Myfortic - Treatment for Extensive cGvHD

Inclusion Criteria: * Age 18 - 60 * Any primary diagnosis requiring treatment by hematopoietic stem cell transplantation * Recipient of a single allogeneic stem cell transplant (bone marrow or peripheral blood stem cells, or cord blood) minimum 80 days ago * Received a graft from a related or an unrelated donor * Conditioning regimen: Myeloablative or non-myeloablative * Patients suffering a first episode of extensive chronic GvHD, without recurrent disease * The diagnosis of chronic GvHD requires the following: * Distinction from acute GvHD * Presence of at least one diagnostic clinical sign of chronic GvHD or presence of at least one distinctive sign confirmed by pertinent biopsy or other relevant diagnostic tests * Exclusion of other possible diagnoses * Receiving a standard prophylaxis regimen for acute GvHD: CsA plus methotrexate, or CSA+MMF for NMA, or a T-cell depleted transplant * Patient gives written informed consent prior to randomization Exclusion Criteria: * Patient age less than 18 years or over 60 years. * GvHD prophylaxis by tacrolimus plus methotrexate * Delayed onset acute GvHD following NMA or DLI * Second allogeneic stem cell transplant * Not the first episode of chronic GvHD needing systemic immunosuppressive therapy. * Limited chronic GvHD (Seattle criteria, see Appendix 1) * Uncontrolled systemic infection which in the opinion of the investigator is associated with an increased risk of the patient's death within 1 week of randomization * In the opinion of the investigator, if the patient has significant medical or psychosocial problems or unstable disease status * Pregnant or lactating females * Known hypersensitivity to mycophenolic acid