<qa>  What is the name of the tumor that is eligible for relapsed or refrac- Patients with relapsed or refractory solid tumors including central nervous system CNS tumors are eligible; patients must have had histologic verification of malignancy at original diagnosis or relapse except in patients with intrinsic brain stem tumors, optic pathway gliomas, or patients with pineal tumors and elevations of cerebrospinal fluid CSF or serum tumor markers including alpha-fetoprotein or beta-human chorionic gonadotropin HCG 