Search

Summary: Graft‐versus‐host disease (GvHD) is a serious complication of allogeneic haematopoietic stem cell transplantation (HSCT). Both anti‐thymocyte globulin (ATG) and post‐transplant cyclophosphamide (PTCy) are used as lymphocyte‐depleting strategies, yet a systematic comparison of transplantation outcomes between these two methods in matched unrelated donors (MUD) transplantations with non‐myeloablative conditioning (NMC) is lacking. Adult patients with haematological malignancies who had undergone MUD HSCT with NMC regimens between 2014 and 2021 at 2 centres in Amsterdam (ATG: n = 95, PTCy: n = 90), were included in this retrospective study. Patient characteristics were comparable between the groups. The cumulative incidence of acute GvHD grade II–IV was 48% in the ATG group compared to 21% in the PTCy group (p < 0.001). The 3‐year moderate/severe chronic GvHD was similar in both groups (p = 0.69). While the relapse rate was comparable between the groups (ATG 31% vs. PTCy 34%, p = 0.94), non‐relapse mortality tended to be higher in the ATG group (17% vs. 9%, p = 0.069). Overall survival was similar in both groups (p = 0.12). In conclusion, PTCy‐based regimens resulted in a significantly lower rate of acute GvHD than ATG‐containing regimens in MUD transplantations with NMC. Whether PTCy results in improved overall survival as compared to ATG needs to be elucidated in larger prospective studies. [ABSTRACT FROM AUTHOR]

Patients with leukemia who receive a T cell-depleted allogeneic stem cell graft followed by postponed donor lymphocyte infusion (DLI) can experience graft-versus-leukemia (GVL) reactivity, with a lower risk of graft-versus-host disease (GVHD). Here, we have investigated the magnitude, diversity, and specificity of alloreactive CD8 T cells in patients who developed GVL reactivity after DLI in the absence or presence of GVHD. We observed a lower magnitude and diversity of CD8 T cells for minor histocompatibility antigens (MiHAs) in patients with selective GVL reactivity without GVHD. Furthermore, we demonstrated that MiHA-specific T cell clones from patients with selective GVL reactivity showed lower reactivity against nonhematopoietic cells, even when pretreated with inflammatory cytokines. Expression analysis of MiHA-encoding genes showed that similar types of antigens were recognized in both patient groups, but in patients who developed GVHD, T cell reactivity was skewed to target broadly expressed MiHAs. As an inflammatory environment can render nonhematopoietic cells susceptible to T cell recognition, prevention of such circumstances favors induction of selective GVL reactivity without development of GVHD., Introduction The curative effect of allogeneic stem cell transplantation (allo-SCT) as a treatment modality for hematological malignancies is based on the capacity of donor T cells to effectively induce graft-versus-leukemia [...]

Patients with hematological malignancies can be successfully treated with HLA-matched T cell-depleted allogeneic stem cell transplantation (alIoSCT) and subsequent donor lymphocyte infusions (DLIs). The efficacy of DLI is mediated by donor T cells recognizing minor histocompatibility antigens (mHags) on malignant recipient cells. Because HLA class II molecules are predominantly expressed on hematopoietic cells, mHag-specific [CD4.sup.+] T cells may selectively mediate graft versus leukemia (GvL) reactivity without graft versus host disease (GvHD). In this study, we used a recombinant bacteria cDNA library for the identification of the first autosomal HLA class II (HLA-DQBl*0603)-restricted mHag LBPI4K2B-1S encoded by the broadly expressed phosphatidylinositol 4-kinase type II [beta] gene. A polyclonal [CD4.sup.+] T cell response against LB-PI4K2B-1S was demonstrated in a patient with relapsed chronic myeloid leukemia (CML) who responded to DLI after HLA-matched alIoSCT. LB-PI4K2B-1S-specific [CD4.sup.+] T cells recognized and lysed the [CD34.sup.+] CML cells of the patient and other leukemic cells as well as high HLA-DQ-expressing normal hematopoietic cells. HLA-DQ expression on normal cells of nonhematopoietic origin was moderately up-regulated by IFN-[gamma], and not sufficient for T cell recognition. We hypothesize that LB-PI4K2B-1S-specific [CD4.sup.+] T cells contributed to the antitumor response by both directly eliminating malignant cells as effector cells and stimulating [CD8.sup.+] T cell immunity as helper cells. donor lymphocyte infusions | hematological malignancies | immunotherapy | stem cell transplantation | T lymphocytes

Minor histocompatibility antigens are the main targets of donor-derived T-cells after allogeneic stem cell transplantation. Identification of these antigens and understanding their biology are a key requisite for more insight into how graft vs. leukemia effect and graft vs. host disease could be separated. We here identified four new HLA class II-restricted minor histocompatibility antigens using whole genome association scanning. For one of the new antigens, i.e., LB-PIP4K2A-1S, we measured strong T-cell recognition of the donor variant PIP4K2A-1N when pulsed as exogenous peptide, while the endogenously expressed variant in donor EBV-B cells was not recognized. We showed that lack of T-cell recognition was caused by intracellular cleavage by a protease named asparagine endopeptidase (AEP). Furthermore, microarray gene expression analysis showed that PIP4K2A and AEP are both ubiquitously expressed in a wide variety of healthy tissues, but that expression levels of AEP were lower in primary acute myeloid leukemia (AML). In line with that, we confirmed low activity of AEP in AML cells and demonstrated that HLA-DRB1*03:01 positive primary AML expressing LB-PIP4K2A-1S or its donor variant PIP4K2A-1N were both recognized by specific T-cells. In conclusion, LB-PIP4K2A-1S not only represents a novel minor histocompatibility antigen but also provides evidence that donor T-cells after allogeneic stem cell transplantation can target the autologous allelic variant as leukemia-associated antigen. Furthermore, it demonstrates that endopeptidases can play a role in cell type-specific intracellular processing and presentation of HLA class II-restricted antigens, which may be explored in future immunotherapy of AML. [ABSTRACT FROM AUTHOR]

