Outcomes of patients with myeloid malignancies treated with allogeneic hematopoietic stem cell transplantation from matched unrelated donors compared with one human leukocyte antigen mismatched related donors using HLA typing at 10 loci

Allogeneic hematopoietic cell transplantation for patients with AML aged 70 years or older in first remission. A study from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation (EBMT)

Accessibility to allogeneic hematopoietic cell transplantation (HCT) programs for older patients is growing constantly. We report on the clinical outcomes of a group of 701 adults aged ≥70 years, with acute myeloid leukemia (AML) in first complete remission (CR1), who received a first HCT, from HLA-matched sibling donors (MSD), 10/10 HLA-matched unrelated donors (UD), 9/10 HLA-mismatched unrelated donors (mUD) or haploidentical (Haplo) donors. The 2-year overall survival (OS) was 48.1%, leukemia-free survival (LFS) 45.3%, relapse incidence (RI) 25.2%, non-relapse mortality (NRM) 29.5% and GVHD-free, relapse-free survival (GRFS), 33.4%. Compared to MSD, patients transplanted from Haplo and UD presented lower RI (HR 0.46, 95% CI 0.25-0.8, p = 0.02 and HR 0.44, 95% CI: 0.28-0.69, p = 0.001, respectively); this translated into prolonged LFS for Haplo (HR 0.62, 95% CI: 0.39-0.99, p = 0.04). Patients transplanted from mUD exhibited the highest NRM incidence (HR 2.33, 95% CI: 1.26-4.31, p = 0.007). HCT in selected adult CR1 AML patients >70 years is feasible and could be associated with good clinical outcomes. Prospective clinical trials are warranted.

HSCT with mismatched unrelated donors: Bone marrow versus peripheral blood stem cells sources in pediatric patients

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (HSCT) from an unrelated HLA-mismatched donor (MMUD) is one of the alternatives where an HLA-matched donor is not found. The aim of this study was to compare bone marrow (BM) versus peripheral blood stem cells (PBSC) as hematopoietic rescue following allogeneic unrelated mismatched stem cell transplantation (MMUD).

METHODS

The patients were divided into two groups: 43 pediatric patients were treated with BM and 17 pediatric patients with PBSC. The study was registered at ClinicalTrials.gov NCT04598789.

RESULTS

The 3-year Overall Survival (OS) was 74% versus 31% (p = .0011). Transplant related mortality (TRM) was 16% versus 33% (p = .025), and relapse incidence (RI) was 16% versus 35% (p = .005). The day-100 acute Graft-versus-host disease (GvHD) incidence grade II-IV and III-IV was 30% versus 28% (p = NS) and 17% versus 17% (p = NS). The 3-year chronic GvHD incidence was 22% versus 33% (p = NS).

CONCLUSION

Despite all the limits of this retrospective study we were able to show how the combination of BM and ATG is able to prevent GvHDs and guarantee a high OS. Future studies addressing the issue of a post-transplant cellular therapy approach may potentially reduce relapses when GvHD is absent.

HSCT with Mismatched Unrelated Donors (MMUD): A Comparison of Different Platforms for GvHD Prophylaxis

HSCT from an unrelated HLA-mismatched donor (MMUD) is one of the alternatives where an HLA-matched donor is not found. The aim of this study was to compare GvHD prophylaxis with anti-thymocyte globulin (ATG) vs. post-transplant cyclophosphamide (PT-Cy). Thirty-nine adult patients were uniformly treated with rabbit ATG-Cy-A-MTX and peripheral blood stem cell (PBSC) and 40 adult patients with PT-Cy-MMF-tacrolimus and PBSC. This retrospective study was registered at ClinicalTrials.gov NCT04598789. Three-year overall survival was 42% vs. 64% for ATG and PT-Cy (p < 0.0005), three-year treatment-related mortality (TRM) was 36% vs. 8% (p = 0.0033) and the three-year relapse incidence (RI) was 15% vs. 28% (p = NS), respectively. The incidences of day-100 GvHD graded II–IV and III–IV were 39% vs. 7% (p = 0.0006) and 11% vs. 0% (p = 0.04), respectively, whereas the three-year cGvHD incidences were 48% vs. 13% (p = 0.0005), respectively. We were able to show how PT-Cy can reduce the incidence of GvHDs and TRM in adults, but relapse remains an issue.

