RESUMO
Hereditary angioedema (HAE) is a rare autosomal dominant disorder caused by a deficiency in functional C1 esterase inhibitor, a serpin family protein that blocks the activity of plasma kallikrein. Insufficient inhibition of plasma kallikrein results in the overproduction of bradykinin, a vasoactive inflammatory mediator that produces both pain and unpredictable swelling during HAE attacks, with potentially life-threatening consequences. We describe the generation of STAR-0215, a humanized IgG1 antibody with a long circulating half-life (t1/2) that potently inhibits plasma kallikrein activity, with a >1000-fold lower affinity for prekallikrein and no measurable inhibitory activity against other serine proteases. The high specificity and inhibitory effect of STAR-0215 is demonstrated through a unique allosteric mechanism involving N-terminal catalytic domain binding, destabilization of the activation domain, and reversion of the active site to the inactive zymogen state. The YTE (M252Y/S254T/T256E) modified fragment crystallizable (Fc) domain of STAR-0215 enhances pH-dependent neonatal Fc receptor binding, resulting in a prolonged t1/2 in vivo (â¼34 days in cynomolgus monkeys) compared with antibodies without this modification. A single subcutaneous dose of STAR-0215 (≥100 mg) was predicted to be active in patients for 3 months or longer, based on simulations using a minimal physiologically based pharmacokinetic model. These data indicate that STAR-0215, a highly potent and specific antibody against plasma kallikrein with extended t1/2, is a potential agent for long-term preventative HAE therapy administered every 3 months or less frequently. SIGNIFICANCE STATEMENT: STAR-0215 is a YTE-modified immunoglobulin G1 monoclonal antibody with a novel binding mechanism that specifically and potently inhibits the enzymatic activity of plasma kallikrein and prevents the generation of bradykinin. It has been designed to be a long-lasting prophylactic treatment to prevent attacks of HAE and to decrease the burden of disease and the burden of treatment for people with HAE.
RESUMO
The design and synthesis of a series of novel tricyclic IAP inhibitors is reported. Rapid assembly of the core tricycle involved two key steps: Rh-catalyzed hydrogenation of an unsaturated bicyclic ring system and a Ru-catalyzed ring closing alkene metathesis reaction. The final Smac mimetics bind to cIAP1 and XIAP BIR3 domains and elicit the desired phenotype in cellular proliferation assays. Dimeric IAP inhibitors were found to possess nanomolar potency in a cellular proliferation assay and favourable in vitro drug-like properties.
Assuntos
Desenho de Fármacos , Compostos Heterocíclicos com 3 Anéis/farmacologia , Proteínas Inibidoras de Apoptose/metabolismo , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Relação Dose-Resposta a Droga , Compostos Heterocíclicos com 3 Anéis/síntese química , Compostos Heterocíclicos com 3 Anéis/química , Humanos , Proteínas Inibidoras de Apoptose/síntese química , Proteínas Inibidoras de Apoptose/química , Estrutura Molecular , Relação Estrutura-AtividadeRESUMO
A series of dimeric compounds based on the AVPI motif of Smac were designed and prepared as antagonists of the inhibitor of apoptosis proteins (IAPs). Optimization of cellular potency, physical properties, and pharmacokinetic parameters led to the identification of compound 14 (AZD5582), which binds potently to the BIR3 domains of cIAP1, cIAP2, and XIAP (IC50 = 15, 21, and 15 nM, respectively). This compound causes cIAP1 degradation and induces apoptosis in the MDA-MB-231 breast cancer cell line at subnanomolar concentrations in vitro. When administered intravenously to MDA-MB-231 xenograft-bearing mice, 14 results in cIAP1 degradation and caspase-3 cleavage within tumor cells and causes substantial tumor regressions following two weekly doses of 3.0 mg/kg. Antiproliferative effects are observed with 14 in only a small subset of the over 200 cancer cell lines examined, consistent with other published IAP inhibitors. As a result of its in vitro and in vivo profile, 14 was nominated as a candidate for clinical development.
