RESUMEN
PURPOSE: To evaluate the preclinical pharmacokinetics and antitumor efficacy of a novel orally bioavailable poly(ADP-ribose) polymerase (PARP) inhibitor, ABT-888. EXPERIMENTAL DESIGN: In vitro potency was determined in a PARP-1 and PARP-2 enzyme assay. In vivo efficacy was evaluated in syngeneic and xenograft models in combination with temozolomide, platinums, cyclophosphamide, and ionizing radiation. RESULTS: ABT-888 is a potent inhibitor of both PARP-1 and PARP-2 with K(i)s of 5.2 and 2.9 nmol/L, respectively. The compound has good oral bioavailability and crosses the blood-brain barrier. ABT-888 strongly potentiated temozolomide in the B16F10 s.c. murine melanoma model. PARP inhibition dramatically increased the efficacy of temozolomide at ABT-888 doses as low as 3.1 mg/kg/d and a maximal efficacy achieved at 25 mg/kg/d. In the 9L orthotopic rat glioma model, temozolomide alone exhibited minimal efficacy, whereas ABT-888, when combined with temozolomide, significantly slowed tumor progression. In the MX-1 breast xenograft model (BRCA1 deletion and BRCA2 mutation), ABT-888 potentiated cisplatin, carboplatin, and cyclophosphamide, causing regression of established tumors, whereas with comparable doses of cytotoxic agents alone, only modest tumor inhibition was exhibited. Finally, ABT-888 potentiated radiation (2 Gy/d x 10) in an HCT-116 colon carcinoma model. In each model, ABT-888 did not display single-agent activity. CONCLUSIONS: ABT-888 is a potent inhibitor of PARP, has good oral bioavailability, can cross the blood-brain barrier, and potentiates temozolomide, platinums, cyclophosphamide, and radiation in syngeneic and xenograft tumor models. This broad spectrum of chemopotentiation and radiopotentiation makes this compound an attractive candidate for clinical evaluation.
Asunto(s)
Bencimidazoles/administración & dosificación , Bencimidazoles/farmacocinética , Inhibidores Enzimáticos/administración & dosificación , Inhibidores Enzimáticos/farmacocinética , Neoplasias/tratamiento farmacológico , Inhibidores de Poli(ADP-Ribosa) Polimerasas , Administración Oral , Animales , Antineoplásicos Alquilantes/uso terapéutico , Disponibilidad Biológica , Barrera Hematoencefálica/metabolismo , Línea Celular Tumoral , Daño del ADN , Modelos Animales de Enfermedad , Perros , Sinergismo Farmacológico , Femenino , Haplorrinos , Humanos , Masculino , Ratones , Ratones Endogámicos , Ratas , Ratas Endogámicas , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
ABT-869 is a structurally novel, receptor tyrosine kinase (RTK) inhibitor that is a potent inhibitor of members of the vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) receptor families (e.g., KDR IC50 = 4 nmol/L) but has much less activity (IC50s > 1 micromol/L) against unrelated RTKs, soluble tyrosine kinases, or serine/threonine kinases. The inhibition profile of ABT-869 is evident in cellular assays of RTK phosphorylation (IC50 = 2, 4, and 7 nmol/L for PDGFR-beta, KDR, and CSF-1R, respectively) and VEGF-stimulated proliferation (IC50 = 0.2 nmol/L for human endothelial cells). ABT-869 is not a general antiproliferative agent because, in most cancer cells, >1,000-fold higher concentrations of ABT-869 are required for inhibition of proliferation. However, ABT-869 exhibits potent antiproliferative and apoptotic effects on cancer cells whose proliferation is dependent on mutant kinases, such as FLT3. In vivo ABT-869 is effective orally in the mechanism-based murine models of VEGF-induced uterine edema (ED50 = 0.5 mg/kg) and corneal angiogenesis (>50% inhibition, 15 mg/kg). In tumor growth studies, ABT-869 exhibits efficacy in human fibrosarcoma and breast, colon, and small cell lung carcinoma xenograft models (ED50 = 1.5-5 mg/kg, twice daily) and is also effective (>50% inhibition) in orthotopic breast and glioma models. Reduction in tumor size and tumor regression was observed in epidermoid carcinoma and leukemia xenograft models, respectively. In combination, ABT-869 produced at least additive effects when given with cytotoxic therapies. Based on pharmacokinetic analysis from tumor growth studies, efficacy correlated more strongly with time over a threshold value (cellular KDR IC50 corrected for plasma protein binding = 0.08 microg/mL, >or=7 hours) than with plasma area under the curve or Cmax. These results support clinical assessment of ABT-869 as a therapeutic agent for cancer.
