RESUMEN
PURPOSE: Bortezomib (Velcade), a dipeptide boronate 20S proteasome inhibitor and an approved treatment option for multiple myeloma, is associated with a treatment-emergent, painful peripheral neuropathy (PN) in more than 30% of patients. Carfilzomib, a tetrapeptide epoxyketone proteasome inhibitor, currently in clinical investigation in myeloma, is associated with low rates of PN. We sought to determine whether PN represents a target-mediated adverse drug reaction (ADR). EXPERIMENTAL DESIGN: Neurodegenerative effects of proteasome inhibitors were assessed in an in vitro model utilizing a differentiated neuronal cell line. Secondary targets of both inhibitors were identified by a multifaceted approach involving candidate screening, profiling with an activity-based probe, and database mining. Secondary target activity was measured in rats and patients receiving both inhibitors. RESULTS: Despite equivalent levels of proteasome inhibition, only bortezomib reduced neurite length, suggesting a nonproteasomal mechanism. In cell lysates, bortezomib, but not carfilzomib, significantly inhibited the serine proteases cathepsin G (CatG), cathepsin A, chymase, dipeptidyl peptidase II, and HtrA2/Omi at potencies near or equivalent to that for the proteasome. Inhibition of CatG was detected in splenocytes of rats receiving bortezomib and in peripheral blood mononuclear cells derived from bortezomib-treated patients. Levels of HtrA2/Omi, which is known to be involved in neuronal survival, were upregulated in neuronal cells exposed to both proteasome inhibitors but was inhibited only by bortezomib exposure. CONCLUSION: These data show that bortezomib-induced neurodegeneration in vitro occurs via a proteasome-independent mechanism and that bortezomib inhibits several nonproteasomal targets in vitro and in vivo, which may play a role in its clinical ADR profile.
Asunto(s)
Ácidos Borónicos/efectos adversos , Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos/etiología , Oligopéptidos/efectos adversos , Inhibidores de Proteasoma , Pirazinas/efectos adversos , Animales , Antineoplásicos/administración & dosificación , Antineoplásicos/efectos adversos , Ácidos Borónicos/administración & dosificación , Bortezomib , Células Cultivadas , Cisteína Endopeptidasas/administración & dosificación , Cisteína Endopeptidasas/efectos adversos , Sistemas de Liberación de Medicamentos , Células Hep G2 , Humanos , Masculino , Modelos Biológicos , Oligopéptidos/administración & dosificación , Complejo de la Endopetidasa Proteasomal/metabolismo , Pirazinas/administración & dosificación , Ratas , Ratas Sprague-DawleyRESUMEN
Carfilzomib is a proteasome inhibitor in clinical development that primarily targets the chymotrypsin-like (CT-L) subunits in both the constitutive proteasome (c20S) and the immunoproteasome (i20S). To investigate the impact of inhibiting the CT-L activity with carfilzomib, we set out to quantitate the levels of CT-L subunits beta5 from the c20S and LMP7 from the i20S in normal and malignant hematopoietic cells. We found that the i20S is a major form of the proteasome expressed in cells of hematopoietic origin, including multiple myeloma (MM) CD138+ tumor cells. Although specific inhibition of either LMP7 or beta5 alone was insufficient to produce an antitumor response, inhibition of all proteasome subunits was cytotoxic to both hematologic tumor cells and peripheral blood mononuclear cells. However, selective inhibition of both beta5 and LMP7 was sufficient to induce an antitumor effect in MM, non-Hodgkin lymphoma, and leukemia cells while minimizing the toxicity toward nontransformed cells. In MM tumor cells, CT-L inhibition alone was sufficient to induce proapoptotic sequelae, including proteasome substrate accumulation, Noxa and caspase 3/7 induction, and phospho-eIF2alpha suppression. These data support a hypothesis that hematologic tumor cells are uniquely sensitive to CT-L inhibition and provide a mechanistic understanding of the clinical safety profile and antitumor activity of proteasome inhibitors.
