Comparison of HLA Allele Mismatch and Antigen Mismatch in Unrelated Bone Marrow Transplantation in Patients with Leukemia

Updated comparable efficacy of cord blood transplantation for chronic myelomonocytic leukaemia: a nationwide study

Chronic myelomonocytic leukaemia (CMML) is a haematological malignancy with a poor prognosis. Allogeneic haematopoietic stem cell transplantation remains the only curative approach. Without human leucocyte antigen-matched related sibling donors, the optimal alternative donor has yet to be established. Although unrelated bone marrow transplantation (UBMT) has been extensively studied, cord blood transplantation (CBT) for CMML remains largely unexplored. This nationwide retrospective study compared the outcomes of UBMT and single-unit umbilical CBT in patients with CMML. This study included 118 patients who underwent their first allo-HSCT during 2013-2021. Of these, 50 received BMT (UBMT group), while 68 underwent CBT (CBT group). The primary endpoint was the 3-year overall survival (OS). There were comparable 3-year OS rates between the UBMT (51.0%, 95% confidence interval [CI]: 34.1-65.5%) and CBT (46.2%, 95% CI: 33.2-58.1%; P = 0.60) groups. In the inverse probability of treatment weighting analysis, CBT did not show significantly improved outcomes compared with UBMT regarding the 3-year OS rate (hazard ratio 0.97 [95% CI: 0.57-1.66], P = 0.91). Thus, CBT may serve as an alternative to UBMT for patients with CMML. Further research is necessary to optimise transplantation strategies and enhance outcomes in patients with CMML undergoing CBT.

Alternative donor strategy in unrelated hematopoietic stem cell transplantation - outcome with mismatched donors

PURPOSE

This study retrospectively investigated the association between the level of human leukocyte antigen (HLA) mismatches (MMs), direction of disparities and differences at particular HLA locus on clinical outcomes of hematopoietic stem cell transplantation (HSCT). Investigated outcomes were overall survival (OS) and disease-free survival (DFS), graft-versus-host disease (GvHD), relapse and non-relapse mortality (NRM).

PATIENTS AND METHODS

Study cohort included 108 adult patients transplanted between 2011 and 2021 and their 9/10 mismatched unrelated donors (MMUD). All individuals were typed for HLA-A, -B, -C, -DRB1, -DQB1 and -DPB1 loci using Polymerase Chain Reaction-Sequence Specific Primers, PCR-Sequence Based Typing and Next-Generation Sequencing. All statistical analyses were done in the MedCalc software, version 19.2.6.

RESULTS

Patients with MMs at HLA-B locus demonstrated worse OS (P ​= ​0.0440, HR ​= ​2.00, n ​= ​20). Absence of HLA-DRB5 was associated with a higher incidence of GvHD (P ​= ​0.0112, HR ​= ​1.93, n ​= ​67). A lower incidence of GvHD was observed in patients with HLA class II MMs compared to patients with HLA class I MMs (P ​= ​0.0166, HR ​= ​1.94, n ​= ​29). Finally, analysis of PIRCHE score (PS) impact revealed that patients with HLA class II PS ​> ​10 in GvH direction showed higher incidence of GvHD compared to patients with HLA class II PS ​< ​10 (P ​= ​0.0073, HR ​= ​2.01, n ​= ​55).

CONCLUSION

Obtained results undisputedly indicate the necessity to further investigate this matter on a larger patient group, with focus on specific HLA alleles to define precisely priority criteria for selecting the best donor for all patients, thus improving the outcome of HSCT with an MMUD.

Identification of two downregulated circRNAs in patients with acute B-lymphocytic leukemia

Acute B-lymphocytic leukemia (B-ALL) is associated with a high mortality rate, with no effective treatment strategies available. The identification of diagnostic and prognostic biomarkers of B-ALL can contribute to the development of novel therapeutic methods and drugs, which can improve the survival outcomes of patients with B-ALL. The present study aimed to identify downregulated circular RNAs (circRNAs) in patients with B-ALL. RNA sequencing was performed to construct the circRNA expression profiles in B-ALL cells and normal human lymphoblasts. The Database for Annotation, Visualization and Integrated Discovery was used to perform Gene Ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses. In addition, reverse transcription-quantitative (RT-q)PCR analysis was performed to detect the expression levels of the downregulated circRNAs. A total of 263 differentially expressed circRNAs were identified, including 76 upregulated and 187 downregulated circRNAs, respectively. The upregulated circRNAs were mainly enriched in ‘macromolecule modification’, ‘protein modification’ and ‘cellular protein modification processes’, while the downregulated circRNAs were mainly enriched in the ‘negative regulation of RNA biosynthetic processes’, ‘natural killer cell-mediated cytotoxicity’ and ‘viral carcinogenesis’. RT-qPCR analysis demonstrated that two of the downregulated circRNAs (hsa_circ_0000745 and chr15:87949594-87966067-), identified during microarray analysis were also significantly downregulated in Ball-1 cells and B-ALL bone marrow samples. Thus, these circRNAs may serve as biomarkers for patients with B-ALL.

BSHI guideline: HLA matching and donor selection for haematopoietic progenitor cell transplantation

A review of the British Society for Histocompatibility and Immunogenetics (BSHI) Guideline 'HLA matching and donor selection for haematopoietic progenitor cell transplantation' published in 2016 was undertaken by a BSHI appointed writing committee. Literature searches were performed and the data extracted were presented as recommendations according to the GRADE nomenclature.

Class II HLA mismatch improves outcomes following haploidentical transplantation with posttransplant cyclophosphamide

HLA disparity is the major predictor of outcome following unrelated donor (UD) transplantation, where a single mismatch (mm) at the HLA-A, HLA-B, HLA-C, or HLA-DRB1 locus leads to increased mortality, and mismatching at multiple loci compounds this effect. In contrast, HLA disparity has not been shown to increase mortality in the context of haploidentical transplant using posttransplant cyclophosphamide (PTCy). To better define the consequences of loci-specific HLA mm, we analyzed 208 consecutive patients undergoing haploidentical transplantation for hematologic malignancy using PTCy at our institution (median age, 52 years [range, 19-75 years]; peripheral blood stem cell, 66%; reduced-intensity conditioning, 59%). Median follow-up was 65.4 months (range, 34.3-157.2 months). In univariate analysis, a single class II HLA mm at HLA-DR, HLA-DQ or a nonpermissive (np) HLA-DP mm had a protective effect on disease-free and overall survival (OS), primarily a result of reduced relapse risk. Furthermore, this survival effect was cumulative, so that patients with 3 class II mm (HLA-DR, HLA-DQ, and np HLA-DP) had the best OS. In multivariate analysis, HLA-DR mm and np HLA-DP mm were both independently associated with improved OS (hazard ratio [HR], 0.43; P =.001; and HR, 0.47; P =.011, respectively). In contrast, single or multiple mm at HLA-A, HLA-B, or HLA-C loci had no effect on acute graft-versus-host disease (GVHD), nonrelapse mortality (NRM), relapse, or survival, although the presence of an HLA-A mm was associated with increased chronic GVHD incidence. The association of class II mm with lower relapse occurred without a corresponding increase in NRM or acute or chronic GVHD. These findings will require validation in larger registry studies.