Assuntos
Alcinos/farmacologia , Antineoplásicos/farmacologia , Materiais Biomiméticos/farmacologia , Descoberta de Drogas , Proteínas Inibidoras de Apoptose/antagonistas & inibidores , Neoplasias/tratamento farmacológico , Oligopeptídeos/farmacologia , Alcinos/síntese química , Alcinos/química , Animais , Antineoplásicos/síntese química , Antineoplásicos/química , Materiais Biomiméticos/síntese química , Materiais Biomiméticos/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Dimerização , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Proteínas Inibidoras de Apoptose/metabolismo , Camundongos , Conformação Molecular , Neoplasias/patologia , Oligopeptídeos/síntese química , Oligopeptídeos/química , Relação Estrutura-Atividade , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
The potent and selective 3-amido-4-anilinoquinoline CSF-1R inhibitor AZ683 suffered from cardiovascular liabilities, which were linked to the off-target activities of the compound and ion channel activity in particular. Less basic and less lipophilic examples from both the quinoline and cinnoline series demonstrated cleaner secondary pharmacology profiles. Cinnoline 31 retained the required potency and oral PK profile, and was progressed through the safety screening cascade to be nominated into development as AZD7507.
Assuntos
Aminoquinolinas/síntese química , Aminoquinolinas/toxicidade , Compostos de Anilina/síntese química , Compostos de Anilina/toxicidade , Sistema Cardiovascular/efeitos dos fármacos , Inibidores Enzimáticos/toxicidade , Compostos Heterocíclicos com 2 Anéis/síntese química , Compostos Heterocíclicos com 2 Anéis/toxicidade , Receptor de Fator Estimulador de Colônias de Macrófagos/antagonistas & inibidores , Aminoquinolinas/química , Aminoquinolinas/farmacologia , Compostos de Anilina/química , Compostos de Anilina/farmacologia , Animais , Células Cultivadas , Cães , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Cobaias , Compostos Heterocíclicos com 2 Anéis/química , Compostos Heterocíclicos com 2 Anéis/farmacologia , Humanos , Concentração Inibidora 50 , Estrutura Molecular , Miócitos Cardíacos/efeitos dos fármacos , RatosRESUMO
B-Raf represents an attractive target for anticancer therapy and the development of small molecule B-Raf inhibitors has delivered new therapies for metastatic melanoma patients. We have discovered a novel class of small molecules that inhibit mutant B-Raf(V600E) kinase activity both in vitro and in vivo. Investigations into the structure-activity relationships of the series are presented along with efforts to improve upon the cellular potency, solubility, and pharmacokinetic profile. Compounds selectively inhibited B-Raf(V600E) in vitro and showed preferential antiproliferative activity in mutant B-Raf(V600E) cell lines and exhibited selectivity in a kinase panel against other kinases. Examples from this series inhibit growth of a B-Raf(V600E) A375 xenograft in vivo at a well-tolerated dose. In addition, aminoquinazolines described herein were shown to display pERK elevation in nonmutant B-Raf cell lines in vitro.
Assuntos
Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas B-raf/antagonistas & inibidores , Quinazolinas/síntese química , Animais , Humanos , Masculino , Melanoma/tratamento farmacológico , Camundongos , Inibidores de Proteínas Quinases/síntese química , Inibidores de Proteínas Quinases/uso terapêutico , Proteínas Proto-Oncogênicas B-raf/genética , Quinazolinas/farmacocinética , Quinazolinas/farmacologia , Ratos , Relação Estrutura-AtividadeRESUMO
A series of structurally unique Smac mimetics that act as antagonists of inhibitor of apoptosis proteins (IAPs) has been discovered. While most previously described Smac mimetics contain the proline ring (or a similar cyclic motif) found in Smac, a key feature of the compounds described herein is that this ring has been removed. Despite this, compounds in this series potently bind to cIAP1 and elicit the expected phenotype of cIAP1 inhibition in cancer cells. Marked selectivity for cIAP1 over XIAP is observed for these compounds, which is attributed to a slight difference in the binding groove between the two proteins and the resulting steric interactions with the inhibitors. XIAP binding can be improved by constraining the inhibitor so that these unfavorable steric interactions are minimized.