Analysis of Single Nucleotide Polymorphisms in the Gamma Block of the Major Histocompatibility Complex in Association with Clinical Outcomes of Hematopoietic Cell Transplantation: A Center for International Blood and Marrow Transplant Research Study

HLA haplotype mismatches have been associated with an elevated risk of acute graft-versus-host disease (aGVHD) in patients undergoing HLA-matched unrelated donor (URD) hematopoietic cell transplantation (HCT). The gamma block (GB) is located in the central MHC region between beta and delta blocks (encoding HLA-B and -C and HLA-DQ and -DR antigens, respectively) and contains numerous inflammatory and immune regulatory genes, including Bf, C2, and C4 genes. A single-center study showed that mismatches in SNPs c.2918+98G, c.3316C, and c.4385C in the GB block (C4 SNPs) were associated with higher risk of grade III-IV aGVHD. We investigated the association of GB SNP (GBS) mismatches with outcomes after 10/10 and 9/10 URD HCT (n = 714). The primary outcome was acute GVHD. Overall survival, disease-free survival, transplantation-related mortality, relapse, chronic GVHD, and engraftment were also analyzed. DNA samples were GBS genotyped by identifying 338 SNPs across 20 kb using the Illumina NGS platform. The overall 100-day incidence of aGVHD grade II-IV and II-IV were 41% and 17%, respectively. The overall incidence of matching at all GBSs tested and at the C4 SNPs were 23% and 81%, respectively. Neither being matched across all GB SNPs tested (versus mismatched) nor having a higher number of GBS mismatches was associated with transplantation outcomes. There was no association between C4 SNP mismatches and outcomes except for an unexpected significant association between having 2 C4 SNP mismatches and a higher hazard ratio (HR) for relapse (association seen in 15 patients only; HR, 3.38, 95% confidence interval, 1.75 to 6.53; P = .0003). These data do not support the hypothesis that mismatching at GB is associated with outcomes after HCT.

NK cell therapy after hematopoietic stem cell transplantation: can we improve anti-tumor effect?

After decades since the discovery of natural killer (NK) cells as potential effector cells fighting malignantly transformed and virally infected cells, little progress has been made in their clinical application. This yet unrealized therapeutic effect is presumably, at least in part, due to low numbers of functional NK cells that could be obtained from the peripheral blood relative to tumor burden. Our group hypothesized that a relatively small NK cell number to targeted malignant cells is the cause of a lack of clinical effect. We pursued obtaining large numbers of NK cells via ex vivo expansion using feeder cells that express membrane-bound IL-21. Early clinical studies demonstrate safety of administration of ex vivo expanded NK cells after transplantation using this method and suggest a therapeutic benefit in terms on decreasing relapse rate and possible control of viral infections post-transplant can be achieved. Successful application of NK cells after hematopoietic stem cell transplantation opens the possibility to effectively enhance the anti-tumor effect and decrease relapse rate post-transplant. Moreover, high doses of NK cells could prove more efficacious in enhancing anti-tumor effects, not only in hematological malignancies, with our without transplantation, but also in solid tumor oncology.

ABO incompatibility in mismatched unrelated donor allogeneic hematopoietic cell transplantation for acute myeloid leukemia: A report from the acute leukemia working party of the EBMT

