[Haploidentical hematopoietic stem cell transplant: How to choose the best donor? Guidelines from the Francophone Society of Bone Marrow Transplantation and Cellular Therapy (SFGM-TC)]

Ageing on the impact of distribution about preformed anti-HLA and anti-MICA antibody specificities in recipients prior to initial HSCT from East China

BACKGROUND

With the development of Hematopoietic Stem Cell Transplantation (HSCT) technology, increasing numbers of elderly patients were undergoing allogeneic HSCT and elderly patients with hematologic malignancies could benefit most from it. Preformed donor-specific human leukocyte antigen (HLA) antibodies (DSA) were associated with graft failure in HLA-mismatched allogeneic HSCT and the absence of DSA was the main criterion of selecting the donor. Except for sensitization events such as transfusion, pregnancy or previous transplantation, ageing affects the humoral immune response both quantitatively and qualitatively. To evaluate the prevalence and distribution of anti-HLA and antibodies of MHC class I chain related antigens A (MICA) specificities in different age groups before initial HSCT would provide HLA and MICA specific antibody profiles under the impact of ageing, which could provide meaningful information in the process of selecting suitable HLA-mismatched donors by avoiding preformed DSA.

RESULTS

There were no significant differences in the distribution of anti-HLA class I, class II and anti-MICA antibodies among the three age groups in this study except that a significant lower negative ratio of anti-HLA class I, class II antibodies and higher positive rate of MICA antibodies with maximum mean fluorescent intensity (MFI) > 5000 in the elderly than in young age group. The distribution of antibody specificities against HLA -A, -B, -C, -DR, -DQ, -DP and MICA antigens in the three age groups were generally consistent. The anti-HLA class I antibody specificities with higher frequencies were A80,A68;B76,B45;Cw17, which were unlikely to become DSA in Chinese. Anti-HLA class II antibody specificities were more likely to become potential DSA than class I.DR7, DR9, DQ7, DQ8 and DQ9 were most likely to become potential DSA.

CONCLUSIONS

The prevalence of anti-HLA and anti-MICA antibodies increased slightly as age increased. While ageing had a small impact on the distribution of antibody specificity frequencies against HLA-A, -B, -C, -DR,-DQ, -DP and MICA antigens in recipients awaiting initial HSCT from East China. The risk of developing preformed DSA was basically consistent in the three age groups and the elderly group might be more favorable in HLA-mismatched HSCT due to higher positive rate of anti-MICA antibody.

Mechanisms of thymic repair of in vitro-induced precursor T cells as a haplo-identical HSCT regimen

Haploidentical hematopoietic stem cell transplantation (haplo-HSCT) is currently an effective treatment for malignant hematological disease, but the immune deficiency and severe infection triggered by slow immune reconstitution are the main causes of high mortality and transplant failure. One of these outstanding problems is thymus damage, which is associated with graft-versus-host disease (GVHD), and preconditioning including irradiation and chemotherapy. Therefore, rapid repair of damaged thymus and rapid proliferation of thymus-derived donor T cells after transplantation are key to solving the problem. This study is designed to accelerate the recovery of thymus-derived T cells after transplantation. Wild-type mice with normal immunity were used as recipients in a haplo-HSCT mouse model to mimic clinical haplo-HSCT. A modified cell culture system using Notch ligand Delta4 and IL-7 was established that is capable of inducing and amplifying the differentiation and proliferation of hematopoietic stem cells into precursor T (preT) cells in vitro. Haplo-HSCT protocol included the preT and G-CSF mobilized donor splenic mononuclear cells (MNC) co-infusion or MNC alone. Thymic GVHD, thymic repair, and thymus-derived T cell development were compared in two groups by polychromatic immunofluorescence tracking, flow cytometry and detection of T cell receptor Vβ. The thymus homing and T-cell regeneration of allogenic preT cells were observed. The functions of preT cells in accelerating immune reconstitution, restoring thymic architecture, weakening GVH effects, and enhancing immuno-tolerance after transplantation were demonstrated. Further studies revealed that allogeneic preT cells induced by a culture system containing IL7 and Delta4 highly express ccr9 and RANKL. Interestingly, the RANK expression was promoted after preT cells' thymus homing. These results suggested that the RANK/RANKL pathway may play an important role in thymus homing. Our results provide a potential therapeutic option to optimize haplo-HSCT. It further opened up a new field of T cell therapy for artificial induction of allogeneic precursor T cells in vitro to repair the damaged thymus from irradiation and chemotherapy, and to compensate for the recovery of immune function in patients with immune deficiency caused by multiple reasons.

