Allogeneic peripheral blood stem cell transplantation with reduced-intensity conditioning: results of a prospective multicentre study.

Reduced-intensity conditioning (RIC) regimens for allogeneic haematopoietic stem cell transplantation (SCT) have been shown to lead to engraftment of donor stem cells without the severe extra-haematological toxicities of traditional myeloablative transplants. Between December 1998 and December 2000, 76 patients underwent a RIC peripheral blood SCT in a prospective multicentre study. The median age was 53 years, and 57 patients were beyond the early phase of their disease. The conditioning regimens consisted of fludarabine (150 mg/m2) plus melphalan (140 mg/m2) or busulphan (10 mg/kg). Graft-versus-host disease (GVHD) prophylaxis consisted of cyclosporin A plus short-course methotrexate. The preparative regimens were well tolerated. All patients experienced severe pancytopenia, but haematological recovery was prompt in all but two cases (early deaths). The 100-d probability of developing grade II-IV acute GVHD was 32% (10% grade III-IV), and the 1-year probability of developing chronic extensive GVHD was 43%. Early complete donor chimaerism was observed in 52/68 patients, and 16 evaluable patients were in complete chimaerism 1 year post transplant. With a median follow-up of 283 d (355 in 48 survivors), the 1-year probability of transplant-related mortality was 20%, and the 1-year overall and progression-free survivals were 60% and 55% respectively. In conclusion, RIC regimens lead to low early toxicity after allografting, with stable donor haematopoietic engraftment, with an apparent low risk of acute GVHD. Chronic GVHD, however, develops in a significant proportion of patients.