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Optimization of the ADME properties and pharmacokinetic (PK) profile of compounds is one of the critical activities in any medicinal chemistry campaign to discover a future clinical candidate. Finding ways to expedite the process to address ADME/PK shortcomings and reduce the number of compounds to synthesize is highly valuable. This article provides practical guidelines and a case study on the use of ML ADME models to guide compound design in small molecule lead optimization. These guidelines highlight that ML models cannot have an impact in a vacuum: they help advance a program when they have the trust of users, are tuned to the needs of the program, and are integrated into decision-making processes in a way that complements and augments the expertise of chemists.
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Alterations in the RAS-MAPK signaling cascade are common across multiple solid tumor types and are a driver for many cancers. NST-628 is a potent pan-RAF-MEK molecular glue that prevents the phosphorylation and activation of MEK by RAF, overcoming the limitations of traditional RAS-MAPK inhibitors and leading to deep durable inhibition of the pathway. Cellular, biochemical, and structural analyses of RAF-MEK complexes show that NST-628 engages all isoforms of RAF and prevents the formation of BRAF-CRAF heterodimers, a differentiated mechanism from all current RAF inhibitors. With a potent and durable inhibition of the RAF-MEK signaling complex as well as high intrinsic permeability into the brain, NST-628 demonstrates broad efficacy in cellular and patient-derived tumor models harboring diverse MAPK pathway alterations, including orthotopic intracranial models. Given its functional and pharmacokinetic mechanisms that are differentiated from previous therapies, NST-628 is positioned to make an impact clinically in areas of unmet patient need. Significance: This study introduces NST-628, a molecular glue having differentiated mechanism and drug-like properties. NST-628 treatment leads to broad efficacy with high tolerability and central nervous system activity across multiple RAS- and RAF-driven tumor models. NST-628 has the potential to provide transformative clinical benefits as both monotherapy and vertical combination anchor.
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Sistema de Señalización de MAP Quinasas , Neoplasias , Inhibidores de Proteínas Quinasas , Humanos , Animales , Ratones , Inhibidores de Proteínas Quinasas/farmacología , Inhibidores de Proteínas Quinasas/uso terapéutico , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Neoplasias/tratamiento farmacológico , Neoplasias/metabolismo , Quinasas raf/metabolismo , Quinasas raf/antagonistas & inhibidores , Línea Celular Tumoral , Proteínas ras/metabolismo , Ensayos Antitumor por Modelo de Xenoinjerto , Encéfalo/metabolismo , Encéfalo/efectos de los fármacos , Quinasas de Proteína Quinasa Activadas por Mitógenos/antagonistas & inhibidores , Quinasas de Proteína Quinasa Activadas por Mitógenos/metabolismoRESUMEN
Background and Aims: Fibrolamellar carcinoma (FLC) is a rare, difficult-to-treat liver cancer primarily affecting pediatric and adolescent patients, and for which precision medicine approaches have historically not been possible. The DNAJB1-PRKACA gene fusion was identified as a driver of FLC pathogenesis. We aimed to assess whether FLC tumors maintain dependency on this gene fusion and determine if PRKACA is a viable therapeutic target. Methods: FLC patient-derived xenograft (PDX) shRNA cell lines were implanted subcutaneously into female NOD-SCID mice and tumors were allowed to develop prior to randomization to doxycycline (to induce knockdown) or control groups. Tumor development was assessed every 2 days. To assess the effect of treatment with novel selective PRKACA small molecule kinase inhibitors, BLU0588 and BLU2864, FLC PDX tumor cells were implanted subcutaneously into NOD-SCID mice and tumors allowed to develop. Mice were randomized to treatment (BLU0588 and BLU2864, orally, once daily) or control groups and tumor size determined as previously. Results: Knockdown of DNAJB1-PRKACA reversed a FLC-specific gene signature and reduced PDX tumor growth in mice compared to the control group. Furthermore, FLC PDX tumor growth was significantly reduced with BLU0588 and BLU2864 treatment vs control (P = .003 and P = .0005, respectively). Conclusion: We demonstrated, using an inducible knockdown and small molecule approaches, that FLC PDX tumors were dependent upon DNAJB1-PRKACA fusion activity. In addition, this study serves as a proof-of-concept that PRKACA is a viable therapeutic target for FLC and warrants further investigation.
