High-Dose Cyclophosphamide for Steroid Refractory GVHD

DISEASE CHARACTERISTICS: * Histologically confirmed acute graft-versus-host disease (GVHD) ≥ clinical grade II, that is steroid refractory * Steroid refractory GVHD is defined as GVHD that has progressed (increasing in grading) despite 49 hours of treatment with methylprednisolone of ≥ 2.0 mg/kg OR GVHD that has failed to improve (no change in grading stage) despite 4 days of treatment with methylprednisolone of ≥ 2.0 mg/kg * Prior allogeneic hematopoietic stem cell transplantation using either bone marrow, peripheral blood stem cells, or cord blood OR prior donor lymphocyte infusion required * Evidence of myeloid engraftment * No chronic GVHD PATIENT CHARACTERISTICS: * ECOG (Eastern Cooperative Oncology Group) performance status (PS) 0-2 OR Karnofsky PS 60-100% * ANC (absolute neutrophil count) \> 500/mm³ * Not pregnant or nursing * Fertile patients must use effective contraception * Must be geographically accessible * No allergy or intolerance to cyclophosphamide or mesna * No HIV positivity * No mechanical ventilation * No active bleeding (excluding gastrointestinal bleeding) or history of hemorrhagic cystitis * No other uncontrolled illness including, but not limited to, the following: * Ongoing or active infection * Medical condition precluding patient from stopping azoles (e.g., fluconazole, itraconazole, or voriconazole) or other adequate antifungal therapy during cyclophosphamide administration * Symptomatic congestive heart failure * Unstable angina pectoris * Psychiatric illness/social situations that would preclude compliance PRIOR CONCURRENT THERAPY: * See Disease Characteristics