Assuntos
Aminas/síntese química , Desenho de Fármacos , Proteínas Inibidoras de Apoptose/antagonistas & inibidores , Peptídeos e Proteínas de Sinalização Intracelular/química , Proteínas Mitocondriais/química , Piperidinas/síntese química , Aminas/química , Aminas/farmacologia , Proteínas Reguladoras de Apoptose , Biomimética , Linhagem Celular Tumoral , Humanos , Concentração Inibidora 50 , Modelos Moleculares , Estrutura Molecular , Piperidinas/química , Piperidinas/farmacologia , Ligação Proteica/efeitos dos fármacos , Relação Estrutura-AtividadeRESUMO
Trk receptor tyrosine kinases have been implicated in cancer and pain. A crystal structure of TrkA with AZ-23 (1a) was obtained, and scaffold hopping resulted in two 5/6-bicyclic series comprising either imidazo[4,5-b]pyridines or purines. Further optimization of these two fusion series led to compounds with subnanomolar potencies against TrkA kinase in cellular assays. Antitumor effects in a TrkA-driven mouse allograft model were demonstrated with compounds 2d and 3a.
RESUMO
3-Amido-4-anilinocinnolines have been identified as potent and highly selective inhibitors of CSF-1R. The synthesis and SAR of these compounds is reported, along with some physical property, pharmacokinetic and kinase selectivity data.
Assuntos
Amidas/síntese química , Compostos de Anilina/síntese química , Compostos Heterocíclicos com 2 Anéis/síntese química , Inibidores de Proteínas Quinases/síntese química , Receptor de Fator Estimulador de Colônias de Macrófagos/antagonistas & inibidores , Amidas/química , Compostos de Anilina/química , Animais , Cães , Compostos Heterocíclicos com 2 Anéis/química , Camundongos , Estrutura Molecular , Inibidores de Proteínas Quinases/química , Ratos , Relação Estrutura-AtividadeRESUMO
BACKGROUND: TrkB expression is associated with poor prognosis for patients with neuroblastoma. AZ623 is a novel potent and selective inhibitor of the Trk family of tyrosine kinases. The authors hypothesized that AZ623 would inhibit TrkB-mediated signaling in neuroblastoma tumor cells and would be synergistic when combined with chemotherapy. METHODS: Neuroblastoma cell lines were screened for TrkB receptor mRNA expression and for their proliferation rates in response to brain-derived neurotrophic factor (BDNF). The effects of AZ623 on Trk receptor phosphorylation, signaling, and cell growth were evaluated in BDNF-treated neuroblastoma cells. Mice with human neuroblastoma xenograft tumors were treated with AZ623 alone and in combination with topotecan, and tumor growth rates were determined during and after treatment. RESULTS: Neuroblastoma cell lines expressed various levels of the TrkB receptor and demonstrated increased proliferation in response to BDNF. BDNF treatment stimulated TrkB phosphorylation and downstream signaling that could be inhibited by AZ623. Neuroblastoma cells demonstrated in vitro sensitivity to AZ623, with concentration that inhibits 50% (IC50) values between 0.8 to 7 µM. AZ623 treatment was found to inhibit BDNF-mediated neuroblastoma cell proliferation. Mice with human neuroblastoma xenograft tumors demonstrated tumor growth inhibition when treated with AZ623 and with AZ623 combined with topotecan. Limited tumor regrowth was noted in mice with tumors treated with AZ623 combined with topotecan after treatment discontinuation. CONCLUSIONS: AZ623 is a novel selective Trk inhibitor that inhibits BDNF-mediated signaling and neuroblastoma cell proliferation. AZ623 treatment inhibits the growth of human neuroblastoma xenograft tumors, and treatment with AZ623 combined with topotecan results in the prolonged inhibition of tumor regrowth. On the basis of these results, further preclinical development is warranted.
