Inclusion Criteria

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 performance status (PS) 0-2 OR Karnofsky PS 60-100%

- ANC > 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