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BACKGROUND: Upregulation of cAMP-dependent and cAMP-independent PKA signaling is thought to promote cystogenesis in polycystic kidney disease (PKD). PKA-I regulatory subunit RIα is increased in kidneys of orthologous mouse models. Kidney-specific knockout of RIα upregulates PKA activity, induces cystic disease in wild-type mice, and aggravates it in Pkd1RC/RC mice. METHODS: PKA-I activation or inhibition was compared with EPAC activation or PKA-II inhibition using Pkd1RC/RC metanephric organ cultures. The effect of constitutive PKA (preferentially PKA-I) downregulation in vivo was ascertained by kidney-specific expression of a dominant negative RIαB allele in Pkd1RC/RC mice obtained by crossing Prkar1αR1αB/WT, Pkd1RC/RC , and Pkhd1-Cre mice (C57BL/6 background). The effect of pharmacologic PKA inhibition using a novel, selective PRKACA inhibitor (BLU2864) was tested in mIMCD3 3D cultures, metanephric organ cultures, and Pkd1RC/RC mice on a C57BL/6 × 129S6/Sv F1 background. Mice were sacrificed at 16 weeks of age. RESULTS: PKA-I activation promoted and inhibition prevented ex vivo P-Ser133 CREB expression and cystogenesis. EPAC activation or PKA-II inhibition had no or only minor effects. BLU2864 inhibited in vitro mIMCD3 cystogenesis and ex vivo P-Ser133 CREB expression and cystogenesis. Genetic downregulation of PKA activity and BLU2864 directly and/or indirectly inhibited many pro-proliferative pathways and were both protective in vivo. BLU2864 had no detectable on- or off-target adverse effects. CONCLUSIONS: PKA-I is the main PKA isozyme promoting cystogenesis. Direct PKA inhibition may be an effective strategy to treat PKD and other conditions where PKA signaling is upregulated. By acting directly on PKA, the inhibition may be more effective than or substantially increase the efficacy of treatments that only affect PKA activity by lowering cAMP.
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Riñón Poliquístico Autosómico Dominante , Riñón Poliquístico Autosómico Recesivo , Animales , Proteínas Quinasas Dependientes de AMP Cíclico/metabolismo , Modelos Animales de Enfermedad , Regulación hacia Abajo , Factores de Intercambio de Guanina Nucleótido/genética , Factores de Intercambio de Guanina Nucleótido/metabolismo , Factores de Intercambio de Guanina Nucleótido/farmacología , Riñón/metabolismo , Ratones , Ratones Endogámicos C57BL , Enfermedades Renales Poliquísticas , Riñón Poliquístico Autosómico Dominante/metabolismo , Receptores de Superficie Celular/genética , Canales Catiónicos TRPP/genética , Canales Catiónicos TRPP/metabolismoRESUMEN
Hepatocellular carcinoma (HCC) is a leading cause of cancer mortality worldwide with no clinically confirmed oncogenic driver. Although preclinical studies implicate the FGF19 receptor FGFR4 in hepatocarcinogenesis, the dependence of human cancer on FGFR4 has not been demonstrated. Fisogatinib (BLU-554) is a potent and selective inhibitor of FGFR4 and demonstrates clinical benefit and tumor regression in patients with HCC with aberrant FGF19 expression. Mutations were identified in the gatekeeper and hinge-1 residues in the kinase domain of FGFR4 upon disease progression in 2 patients treated with fisogatinib, which were confirmed to mediate resistance in vitro and in vivo. A gatekeeper-agnostic, pan-FGFR inhibitor decreased HCC xenograft growth in the presence of these mutations, demonstrating continued FGF19-FGFR4 pathway dependence. These results validate FGFR4 as an oncogenic driver and warrant further therapeutic targeting of this kinase in the clinic. SIGNIFICANCE: Our study is the first to demonstrate on-target FGFR4 kinase domain mutations as a mechanism of acquired clinical resistance to targeted therapy. This further establishes FGF19-FGFR4 pathway activation as an oncogenic driver. These findings support further investigation of fisogatinib in HCC and inform the profile of potential next-generation inhibitors.See related commentary by Subbiah and Pal, p. 1646.This article is highlighted in the In This Issue feature, p. 1631.