Assuntos
Neoplasias Encefálicas/tratamento farmacológico , Fator Neurotrófico Derivado do Encéfalo/antagonistas & inibidores , Proliferação de Células/efeitos dos fármacos , Neuroblastoma/tratamento farmacológico , Topotecan/administração & dosagem , Animais , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Neoplasias Encefálicas/patologia , Fator Neurotrófico Derivado do Encéfalo/farmacologia , Linhagem Celular Tumoral , Relação Dose-Resposta a Droga , Sinergismo Farmacológico , Humanos , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Camundongos Transgênicos , Neuroblastoma/patologia , Inibidores de Proteínas Quinases/farmacologia , Inibidores de Proteínas Quinases/uso terapêutico , Receptor trkB/antagonistas & inibidores , Transdução de Sinais/efeitos dos fármacos , Especificidade por Substrato , Topotecan/farmacologia , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Tropomyosin-related kinases (TrkA, TrkB, and TrkC) are receptor tyrosine kinases that, along with their ligands, the neurotrophins, are involved in neuronal cell growth, development, and survival. The Trk-neurotrophin pathway may also play a role in tumorigenesis through oncogenic fusions, mutations, and autocrine signaling, prompting the development of novel Trk inhibitors as agents for cancer therapy. This report describes the identification of AZ-23, a novel, potent, and selective Trk kinase inhibitor. In vitro studies with AZ-23 showed improved selectivity over previous compounds and inhibition of Trk kinase activity in cells at low nanomolar concentrations. AZ-23 showed in vivo TrkA kinase inhibition and efficacy in mice following oral administration in a TrkA-driven allograft model and significant tumor growth inhibition in a Trk-expressing xenograft model of neuroblastoma. AZ-23 represents a potent and selective Trk kinase inhibitor from a novel series with the potential for use as a treatment for cancer.
Assuntos
Neuroblastoma/tratamento farmacológico , Inibidores de Proteínas Quinases/uso terapêutico , Pirimidinas/antagonistas & inibidores , Pirimidinas/uso terapêutico , Receptor trkA/antagonistas & inibidores , Ensaios Antitumorais Modelo de Xenoenxerto , Administração Oral , Animais , Disponibilidade Biológica , Proliferação de Células/efeitos dos fármacos , Ensaio de Imunoadsorção Enzimática , Humanos , Immunoblotting , Masculino , Camundongos , Camundongos Endogâmicos NOD , Camundongos Nus , Camundongos SCID , Neuroblastoma/metabolismo , Neuroblastoma/patologia , Fosforilação/efeitos dos fármacos , Inibidores de Proteínas Quinases/farmacocinética , Pirimidinas/farmacocinética , Receptores de Interleucina-2/fisiologia , Distribuição Tecidual , Células Tumorais CultivadasRESUMO
3-amido-4-anilinoquinolines are potent and highly selective inhibitors of CSF-1R. Their synthesis and SAR is reported, along with initial efforts to optimize the physical properties and PK through modifications at the quinoline 6- and 7-positions.
Assuntos
Química Farmacêutica/métodos , Neoplasias/tratamento farmacológico , Quinolinas/química , Quinolinas/farmacocinética , Receptor de Fator Estimulador de Colônias de Macrófagos/antagonistas & inibidores , Receptor de Fator Estimulador de Colônias de Macrófagos/química , Administração Oral , Animais , Antineoplásicos/síntese química , Antineoplásicos/química , Desenho de Fármacos , Humanos , Concentração Inibidora 50 , Cinética , Modelos Químicos , Inibidores de Proteínas Quinases/síntese química , Inibidores de Proteínas Quinases/química , RatosRESUMO
The optimization of compounds from the 3-amido-4-anilinoquinolines series of CSF-1R kinase inhibitors is described. The series has excellent activity and kinase selectivity. Excellent physical properties and rodent PK profiles were achieved through the introduction of cyclic amines at the quinoline 6-position. Compounds with good activity in a mouse PD model measuring inhibition of pCSF-1R were identified.
