) phosphorylation and proliferation in several cell lines were also determined. Finally, the inhibitor was tested in HT-29 (colorectal) and BxPC3 (pancreatic) xenograft tumor models. RESULTS: The IC(50) of ARRY-142886 was determined to be 14 nmol/L against purified MEK1. This activity is not competitive with ATP, which is consistent with the high specificity of compound for MEK1/2. Basal and epidermal growth factor-induced ERK1/2 phosphorylation was inhibited in several cell lines as well as 12-O-tetradecanoylphorbol-13-acetate-induced ERK1/2 phosphorylation in isolated peripheral blood mononuclear cells. Treatment with ARRY-142886 resulted in the growth inhibition of several cell lines containing B-Raf and Ras mutations but had no effect on a normal fibroblast cell line. When dosed orally, ARRY-142886 was capable of inhibiting both ERK1/2 phosphorylation and growth of HT-29 xenograft tumors in nude mice. Tumor regressions were also seen in a BxPC3 xenograft model. In addition, tumors remained responsive to growth inhibition after a 7-day dosing holiday. CONCLUSIONS: ARRY-142886 is a potent and selective MEK1/2 inhibitor that is highly active in both in vitro and in vivo tumor models. This compound is currently being investigated in clinical studies.
Asunto(s)
Bencimidazoles/farmacología , Inhibidores Enzimáticos/farmacología , MAP Quinasa Quinasa 1/efectos de los fármacos , MAP Quinasa Quinasa 2/efectos de los fármacos , Animales , Western Blotting , Proliferación Celular/efectos de los fármacos , Humanos , Concentración 50 Inhibidora , Ratones , Proteína Quinasa 3 Activada por Mitógenos/efectos de los fármacos , Fosforilación/efectos de los fármacos , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
KRAS is the most frequently mutated driver oncogene in human cancer, and KRAS mutations are commonly associated with poor prognosis and resistance to standard treatment. The ability to effectively target and block the function of mutated KRAS has remained elusive despite decades of research. Recent findings have demonstrated that directly targeting KRAS-G12C with electrophilic small molecules that covalently modify the mutated codon 12 cysteine is feasible. We have discovered a series of tetrahydropyridopyrimidines as irreversible covalent inhibitors of KRAS-G12C with in vivo activity. The PK/PD and efficacy of compound 13 will be highlighted.
RESUMEN
Larotrectinib, a selective TRK tyrosine kinase inhibitor (TKI), has demonstrated histology-agnostic efficacy in patients with TRK fusion-positive cancers. Although responses to TRK inhibition can be dramatic and durable, duration of response may eventually be limited by acquired resistance. LOXO-195 is a selective TRK TKI designed to overcome acquired resistance mediated by recurrent kinase domain (solvent front and xDFG) mutations identified in multiple patients who have developed resistance to TRK TKIs. Activity against these acquired mutations was confirmed in enzyme and cell-based assays and in vivo tumor models. As clinical proof of concept, the first 2 patients with TRK fusion-positive cancers who developed acquired resistance mutations on larotrectinib were treated with LOXO-195 on a first-in-human basis, utilizing rapid dose titration guided by pharmacokinetic assessments. This approach led to rapid tumor responses and extended the overall duration of disease control achieved with TRK inhibition in both patients.Significance: LOXO-195 abrogated resistance in TRK fusion-positive cancers that acquired kinase domain mutations, a shared liability with all existing TRK TKIs. This establishes a role for sequential treatment by demonstrating continued TRK dependence and validates a paradigm for the accelerated development of next-generation inhibitors against validated oncogenic targets. Cancer Discov; 7(9); 963-72. ©2017 AACR.See related commentary by Parikh and Corcoran, p. 934This article is highlighted in the In This Issue feature, p. 920.