The number of HLA-haploidentical hematopoietic cell transplants continues to increase worldwide due to recent improvements in outcomes, allowing more patients with hematological malignancies and ...non-malignant disorders to benefit from this procedure and have a chance to cure their disease. Despite these encouraging results, questions remain as multiple donors are usually available for transplantation, and choosing the best HLA-haploidentical donor for transplantation remains a challenge. Several approaches to haploidentical transplantation have been developed over time and, based on the graft received, can be grouped as follows: T-cell depleted haploidentical transplants, either complete or partial, or with T-cell replete grafts, performed with post-transplant cyclophosphamide-based graft-versus-host disease (GVHD) prophylaxis, or G-CSF-primed bone marrow graft and enhanced GVHD prophylaxis. Carefully selecting the donor can help optimize transplant outcomes for recipients of haploidentical donor transplants. Variables usually considered in the donor selection include presence of donor-specific antibodies in the recipient, donor age, donor/recipient gender and ABO combinations, and immunogenic variables, such as natural killer cell alloreactivity or KIR haplotype. Here we provide a comprehensive review of available evidence for selecting haploidentical donors for transplantation, and summarize the recommendations from the European Society for Blood and Marrow Transplantation (EBMT) on donor selection for different transplant platforms.
With increasing numbers of patients with hematologic malignancies requiring allogeneic hematopoietic cell transplant (HCT), including minority racial and ethnic groups, the limited availability of ...matched related donors and matched unrelated donors remains a significant obstacle. Hence, the use of alternative donors such as haploidentical and mismatched unrelated donors (MMUDs) is on the rise. Herein, we present case studies to outline a rational and stepwise approach with a focus on the use of MMUD for HCT in patients with hematologic malignancies. We also review novel approaches used to reduce the incidence of severe graft-versus-host disease and improve HCT outcomes in patients undergoing MMUD HCT.
HLA Class I and II expression are known to differ locus‐to‐locus, however, HLA expression on the cell‐surface is frequently reported as the total amount of HLA Class I or II antigens. This is despite ...evidence that indicates the differential expression of HLA can influence patient outcomes post‐transplantation. Although numerous commercially available HLA monoclonal antibodies (mAbs) exist to characterize HLA expression, there is currently a lack of detailed information regarding their reactivities to HLA specificities. The specificities of locus‐specific HLA mAbs (nine Class I and four Class II mAbs) were evaluated by two solid‐phase Luminex single antigen bead assays. The reactivity patterns of these mAbs were then confirmed by flow cytometry using lymphocytes and PBSCs (peripheral blood stem cells). Out of the 13 HLA mAbs tested, only four (one Class I and three Class II mAbs) displayed intra‐locus reactivity without also reacting to inter‐locus specificities. Epitope analysis revealed the presence of shared epitopes across numerous HLA loci, explaining much of the observed inter‐locus reactivity. The specificity of the HLA mAbs seen in solid‐phase assays was confirmed against PBSCs and lymphocytes by flow cytometry. Using this method, we observed differences in the cell surface expression of HLA‐C, HLA‐DR, HLA‐DQ, and HLA‐DP between PBSCs and lymphocytes. Our results emphasize the need to characterize the reactivity patterns of HLA mAbs using solid‐phase assays before their use on cells. Through understanding the reactivity of these HLA mAbs, the cellular expression of HLA can be more accurately assessed in downstream assays.
•In Ph+ ALL, allogeneic transplant in first remission does not improve survival for patients achieving a deep molecular remission.•The use of transplant was associated with lower incidence of disease ...relapse but increased treatment-related mortality.