Asunto(s)
Apoptosis/efectos de los fármacos , Neoplasias Hematológicas/tratamiento farmacológico , Oligopéptidos/farmacología , Inhibidores de Proteasas/farmacología , Inhibidores de Proteasoma , Caspasa 3/metabolismo , Caspasa 7/metabolismo , Dominio Catalítico , Línea Celular Tumoral , Quimotripsina/antagonistas & inhibidores , Quimotripsina/metabolismo , Ensayos de Selección de Medicamentos Antitumorales/métodos , Inducción Enzimática/efectos de los fármacos , Factor 2 Eucariótico de Iniciación/metabolismo , Regulación Enzimológica de la Expresión Génica/efectos de los fármacos , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Neoplasias Hematológicas/enzimología , Humanos , Oligopéptidos/uso terapéutico , Inhibidores de Proteasas/uso terapéutico , Complejo de la Endopetidasa Proteasomal/metabolismo , Proteínas Proto-Oncogénicas c-bcl-2/metabolismoRESUMEN
Proteasome inhibition has been validated as a therapeutic modality in the treatment of multiple myeloma and non-Hodgkin's lymphoma. Carfilzomib, an epoxyketone currently undergoing clinical trials in malignant diseases, is a highly selective inhibitor of the chymotrypsin-like (CT-L) activity of the proteasome. A chemistry effort was initiated to discover orally bioavailable analogues of carfilzomib, which would have potential for improved dosing flexibility and patient convenience over intravenously administered agents. The lead compound, 2-Me-5-thiazole-Ser(OMe)-Ser(OMe)-Phe-ketoepoxide (58) (PR-047), selectively inhibited CT-L activity of both the constitutive proteasome (beta5) and immunoproteasome (LMP7) and demonstrated an absolute bioavailability of up to 39% in rodents and dogs. It was well tolerated with repeated oral administration at doses resulting in >80% proteasome inhibition in most tissues and elicited an antitumor response equivalent to intravenously administered carfilzomib in multiple human tumor xenograft and mouse syngeneic models. The favorable pharmacologic profile supports its further development for the treatment of malignant diseases.
Asunto(s)
Dipéptidos/síntesis química , Dipéptidos/farmacología , Diseño de Fármacos , Inhibidores Enzimáticos/síntesis química , Inhibidores Enzimáticos/farmacología , Oligopéptidos/síntesis química , Oligopéptidos/farmacología , Inhibidores de Proteasoma , Tiazoles/síntesis química , Tiazoles/farmacología , Administración Oral , Animales , Antineoplásicos/química , Antineoplásicos/farmacología , Disponibilidad Biológica , Línea Celular , Dipéptidos/química , Dipéptidos/farmacocinética , Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/farmacocinética , Humanos , Cinética , Ratones , Oligopéptidos/química , Oligopéptidos/farmacocinética , Relación Estructura-Actividad , Especificidad por Sustrato , Tiazoles/química , Tiazoles/farmacocinéticaRESUMEN
Clinical studies with bortezomib have validated the proteasome as a therapeutic target for the treatment of multiple myeloma and non-Hodgkin's lymphoma. However, significant toxicities have restricted the intensity of bortezomib dosing. Here we describe the antitumor activity of PR-171, a novel epoxyketone-based irreversible proteasome inhibitor that is currently in clinical development. In comparison to bortezomib, PR-171 exhibits equal potency but greater selectivity for the chymotrypsin-like activity of the proteasome. In cell culture, PR-171 is more cytotoxic than bortezomib following brief treatments that mimic the in vivo pharmacokinetics of both molecules. Hematologic tumor cells exhibit the greatest sensitivity to brief exposure, whereas solid tumor cells and nontransformed cell types are less sensitive to such treatments. Cellular consequences of PR-171 treatment include the accumulation of proteasome substrates and induction of cell cycle arrest and/or apoptosis. Administration of PR-171 to animals results in the dose-dependent inhibition of the chymotrypsin-like proteasome activity in all tissues examined with the exception of the brain. PR-171 is well tolerated when administered for either 2 or 5 consecutive days at doses resulting in >80% proteasome inhibition in blood and most tissues. In human tumor xenograft models, PR-171 mediates an antitumor response that is both dose and schedule dependent. The antitumor efficacy of PR-171 delivered on 2 consecutive days is stronger than that of bortezomib administered on its clinical dosing schedule. These studies show the tolerability, efficacy, and dosing flexibility of PR-171 and provide validation for the clinical testing of PR-171 in the treatment of hematologic malignancies using dose-intensive schedules.
