Matching at Human Leukocyte Antigen-C Improved the Outcomes after Double Umbilical Cord Blood Transplantation for Recipients of Two to Four of Six Human Leukocyte Antigen-Matched Grafts

Combined impact of HLA-allele matching and the CD34-positive cell dose on optimal unit selection for single-unit cord blood transplantation in adults

The combined effects of HLA-allele matching at six-loci (HLA-A, -B, -C, -DRB1, -DQB1, and -DPB1) and CD34⁺ cell dose on clinical outcomes were analyzed in 1,226 adult cases with single-unit unrelated cord blood transplantation. In the six-loci analysis, low HLA-allele matches did not significantly increase the overall mortality compared to higher matches, whereas in the five-loci analysis excluding HLA-DPB1, they caused a higher overall mortality (HR 1.42, p = .002), possibly due to the graft-versus-leukemia effect of HLA-DPB1 mismatches. A lower CD34⁺ cell dose (<.50 × 10⁵/kg) resulted in higher mortality and lower engraftment; these inferior outcomes were offset by high HLA-allele matches (7-10/10 match), while the inferior outcomes of low HLA-allele matches were improved by increasing the CD34⁺ cell dose. Consideration of the combined effects of the CD34⁺ cell dose and HLA matching may expand the options for transplantable units when HLA matching or the CD34⁺ cell dose is inadequate.

Role of Stem-Cell Transplantation in Leukemia Treatment

Stem cells (SCs) play a major role in advanced fields of regenerative medicine and other research areas. They are involved in the regeneration of damaged tissue or cells, due to their self-renewal characteristics. Tissue or cells can be damaged through a variety of diseases, including hematologic and nonhematologic malignancies. In regard to this, stem-cell transplantation is a cellular therapeutic approach to restore those impaired cells, tissue, or organs. SCs have a therapeutic potential in the application of stem-cell transplantation. Research has been focused mainly on the application of hematopoietic SCs for transplantation. Cord blood cells and human leukocyte antigen-haploidentical donors are considered optional sources of hematopoietic stem-cell transplantation. On the other hand, pluripotent embryonic SCs and induced pluripotent SCs hold promise for advancement of stem-cell transplantation. In addition, nonhematopoietic mesenchymal SCs play their own significant role as a functional bone-marrow niche and in the management of graft-vs-host disease effects during the posttransplantation process. In this review, the role of different types of SCs is presented with regard to their application in SC transplantation. In addition to this, the therapeutic value of autologous and allogeneic hematopoietic stem-cell transplantation is assessed with respect to different types of leukemia. Highly advanced and progressive scientific research has focused on the application of stem-cell transplantation on specific leukemia types. We evaluated and compared the therapeutic potential of SC transplantation with various forms of leukemia. This review aimed to focus on the application of SCs in the treatment of leukemia.

Guidelines for Cord Blood Unit Selection

Optimal cord blood (CB) unit selection is critical to maximize the likelihood of successful engraftment and survival after CB transplantation (CBT). However, unit selection can be complex because multiple characteristics must be considered including unit cell dose, donor-recipient human leukocyte antigen (HLA) match, and unit quality. This review provides evidence-based and experience-based comprehensive guidelines for CB unit selection. Topics addressed include the use of both the TNC and the CD34⁺ cell dose, as well as the CD34⁺ cell to TNC content ratio to evaluate unit progenitor cell content and engraftment potential, the acceptable TNC and CD34⁺ cell dose criteria that define an adequate single-unit graft, and the indication and acceptable cell dose criteria for double-unit grafts. The acceptable criteria for 6-loci (HLA-A, -B antigen, -DRB1 allele) and 8-allele (HLA-A, -B, -C, -DRB1) donor-recipient HLA match, the evaluation of patients with donor-specific HLA antibodies, and the multiple determinants of unit quality are also reviewed in detail. Finally, a practical step-by-step guide to CB searches and the principles that guide ultimate graft selection are outlined.

Reduced-Intensity versus Myeloablative Conditioning in Cord Blood Transplantation for Acute Myeloid Leukemia (40-60 years) across Highly Mismatched HLA Barriers-On Behalf of Eurocord and the Cellular Therapy & Immunobiology Working Party (CTIWP) of EBMT

The use of myeloablative conditioning (MAC) in umbilical cord blood transplantation (UCBT) has been associated with high nonrelapse mortality (NRM) in patients aged >40 years, especially those having a high HLA disparity, thus limiting wider applications. We hypothesized that the NRM advantage of reduced-intensity conditioning (RIC) and higher graft-versus-leukemia effect associated with greater HLA disparities would expand its use for patients (aged 40 to 60 years) without compromising efficacy and compared outcomes between RIC and MAC regimens. In total, 288 patients aged 40 to 60 years, with de novo acute myeloid leukemia, receiving UCBT with at least 2 HLA mismatches with RIC (n = 166) or MAC (n = 122) regimens were included. As compared to RIC, the MAC cohort included relatively younger patients, having received more single UCBT, with lower total nucleated cell counts and more in vivo T cell depletion. Median time to neutrophil engraftment, infections (bacterial, viral, and fungal), and grade II to IV acute and chronic graft-versus-host disease were similar in both groups. In the multivariate analysis, overall survival (hazard ratio [HR], 0.98; P = .9), NRM (HR, 0.68; P = .2), and relapse (HR, 1.24; P = .5) were not different between RIC and MAC. Refractory disease was associated with worse survival. Outcomes of UBCT for patients aged 40 to 60 years having ≥2 HLA mismatches are comparable after the RIC or MAC regimen.

Composite GRFS and CRFS Outcomes After Adult Alternative Donor HCT

PURPOSE

There is no consensus on the best choice of an alternative donor (umbilical cord blood [UCB], haploidentical, one-antigen mismatched [7/8]-bone marrow [BM], or 7/8-peripheral blood [PB]) for hematopoietic cell transplantation (HCT) for patients lacking an HLA-matched related or unrelated donor.