ABO incompatibility is commonly observed in stem cell transplantation and its impact in this setting has been extensively investigated. HLA-mismatched unrelated donors (MMURD) are often used as an alternative stem cell source but are associated with increased transplant related complications. Whether ABO incompatibility affects outcome in MMURD transplantation for acute myeloid leukemia (AML) patients is unknown. We evaluated 1,013 AML patients who underwent MMURD transplantation between 2005 and 2014. Engraftment rates were comparable between ABO matched and mismatched patients, as were relapse incidence [34%; 95% confidence interval (CI), 28-39; for ABO matched vs. 36%; 95% CI, 32-40; for ABO mismatched; P = .32], and nonrelapse mortality (28%; 95% CI, 23-33; for ABO matched vs. 25%; 95% CI, 21-29; for ABO mismatched; P = .2). Three year survival was 40% for ABO matched and 43% for ABO mismatched patients (P = .35), Leukemia free survival rates were also comparable between groups (37%; 95% CI, 32-43; for ABO matched vs. 38%; 95% CI, 33-42; for ABO mismatched; P = .87). Incidence of grade II-IV acute graft versus host disease was marginally lower in patients with major ABO mismatching (Hazard ratio of 0.7, 95% CI, 0.5-1; P = .049]. ABO incompatibility probably has no significant clinical implications in MMURD transplantation.

Outcomes of haploidentical transplant compared with matched donor allogeneic stem cell transplant

The risk of acute and chronic graft-versus-host disease (GVHD) with haploidentical transplant with post-transplant high-dose cyclophosphamide may be lower compared with matched unrelated donor transplant and largely similar to matched related donor transplant. The lower probability of GVHD with the haploidentical donor may result in a risk of nonrelapse mortality that is at least similar to or even lower than the matched donor. The incidence of relapse and survival are also largely similar to different donor types. Haploidentical transplant may be associated with slower engraftment. Given a lower risk of GVHD, haploidentical transplant has gained popularity. Additionally, the use of post-transplant high-dose cyclophosphamide has been extended to lower the risk of GVHD with matched donor and mismatched unrelated donor transplant.

MHC Class I Chain-Related Gene A (MICA) Donor-Recipient Mismatches and MICA-129 Polymorphism in Unrelated Donor Hematopoietic Cell Transplantations Has No Impact on Outcomes in Acute Lymphoblastic Leukemia, Acute Myeloid Leukemia, or Myelodysplastic Syndrome: A Center for International Blood and Marrow Transplant Research Study

Single-center studies have previously reported associations of MHC Class I Chain-Related Gene A (MICA) polymorphisms and donor-recipient MICA mismatching with graft-versus-host disease (GVHD) after unrelated donor hematopoietic cell transplantation (HCT). In this study, we investigated the association of MICA polymorphism (MICA-129, MM versus MV versus VV) and MICA mismatches after HCT with 10/10 HLA-matched (n = 552) or 9/10 (n = 161) unrelated donors. Included were adult patients with a first unrelated bone marrow or peripheral blood HCT for acute lymphoblastic leukemia, acute myeloid leukemia, or myelodysplastic syndrome that were reported to the Center for International Blood and Marrow Transplant Research between 1999 and 2011. Our results showed that neither MICA mismatch nor MICA-129 polymorphism were associated with any transplantation outcome (P < .01), with the exception of a higher relapse in recipients of MICA-mismatched HLA 10/10 donors (hazard ratio [HR], 1.7; P = .003). There was a suggestion of association between MICA mismatches and a higher risk of acute GVHD grades II to IV (HR, 1.4; P = .013) There were no significant interactions between MICA mismatches and HLA matching (9/10 versus 10/10). In conclusion, the findings in this cohort did not confirm prior studies reporting that MICA polymorphism and MICA mismatches were associated with HCT outcomes.

Impact of HLA-Mismatch in Unrelated Donor Hematopoietic Stem Cell Transplantation: A Meta-Analysis

The magnitude of risk associated with 9/10 mismatched unrelated donor (MMURD) hematopoietic stem cell transplantation and that of mismatches at the individual HLA loci remain unclear. We performed a meta-analysis to assess the difference in clinical outcomes between matched unrelated donor (MUD) and MMURD transplantation. A comprehensive search of Medline and Embase for manuscripts regarding transplantation outcomes in primarily adult patients with hematologic malignancies was performed. The pooled effect estimates were calculated using DerSimonian-Laird random effects models. A total of 13 studies were included, reporting on 13,446 transplants. 9/10 MMURD transplantation was associated with worse overall survival compared to 10/10 MUD transplantation (pooled HR: 1.27, 95% CI: 1.12-1.45; n = 7 studies). Mismatch at HLA-A, -B, or -C was associated with significantly worse overall survival compared to MUD transplantation, while there was no significant difference associated with -DQ or -DPB1 mismatch. Inferior survival associated with HLA-DRB1 mismatch could not be ruled out. Data on acute and chronic graft-versus-host disease were scarce but favored MUD transplantation. In summary, this meta-analysis of the available literature favored MUD over MMURD transplantation in hematologic malignancies and further quantifies the risks associated with specific HLA-allele mismatches. Am. J. Hematol. 91:551-555, 2016. © 2016 Wiley Periodicals, Inc.