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Carcinoma Hepatocelular/diagnóstico por imagen , Resistencia a Antineoplásicos , Neoplasias Hepáticas/diagnóstico por imagen , Piranos/farmacología , Quinazolinas/farmacología , Receptor Tipo 4 de Factor de Crecimiento de Fibroblastos/genética , Anciano de 80 o más Años , Animales , Carcinoma Hepatocelular/tratamiento farmacológico , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/metabolismo , Línea Celular Tumoral , Femenino , Factores de Crecimiento de Fibroblastos/metabolismo , Regulación Neoplásica de la Expresión Génica , Humanos , Neoplasias Hepáticas/tratamiento farmacológico , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/metabolismo , Masculino , Ratones , Persona de Mediana Edad , Modelos Moleculares , Mutación , Trasplante de Neoplasias , Dominios Proteicos , Receptor Tipo 4 de Factor de Crecimiento de Fibroblastos/química , Receptor Tipo 4 de Factor de Crecimiento de Fibroblastos/metabolismoRESUMEN
Outcomes for patients with advanced hepatocellular carcinoma (HCC) remain poor despite recent progress in drug development. Emerging data implicate FGF19 as a potential HCC driver, suggesting its receptor, FGFR4, as a novel therapeutic target. We evaluated fisogatinib (BLU-554), a highly potent and selective oral FGFR4 inhibitor, in a phase I dose-escalation/dose-expansion study in advanced HCC using FGF19 expression measured by IHC as a biomarker for pathway activation. For dose escalation, 25 patients received 140 to 900 mg fisogatinib once daily; the maximum tolerated dose (600 mg once daily) was expanded in 81 patients. Fisogatinib was well tolerated; most adverse events were manageable, grade 1/2 gastrointestinal events, primarily diarrhea, nausea, and vomiting. Across doses, the overall response rate was 17% in FGF19-positive patients [median duration of response: 5.3 months (95% CI, 3.7-not reached)] and 0% in FGF19-negative patients. These results validate FGFR4 as a targetable driver in FGF19-positive advanced HCC. SIGNIFICANCE: Fisogatinib elicited clinical responses in patients with tumor FGF19 overexpression in advanced HCC. These results validate the oncogenic driver role of the FGFR4 pathway in HCC and the use of FGF19 as a biomarker for patient selection.See related commentary by Subbiah and Pal, p. 1646.This article is highlighted in the In This Issue feature, p. 1631.
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Carcinoma Hepatocelular/tratamiento farmacológico , Factores de Crecimiento de Fibroblastos/metabolismo , Neoplasias Hepáticas/tratamiento farmacológico , Piranos/administración & dosificación , Quinazolinas/administración & dosificación , Adulto , Anciano , Anciano de 80 o más Años , Biomarcadores de Tumor/metabolismo , Carcinoma Hepatocelular/metabolismo , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Esquema de Medicación , Femenino , Humanos , Neoplasias Hepáticas/metabolismo , Masculino , Persona de Mediana Edad , Piranos/efectos adversos , Quinazolinas/efectos adversos , Receptor Tipo 4 de Factor de Crecimiento de Fibroblastos/antagonistas & inhibidores , Transducción de Señal/efectos de los fármacos , Resultado del Tratamiento , Adulto JovenRESUMEN
The interconnected PI3K and MAPK signaling pathways are commonly perturbed in cancer. Dual inhibition of these pathways by the small-molecule PI3K inhibitor pictilisib (GDC-0941) and the MEK inhibitor cobimetinib (GDC-0973) suppresses cell proliferation and induces cell death better than either single agent in several preclinical models. Using mass spectrometry-based phosphoproteomics, we have identified the RING finger E3 ubiquitin ligase RNF157 as a target at the intersection of PI3K and MAPK signaling. We demonstrate that RNF157 phosphorylation downstream of the PI3K and MAPK pathways influences the ubiquitination and stability of RNF157 during the cell cycle in an anaphase-promoting complex/cyclosome-CDH1-dependent manner. Deletion of these phosphorylation-targeted residues on RNF157 disrupts binding to CDH1 and protects RNF157 from ubiquitination and degradation. Expression of the cyclin-dependent kinase 2 (CDK2), itself a downstream target of PI3K/MAPK signaling, leads to increased phosphorylation of RNF157 on the same residues modulated by PI3K and MAPK signaling. Inhibition of PI3K and MEK in combination or of CDK2 by their respective small-molecule inhibitors reduces RNF157 phosphorylation at these residues and attenuates RNF157 interaction with CDH1 and its subsequent degradation. Knockdown of endogenous RNF157 in melanoma cells leads to late S phase and G2/M arrest and induces apoptosis, the latter further potentiated by concurrent PI3K/MEK inhibition, consistent with a role for RNF157 in the cell cycle. We propose that RNF157 serves as a novel node integrating oncogenic signaling pathways with the cell cycle machinery and promoting optimal cell cycle progression in transformed cells.
