The purpose of this study is to determine whether very high dosages of chemotherapy will improve the chance of surviving cancer.

This is a phase II trial designed to provide a transplant option for patients with rare poor-prognosis cancers. The protocol is only open to patients with metastatic or relapsed cancers for whom the probability of remaining free of progressive disease for one year after being brought into remission is < 25%. Patients eligible for this study have been diagnosed with a form of cancer that leads to death more than 75% of the time when treated with standard therapy doses of chemotherapy and/ or radiation therapy. Under this treatment intensification protocol the expectation is that the one year progression-free survival for this group of patients will rise to 40%. Patients eligible for this protocol will be followed for one year post-transplant. Patients alive and free of progressive disease at the end of this period will be considered successes.

Inclusion Criteria:

• Patients must be ineligible for other IRB-approved myeloablative regimens, be 21 years old or younger, and must have a histologically-confirmed Wilms' tumor, liver cancer, recurrent brain tumor of childhood, nasopharyngeal carcinoma, fibrosarcoma, desmoplastic small round cell tumor, germ cell tumor or other small round cell tumor, which:

  1. is metastatic and has < 25% cure rate with conventional treatment; or
  2. progressed after prior chemotherapy and has < 25% salvage rate with non-myeloablative therapies.

• Disease status: Within 3 weeks of initiation of this protocol, patients must:

  1. be in a complete or good partial remission (section 7.4); or
  2. have a "chemosensitive" tumor, which is defined as a > 50% decrease in at least one measurable tumor parameter attributable to prior chemotherapy, without evidence of progressive disease by any other parameter.

• Prior chemotherapy: Before entry to this protocol, patients must have derived maximal benefit from conventional, i.e., nonmyeloablative, doses of combination chemotherapy. Conventional therapy should be continued until either a complete remission is achieved, no further benefit from non-myeloablative dosing can be appreciated, or toxicity from conventional therapy is perceived as limiting in the absence of stem cell rescue. The cancer must be proven to be sensitive to alkylating agents. This means that, in addition to, or as part of, the appropriate chemotherapy protocol for the specific cancer in question, all patients must have received and responded to a minimum of:

  1. 2 courses of high-dose cyclophosphamide, totaling > 4200 mg/m2; or
  2. courses of high-dose ifosfamide totaling > 12 gm/m2.
  3. 1 course of "a)" above, plus 1 course of 'b)" above.
  4. Equivalent high dose alkylating agents as described in 3.3 a, b, and c.

• Patients must have adequate renal hepatic, and cardiac function (sections 4.4-4.6).

• Patients must meet at least one of the following stem cell requirements (Peripheral blood collection is to be preferred when available as an option):

  1. Harvested bone marrow must contain 1 x 108 nucleated cells per kg of body weight, or,
  2. Peripheral blood collection should include at least 2 x 106 CD34+ cells/kg.

• Informed consent must be signed indicating patient and/or parental awareness of the investigational nature of this program