Peripheral blood progenitor cell (PBPC) mobilization in heavily pretreated patients with germ cell tumors: A report of 34 cases

The aim of the study was to evaluate peripheral blood progenitor cell mobilization by disease-specific chemotherapy in heavily pretreated patients with germ cell tumor (GCT), scheduled for high-dose chemotherapy. Thirty-four consecutive patients, 29 males and five females, with advanced GCT referred to our department for high-dose chemotherapy were evaluated retrospectively. Sixteen patients were mobilized by vinblastine 0.11 mg/kg on days 1 and 2, ifosfamide 1200 mg/m² days 1-5 and cisplatin 20 mg/m² days 1-5 (VeIP). In 10 patients, etoposide 75 mg/m² days 1-5 was used instead of vinblastine (VIP), while in eight patients the mobilization was attempted by administering 7 g/m² of cyclophosphamide. The choice of either etoposide or vinblastine was predicated upon which of these two drugs was associated with best results during premobilization chemotherapy. Cyclophosphamide was selected in patients refractory to previous cisplatin-based salvage chemotherapy. Twenty-five out of 34 patients underwent a successful PBPC collection. In 17 of them one leukapheresis procedure was sufficient to collect the target number of CD34⁺ cells, while in eight patients a double procedure was necessary. Altogether 33 aphereses were performed in 25 patients. In nine patients leukapheresis was not attempted. This was due to the fact that the chemotherapy failed to mobilize the target number of CD34⁺ cells in eight of them, treated with the VeIP mobilizing regimen, while one patient treated with high-dose cyclophosphamide rapidly progressed during therapy and for this reason leukapheresis was not undertaken. In conclusion, in heavily pretreated patients with GCT, PBPC mobilization is feasible by a further course of salvage chemotherapy. The choice of either etoposide (VIP) or vinblastine (VeIP) can be predicated upon which of these two drugs was associated with best results during premobilization chemotherapy. In our hands, VeIP seems to be less satisfactory as mobilizing treatment than VIP, possibly due to a superior number of premobilization courses of chemotherapy in some patients. Moreover, high-dose cyclophosphamide remains a good alternative for mobilizing patients refractory to salvage chemotherapy.