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Apoptosis , Sistema de Señalización de MAP Quinasas , Melanoma/metabolismo , Fosfatidilinositol 3-Quinasa/metabolismo , Procesamiento Proteico-Postraduccional , Transducción de Señal , Ubiquitina-Proteína Ligasas/metabolismo , Sustitución de Aminoácidos , Antígenos CD , Apoptosis/efectos de los fármacos , Cadherinas/antagonistas & inhibidores , Cadherinas/genética , Cadherinas/metabolismo , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Quinasa 2 Dependiente de la Ciclina/antagonistas & inhibidores , Quinasa 2 Dependiente de la Ciclina/genética , Quinasa 2 Dependiente de la Ciclina/metabolismo , Inhibidores Enzimáticos/farmacología , Estabilidad de Enzimas/efectos de los fármacos , Eliminación de Gen , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Humanos , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Melanoma/tratamiento farmacológico , Melanoma/enzimología , Melanoma/patología , Proteínas de Neoplasias/antagonistas & inhibidores , Proteínas de Neoplasias/química , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Inhibidores de las Quinasa Fosfoinosítidos-3 , Fosforilación/efectos de los fármacos , Mutación Puntual , Procesamiento Proteico-Postraduccional/efectos de los fármacos , Interferencia de ARN , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/metabolismo , Fase S/efectos de los fármacos , Transducción de Señal/efectos de los fármacos , Ubiquitina-Proteína Ligasas/antagonistas & inhibidores , Ubiquitina-Proteína Ligasas/química , Ubiquitina-Proteína Ligasas/genética , Ubiquitinación/efectos de los fármacosRESUMEN
BACKGROUND: The fibroblast growth factor receptor 4 (FGFR4) pathway is an essential regulatory component of bile acid synthesis, and its relationship with hepatocellular carcinoma (HCC) has been reported. We investigated the gene expression and clinical significance of FGFR4 and related pathways in intrahepatic cholangiocarcinoma (iCCA). RESULTS: The median age was 56 years (range 30-78) and 34 patients (74%) were male. Six patients (13%) had hepatitis B virus infection, with or without liver cirrhosis. Overall survival was significantly associated with FGFR4 (p = 0.004), FGF19 (p = 0.047), FGF21 (p = 0.04), and KLB (p = 0.03) expression. In the multivariate analysis with potential prognostic factors, high expression of FGF19, FGF21, and FGFR4 was significantly associated with better survival. In the analysis using the TCGA iCCA dataset, mRNA overexpression of at least 1 of the FGFR4-related genes was significantly associated with better disease-free survival (p = 0.02). MATERIALS AND METHODS: We assessed the expression of 98 genes in formalin-fixed paraffin embedded tumor tissue specimens from 46 patients with surgically resected iCCA using a NanoString platform. This included 10 FGF pathway genes (e.g. FGFR1-4, KLB, FGF3, 4, 19, 21, and 23), 19 distal marker genes (e.g. CYP7A1 and CYP17A1), 31 genes relevant to HCC and iCCA (e.g. AFP, TS), 18 copy number variation matched genes, and 20 control genes. Log-transformation of gene expression was performed for normalization and statistical analysis. Overall survival was correlated with gene expression (< median vs. ≥ median) using a log-rank test. The prognostic impact of FGFR4-related genes was validated using the public TCGA dataset for iCCA. CONCLUSIONS: Our results indicate that mRNA expression of FGFR4-related genes may be a biomarker to define the distinctive molecular phenotype of iCCA. Future preclinical and clinical validation is required to define the role of the FGFR4 pathway in iCCA.
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Neoplasias de los Conductos Biliares/patología , Biomarcadores de Tumor/análisis , Colangiocarcinoma/patología , Receptor Tipo 4 de Factor de Crecimiento de Fibroblastos/biosíntesis , Adulto , Anciano , Neoplasias de los Conductos Biliares/mortalidad , Colangiocarcinoma/mortalidad , Supervivencia sin Enfermedad , Femenino , Perfilación de la Expresión Génica , Humanos , Estimación de Kaplan-Meier , Masculino , Persona de Mediana Edad , Receptor Tipo 4 de Factor de Crecimiento de Fibroblastos/análisis , TranscriptomaRESUMEN
Letrozole is a commonly used treatment option for metastatic hormone receptor-positive (HR+) breast cancer, but many patients ultimately relapse. Due to the importance of phosphoinositide-3 kinase (PI3K) in breast cancer, PI3K inhibitors such as taselisib are attractive for combination with endocrine therapies such as letrozole. Taselisib was evaluated as a single agent and in combination with letrozole in a breast cancer cell line engineered to express aromatase. The combination of taselisib and letrozole decreased cellular viability and increased apoptosis relative to either single agent. Signaling cross-talk between the PI3K and ER pathways was associated with efficacy for the combination. In a secreted factor screen, multiple soluble factors, including members of the epidermal and fibroblast growth factor families, rendered breast cancer cells non-responsive to letrozole. It was discovered that many of these factors signal through the PI3K pathway and cells remained sensitive to taselisib in the presence of the soluble factors. We also found that letrozole resistant lines have elevated PI3K pathway signaling due to an increased level of p110α, but are still sensitive to taselisib. These data provide rationale for clinical evaluation of PI3K inhibitors to overcome resistance to endocrine therapies in ER+ breast cancer.