[Graft failure, poor graft function erythroblastopenia: Actualization of definitions, diagnosis and treatment: Guidelines from the SFGM-TC]

In this article, we discuss again the definition, the risk factor and guideline to treat the graft failure, the poor graft function and erythrobalstopenia. Graft failure is a severe but rare complication after hematopoietic cell transplantation (HCT). Despite disparity in the literature, we defined this complication and discussed the factor risks and recommendation for treatment based on new studies. Poor graft function is also a more frequent complication after HCT. New studies will soon be available to prove or not the current recommendation suggested in this article based on therapeutics medicine or cellular therapy. Erythroblastopenia, is a rarer complication post HCT. Despite anticipation for a better choice of compatibility donor/recipient, some patients still suffer from this complication.

Effect of donor characteristics on T cell-replete haploidentical stem cell transplantation over the last 10 years at a single institution

One of the most complex issues with haploidentical stem cell transplantation (haplo-SCT) is donor selection, given that multiple haploidentical donors are often available for a given recipient. To develop evidence-based guidance for donor selection in the setting of anti-thymocyte globulin-based haplo-SCT, we performed a prospective cohort study of 512 patients with haematological malignancies who had haplo-SCT to determine which donor variables were most important in favouring transplant outcomes. Increasing donor age was associated with poorer overall survival (OS) [hazard ratio (HR) 1·08, P = 0·044]. Female donors to male recipients was significantly associated with higher non-relapse mortality (NRM; HR 2·05, P = 0·006). Furthermore, increasing donor age had a higher risk of Grades 3-4 acute graft-versus-host disease (aGVHD; HR 1·17, P = 0·005), female donors to male recipients was associated with a higher risk of Grades 2-4 aGVHD (HR 1·50, P = 0·022). Sibling donors had superior OS, disease-free survival, and NRM than parental donors in patients aged <35 years. However, sibling donors had higher NRM than offspring donors in patients aged ≥35 years. A younger donor, usually a young sibling in younger recipients (aged <35 years) or a young offspring in older patients (aged ≥35 years) and avoiding female donors to male recipients should be preferred when multiple haploidentical donors are available.

Relevance of Polymorphic KIR and HLA Class I Genes in NK-Cell-Based Immunotherapies for Adult Leukemic Patients

Simple Summary

Immunotherapies are promising approaches to curing different acute leukemias. Natural killer (NK) cells are lymphocytes that are efficient in the elimination of leukemic cells. NK-cell-based immunotherapies are particularly attractive, but the landscape of the heterogeneity of NK cells must be deciphered. This review provides an overview of the polymorphic KIR and HLA class I genes that modulate the NK cell repertoire and how these markers can improve the outcomes of patients with acute leukemia. A better knowledge of these genetic markers that are linked to NK cell subsets that are efficient against hematological diseases will optimize hematopoietic stem-cell donor selection and NK immunotherapy design.

Abstract

Since the mid-1990s, the biology and functions of natural killer (NK) cells have been deeply investigated in healthy individuals and in people with diseases. These effector cells play a particularly crucial role after allogeneic hematopoietic stem-cell transplantation (HSCT) through their graft-versus-leukemia (GvL) effect, which is mainly mediated through polymorphic killer-cell immunoglobulin-like receptors (KIRs) and their cognates, HLA class I ligands. In this review, we present how KIRs and HLA class I ligands modulate the structural formation and the functional education of NK cells. In particular, we decipher the current knowledge about the extent of KIR and HLA class I gene polymorphisms, as well as their expression, interaction, and functional impact on the KIR⁺ NK cell repertoire in a physiological context and in a leukemic context. In addition, we present the impact of NK cell alloreactivity on the outcomes of HSCT in adult patients with acute leukemia, as well as a description of genetic models of KIRs and NK cell reconstitution, with a focus on emergent T-cell-repleted haplo-identical HSCT using cyclosphosphamide post-grafting (haplo-PTCy). Then, we document how the immunogenetics of KIR/HLA and the immunobiology of NK cells could improve the relapse incidence after haplo-PTCy. Ultimately, we review the emerging NK-cell-based immunotherapies for leukemic patients in addition to HSCT.

[Establishment of Hematopoietic cell transplantation program in developing countries : Guidelines from the francophone Society of bone marrow transplantation and cellular therapy (SFGM-TC)]

Hematopoietic cell transplantation (HCT) is the curative treatment for many malignant and non-malignant blood disorders and some solid cancers. However, transplant procedures are considered tertiary level care requiring a high degree of technicality and expertise and generating very high costs for hospital structures in developing countries as well as for patients without health insurance. During the 11th annual harmonization workshops of the francophone Society of bone marrow transplantation and cellular therapy (SFGM-TC), a designated working group reviewed the literature in order to elaborate unified guidelines, for developing the transplant activity in emerging countries. Access to infrastructure must comply with international standards and therefore requires a hospital system already in place, capable of accommodating and supporting the HCT activity. In addition, the commitment of the state and the establishment for the financing of the project seems essential.

