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Background: Between 20% and 30% of patients with advanced germ cell tumors (GCTs) fail to have durable complete response to conventional cisplatin-based induction chemotherapy. However, third-line therapy with high-dose carboplatin and etoposide plus autlogous bone marrow transplantation (AuBMT) has induced durable complete response in 10%-20% of patients with cisplatin-resistant GCT. Purpose: We conducted a phase II trial of first-line therapy that included high-dose carboplatin and etoposide plus AuBMT in untreated men with advanced GCTs and unfavorable prognosis (i.e., 'poor-risk' patients). Methods: Twenty-eight patients were treated with a conventional-dose, cisplatin-containing regimen (VAB-6 [cisplatin, vinblastine, bleomycin, cyclophosphamide, dactinomycin]) with or without high-dose carboplatin (1500 mg/[m.sup.2]) and etoposide (1200 mg/[m.sup.2]) plus AuBMT. Twenty-two of these patients were selected for treatment with two cycles of high-dose carboplatin and etoposide plus AuBMT when reduced clearance of serum tumur markers (alpha-fetoprotein [AFP] or human chorionic gonadotropin [HCG]), as evidenced by prolonged half-life (>7 days for AFP and >3 days for HCG), was observed after two cycles of conventional treatment. Results: Fifteen (56%) of 27 patients considered assessable for response achieved a complete response (12 treated with high-dose chemotherapy plus AuBMT). Sixteen (57%) are alive; 13 (46%) are free of disease at a median follow-up of 31.2 months. For 36 cycles of high-dose chemotherapy, the median duration from bone marrow infusion until a granulocyte count of [0.5/mm.sup.3] and a platelet count of [50 000/mm.sup.3] was 16 days (range, 7-41 days and 8-30 days, respectively). Analysis showed a trend toward improved survival (P = .07) in patients treated with high-dose chemotherapy in this study, compared with 68 poor-risk patients with GCT treated with conventional-dose therapy alone in two earlier studies. Toxicity was not cumulative, and recovery of blood counts after AuBMT was generally rapid. Conclusions: Inclusion of high-dose carboplatin-containing chemotherapy in treatment of poor-risk GCT patients is feasible when serum tumor marker half-life is used to predict resistance to standard cisplatin-based therapy. High-dose therapy in this setting was well tolerated. Implications: Early use of a dose-intensive regimen may increase survival compared with conventional-dose therapy alone. Further studies with standard induction therapy and intensive high-dose therapy using hematopoietic growth factor support are warranted, followed by a randomized trial comparing this strategy with standard therapy.

Background. This study compared the efficacy of granulocyte-macrophage colony-stimulating factor (GM-CSF) alone or in combination with peripheral blood-derived hematopoietic progenitor cells (PBP) as support for patients receiving high-dose chemotherapy and assessed the adequacy of these strategies as alternatives to autologous bone marrow rescue. Methods. The authors studied patients with metastatic breast carcinoma who had a major response to conventional chemotherapy or had achieved a complete remission by surgical resection of all known metastases. They were treated with carboplatin 1500 mg/[m.sup.2], etoposide 1200 mg/[m.sup.2], and cyclophosphamide 5.0g/[m.sup.2]. Before this high-dose chemotherapy, the patients had been randomly assigned to one of two hematopoietic support strategies: GM-CSF alone (Group 1) or GM-CSF-primed PBP and GM-CSF (Group 2). Autologous bone marrow was harvested from all patients for use only in the event of persistent pancytopenia with marrow aplasia on day 15. Results. A total of 18 patients were treated. Randomization was halted after the initial 10 patients because of the significant advantages for patients in Group 2 in comparison with those in Group 1 in regard to (1) the median number of days to absolute neutrophil count 0.5 x [10.sup.9]/l (12 versus 21) and platelet count to 50 x [10.sup.9]/1 (13 versus 23), (2) platelet transfusions (3 versus 15.5), and (3) episodes of neutropenic sepsis (0 versus 4, respectively). One patient in Group 1 died from treatment-related complications. All patients in Group 1 required bone marrow reinfusion. No patient in Group 2 required bone marrow reinfusion, and no early mortality was observed in this group. Eight subsequent patients were treated with PBP and GM-CSF (Group 3). This group was more heavily pretreated than Groups 1 or 2 and had a slower hematologic recovery than Group 2. However, none of these patients required bone marrow reinfusion. The four patients in Group 1 that did not have early bone marrow rescue all had neutrophil counts of 0.0 on day 15. For Groups 2 and 3, the neutrophil counts on day 15 ranged from 0.3-2.1 x [10.sup.9]/1 (median, 1.9) and from 0.2-2.1 x [10.sup.9]/1 (median 0.6), respectively. Conclusions. The use of PBP plus GM-CSF accelerated hematologic recovery after this chemotherapeutic regimen compared with GM-CSF alone; there were reduced morbidity and platelet transfusion requirements. Recovery was sufficiently rapid that PBP were an acceptable alternative to autologous bone marrow transplantation in patients receiving high-dose carboplatin, etoposide, and cyclophosphamide. Cancer 1993; 71:2515-21.

We describe the effects of 4-hydroperoxycyclophospha-mide (4-HC) on the hematopoietic and stromal elements of human bone marrow. Marrow cells were exposed to 4-HC and then assayed for mixed (CFU-Mix), erythroid (BFU-E), granulomonocytic (CFU-GM), and marrow fibroblast (CFU-F) colony-forming cells and studied in the long-term marrow culture (LTMC) system. The inhibition of colony formation by 4-HC was dose and cell-concentration dependent. The cell most sensitive to 4-HC was CFU-Mix (ID50, 31 μmol/L) followed by BFU-E (ID5041 μmol/L), CFU-GM (ID5089 μmol/L), and CFU-F (ID50235 μmol/L). In LTMC, a dose-related inhibition of CFU-GM production was noted. Marrows treated with 300 μmol/L 4-HC were completely depleted of CFU-GM but were able to generate these progenitors in LTMC. Marrow stromal progenitors giving rise to stromal layers in LTMC, although less sensitive to 4-HC cytotoxicity, were damaged by 4-HC also in a dose-related manner. Marrows treated with 4-HC up to 300 μmol/L, gave rise to stromal layers composed of fibroblasts, endothelial cells, adipocytes, and macrophages. Cocultivation experiments with freshly isolated autologous hematopoietic cells showed that stromal layers derived from 4-HC-treated marrows were capable of sustaining the long-term production of CFU-GM as well as controls. In conclusion: (1) Hematopoietic progenitors cells, CFU-Mix, BFU-E, and CFU-GM, are highly sensitive to 4-HC, whereas marrow stromal progenitor cells are relatively resistant. (2) Marrows treated with 300 μmol/L 4-HC that are depleted of CFU-Mix, BFU-E, and CFU-GM can generate CFU-GM in LTMC, suggesting that most primitive hematopoietic stem cells (not represented by CFU-Mix) are spared by 4-HC up to this dose. (3) Consequently, the above colony assays are not suitable tools for predicting pluripotent stem cell survival after 4-HC treatment in vitro.