RESUMEN
PURPOSE: Microtubules play a critical role in many cellular functions, including cell division and mitosis. ABT-751 is a novel sulfonamide antimitotic that binds to the colchicine site on beta-tubulin that leads to a block in the cell cycle at the G2M phase, resulting in cellular apoptosis. ABT-751 was investigated in this phase 1 trial designed to assess its maximum tolerated dose (MTD), dose-limiting toxicity (DLT), tolerability, and pharmacokinetics. EXPERIMENTAL DESIGN: ABT-751 was administered on a daily (q.d.) or twice daily (b.i.d.) oral schedule for 7 days every 3 weeks to 39 patients with refractory solid tumors. Toxicity was monitored weekly. Plasma and urine ABT-751 and metabolite pharmacokinetics were determined. RESULTS: The MTD for the q.d. schedule was 250 mg/d. DLTs during cycle 1 were abdominal pain, constipation, and fatigue. The MTD on the b.i.d. schedule was 150 mg. Cycle 1 of therapy with the 175 mg b.i.d. schedule was tolerated without DLT. However, six of seven patients reported grade 3 toxicity (ileus, constipation, abdominal pain, or fatigue), which occurred in cycle 2 or 3. ABT-751 was absorbed after oral administration with an overall mean T(max) of about 2 hours. The pharmacokinetics of ABT-751 were dose-proportional and time-independent. There was minimal accumulation of ABT-751 after multiple q.d. and b.i.d. doses. Efficacious concentrations, as determined from preclinical models (0.5-1.5 microg/mL), were achieved in all subjects. ABT-751 metabolism occurred primarily by glucuronidation and sulfation. No complete or partial tumor responses were noted, but one patient had a minor response, and four patients had stable disease lasting at least 6 months. CONCLUSIONS: The MTD and recommended phase 2 doses for ABT-751 were 250 mg q.d. and 150 mg b.i.d. on a 7-day schedule given every 3 weeks, due to subsequent cycle toxicities at 175 mg b.i.d. dosing. Toxicities were abdominal pain, constipation, and neuropathy.
Asunto(s)
Neoplasias/sangre , Sulfonamidas/farmacocinética , Sulfonamidas/toxicidad , Administración Oral , Adulto , Anciano , Disponibilidad Biológica , División Celular/efectos de los fármacos , Esquema de Medicación , Femenino , Humanos , Masculino , Persona de Mediana Edad , Neoplasias/orina , Seguridad , Sulfonamidas/uso terapéuticoRESUMEN
PURPOSE: To determine the toxicity profile, dose-limiting toxicities, and maximum tolerated dose of ABT-751 administered orally once daily for 7 days, repeated every 21 days. EXPERIMENTAL DESIGN: Patients who were =18 years of age, with relapsed or refractory solid tumors, and who were able to swallow capsules were eligible. The starting dose was 100 mg/m(2)/d (n = 3) and was escalated to 130 mg/m(2)/d (n = 6), 165 mg/m(2)/d (n = 6), 200 mg/m(2)/d (n = 6), and 250 mg/m(2)/d (n = 2) in cohorts of three to six patients. The maximum tolerated dose was determined from dose-limiting toxicities occurring during the first treatment cycle. RESULTS: Twenty-four children (median age, 13 years; range, 4-18 years) were enrolled; 23 were evaluable for toxicity. Diagnoses included neuroblastoma (n = 8), sarcomas (n = 8), primary brain tumors (n = 2), Wilms' tumor (n = 2), and other solid tumors (n = 3). Dose-limiting toxicities (grade 3 sensory and motor neuropathy, grade 3 hypertension, and grade 3 fatigue) were observed in patients enrolled at the 250 mg/m(2)/d dose level. The maximum tolerated dose of ABT-751 administered daily for 7 days every 21 days was 200 mg/m(2)/d. Non-dose-limiting toxicities at the maximum tolerated dose included anemia, fatigue, peripheral sensory neuropathy, abdominal pain, nausea, constipation, anorexia, fever, and weight loss. Myelosuppression was minimal at the maximum tolerated dose. The median number of cycles administered is 2 (range, 1-50). No significant ABT-751-related cumulative toxicities were observed. CONCLUSION: ABT-751 is well tolerated in children. The recommended dose for phase 2 trials in solid tumors is 200 mg/m(2)/d administered orally, daily for 7 days every 21 days. This dose is >40% higher than the maximum tolerated dose in adults receiving the same dosing schedule.