Life-threatening thrombocytopenia (low platelet count) and neutropenia (low white blood count) remain the major dose-limiting toxicities following chemotherapy treatment for cancer. The only remedy for thrombocytopenia at present is platelet transfusion, which is effective in preventing life-threatening hemorrhage, but may lead to other complications. Preclinical studies and studies in adults have shown recombinant human thrombopoietin (rhTPO) to be effective in stimulating platelet production. The initial phase of this trial will evaluate the safety of rhTPO use immediately after chemotherapy with ifosfamide, carboplatin, and etoposide in children with solid tumors and lymphomas. The second phase of the study will evaluate the effectiveness of rhTPO in decreasing the duration of low platelet count after chemotherapy.

Inclusion Criteria:

• Diagnosis of recurrent, refractory, or previously untreated malignant solid tumor or recurrent/refractory lymphoma for which Ifosfamide, Carboplatin, and Etoposide chemotherapy is the most appropriate treatment.
• Adequate liver and kidney function.
• Adequate performance status.