Is there a stronger graft-versus-leukemia effect using HLA-haploidentical donors compared with HLA-identical siblings?

Haploidentical hematopoietic stem cell transplants (HSCTs) are increasingly used, but it is unknown whether they have a stronger graft-versus-leukemia (GVL) effect. We analyzed 10 679 acute leukemia patients who underwent HSCT from an HLA-matched sibling donor (MSD, n=9815) or a haploidentical donor (⩾2 HLA-antigen disparity, n=864) between 2007 and 2012, reported to the European Group for Blood and Marrow Transplantation. In a Cox regression model, acute and chronic graft-versus-host disease (GVHD) was added as time-dependent variables. There was no difference in probability of relapse between recipients of haploidentical and MSD grafts. Factors of importance for relapse after T-cell-replete grafts included remission status at HSCT, Karnofsky score ⩽80, acute GVHD of grade II or higher and chronic GVHD (P<10(-5)). Patients with post-transplant cyclophosphamide (n=194) had similar outcome as other T-cell-replete haploidentical transplants (n=369). Non-relapse mortality was significantly higher in the haploidentical group compared with that in MSD patients (P<10(-5)). Leukemia-free survival was superior in the MSD patients receiving T-cell-replete (P<10(-5)) or T-cell-depleted grafts (P=0.0006). The risk of relapse was the same in acute leukemia patients who received haploidentical donor grafts as in those given MSD transplants, suggesting a similar GVL effect.

Comparison of outcomes after unrelated cord blood and unmanipulated haploidentical stem cell transplantation in adults with acute leukemia

Outcomes after unmanipulated haploidentical stem cell transplantation (Haplo) and after unrelated cord blood transplantation (UCBT) are encouraging and have become alternative options to treat patients with high-risk acute leukemia without human leukocyte antigen (HLA) matched donor. We compared outcomes after UCBT and Haplo in adults with de novo acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). Median follow-up was 24 months. Analysis was performed separately for patients with AML, n=918 (Haplo=360, UCBT=558) and ALL, n=528 (Haplo=158 and UCBT=370). UCBT was associated with delayed engraftment and higher graft failure in both AML and ALL recipients. In multivariate analysis, UCBT was associated with lower incidence of chronic graft-vs-host disease both in the AML group (hazard ratio (HR)=0.63, P=0.008) and in the ALL group (HR=0.58, P=0.01). Not statistically significant differences were observed between Haplo and UCBT for relapse incidence (HR=0.95, P=0.76 for AML and HR=0.82, P=0.31 for ALL), non-relapse mortality (HR=1.16, P=0.47 for AML and HR=1.23, P=0.23 for ALL) and leukemia-free survival (HR 0.78, P=0.78 for AML and HR=1.00, P=0.84 for ALL). There were no statistically differences on main outcomes after unmanipulated Haplo and UCBT, and both approaches are valid for acute leukemia patients lacking a HLA matched donor. Both strategies expand the donor pool for patients in need.

A survey on unmanipulated haploidentical hematopoietic stem cell transplantation in adults with acute leukemia

The use of unmanipulated graft is increasingly adopted in the setting of allogeneic hematopoietic stem cell transplantation from haploidentical family donors (haplo-SCT) in acute leukemia (AL). We analyzed the outcome of 229 adult patients with de novo AL, who received an unmanipulated haploidentical transplant as their first allo-SCT between 2007 and 2011. Median follow-up was 30 months. Disease status at transplant was: first complete remission (CR1) for 77, second CR (CR2) for 56, and advanced for 96 patients. One hundred and seventy-one patients received in vivo T-cell depletion by monoclonal antibodies (75%). The 60-day cumulative incidence (CI) of engraftment was 93±2%. The 100-day CI of acute graft-versus-host disease (GvHD) was 32±3% for grade II-IV, 12±3% for grade III-IV. The 3-year CI of chronic GvHD was 34±3%. The 3-year CI of non-relapse mortality was 31±4% with in vivo T-cell depletion and 17±5% without. At 3 years, for patients transplanted in CR1, CR2 or advanced disease leukemia-free survival was 44±6, 42±7 and 12±3%, overall survival was 55±6, 51±7 and 14±4% and CI of relapse was 32±6, 24±6 and 61±5%, respectively. These data suggest that unmanipulated haplo-SCT is a valid treatment option for adult AL patients in complete remission lacking a matched donor.

Unrelated donor search and unrelated donor transplantation in the adult aplastic anaemia patient aged 18-40 years without an HLA-identical sibling and failing immunosuppression

Currently at least 75% of patients with severe aplastic anaemia can be successfully transplanted using a matched unrelated donor (UD) haematopoietic SCT (HSCT). For children, outcomes are similar to matched sibling donor (MSD) HSCT. This improvement in outcome over time is likely due to improved HLA tissue typing to identify better matched donors, improvements in the conditioning regimen, particularly fludarabine-based regimens, and improved supportive care. Graft rejection occurs in ∼15% of adults, but is less frequent in children. Chronic GVHD remains a concern but may be reduced by using Alemtuzumab instead of ATG. UD HSCT should be considered early after failure to respond to one course of immunosuppressive therapy, but for children who lack a MSD up front matched UD HSCT may be considered.

The impact of center experience on results of reduced intensity: allogeneic hematopoietic SCT for AML. An analysis from the Acute Leukemia Working Party of the EBMT

Allogeneic hematopoietic SCT with reduced-intensity conditioning (RIC-HSCT) is increasingly adopted for the treatment of older adults with AML. Our goal was to verify for the first time, if center experience influences outcome of RIC-HSCT. Results of 1413 transplantations from HLA-matched related or unrelated donors for adult patients with AML in first CR were analyzed according to the level of center activity. Transplants were performed in 203 European centers between 2001 and 2007. The 2-year probability of leukemia-free survival (LFS) after RIC-HSCT performed in centers with the lowest activity (< or =15 procedures/7 years) was 43±3% compared with 55±2% in the remainder (P<0.001). The incidence of non-relapse mortality (NRM) was 24±3% and 15±1% (P=0.004), whilst relapse rate was 33±3% and 31±1% (P=0.33), respectively. In a multivariate model, adjusted for other prognostic factors, low RIC-HSCT activity was associated with decreased chance of LFS (hazard ratio (HR)=0.64; P<0.001) and increased risk of NRM (HR=1.47, P=0.04) and relapse (HR=1.41, P=0.01). Center experience is a very important predictor of outcome and should be considered in future analyses evaluating the results of RIC-HSCT. The reasons why centers with low RIC-HSCT activity have worse outcomes should be further investigated.