Mismatched unrelated alternative donors for hematological malignancies

For the majority of hematologic malignancies allogeneic hematopoietic cell transplantation (HCT) is the only curative treatment option. Sibling donors have been the standard for adult patients. Since there is not a suitable family donor for all patients, the need for alternative donors for HCT is great. Fortunately, the availability of unrelated volunteer donor registries has expanded over the years and the results of HCT with matched unrelated donors (MUD) are comparable to the results with matched related donors (MRD). Nevertheless, there are many patients lacking a well-matched donor. To increase the applicability of transplantation, alternative donors such as mismatched unrelated donors (MMURD), cord blood stem cell products and haploidentical related donors have been widely used. This review seeks to give insights into the use of MMUD donors for HCT and summarize the existing data.

A single high-resolution HLA mismatch has a similar adverse impact on the outcome of related hematopoietic stem cell transplantation as a single low-resolution HLA mismatch

The relative importance of the resolution level of HLA typing has not been fully defined for related donor transplantation. To address this question, we retrospectively evaluated patients who underwent a first related hematopoietic stem cell transplantation (HSCT) from 2000 to 2011 from an HLA high-resolution matched (MRD, n = 2,244), high-resolution 1 locus-mismatched (HR-MMRD, n = 116), or low-resolution 1 locus-mismatched related donor (LR-MMRD, n = 396) in the graft-versus-host direction at three loci (HLA A, B, and DRB1) using the database of the Japan Society for Hematopoietic Cell Transplantation. The median age was 40 years (0-74). The median follow-up duration of surviving patients was 950 days. Although the cumulative incidences of grade III-IV acute graft-versus-host disease (GVHD) in the HR-MMRD and LR-MMRD groups were significantly higher than those in the MRD group (HR-MMRD 19.8%, LR-MMRD 20.4%, and MRD 9.5%), there was no statistically significant difference between the HR-MMRD and LR-MMRD groups (P = 0.65). Although both HR-MMRD and LR-MMRD were significantly associated with an increased risk of non-relapse mortality and a worse overall survival, there was no statistically significant difference between the HR-MMRD and LR-MMRD groups. In conclusion, LR-MM and HR-MM have a similar adverse impact on the outcome in related HSCT.

Hematopoietic stem cell transplantation donor sources in the 21st century: choosing the ideal donor when a perfect match does not exist

Most patients who require allogeneic stem cell transplantation do not have a matched sibling donor, and many patients do not have a matched unrelated donor. In an effort to increase the applicability of transplantation, alternative donors such as mismatched adult unrelated donors, haploidentical related donors, and umbilical cord blood stem cell products are frequently used when a well matched donor is unavailable. We do not yet have the benefit of randomized trials comparing alternative donor stem cell sources to inform the choice of donor; however, the existing data allow some inferences to be made on the basis of existing observational and phase 2 studies. All 3 alternative donor sources can provide effective lymphohematopoietic reconstitution, but time to engraftment, graft failure rate, graft-versus-host disease, transplant-related mortality, and relapse risk vary by donor source. These factors all contribute to survival outcomes and an understanding of them should help guide clinicians when choosing among alternative donor sources when a matched related or matched unrelated donor is not available.

