Escalating high-dose carboplatin and autologous bone marrow transplantation in solid tumors

Twenty-seven patients with poor-prognosis malignancies were treated with a combination (CARBOPEC) of fixed-dose etoposide (1,750 mg/m2), cyclophosphamide (6,400 mg/m2), and escalating doses of carboplatin (from 800 to 1,600 mg/m2) followed by autologous bone marrow transplantation (ABMT). All patients had previously received platinum derivatives. The diagnoses were as follows: germ cell tumors (GCTs; n = 15); ovarian carcinomas (n = 8); rhabdomyosarcomas (n = 3), and Hodgkin's disease (n = 1). All 27 patients were fully evaluated for toxicity. The median duration of granulocytopenia (leukocytes < 0.5 x 10(9)/l) and thrombocytopenia (platelets < 20 x 10(9)/l) was 23 and 20 days, respectively. Hematologic growth factors were used in 3 cases. The main nonhematologic toxicity was gastrointestinal, with moderate to severe diarrhea in 18 patients. No significant renal toxicity was observed. The overall response rate to this high-dose chemotherapy was 55%, with a complete response (CR) rate of 45% (9 patients). The median duration of CR was 9 months. Five of the 27 patients are alive with no evidence of disease (NED) at 5, 22, 27, 40, and 43 months after ABMT. Four of the 11 patients with refractory GCTs have NED at 5, 22, 27, and 40 months, together with 1 of the 3 responders (43 months). Our study shows the encouraging antitumor activity of this regimen. Similar chemotherapy schedules have also been used with high response rates in GCT, ovarian cancer, breast cancer, and soft tissue sarcoma in children. The CARBOPEC protocol seems to be a good candidate for therapy intensification in patients with various malignancies. A European trial for salvage therapy in GCT will be activated in the near future. Moreover, results should improve with the widespread use of hematopoietic growth factors and optimization of carboplatin administration that takes pharmacokinetic parameters into account.