[Definition and standardization of histocompatibility requests depending on patient course and donor type: Guidelines from the Francophone Society of Bone Marrow Transplantation and Cellular Therapy (SFGM-TC) and the Francophone Society of Histocompatibility and Immunogenetics (SFHI)]

Standardization of histocompatibility tests for allogeneic hematopoietic cell transplants, harmonization of information transmitted to clinicians are part of quality improvement and optimization of human and economic resources. New HLA typing technologies provide high-resolution information within a reasonable time frame. Knowledge of high-resolution HLA typing for the patient and their relatives is essential for a better interpretation of compatibilities. HLA-DPB1 typing must be considered in transplant field regardless of the donor type. The benefits of using search and match programs are considerable. It saves time and reduces additional typing costs by providing rapid information about the likelihood to identify a matched unrelated donor. A backup therapy considering alternative cell sources or treatment can therefore be quickly implemented. The importance of knowledge and consideration of patient immunization for donor choice was explored in previous workshops of the SFGM-TC (2018 and 2019). The published recommendations remain applicable. The routine follow-up protocol and in case of desensitization will be detailed here. This harmonization must be accompanied by the standardization of information to be returned to the clinician regarding the donor finding possibilities for the patient. This will guarantee a similar quality level in every center.

Grade 2 acute GVHD is a factor of good prognosis in patients receiving peripheral blood stem cells haplo-transplant with post-transplant cyclophosphamide

BACKGROUND

The impact of acute graft versus host disease (GVHD) on survivals for patients receiving a haploidentical allogeneic stem-cell transplant (Allo-SCT) with peripheral blood stem-cells (PBSC) complemented by post-transplant cyclophosphamide (PTCY) is ill-known.

MATERIAL AND METHODS

This retrospective study included 131 patients who received a PBSC haplograft in order to precise the impact of acute GVHD on outcomes. There were 78 males and 53 females and the median age for the whole cohort was 59 years (range: 20-71). Thirty-five patients were allografted for a lymphoid disease and 96 for a myeloid malignancy, including 67 patients with acute myeloid leukemia (AML).

RESULTS

The cumulative incidence (CI) of day 100 grade 2-4 and 3-4 acute GVHD was 43.4 + 4.6% and 16.7 + 3.4%, respectively. The 2-year CI of moderate/severe chronic GVHD was 10.1 + 2.8%. The only factor affecting the occurrence of GVHD was GVHD prophylaxis. Indeed, CI of day 100 grade 2-4 (but not grade 3-4) acute GVHD was significantly reduced when adding anti-thymoglobulin (ATG) to PTCY. However, in multivariate analysis, grade 2 acute GVHD was significantly associated with better disease-free (HR: 0.36; 95%CI: 0.19-0.69, p = .002) and overall (HR: 0.35; 95%CI: 0.1-0.70, p = .003) survivals. The same results were observed when considering only AML patients.

CONCLUSION

Acute grade 2 GVHD is a factor of good prognosis after PBSC haplotransplant with PTCY. Further and larger studies are needed to clarify the complex question of GVHD prophylaxis in the setting of haplo-transplant, especially that of combining ATG and PTCY.

[Relevance of antibodies in hematopoietic stem cell transplantation: Antibodies anti-HLA, anti-platelets, anti-granulocytes, anti-erythrocytes and anti-MICA. Guidelines from the Francophone Society of Bone Marrow Transplantation and Cellular Therapy (SFGM-TC)]

The presence of allo-antibodies in the serum of a recipient awaiting hematopoietic stem cell transplantation (HSCT) may have an impact on transfusion efficiency and/or donor choice, especially in the absence of an identical sibling donor. Prior to transplantation, donor specific anti-HLA (Human Leukocyte Antigen) antibodies (DSA) have a recognized effect on transplant outcome, correlated with the increasing MFI value and with the ability of such antibody to fix the complement fraction. Anti-platelet antibodies (anti-HLA class I and anti-HPA [Human Platelet Antigen]) are better involved in transfusion inefficiency and can be responsible for refractory status. ABO incompatibilities require a specific treatment of the graft in presence of high titer to avoid hemolytic adverse effects. Investigations of these antibodies should be carried out on a regular basis in order to establish appropriate transfusion recommendation, select an alternative donor when possible or adapt the source of cells. After transplantation, in case of delayed recovery or graft rejection, long term aplasia, persistent mixed chimerism or late release, and after elimination of the main clinical causes, a biological assessment targeted on the different type of antibodies will have to be performed in order to orient towards the cause or the appropriate therapy. Further studies should be carried out to determine the impact of anti-MICA antibodies and recipient specific anti-HLA antibodies, on the outcome of the transplantation.