Assuntos
Química Farmacêutica/métodos , Neoplasias/tratamento farmacológico , Quinolinas/química , Quinolinas/farmacocinética , Receptor de Fator Estimulador de Colônias de Macrófagos/antagonistas & inibidores , Receptor de Fator Estimulador de Colônias de Macrófagos/química , Aminas/química , Animais , Antineoplásicos/síntese química , Antineoplásicos/química , Canal de Potássio ERG1 , Canais de Potássio Éter-A-Go-Go/metabolismo , Humanos , Concentração Inibidora 50 , Cinética , Camundongos , Modelos Químicos , Inibidores de Proteínas Quinases/síntese química , Inibidores de Proteínas Quinases/química , RatosRESUMO
The bisamide class of kinase inhibitors was identified as being active against CSF-1R. The synthesis and SAR of pyridyl and thiazolyl bisamides are reported, along with the pharmacokinetic properties and in vivo activity of selected examples.
Assuntos
Amidas/farmacologia , Antineoplásicos/farmacologia , Neoplasias/tratamento farmacológico , Neoplasias/metabolismo , Receptor de Fator Estimulador de Colônias de Macrófagos/antagonistas & inibidores , Tiazóis/farmacologia , Células 3T3 , Amidas/química , Amidas/farmacocinética , Animais , Antineoplásicos/química , Antineoplásicos/farmacocinética , Feminino , Humanos , Camundongos , Camundongos Nus , Ratos , Receptor de Fator Estimulador de Colônias de Macrófagos/genética , Tiazóis/química , Tiazóis/farmacocinéticaRESUMO
The design, synthesis and biological evaluation of a series of 4-aminopyrazolylpyrimidines as potent Trk kinase inhibitors is reported. High-throughput screening identified a promising hit in the 4-aminopyrazolylpyrimidine chemotype. Initial optimization of the series led to more potent Trk inhibitors. Further optimization using two strategies resulted in significant improvement of physical properties and led to the discovery of 10z (AZ-23), a potent, orally bioavailable Trk A/B inhibitor. The compound offers the potential to test the hypothesis that modulation of Trk activity will be of benefit in the treatment of cancer and other indications in vivo.
Assuntos
Aminas/química , Inibidores de Proteínas Quinases/síntese química , Inibidores de Proteínas Quinases/farmacologia , Pirazóis/química , Pirimidinas/síntese química , Pirimidinas/farmacologia , Receptor trkA/antagonistas & inibidores , Animais , Linhagem Celular , Humanos , Masculino , Modelos Moleculares , Estrutura Molecular , Inibidores de Proteínas Quinases/química , Pirimidinas/química , Ratos , Ratos Wistar , Receptor trkA/química , Receptor trkA/metabolismo , Relação Estrutura-AtividadeRESUMO
A new series of MEK1 inhibitors, the 4-anilino-5-carboxamido-2-pyridones, were designed and synthesized using a combination of medicinal chemistry, computational chemistry, and structural elucidation. The effect of variation in the carboxamide side chain, substitution on the pyridone nitrogen, and replacement of the 4'-iodide were all investigated. This study afforded several compounds which were either equipotent or more potent than the clinical candidate CI-1040 (1) in an isolated enzyme assay, as well as murine colon carcinoma (C26) cells, as measured by suppression of phosphorylated ERK substrate. Most notably, pyridone 27 was found to be more potent than 1 in vitro and produced a 100% response rate at a lower dose than 1, when tested for in vivo efficacy in animals bearing C26 tumors.
