Temozolomide associated with PEG-interferon in patients with metastatic melanoma: a multicenter prospective phase I/II study

Metastatic melanoma treatment remains disappointing, and a combined approach by chemotherapy and immunotherapy might increase the response rates through a synergistic action. Accordingly, a clinical trial using oral temozolomide (TMZ) and subcutaneous PEG-interferon alpha-2b (PEG) in patients with metastatic melanoma was designed to determine the maximal tolerated dosage of both drugs and the antitumoral response. A multicenter, prospective, phase I/II study was conducted in 31 metastatic melanoma patients, without cerebral metastasis. Dose escalation was performed according to the modified continual reassessment method scale and resulted in four cohorts of patients: TMZ 150 mg/m2 5 days/week each 4 weeks and PEG 0.5 microg/kg/week - TMZ 150 mg/m2 5 days/week and PEG 1.0 microg/kg/week - TMZ 200 mg/m2 5 days/week and PEG 0.5 microg/kg/week - TMZ 200 mg/m2 5 days/week and PEG 1.0 microg/kg/week. Patients received a maximum of six cycles. Thirty-three patients were enrolled in this study: one in the first dose level, one in the second one, 18 in the third one and 11 in the fourth one. At level 4, four of 11 patients experienced dose-limiting toxicity and four nondose-limiting toxicity; toxicity was mainly hematologic (grade IV thrombocytopenia). An objective response was observed in five patients (two complete response and three partial response) receiving level 3 or 4 of treatment. The disease remained stable in three patients, and six of 31 patients were alive 24 months after enrollment. The association of oral TMZ with subcutaneous PEG in metastatic melanoma displayed an unacceptable hematological toxicity with the dosages of 200 mg/m2 5 days/week and 1 microg/week, respectively. At a lower level, this treatment was effective and deserves further investigations to define its indications in metastatic melanoma patients.