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.