Assuntos
Amidas/síntese química , Compostos de Anilina/síntese química , Antineoplásicos/síntese química , MAP Quinase Quinase 1/antagonistas & inibidores , MAP Quinase Quinase 2/antagonistas & inibidores , Piridonas/síntese química , Amidas/química , Amidas/farmacologia , Compostos de Anilina/química , Compostos de Anilina/farmacologia , Animais , Antineoplásicos/química , Antineoplásicos/farmacologia , Benzamidas/farmacologia , Linhagem Celular Tumoral , Ensaios de Seleção de Medicamentos Antitumorais , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , MAP Quinase Quinase 1/química , MAP Quinase Quinase 2/química , Masculino , Camundongos , Modelos Moleculares , Transplante de Neoplasias , Fosforilação , Piridonas/química , Piridonas/farmacologia , Ratos , Relação Estrutura-AtividadeRESUMO
The MEK-ERK growth signaling pathway is important in human hepatocellular carcinoma (HCC). To evaluate the targeting of this pathway in HCC, we characterized a novel, orally-active MEK inhibitor, PD184161, using human HCC cells (HepG2, Hep3B, PLC, and SKHep) and in vivo human tumor xenografts. PD184161 inhibited MEK activity (IC50 = 10-100 nM) in a time- and concentration-dependent manner more effectively than PD098059 or U0126. PD184161 inhibited cell proliferation and induced apoptosis at concentrations of > or = 1.0 microM in a time- and concentration-dependent manner. In vivo, tumor xenograft P-ERK levels were significantly reduced 3 to 12 hours after an oral dose of PD184161 (P < .05). Contrarily, tumor xenograft P-ERK levels following long-term (24 days) daily dosing of PD184161 were refractory to this signaling effect. PD184161 significantly suppressed tumor engraftment and initial growth (P < .0001); however, established tumors were not significantly affected. In conclusion, PD184161 has antitumor effects in HCC in vitro and in vivo that appear to correlate with suppression of MEK activity. These studies demonstrate that PD184161 is unable to suppress MEK activity in HCC xenografts in the long term. Thus, we speculate that the degree of success of MEK targeted treatment in HCC and other cancers may, in part, depend on the discovery of mechanisms governing MEK inhibitor signaling resistance.
Assuntos
Compostos de Anilina/farmacologia , Antineoplásicos/farmacologia , Benzamidas/farmacologia , Inibidores Enzimáticos/farmacologia , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Neoplasias Hepáticas/tratamento farmacológico , Neoplasias Hepáticas/enzimologia , MAP Quinase Quinase Quinases/metabolismo , Animais , Butadienos/farmacologia , Linhagem Celular Tumoral , Proliferação de Células , Flavonoides/farmacologia , Humanos , Camundongos , Camundongos Nus , Transplante de Neoplasias , Nitrilas/farmacologiaRESUMO
PD184352/CI-1040 is a potent and selective MEK1/2 inhibitor that represents the first MEK-targeted agent to enter clinical trials. Here, we report the development and molecular characterization of CI-1040 resistance in the murine colon 26 (C26) carcinoma cell line. The growth rate of the resistant line (C26/CI-1040r) in the presence of 2 microM CI-1040 is comparable to that of parental C26 cells in the absence of CI-1040. C26/CI-1040r cells are approximately 100-fold more resistant than the parental line to CI-1040 inhibition in soft agar and are less sensitive to the induction of apoptosis that normally occurs in response to CI-1040 treatment. K-ras expression is significantly elevated in C26/CI-1040r cells. We confirmed a causative role for K-ras in conferring resistance to CI-1040 by transfecting K-ras into parental C26 cells, whereupon an elevation in the levels of phosphorylated ERK1/2 was observed in addition to resistance to CI-1040. Furthermore, an in vivo-derived MEK inhibitor-resistant line also shows increased K-ras expression. Our data suggest that increasing activated K-ras expression represents one potential mechanism by which tumor cells that initially are responsive to blockade of the MAP kinase pathway can overcome their sensitivity to MEK inhibition.