Immunosuppressed patients with hematological malignancies are at risk for invasive fungal infections (IFI), including infections with Fusarium species (spp.), which are increasingly reported. Particularly at risk are patients with acute myeloid leukemia (AML) treated with high-dose cytarabine as remission-induction therapy. Whether cytarabine increases the risk of IFI in comparison to other chemotherapy remains not fully determined. Additionally, no clear correlation between the in vitro established minimal inhibitory concentrations (MICs) of antifungal agents and clinical outcome has been established for fusariosis. To increase awareness and knowledge of invasive fusariosis, we report two cases of Fusarium spp. infections in neutropenic patients following treatment with cytarabine for AML. Despite high MICs for azoles both patients were treated with an azole in combination with liposomal amphotericin B. The combination therapy was successful in one patient, however the other patient did not survive the disseminated Fusarium infection. [ABSTRACT FROM AUTHOR]

Abstract: Clinical studies have demonstrated that HLA-DPB1–mismatched allogeneic stem cell transplantation (allo-SCT) is associated with a decreased risk of disease relapse and an increased risk of graft-versus-host disease (GVHD) compared with HLA-DPB1–matched SCT. In T cell–depleted allo-SCT, mismatching of HLA-DPB1 was not associated with an increased risk of severe GVHD, but a significant decreased risk of disease relapse was still observed. To investigate whether patient HLA-DP–specific CD4+ T cell responses were frequently induced after T cell–depleted HLA-DPB1–mismatched allo-SCT and donor lymphocyte infusion (DLI), we developed a method to screen for the presence of HLA-DP–specific CD4+ T cells using CD137 as an activation marker and analyzed 24 patient–donor combinations. The patients suffered from various B cell malignancies, multiple myeloma, and myeloid leukemias. Patient HLA-DP–specific CD4+ T cells were detected after DLI in 13 of 18 patients who exhibited a clinical response to DLI, compared with only 1 of 6 patients without a clinical response to DLI. Eight patients developed significant GVHD. These data show that patient HLA-DP–specific CD4+ T cells frequently occur after HLA-DPB1–mismatched T cell–depleted allo-SCT and DLI, and are associated with graft-versus-leukemia reactivity both in the presence and absence of GVHD. [Copyright &y& Elsevier]

Clinical studies have indicated that HLA-DPB1 functions as a classical transplantation antigen in allogeneic stem cell transplantation. Mismatching for HLA-DPB1 was associated with an increased risk of graft-versus-host disease (GVHD), but also a decreased risk of disease relapse. However, specific HLA-DPB1 mismatches were associated with poor clinical outcome. It was suggested that this unfavorable effect was caused by a difference in immunogenicity between HLA-DPB1 alleles. To analyze whether immunogenicity of HLA-DPB1 mismatches could be predicted based on the presence or absence of specific amino acid sequences we developed a model to generate allo-HLA-DPB1 responses in vitro. We tested in total 48 different stimulator/responder combinations by stimulating CD4+ T cells from 5 HLA-DPB1 homozygous individuals with the same antigen-presenting cells transduced with different allo-HLA-DPB1 molecules. HLA-DPB1 molecules used for stimulation comprised 76% to 99% of HLA-DPB1 molecules present in different ethnic populations. We show that all HLA-DPB1 mismatches as defined by allele typing resulted in high-frequency immune responses. Furthermore, we show that crossrecognition of different HLA-DPB1 molecules is a broadly observed phenomenon. We confirm previously described patterns in crossrecognition, and demonstrate that a high degree in similarity between HLA-DPB1 molecules is predictive for crossrecognition, but not for immunogenicity. [ABSTRACT FROM AUTHOR]

Human hematopoiesis is critically dependent on the transcription factor GATA2. Patients with GATA2 deficiency typically present with myelodysplastic syndrome, reduced numbers of monocytes, NK cells and B cells, and/or opportunistic infections. Here, we present two families that harbor distinct GATA2 mutations with highly variable onset and course of disease. We discuss the use of allogeneic hematopoietic cell transplantation in these patients, especially as treatment for pulmonary alveolar proteinosis. • GATA2 deficiency is a multifaceted disease and information on the mutation type can be helpful to appraise its impact. • Allogeneic HCT can improve PAP and should be considered at an early stage in case of organ damage. • Lung function data pre and post allogeneic HCT are needed to define the critical window for allogeneic HCT in PAP treatment • Pre-existent GATA2-associated inflammatory or infectious complications are likely to aggravate shortly after allogeneic HCT. [ABSTRACT FROM AUTHOR]