Asunto(s)
Antineoplásicos/farmacología , Oligopéptidos/farmacología , Complejo de la Endopetidasa Proteasomal/metabolismo , Animales , Apoptosis , Ácidos Borónicos/farmacología , Bortezomib , Quimotripsina/metabolismo , Quimotripsina/farmacología , Relación Dosis-Respuesta a Droga , Humanos , Concentración 50 Inhibidora , Masculino , Ratones , Trasplante de Neoplasias , Pirazinas/farmacología , Ratas , Ratas Sprague-DawleyRESUMEN
The proteasome has emerged as an important target for cancer therapy with the approval of bortezomib, a first-in-class, reversible proteasome inhibitor, for relapsed/refractory multiple myeloma (MM). However, many patients have disease that does not respond to bortezomib, whereas others develop resistance, suggesting the need for other inhibitors with enhanced activity. We therefore evaluated a novel, irreversible, epoxomicin-related proteasome inhibitor, carfilzomib. In models of MM, this agent potently bound and specifically inhibited the chymotrypsin-like proteasome and immunoproteasome activities, resulting in accumulation of ubiquitinated substrates. Carfilzomib induced a dose- and time-dependent inhibition of proliferation, ultimately leading to apoptosis. Programmed cell death was associated with activation of c-Jun-N-terminal kinase, mitochondrial membrane depolarization, release of cytochrome c, and activation of both intrinsic and extrinsic caspase pathways. This agent also inhibited proliferation and activated apoptosis in patient-derived MM cells and neoplastic cells from patients with other hematologic malignancies. Importantly, carfilzomib showed increased efficacy compared with bortezomib and was active against bortezomib-resistant MM cell lines and samples from patients with clinical bortezomib resistance. Carfilzomib also overcame resistance to other conventional agents and acted synergistically with dexamethasone to enhance cell death. Taken together, these data provide a rationale for the clinical evaluation of carfilzomib in MM.
Asunto(s)
Mieloma Múltiple/tratamiento farmacológico , Mieloma Múltiple/patología , Oligopéptidos/farmacología , Oligopéptidos/uso terapéutico , Inhibidores de Proteasoma , Ubiquitina , Antineoplásicos/farmacología , Antineoplásicos/uso terapéutico , Apoptosis/efectos de los fármacos , Ácidos Borónicos/farmacología , Bortezomib , Proliferación Celular/efectos de los fármacos , Evaluación Preclínica de Medicamentos , Resistencia a Antineoplásicos/efectos de los fármacos , Humanos , Modelos Biológicos , Inhibidores de Proteasas/farmacología , Inhibidores de Proteasas/uso terapéutico , Pirazinas/farmacología , Transducción de Señal/efectos de los fármacos , Células Tumorales Cultivadas , Ubiquitina/antagonistas & inhibidores , Ubiquitina/metabolismoRESUMEN
New inhibitors of palmitoyl-CoA oxidation are based on the introduction of nitrogen heterocycles in the 'Western Portion' of the molecule. SAR studies led to the discovery of CVT-4325 (shown), a potent FOXi (IC50=380 nM rat mitochondria) with favorable PK properties (F=93%, t(1/2)=13.6h, dog).
