Phase I/II trial of carboplatin dose escalation in combination chemotherapy with etoposide, bleomycin and GM-CSF support for poor prognosis nonseminomatous germ cell tumors patients.

To determine the maximum tolerated dose (MTD), and therapeutic efficacy of carboplatin (CBDCA) in combination with etoposide and bleomycin (CEB) as initial chemotherapy for poor prognosis germ cell tumors, a CBDCA dose escalation supported with GM-CSF had been performed. Twenty four untreated patients were treated with CBDCA 400 mg/m2 on day 1, etoposide 100 mg/m2 on days 1 to 5 and bleomycin 30 mg on days 1, 3, 5. Four cycles were scheduled at 21-day interval. The first cohort of 6 patients received only initial chemotherapy regimen. In the subsequent cohorts of six patients, the CBDCA dose was increased by 100 mg/m2. A fixed dose and schedule of GM-CSF at 5 micrograms/kg subcutaneously was given on days 6 through 15. Myelosuppression, with neutropenic fever and hemorrhages, was the dose-limiting toxicity at the 600 mg/m2 dose level. The recommended dose of CBDCA is 500 mg/m2. Overall complete response (CR) rate was 71% and with median follow up of 25 (16-34) months, 58% of patients are alive and have no evidence of disease (NED). A higher number of CR was achieved with CBDCA dose higher than 400 mg/m2 compared with CBDCA dose of 400 mg/m2 (92 vs. 50%, p = 0.03), as well as a higher proportion of patients who are alive and with NED (75 vs. 42%, p = 0.1). Despite GM-CSF support, the MTD of CBDCA could not be increased beyond 500 mg/m2 (50% of the dose escalation), due to severe myelosuppression. The treatment outcomes obtained with CEB in our study are no better than the standard cisplatin-based chemotherapy. Further studies of this regimen, where CBDCA dose should be calculated according to the patients glomerular filtration rate are warranted.