High-Dose Chemotherapy and Stem Cell Transplant in Treating Patients With Metastatic Germ Cell Tumors That Have Not Responded to First-Line Therapy

RATIONALE: Drugs used in chemotherapy work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. An autologous stem cell transplant may be able to replace blood-forming cells that were destroyed by chemotherapy. PURPOSE: This phase II trial is studying the side effects of giving high-dose chemotherapy together with stem cell transplant and to see how well it works in treating patients with metastatic germ cell tumors that have not responded to first-line therapy.

OBJECTIVES: * To evaluate the efficacy of high-dose chemotherapy comprising carboplatin and etoposide (CE) in combination with autologous hematopoietic stem cell transplantation using the CE regimen as initial salvage treatment in patients with relapsed or refractory, metastatic germ cell tumors that did not respond to first-line treatment. * To evaluate the toxicity associated with this regimen in these patients. * To evaluate biological correlates of outcome in patients with available tissue pre- and post-treatment. OUTLINE: * Conventional-dose chemotherapy: Patients receive ifosfamide on days 1 and 2, followed by cisplatin and etoposide on days 3-5, and dexamethasone on days 1-5. Patients undergo leukapheresis daily for stem cell harvest. Patients also receive conventional filgrastim (G-CSF) subcutaneously (SC) once a day beginning 48 hours after completion of chemotherapy until adequate collection of stem cells are obtained. Treatment repeats every 21 days for 1 or 2 courses. * High-dose (HD) chemotherapy: Patients receive HD carboplatin and etoposide once a day on days 1-3. Treatments repeat every 30-40 days for 2 courses. * Autologous hematopoietic stem cell transplantation: Patients undergo reinfusion of autologous stem cells on day 6 (after HD chemotherapy on days 1-5). Patients then receive one dose of pegfilgrastim SC beginning 6 hours after completion of stem cell infusion or conventional filgrastim SC once daily beginning 4 days after completion of stem cell infusion and continuing until blood counts recover.