Asunto(s)
Antioxidantes/farmacología , Antioxidantes/farmacocinética , Ácidos Grasos/metabolismo , Oxadiazoles/farmacología , Oxadiazoles/farmacocinética , Palmitoil Coenzima A/antagonistas & inhibidores , Administración Oral , Animales , Disponibilidad Biológica , Perros , Ácidos Grasos/química , Humanos , Conformación Molecular , Oxidación-Reducción/efectos de los fármacos , Palmitoil Coenzima A/metabolismo , Ratas , Relación Estructura-ActividadRESUMEN
Atrial fibrillation (AF) is the most commonly encountered sustained clinical arrhythmia with an estimated 2.3 million cases in the US (2001). A(1) adenosine receptor agonists can slow the electrical impulse propagation through the atrioventricular (AV) node (i.e., negative dromotropic effect) resulting in prolongation of the stimulus-to-His bundle (S-H) interval to potentially reduce ventricular rate. Compounds that are full agonists of the A(1) adenosine receptor can cause high grade AV block. Therefore, it is envisioned that a compound that is a partial agonist of the A(1) adenosine receptor could avoid this deleterious effect. 5(') Phenyl sulfides (e.g., 17, EC(50)=1.26 microM) and phenyl ethers (e.g., 28, EC(50)=0.2 microM) are partial agonists with respect to their AV nodal effects in guinea pig isolated hearts. Additional affinity, GTPgammaS binding data suggesting partial activity of the A(1) adenosine receptor, and PK results for 5(') modified adenosine derivatives are shown.
Asunto(s)
Agonistas del Receptor de Adenosina A1 , Antiarrítmicos/síntesis química , Éteres/síntesis química , Hidrocarburos Aromáticos/química , Sulfuros/síntesis química , Adenosina/metabolismo , Animales , Antiarrítmicos/farmacocinética , Arritmias Cardíacas/tratamiento farmacológico , Nodo Atrioventricular/efectos de los fármacos , Nodo Atrioventricular/metabolismo , Sitios de Unión , Fascículo Atrioventricular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Éteres/farmacocinética , Cobayas , Frecuencia Cardíaca/efectos de los fármacos , Frecuencia Cardíaca/fisiología , Receptor de Adenosina A1/metabolismo , Relación Estructura-Actividad , Sulfuros/farmacocinéticaRESUMEN
We describe the synthesis of novel inhibitors of fatty acid oxidation as potential metabolic modulators for the treatment of stable angina. Replacement of the 2H-benzo[d]1,3-dioxolene ring system in our initial lead 3 with different benzthiazoles, benzoxazoles and introducing small alkyl substituents into the piperazine ring resulted in analogues with enhanced inhibitory activity against 1-(14)[C]-palmitoyl-CoA oxidation in isolated rat heart mitochondria (6, IC(50)=70 nM; 25, IC(50)=23 nM).
Asunto(s)
Compuestos Epoxi/farmacología , Ácidos Grasos/metabolismo , Animales , Humanos , Hígado/efectos de los fármacos , Hígado/enzimología , Microsomas Hepáticos/efectos de los fármacos , Microsomas Hepáticos/metabolismo , Mitocondrias Cardíacas/efectos de los fármacos , Mitocondrias Cardíacas/metabolismo , Estructura Molecular , Oxidación-Reducción/efectos de los fármacos , Palmitoil Coenzima A/efectos de los fármacos , Palmitoil Coenzima A/metabolismo , Ratas , Relación Estructura-ActividadRESUMEN
New inhibitors of palmitoylCoA oxidation were synthesized based on a structurally novel lead, CVT-3501 (1). Investigation of structure-activity relationships was conducted with respect to potency of inhibition of cardiac mitochondrial palmitoylCoA oxidation and metabolic stability. Potent and metabolically stable analogues 33, 42, and 43 were evaluated in vitro for cytochrome P450 inhibition and potentially adverse electrophysiological effects. Compound 33 was also found to have favorable pharmacokinetic properties in rat.