Impact of HLA allele mismatch on the clinical outcome in serologically matched related hematopoietic SCT

In unrelated hematopoietic SCT (HSCT), HLA allele mismatch has been shown to have a significant role. To clarify the importance of HLA allele mismatch in the GVH direction in related HSCT, we retrospectively evaluated 2377 patients who received stem cells from an HLA serologically matched related donor in the GVH direction using the database of the Japan Society for Hematopoietic Cell Transplantation. The cumulative incidences of grade II-IV and grade III-IV acute GVHD in patients with an HLA allele-mismatched donor (n=133, 5.6%) were significantly higher than those in patients with an HLA allele-matched donor. Multivariate analyses showed that the presence of HLA allele mismatch was associated with increased risks of grade II-IV and grade III-IV acute GVHD. In particular, HLA-B mismatch and multiple allele mismatches were associated with an increased risk of acute GVHD. The presence of HLA allele mismatch was associated with an inferior OS owing to an increased risk of non-relapse mortality (NRM). In conclusion, the presence of HLA allele mismatch in the GVH direction in related HSCT was associated with increased risks of GVHD and NRM, which led to an inferior OS. HLA allele typing is recommended in related HSCT.

Advances in haploidentical stem cell transplantation

Hematopoietic stem cell transplantation from haploidentical donors is an attractive method of transplantation due to the immediate donor availability, ease of stem cell procurement and the possibility to collect additional donor cells for cellular therapy, if needed. Historically, maintaining T-cells in the graft has been associated with very high rates of graft-versus-host disease, while T-cell depleted haploidentical transplantation has been limited by a higher incidence of graft rejection and delayed immune reconstitution post-transplant. Recent approaches attempt to maintain the T-cells in the graft while effectively preventing the development of graft-versus-host disease post-transplant. Selective depletion of alloreactive T-cells post-transplant using high-dose post-transplant cyclophosphamide is under investigation as a promising alternative in haploidentical transplantation. While engraftment has improved and graft-versus-host disease is controlled with this approach, future directions should focus on optimizing conditioning regimens and the prevention of disease relapse post-transplant.

Donor selection in T cell-replete haploidentical hematopoietic stem cell transplantation: knowns, unknowns, and controversies

Multiple donors are generally available for haploidentical hematopoietic stem cell transplantation. Here we discuss the factors that should be considered when selecting donors for this type of transplantation according to the currently available evidence. Donor-specific anti-HLA antibodies (DSAs) increase the risk of graft failure and should be avoided whenever possible. Strategies to manage recipients with DSAs are discussed. One should choose a full haplotype mismatch rather than a better-matched donor and maximize the dose of infused hematopoietic cells. Donor age and sex are other important factors. Other factors, including predicted natural killer cell alloreactivity and consideration of noninherited maternal alleles, are more controversial. Larger studies are needed to further clarify the role of these factors for donor selection in haploidentical hematopoietic stem cell transplantation.

TNF-inhibition with etanercept for graft-versus-host disease prevention in high-risk HCT: lower TNFR1 levels correlate with better outcomes

Graft-versus-host disease (GVHD) causes most non-relapse mortality (NRM) after alternative donor (unrelated and mismatched related) hematopoietic cell transplant (HCT). We previously showed that increases in day +7 TNF-receptor-1 (TNFR1) ratios (posttransplantation day +7/pretransplantation baseline) after myeloablative HCT correlate with outcomes including GVHD, NRM, and survival. Therefore, we conducted a phase II trial at 2 centers, testing whether the addition of the TNF-inhibitor etanercept (25 mg twice weekly from start of conditioning to day +56) to standard GVHD prophylaxis would lower TNFR1 levels, reduce GVHD rates, and improve NRM and survival. Patients underwent myeloablative HCT from a matched unrelated donor (URD; N = 71), 1-antigen mismatched URD (N = 26), or 1-antigen mismatched related donor (N = 3) using either total body irradiation (TBI)-based conditioning (N = 29) or non-TBI-based conditioning (N = 71). Compared to historical controls, the increase in posttransplantation day +7 TNFR1 ratios was not altered in patients who received TBI-based conditioning, but was 40% lower in patients receiving non-TBI-based conditioning. The latter group experienced relatively low rates of severe grade 3 to 4 GVHD (14%), 1-year NRM (16%), and high 1-year survival (69%). These findings suggest that (1) the effectiveness of TNF-inhibition with etanercept may depend on the conditioning regimen, and (2) attenuating the expected rise in TNFR1 levels early posttransplantation correlates with good outcomes.