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A series of 4-azaindole-containing p21-activated kinase-1 (PAK1) inhibitors was prepared with the goal of improving physicochemical properties relative to an indole starting point. Indole 1 represented an attractive, non-basic scaffold with good PAK1 affinity and cellular potency but was compromised by high lipophilicity (clogD=4.4). Azaindole 5 was designed as an indole surrogate with the goal of lowering logD and resulted in equipotent PAK1 inhibition with a 2-fold improvement in cellular potency over 1. Structure-activity relationship studies around 5 identified additional 4-azaindole analogs with superior PAK1 biochemical activity (Ki <10nM) and up to 24-fold selectivity for group I over group II PAKs. Compounds from this series showed enhanced permeability, improved aqueous solubility, and lower plasma protein binding over indole 1. The improvement in physicochemical properties translated to a 20-fold decrease in unbound clearance in mouse PK studies for azaindole 5 relative to indole 1.
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Indoles/farmacología , Inhibidores de Proteínas Quinasas/farmacología , Quinasas p21 Activadas/antagonistas & inhibidores , Animales , Perros , Relación Dosis-Respuesta a Droga , Humanos , Indoles/síntesis química , Indoles/química , Células de Riñón Canino Madin Darby , Ratones , Ratones Desnudos , Modelos Moleculares , Estructura Molecular , Inhibidores de Proteínas Quinasas/síntesis química , Inhibidores de Proteínas Quinasas/química , Relación Estructura-Actividad , Quinasas p21 Activadas/metabolismoRESUMEN
p21-activated kinase 1 (PAK1) has an important role in transducing signals in several oncogenic pathways. The concept of inhibiting this kinase has garnered significant interest over the past decade, particularly for targeting cancers associated with PAK1 amplification. Animal studies with the selective group I PAK (pan-PAK1, 2, 3) inhibitor G-5555 from the pyrido[2,3-d]pyrimidin-7-one class uncovered acute toxicity with a narrow therapeutic window. To attempt mitigating the toxicity, we introduced significant structural changes, culminating in the discovery of the potent pyridone side chain analogue G-9791. Mouse tolerability studies with this compound, other members of this series, and compounds from two structurally distinct classes revealed persistent toxicity and a correlation of minimum toxic concentrations and PAK1/2 mediated cellular potencies. Broad screening of selected PAK inhibitors revealed PAK1, 2, and 3 as the only overlapping targets. Our data suggest acute cardiovascular toxicity resulting from the inhibition of PAK2, which may be enhanced by PAK1 inhibition, and cautions against continued pursuit of pan-group I PAK inhibitors in drug discovery.
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Enfermedades Cardiovasculares/tratamiento farmacológico , Inhibidores de Proteínas Quinasas/farmacología , Piridinas/farmacología , Pirimidinas/farmacología , Quinasas p21 Activadas/antagonistas & inhibidores , Enfermedad Aguda , Animales , Relación Dosis-Respuesta a Droga , Femenino , Ratones , Ratones Endogámicos BALB C , Estructura Molecular , Inhibidores de Proteínas Quinasas/síntesis química , Inhibidores de Proteínas Quinasas/química , Piridinas/síntesis química , Piridinas/química , Piridonas , Pirimidinas/síntesis química , Pirimidinas/química , Relación Estructura-Actividad , Quinasas p21 Activadas/metabolismoRESUMEN
Signaling pathways intersecting with the p21-activated kinases (PAKs) play important roles in tumorigenesis and cancer progression. By recognizing that the limitations of FRAX1036 (1) were chiefly associated with the highly basic amine it contained, we devised a mitigation strategy to address several issues such as hERG activity. The 5-amino-1,3-dioxanyl moiety was identified as an effective means of reducing pK a and logP simultaneously. When positioned properly within the scaffold, this group conferred several benefits including potency, pharmacokinetics, and selectivity. Mouse xenograft PK/PD studies were carried out using an advanced compound, G-5555 (12), derived from this approach. These studies concluded that dose-dependent pathway modulation was achievable and paves the way for further in vivo investigations of PAK1 function in cancer and other diseases.
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p21-activated kinases (Paks) have been shown to regulate cytoskeleton rearrangements, cell proliferation, attachment, and migration in a variety of cellular contexts, including endothelial cells. However, the role of endothelial Pak in embryo development has not been reported, and currently, there is no consensus on the endothelial function of individual Pak isoforms, in particular p21-activated kinase 2 (Pak2), the main Pak isoform expressed in endothelial cells. In this work, we employ genetic and molecular studies that show that Pak2, but not Pak1, is a critical mediator of development and maintenance of endothelial cell function. Endothelial depletion of Pak2 leads to early embryo lethality due to flawed blood vessel formation in the embryo body and yolk sac. In adult endothelial cells, Pak2 depletion leads to severe apoptosis and acute angiogenesis defects, and in adult mice, endothelial Pak2 deletion leads to increased vascular permeability. Furthermore, ubiquitous Pak2 deletion is lethal in adult mice. We show that many of these defects are mediated through a newly unveiled Pak2/Bmk1 pathway. Our results demonstrate that endothelial Pak2 is essential during embryogenesis and also for adult blood vessel maintenance, and they also pinpoint the Bmk1/Erk5 pathway as a critical mediator of endothelial Pak2 signaling.