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Historically, Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) has been associated with poor outcomes, and allogeneic hematopoietic cell transplantation (allo-HCT) is recommended in first complete remission (CR1). However, in the tyrosine kinase inhibitor (TKI) era, rapid attainment of a complete molecular remission (CMR) is associated with excellent outcomes without allo-HCT, suggesting transplant may not be required for these patients. To test this hypothesis, we retrospectively identified adult patients with Ph+ ALL treated with induction therapy, including TKIs, and attained CMR within 90 days of diagnosis at 5 transplant centers in the United States. We compared outcomes of those who did and did not receive allo-HCT in first remission. We identified 230 patients (allo-HCT: 98; non-HCT: 132). The allo-HCT cohort was younger with better performance status. On multivariable analysis (MVA), allo-HCT was not associated with improved overall survival (adjusted hazard ratio aHR: 1.05; 95% CI, 0.63-1.73) or relapse-free survival (aHR: 0.86; 95% CI, 0.54-1.37) compared with non-HCT treatment. Allo-HCT was associated with a lower cumulative incidence of relapse (aHR: 0.32; 95% CI, 0.17-0.62) but higher non-relapse mortality (aHR: 2.59; 95% CI, 1.37-4.89). Propensity score matching analysis confirmed results of MVA. Comparison of reduced-intensity HCT to non-HCT showed no statistically significant difference in any of the above endpoints. In conclusion, adult patients with Ph+ ALL who achieved CMR within 90 days of starting treatment did not derive a survival benefit from allo-HCT in CR1 in this retrospective study.
Regimens combining intensive chemotherapy with tyrosine kinase inhibitors have improved outcomes for adults with Philadelphia chromosome positive acute lymphoblastic leukemia (Ph+ ALL). In this month’s CME article, a retrospective analysis incorporating propensity matching, Ghobadi and colleagues find that in patients achieving complete molecular remission by 90 days, elective allogeneic transplant in first remission reduces the risk of relapse at the expense of transplant-related morbidity and mortality, providing no survival benefit. These data argue for reserving allogeneic transplant for salvage in such patients.
A mismatch at HLA-DPB1 locus is associated with higher acute GVHD and lower relapse rate after myeloablative (MAC) allogeneic hematopoietic cell transplantation (alloHCT). Also, in MAC setting, ...mismatch permissiveness and expression level impact alloHCT outcomes. However, in reduced intensity conditioning (RIC), DP mismatch effect on transplant outcomes is unknown. We retrospectively evaluated DP mismatch influence (number, permissiveness, and expression) on HCT outcomes in 310 patients with high-resolution typing (HLA-A, -B, -C, -DRB1, -DQB1, and -DPB1), who underwent RIC HCT. By multivariable analysis, 11/12 had better overall survival (OS) and relapse vs. 12/12 (HR = 1.61 and 2.02; p = 0.04 and 0.01, respectively) and better OS vs. 10/12 (HR = 1.68; p = 0.02). Within the 11/12, nonpermissive (NoPR) mismatch was associated with higher risk of grade II-IV acute GVHD (HR = 1.97; p = 0.005) and nonrelapse mortality (HR = 2.13; p = 0.02) vs. permissive (PR). Grouping 11/12 based on the DP expression conferred higher mortality (HR = 3.78; p = 0.003) when low expressers received a graft from high expressers (AG) vs. low expressers (AA). Better OS was achieved in PR 11/12, when expression was low in patient and donor (AA) vs. all other combinations. Therefore, in RIC HCT, a single-DP mismatch has a protective role, especially in permissive setting, when donor and recipient are low expressers.
Allogeneic hematopoietic cell transplantation (allo-HCT) is a curative therapy for many malignant and non-malignant hematologic disorders. Chronic graft-versus-host (cGVHD) disease remains a ...significant hurdle for long-term survival in patients post allo-HCT, and it remains the leading cause of late non-relapse mortality. The risk factors for development of cGVHD include degree of human leukocyte antigen (HLA) disparity, increasing recipient age, use of peripheral blood stem cells as a source, myeloablative conditioning regimens, prior acute GVHD (aGVHD), and female donor to male recipient. Our biological understanding of cGVHD is mostly derived from transplantation mouse models and patient data. There are three distinct phases in the development of cGVHD. Approaches to prevent GVHD include pharmacologic strategies such as calcineurin inhibitors (cyclosporine, tacrolimus) combined with methotrexate or mTOR inhibitors (sirolimus), and IMP dehydrogenase inhibitors (mycophenolate mofetil). Increasingly, posttransplant cyclophosphamide is emerging as a promising strategy for GVCHD prevention especially in a setting of reduced intensity conditioning. Other approaches include serotherapy (ATG, Campath) and graft manipulation strategies. A significant obstacle to evaluating the response of novel GVHD-directed therapies has been standardized response assessments. This has functioned as a barrier to designing and interpreting clinical trials that are structured around the treatment of cGVHD. Novel endpoints including failure-free survival, Graft-versus-host disease-free, relapse-free survival (GRFS), and current GVHD-free, relapse-free survival (CGRFS) may create a clearer picture for post-HCT outcomes. Targeted therapies including Bruton's tyrosine kinase inhibition, JAK1/2 inhibition, and ROCK2 inhibitors have improved cGVHD therapy, especially in the steroid refractory setting. Continued improvement in prophylactic strategies for cGVHD, identification of accurate cGVHD treatment endpoints, and access to novel therapeutic agents are expected to improve cGVHD outcomes.