Assuntos
Benzamidas/farmacologia , Resistencia a Medicamentos Antineoplásicos , Inibidores Enzimáticos/farmacologia , MAP Quinase Quinase Quinases/antagonistas & inibidores , Proteínas Proto-Oncogênicas p21(ras)/fisiologia , Ágar/química , Animais , Apoptose , Ciclo Celular , Linhagem Celular Tumoral , Relação Dose-Resposta a Droga , Fator de Crescimento Epidérmico/metabolismo , Immunoblotting , Imunoprecipitação , Sistema de Sinalização das MAP Quinases , Camundongos , Camundongos Endogâmicos BALB C , Transplante de Neoplasias , Análise de Sequência com Séries de Oligonucleotídeos , Proteínas Proto-Oncogênicas p21(ras)/metabolismo , RNA/metabolismo , RNA Complementar/metabolismo , Timidina/química , Fatores de Tempo , Transfecção , Regulação para CimaRESUMO
MEK1 and MEK2 are closely related, dual-specificity tyrosine/threonine protein kinases found in the Ras/Raf/MEK/ERK mitogen-activated protein kinase (MAPK) signaling pathway. Approximately 30% of all human cancers have a constitutively activated MAPK pathway, and constitutive activation of MEK1 results in cellular transformation. Here we present the X-ray structures of human MEK1 and MEK2, each determined as a ternary complex with MgATP and an inhibitor to a resolution of 2.4 A and 3.2 A, respectively. The structures reveal that MEK1 and MEK2 each have a unique inhibitor-binding pocket adjacent to the MgATP-binding site. The presence of the potent inhibitor induces several conformational changes in the unphosphorylated MEK1 and MEK2 enzymes that lock them into a closed but catalytically inactive species. Thus, the structures reported here reveal a novel, noncompetitive mechanism for protein kinase inhibition.
Assuntos
Inibidores Enzimáticos/farmacologia , MAP Quinase Quinase 1/química , MAP Quinase Quinase 1/metabolismo , MAP Quinase Quinase 2/química , MAP Quinase Quinase 2/metabolismo , Sítios de Ligação , Sequência Conservada , Dimerização , Inibidores Enzimáticos/química , Humanos , MAP Quinase Quinase 1/antagonistas & inibidores , MAP Quinase Quinase 2/antagonistas & inibidores , Modelos Moleculares , Estrutura Molecular , Estrutura Quaternária de Proteína , Homologia Estrutural de ProteínaRESUMO
PURPOSE: To evaluate the antitumor activity, safety, immune response, and replication of CI-1042 (ONYX-015), an E1B 55-kd gene-deleted replication-selective adenovirus, administered intravenously to patients with metastatic colorectal cancer PATIENTS AND METHODS: Eighteen patients with metastatic colorectal cancer for whom prior chemotherapy failed were enrolled onto an open-label, multicenter, phase II study. CI-1042 was administered intravenously at a dose of 2 x 1012 viral particles every 2 weeks. Patients were evaluated for tumor response and toxicity; in addition, blood samples were taken for adenovirus DNA and neutralizing antibody analysis. RESULTS: Common toxicities included flu-like symptoms, nausea, and emesis. All 18 patients eventually were removed from study because of progressive disease. Seven patients were assessed as having stable disease after 2 months of treatment, whereas two patients were considered to have stable disease after 4 months. Detectable circulating CI-1042 DNA was identified in 36% of patients 72 hours after last infusion, which is suggestive of ongoing viral replication. CONCLUSION: In this phase II study, intravenous CI-1042 was administered safely to patients with advanced colorectal cancer. Toxicity was manageable, consisting primarily of flu-like symptoms. Stable disease was experienced by seven patients for 11 to 18 weeks.