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Endotelio/embriología , Endotelio/metabolismo , Proteína Quinasa 7 Activada por Mitógenos/metabolismo , Transducción de Señal , Quinasas p21 Activadas/metabolismo , Animales , Permeabilidad Capilar , Anomalías Cardiovasculares/embriología , Anomalías Cardiovasculares/genética , Anomalías Cardiovasculares/metabolismo , Sistema Cardiovascular/embriología , Sistema Cardiovascular/metabolismo , Movimiento Celular , Proliferación Celular , Supervivencia Celular , Pérdida del Embrión , Embrión de Mamíferos/embriología , Embrión de Mamíferos/metabolismo , Endotelio/citología , Femenino , Eliminación de Gen , Regulación del Desarrollo de la Expresión Génica , Células Endoteliales de la Vena Umbilical Humana , Masculino , Ratones Endogámicos C57BL , Interferencia de ARN , Quinasas p21 Activadas/genéticaRESUMEN
The p21-activated kinases (PAKs) play important roles in cytoskeletal organization, cellular morphogenesis, and survival and have generated significant attention as potential therapeutic targets for cancer. Following a high-throughput screen, we identified an aminopyrazole scaffold-based series that was optimized to yield group I selective PAK inhibitors. A structure-based design effort aimed at targeting the ribose pocket for both potency and selectivity led to much-improved group I vs II selectivity. Early lead compounds contained a basic primary amine, which was found to be a major metabolic soft spot with in vivo clearance proceeding predominantly via N-acetylation. We succeeded in identifying replacements with improved metabolic stability, leading to compounds with lower in vivo rodent clearance and excellent group I PAK selectivity.
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Diseño de Fármacos , Inhibidores de Proteínas Quinasas/química , Inhibidores de Proteínas Quinasas/farmacología , Pirazoles/química , Pirazoles/farmacología , Quinasas p21 Activadas/antagonistas & inhibidores , Animales , Humanos , Ratones , Simulación del Acoplamiento Molecular , Inhibidores de Proteínas Quinasas/farmacocinética , Pirazoles/farmacocinética , Ratas , Quinasas p21 Activadas/química , Quinasas p21 Activadas/metabolismoRESUMEN
To increase kinase selectivity in an aminopyrazole-based PAK1 inhibitor series, analogues were designed to interact with the PAK1 deep-front pocket pre-DFG residue Thr-406, a residue that is hydrophobic in most kinases. This goal was achieved by installing lactam head groups to the aminopyrazole hinge binding moiety. The corresponding analogues represent the most kinase selective ATP-competitive Group I PAK inhibitors described to date. Hydrogen bonding with the Thr-406 side chain was demonstrated by X-ray crystallography, and inhibitory activities, particularly against kinases with hydrophobic pre-DFG residues, were mitigated. Leveraging hydrogen bonding side chain interactions with polar pre-DFG residues is unprecedented, and similar strategies should be applicable to other appropriate kinases.
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Kinase inhibitors have played an increasingly prominent role in the treatment of cancer and other diseases. Currently, more than 25 oncology drugs that target kinases have been approved, and numerous additional therapeutics are in various stages of clinical evaluation. In this Review, we provide an in-depth analysis of activation mechanisms for kinases in cancer, highlight recent successes in drug discovery, and demonstrate the clinical impact of selective kinase inhibitors. We also describe the substantial progress that has been made in designing next-generation inhibitors to circumvent on-target resistance mechanisms, as well as ongoing strategies for combining kinase inhibitors in the clinic. Last, there are numerous prospects for the discovery of novel kinase targets, and we explore cancer immunotherapy as a new and promising research area for studying kinase biology.