Asunto(s)
Inhibidores Enzimáticos/farmacología , Indazoles/farmacología , Compuestos de Fenilurea/farmacología , Proteínas Tirosina Quinasas Receptoras/antagonistas & inhibidores , Células 3T3 , Animales , Ciclo Celular/efectos de los fármacos , División Celular/efectos de los fármacos , Córnea , Edema , Femenino , Ratones , Neovascularización Fisiológica/efectos de los fármacos , Fosforilación , Receptores del Factor de Crecimiento Derivado de Plaquetas/antagonistas & inhibidores , Receptores del Factor de Crecimiento Derivado de Plaquetas/metabolismo , Receptores de Factores de Crecimiento Endotelial Vascular/antagonistas & inhibidores , Receptores de Factores de Crecimiento Endotelial Vascular/metabolismo , Vasos Retinianos/efectos de los fármacos , Vasos Retinianos/fisiología , Útero/efectos de los fármacos , Útero/fisiopatologíaRESUMEN
The synthesis and biological evaluation of a series of heterocyclic analogues of the previously reported LTA(4) hydrolase inhibitor 1b are described. Imidazopyridine and purine analogues are specifically highlighted with several demonstrating excellent potency in our in vitro assays, as well as good oral activity in a mouse ex vivo assay.
Asunto(s)
Inhibidores Enzimáticos/síntesis química , Inhibidores Enzimáticos/farmacología , Epóxido Hidrolasas/antagonistas & inhibidores , Purinas/síntesis química , Purinas/farmacología , Piridinas/síntesis química , Piridinas/farmacología , Animales , Epóxido Hidrolasas/sangre , Compuestos Heterocíclicos/síntesis química , Compuestos Heterocíclicos/farmacología , Humanos , Técnicas In Vitro , Indicadores y Reactivos , Ratones , Proteínas Recombinantes/antagonistas & inhibidores , Relación Estructura-ActividadRESUMEN
The synthesis and biological evaluation of a series of functionalized pyrrolidine- and piperidine-containing analogues of our lead LTA(4) hydrolase inhibitor, SC-57461A, is described. A number of compounds showed excellent potency in our in vitro screens and several demonstrated good oral activity in a mouse ex vivo assay. These efforts led to the identification of SC-56938 (14) as a potent, orally active inhibitor of LTA(4) hydrolase.
Asunto(s)
Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/farmacología , Epóxido Hidrolasas/antagonistas & inhibidores , Piperidinas/química , Piperidinas/farmacología , Pirrolidinas/química , Pirrolidinas/farmacología , beta-Alanina/análogos & derivados , beta-Alanina/química , Administración Oral , Animales , Humanos , Concentración 50 Inhibidora , Ratones , Relación Estructura-ActividadRESUMEN
Leukotriene B(4) (LTB(4)) is a potent, proinflammatory mediator involved in the pathogenesis of a number of diseases including inflammatory bowel disease, psoriasis, rheumatoid arthritis, and asthma. The enzyme LTA(4) hydrolase represents an attractive target for pharmacological intervention in these disease states, since the action of this enzyme is the rate-limiting step in the production of LTB(4). Our previous efforts focused on the exploration of a series of analogues related to screening hit SC-22716 (1, 1-[2-(4-phenylphenoxy)ethyl]pyrrolidine) and resulted in the identification of potent, orally active inhibitors such as 2. Additional structure-activity relationship studies around this structural class resulted in the identification of a series of alpha-, beta-, and gamma-amino acid analogues that are potent inhibitors of the LTA(4) hydrolase enzyme and demonstrated good oral activity in a mouse ex vivo whole blood LTB(4) production assay. The efforts leading to the identification of clinical candidate SC-57461A (8d, 3-[methyl[3-[4-(phenylmethyl)phenoxy]propyl]amino]propanoic acid) are described.