Comparable outcome after single-antigen-mismatched versus matched unrelated donor haematopoietic cell transplantation

Allogeneic haematopoietic stem cell transplantation (HSCT) is a proven treatment for patients with haematological malignancies. In this retrospective analysis, the impact of donor matching on outcome of unrelated HSCT was analysed in patients transplanted at the University of Leipzig.

From 2000 to 2009, 206 patients were transplanted from unrelated donors, of which 51 were mismatched (39 in 1 and 12 in ≥ 2 HLA-antigens), using peripheral blood or bone marrow grafts after total body irradiation and cyclophosphamide or busulfan and cyclophosphamide preparative regimens in combination with ATG. For graft-versus-host disease (GvHD) prophylaxis cyclosporine and MTX were administered.

After a median follow-up of 49 months, outcome at 5 years in recipients of HLA-identical grafts was comparable to that of patients transplanted from HLA-incompatible donors with an overall survival (OS) of 52 % (95 % CI 43-61) versus 48 % (95 % CI 34-63), respectively (p = 0.48). Results were also comparable for event-free survival at 5 years [47 % (95 % CI 38-56) vs. 39 % (95 % CI 25-54); p = 0.44], relapse incidence (RI) [29 % (95 % CI 20-38) vs. 41 (95 % CI 25-57); p = 0.22] and non-relapse mortality [24 % (95 % CI 16-33) vs. 20 % (95 % CI 8-33); p = 0.84] in the matched versus mismatched groups. Incidence of acute and chronic GvHD was similar in both groups. Advanced disease (p = 0.02) and low-resolution typing (p = 0.04) are risk factors for OS and RI in univariate and multivariate analysis.

Donors with one antigen mismatch are an acceptable option for patients with malignant disease for whom no fully matched donor is available.