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Antineoplásicos/uso terapéutico , Terapia Molecular Dirigida/métodos , Proteínas de Neoplasias/antagonistas & inhibidores , Neoplasias/tratamiento farmacológico , Inhibidores de Proteínas Quinasas/uso terapéutico , Antineoplásicos/farmacología , Protocolos de Quimioterapia Combinada Antineoplásica/farmacología , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Apoptosis/efectos de los fármacos , Apoptosis/fisiología , Diseño de Fármacos , Resistencia a Antineoplásicos , Sinergismo Farmacológico , Activación Enzimática/efectos de los fármacos , Amplificación de Genes , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Fusión Génica , Humanos , Inmunoterapia/métodos , Proteínas de Neoplasias/genética , Neoplasias/enzimología , Neoplasias/genética , Proteínas de Fusión Oncogénica/antagonistas & inhibidores , Proteínas de Fusión Oncogénica/genética , Fosforilación/efectos de los fármacos , Mutación Puntual , Inhibidores de Proteínas Quinasas/farmacología , Procesamiento Proteico-Postraduccional/efectos de los fármacos , Transducción de Señal/efectos de los fármacos , Transducción de Señal/fisiología , Especificidad por SustratoRESUMEN
INTRODUCTION: Breast cancer, the most common cause of cancer-related deaths worldwide among women, is a molecularly and clinically heterogeneous disease. Extensive genetic and epigenetic profiling of breast tumors has recently revealed novel putative driver genes, including p21-activated kinase (PAK)1. PAK1 is a serine/threonine kinase downstream of small GTP-binding proteins, Rac1 and Cdc42, and is an integral component of growth factor signaling networks and cellular functions fundamental to tumorigenesis. METHODS: PAK1 dysregulation (copy number gain, mRNA and protein expression) was evaluated in two cohorts of breast cancer tissues (n=980 and 1,108). A novel small molecule inhibitor, FRAX1036, and RNA interference were used to examine PAK1 loss of function and combination with docetaxel in vitro. Mechanism of action for the therapeutic combination, both cellular and molecular, was assessed via time-lapse microscopy and immunoblotting. RESULTS: We demonstrate that focal genomic amplification and overexpression of PAK1 are associated with poor clinical outcome in the luminal subtype of breast cancer (P=1.29×10(-4) and P=0.015, respectively). Given the role for PAK1 in regulating cytoskeletal organization, we hypothesized that combination of PAK1 inhibition with taxane treatment could be combined to further interfere with microtubule dynamics and cell survival. Consistent with this, administration of docetaxel with either a novel small molecule inhibitor of group I PAKs, FRAX1036, or PAK1 small interfering RNA oligonucleotides dramatically altered signaling to cytoskeletal-associated proteins, such as stathmin, and induced microtubule disorganization and cellular apoptosis. Live-cell imaging revealed that the duration of mitotic arrest mediated by docetaxel was significantly reduced in the presence of FRAX1036, and this was associated with increased kinetics of apoptosis. CONCLUSIONS: Taken together, these findings further support PAK1 as a potential target in breast cancer and suggest combination with taxanes as a viable strategy to increase anti-tumor efficacy.
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Apoptosis/efectos de los fármacos , Neoplasias de la Mama/metabolismo , Microtúbulos/metabolismo , Inhibidores de Proteínas Quinasas/farmacología , Moduladores de Tubulina/farmacología , Quinasas p21 Activadas/antagonistas & inhibidores , Apoptosis/genética , Neoplasias de la Mama/genética , Neoplasias de la Mama/mortalidad , Neoplasias de la Mama/patología , Puntos de Control del Ciclo Celular/efectos de los fármacos , Línea Celular Tumoral , Variaciones en el Número de Copia de ADN , Docetaxel , Sinergismo Farmacológico , Femenino , Amplificación de Genes , Expresión Génica , Humanos , Pronóstico , Transducción de Señal/efectos de los fármacos , Taxoides/farmacología , Quinasas p21 Activadas/genética , Quinasas p21 Activadas/metabolismoRESUMEN
Neurofibromatosis type 2 (NF2) is an autosomal dominant disorder characterized by the development of multiple tumors in the central nervous system, most notably schwannomas and meningiomas. Mutational inactivation of NF2 is found in 40-60% of sporadic meningiomas, but the molecular mechanisms underlying malignant changes of meningioma cells remain unclear. Because group I p21-activated kinases (Paks) bind to and are inhibited by the NF2-encoded protein Merlin, we assessed the signaling and anti-tumor effects of three group-I specific Pak inhibitors - Frax597, 716 and 1036 - in NF2-/- meningiomas in vitro and in an orthotopic mouse model. We found that these Pak inhibitors suppressed the proliferation and motility of both benign (Ben-Men1) and malignant (KT21-MG1) meningiomas cells. In addition, we found a strong reduction in phosphorylation of Mek and S6, and decreased cyclin D1 expression in both cell lines after treatment with Pak inhibitors. Using intracranial xenografts of luciferase-expressing KT21-MG1 cells, we found that treated mice showed significant tumor suppression for all three Pak inhibitors. Similar effects were observed in Ben-Men1 cells. Tumors dissected from treated animals exhibited an increase in apoptosis without notable change in proliferation. Collectively, these results suggest that Pak inhibitors might be useful agents in treating NF2-deficient meningiomas.
