The impact of HLA matching on long-term transplant outcome after allogeneic hematopoietic stem cell transplantation for CLL: a retrospective study from the EBMT registry

We analyzed 368 chronic lymphocytic leukemia patients who underwent allogeneic hematopoietic stem cell transplantation reported to the EBMT registry between 1995 and 2007. There were 198 human leukocyte antigen (HLA)-identical siblings; among unrelated transplants, 31 were well matched in high resolution ('well matched' unrelated donor, WMUD), and 139 were mismatched (MM), including 30 matched in low resolution; 266 patients (72%) received reduced-intensity conditioning and 102 (28%) received standard. According to the EBMT risk score, 11% were in scores 1-3, 23% in score 4, 40% in score 5, 22% in score 6 and 4% in score 7. There was no difference in overall survival (OS) at 5 years between HLA-identical siblings (55% (48-64)) and WMUD (59% (41-84)), P=0.82. In contrast, OS was significantly worse for MM (37% (29-48) P=0.005) due to a significant excess of transplant-related mortality. Also OS worsened significantly when EBMT risk score increased. HLA matching had no significant impact on relapse (siblings: 24% (21-27); WMUD: 35% (26-44), P=0.11 and MM: 21% (18-24), P=0.81); alemtuzumab T-cell depletion and stem cell source (peripheral blood) were associated with an increased risk. Our findings support the use of WMUD as equivalent alternative to HLA-matched sibling donors for allogeneic HSCT in CLL, and justify the application of EBMT risk score in this disease

Why aren’t we performing more allografts for aggressive non-Hodgkin’s lymphoma?

Allogeneic stem cell transplantation has an under-appreciated role in the management of intermediate-grade non-Hodgkin's lymphoma. It provides several advantages over autologous stem cell transplantation including provision of a lymphoma-free graft, reduced rates of secondary myelodysplastic syndrome and leukemia, and a potentially curative graft-versus-lymphoma effect. When applied to chemosensitive patients, the lower relapse rates and reasonable long-term outcomes make allogeneic transplantation a promising therapy to pursue. Patient populations, such as those with bone marrow involvement or very high-risk disease, can be identified as having suboptimal outcomes after autotransplantation and may benefit from such an approach. While the exact role of allogeneic stem cell transplantation remains to be determined, broad recommendations can be suggested for the management of patients with intermediate-grade lymphoma. New approaches to allogeneic transplantation, including the use of matched-unrelated donors and reduced-intensity conditioning regimens, may expand the applicability of this potentially curative modality