Purpose T-cell-replete HLA-haploidentical donor hematopoietic transplantation using post-transplant cyclophosphamide was originally described using bone marrow (BM). With increasing use of mobilized ...peripheral blood (PB), we compared transplant outcomes after PB and BM transplants. Patients and Methods A total of 681 patients with hematologic malignancy who underwent transplantation in the United States between 2009 and 2014 received BM (n = 481) or PB (n = 190) grafts. Cox regression models were built to examine differences in transplant outcomes by graft type, adjusting for patient, disease, and transplant characteristics. Results Hematopoietic recovery was similar after transplantation of BM and PB (28-day neutrophil recovery, 88% v 93%, P = .07; 100-day platelet recovery, 88% v 85%, P = .33). Risks of grade 2 to 4 acute (hazard ratio HR, 0.45; P < .001) and chronic (HR, 0.35; P < .001) graft-versus-host disease were lower with transplantation of BM compared with PB. There were no significant differences in overall survival by graft type (HR, 0.99; P = .98), with rates of 54% and 57% at 2 years after transplantation of BM and PB, respectively. There were no differences in nonrelapse mortality risks (HR, 0.92; P = .74) but relapse risks were higher after transplantation of BM (HR, 1.49; P = .009). Additional exploration confirmed that the higher relapse risks after transplantation of BM were limited to patients with leukemia (HR, 1.73; P = .002) and not lymphoma (HR, 0.87; P = .64). Conclusion PB and BM grafts are suitable for haploidentical transplantation with the post-transplant cyclophosphamide approach but with differing patterns of treatment failure. Although, to our knowledge, this is the most comprehensive comparison, these findings must be validated in a randomized prospective comparison with adequate follow-up.
Background
Studies have suggested that acute myeloid leukemia (AML) patients with incomplete hematologic recovery undergoing allogeneic stem cell transplantation (allo‐HSCT) had inferior overall ...survival (OS).
Study Design and Methods
This single‐center, retrospective study of AML patients evaluated the relationship between red blood cell (RBC) and platelet (PLT) transfusion requirements during the first 30 days and long‐term outcomes after allo‐HSCT through multivariate analyses.
Results
A total of 692 AML patients received peripheral blood stem cells (89.2%), marrow (5.6%), or umbilical cord (5.2%) from matched related (37.4%), unrelated (49.1%), or haploidentical (8.2%) donors in 2011–2017. Transfusion requirements during the first 30 days for RBC (89.5% transfused, median 3, range 1–18 units) or PLT (98.2% transfused, median 6, range 1–144 units) were variable. By Day 30, 56.7% (95% confidence interval CI: 52.8–60.3%) and 86.1% (95% CI: 83.2–88.5%) had achieved RBC and PLT transfusion independence, respectively.
Median follow‐up among survivors (n = 307) was 7.1 years (range: 2.7–11.8). Lack of RBC transfusion independence by Day 30 was strongly and independently associated with worse 5‐year OS (39.2% vs. 59.6%, adjusted hazard ratio HR 1.83, 95% CI: 1.49–2.25), leukemia‐free survival (35.8% vs. 55.5%, HR = 1.75, 95% CI: 1.43–2.14), and NRM (29.7% vs. 13.7%, HR = 2.05, 95% CI: 1.45–2.89) (p < .001). There was no difference in relapse rates among patients who achieved or did not achieve RBC (p = .34) or PLT (p = .64) transfusion independence.
Conclusion
Prolonged RBC dependence predicted worse survival and NRM rates, but not increased relapse. Posttransplant surveillance of such patients should be adjusted with more attention to non‐relapse complications.
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