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Meningioma/metabolismo , Neurofibromina 2/deficiencia , Quinasas p21 Activadas/metabolismo , Animales , Antineoplásicos/farmacología , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Encéfalo/patología , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Proliferación Celular/genética , Doxiciclina/farmacología , Regulación Neoplásica de la Expresión Génica , Humanos , Immunoblotting , Meningioma/genética , Meningioma/terapia , Ratones SCID , Neurofibromina 2/genética , Piridonas/farmacología , Pirimidinas/farmacología , Interferencia de ARN , Tratamiento con ARN de Interferencia , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Carga Tumoral/efectos de los fármacos , Carga Tumoral/genética , Ensayos Antitumor por Modelo de Xenoinjerto/métodos , Quinasas p21 Activadas/antagonistas & inhibidores , Quinasas p21 Activadas/genéticaRESUMEN
Activating mutations in the KRAS oncogene occur in approximately 90% of pancreatic cancers, resulting in aberrant activation of the MAPK and the PI3K pathways, driving malignant progression. Significant efforts to develop targeted inhibitors of nodes within these pathways are underway and several are currently in clinical trials for patients with KRAS-mutant tumors, including patients with pancreatic cancer. To model MEK and PI3K inhibition in late-stage pancreatic cancer, we conducted preclinical trials with a mutant Kras-driven genetically engineered mouse model that faithfully recapitulates human pancreatic ductal adenocarcinoma development. Treatment of advanced disease with either a MEK (GDC-0973) or PI3K inhibitor (GDC-0941) alone showed modest tumor growth inhibition and did not significantly enhance overall survival. However, combination of the two agents resulted in a significant survival advantage as compared with control tumor-bearing mice. To model the clinical scenario, we also evaluated the combination of these targeted agents with gemcitabine, the current standard-of-care chemotherapy for pancreatic cancer. The addition of MEK or PI3K inhibition to gemcitabine, or the triple combination regimen, incrementally enhanced overall survival as compared with gemcitabine alone. These results are reminiscent of the survival advantage conferred in this model and in patients by the combination of gemcitabine and erlotinib, an approved therapeutic regimen for advanced nonresectable pancreatic cancer. Taken together, these data indicate that inhibition of MEK and PI3K alone or in combination with chemotherapy do not confer a dramatic improvement as compared with currently available therapies for patients with pancreatic cancer.
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Protocolos de Quimioterapia Combinada Antineoplásica/administración & dosificación , Carcinoma Ductal Pancreático/tratamiento farmacológico , Desoxicitidina/análogos & derivados , MAP Quinasa Quinasa 1/antagonistas & inhibidores , Neoplasias Pancreáticas/tratamiento farmacológico , Inhibidores de las Quinasa Fosfoinosítidos-3 , Inhibidores de Proteínas Quinasas/administración & dosificación , Animales , Protocolos de Quimioterapia Combinada Antineoplásica/farmacología , Azetidinas/administración & dosificación , Azetidinas/farmacología , Carcinoma Ductal Pancreático/genética , Línea Celular Tumoral , Desoxicitidina/administración & dosificación , Desoxicitidina/farmacología , Relación Dosis-Respuesta a Droga , Humanos , Indazoles/administración & dosificación , Indazoles/farmacología , Ratones , Modelos Biológicos , Mutación , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/patología , Piperidinas/administración & dosificación , Piperidinas/farmacología , Inhibidores de Proteínas Quinasas/farmacología , Proteínas Proto-Oncogénicas p21(ras)/genética , Nivel de Atención , Sulfonamidas/administración & dosificación , Sulfonamidas/farmacología , Ensayos Antitumor por Modelo de Xenoinjerto , GemcitabinaRESUMEN
The p21-activated kinase (PAK) family of serine/threonine protein kinases plays important roles in cytoskeletal organization, cellular morphogenesis, and survival, and members of this family have been implicated in many diseases including cancer, infectious diseases, and neurological disorders. Owing to their large and flexible ATP binding cleft, PAKs, particularly group I PAKs (PAK1, -2, and -3), are difficult to drug; hence, few PAK inhibitors with satisfactory kinase selectivity and druglike properties have been reported to date. Examples are a recently discovered group II PAK (PAK4, -5, -6) selective inhibitor series based on a benzimidazole core, a group I PAK selective series based on a pyrido[2,3-d]pyrimidine-7-one core, and an allosteric dibenzodiazepine PAK1 inhibitor series. Only one compound, an aminopyrazole based pan-PAK inhibitor, entered clinical trials but did not progress beyond phase I trials. Clinical proof of concept for pan-group I, pan-group II, or PAK isoform selective inhibition has yet to be demonstrated.