METHODS

We report composite end points of graft-versus-host disease (GVHD)-free relapse-free survival (GRFS) and chronic GVHD (cGVHD)-free relapse-free survival (CRFS) in 2,198 patients who underwent UCB (n = 838), haploidentical (n = 159), 7/8-BM (n = 241), or 7/8-PB (n = 960) HCT. All groups were divided by myeloablative conditioning (MAC) intensity or reduced intensity conditioning (RIC), except haploidentical group in which most received RIC. To account for multiple testing, P < .0071 in multivariable analysis and P < .00025 in direct pairwise comparisons were considered statistically significant.

RESULTS

In multivariable analysis, haploidentical group had the best GRFS, CRFS, and overall survival (OS). In the direct pairwise comparison of other groups, among those who received MAC, there was no difference in GRFS or CRFS among UCB, 7/8-BM, and 7/8-PB with serotherapy (alemtuzumab or antithymocyte globulin) groups. In contrast, the 7/8-PB without serotherapy group had significantly inferior GRFS, higher cGVHD, and a trend toward worse CRFS (hazard ratio [HR], 1.38; 95% CI, 1.13 to 1.69; P = .002) than the 7/8-BM group and higher cGVHD and trend toward inferior CRFS (HR, 1.36; 95% CI, 1.14 to 1.63; P = .0006) than the UCB group. Among patients with RIC, all groups had significantly inferior GRFS and CRFS compared with the haploidentical group.

CONCLUSION

Recognizing the limitations of a registry retrospective analysis and the possibility of center selection bias in choosing donors, our data support the use of UCB, 7/8-BM, or 7/8-PB (with serotherapy) grafts for patients undergoing MAC HCT and haploidentical grafts for patients undergoing RIC HCT. The haploidentical group had the best GRFS, CRFS, and OS of all groups.

Selection of unrelated donors and cord blood units for hematopoietic cell transplantation: guidelines from the NMDP/CIBMTR

Allogeneic hematopoietic cell transplantation involves consideration of both donor and recipient characteristics to guide the selection of a suitable graft. Sufficient high-resolution donor-recipient HLA match is of primary importance in transplantation with adult unrelated donors, using conventional graft-versus-host disease prophylaxis. In cord blood transplantation, optimal unit selection requires consideration of unit quality, cell dose and HLA-match. In this summary, the National Marrow Donor Program (NMDP) and the Center for International Blood and Marrow Transplant Research, jointly with the NMDP Histocompatibility Advisory Group, provide evidence-based guidelines for optimal selection of unrelated donors and cord blood units.

What compatibility in 2017 for the haematopoietic stem cell transplantation?

The diversification of potential donors to perform stem cell allografts now enables to propose a compatible graft cell source adapted to the different clinical situations. Transplants with a geno-identical sibling donor, otherwise with the most HLA-compatible unrelated donor, remain the first-line solutions. Alternative transplants allow to graft patients having no donors in international registries, owing to the rarity of their HLA typing. They are carried out with fairly incompatible grafts and are therefore limited by the existence in the recipient of preformed anti-HLA antibodies which predispose to their rejection. The simple prevention of acute Graft-versus-host disease in haplo-identical transplants, as well as the availability of donors, explain why they have very often replaced placental stem cell transplants. These latter remain useful for pediatric patients or in the absence of family donors.

Patients Lacking a KIR-Ligand of HLA Group C1 or C2 Have a Better Outcome after Umbilical Cord Blood Transplantation

Donor natural killer (NK) cells can destroy residual leukemic cells after allogeneic hematopoietic stem cell transplantation. This effect is based on the interaction of killer-cell immunoglobulin-like receptors (KIR) of donor NK cells with ligands of the major histocompatibility complex found on the surface of the target cells. HLA-C1 subtypes provide the ligand for KIR2DL2 and KIR2DL3 and the HLA-C2 subtypes for KIR2DL1. We have studied the probability of relapse (PR) after single-unit unrelated cord blood transplantation (UCBT) in relation to the potential graft-vs.-leukemia effect mediated by NK cells present in the umbilical cord blood (UCB) by analyzing KIR-ligand and HLA-C typing of the receptor. Data from 33 consecutive patients given a single unit UCBT were included. We have considered two groups of patients based on the absence or the presence of one of the C-ligands for inhibitory KIR and the incompatibility HLA-C1/2 between UCB and patients. Group 1 (n = 21): the patient lacks a C-ligand for inhibitory KIR present in UCB NK cells, i.e., patients homozygous C1/C1 or C2/C2. Group 2 (n = 12): patients heterozygous C1/C2 in which KIR-mediated graft-vs.-leukemia effect is not expected (presence of both C ligands for inhibitory KIR in the receptor). With a median follow-up post-UCBT of 93 months, patients with absence of a C-ligand for inhibitory KIRs (Group 1) showed a lower actuarial PR than patients with both C-ligands (group 2): 21 ± 10 vs. 68 ± 18% at 2 year and 36 ± 13 vs. 84 ± 14% at 5 years (p = 0.025), respectively. In patients with acute lymphoblastic leukemia, the 2-year PR was 36 ± 21% for group 1 and 66 ± 26% for 2 (p = 0.038). Furthermore, group 1 had a lower incidence of grades II–IV acute graft-vs.-host disease (p = 0.04). In the setting of UCBT, the absence of a C-ligand (C1 or C2) of inhibitory KIR in the patient is associated with lower PR, which is probably due to the graft-vs.-host leukemia effect caused by UCB NK cells that lack a ligand for the inhibitory KIR 2DL1/2DL2/2DL3.