Immune-Mediated Hematopoietic Failure after Allogeneic Hematopoietic Stem Cell Transplantation: A Common Cause of Late Graft Failure in Patients with Complete Donor Chimerism

Poor graft function after haploidentical stem cell transplantation with post-transplant cyclophosphamide

This is a retrospective cohort study of consecutive adult patients who received a haploidentical-SCT (haplo-SCT) with post-transplant cyclophosphamide (PT-Cy) in a single centre. Poor graft function (PGF) was defined as the occurrence of either persistent neutropenia (ANC < 0.5 × 10⁹/µL) with poor response to granulocyte colony-stimulating factors (G-CSF) and/or thrombocytopenia (platelets < 20 × 10⁹/L) with transfusion dependence, with complete donor chimerism and without concurrent severe GVHD or underlying disease relapse, during the first 12 months after transplantation. Forty-four (27.5%) out of 161 patients were diagnosed with PGF. Previous CMV reactivation was significantly more frequent in patients with PGF (88.6% versus 73.5%, p = 0.04) and the number of reactivations was also higher in these patients. Besides, early CMV reactivations in the first 6 months post-SCT were also significantly more frequent among patients with PGF (88.6% versus 71.8% p = 0.025). Thirty-two percent of patients with PGF were treated with increasing doses of thrombopoietin-receptor agonists (TRA) and 7 patients were treated with a donor CD34 + selected boost. In total, 93.2% of patients reached adequate peripheral blood counts in a median time of 101 days (range 11-475) after diagnosis. PGF is a frequent complication after haplo-SCT with PT-Cy. CMV reactivation might be the most relevant factor associated to its development. Even when most patients recover peripheral counts with support therapy, there is a group of patients with persistent cytopenias who can effectively be treated with TRA and/or a boost of CD34 + selective cells.

RETRACTED: The impact of second-donor lymphocyte infusion on secondary graft failure after allogeneic hematopoietic stem cell transplantation through activation of Foxp3 and regulatory T cells

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). The Editor of Cytotherapy has retracted this article. The article duplicates significant parts of a paper that had already appeared in Transplantation and Cellular Therapy, Volume 28, Issue 3, 2022, Pages 152.e1-152.e7, https://doi.org/10.1016/j.jtct.2021.12.017 In accordance with Committee on Publication Ethics (COPE) and Elsevier's policies, the authors have been contacted. After considering the author's response, the decision has been made to retract the paper. Redundant publications overweigh the relative importance of published findings and distort the academic record of the authors. One of the conditions of submission of a paper for publication is therefore that authors declare explicitly that the paper has not been previously published and is not under consideration for publication elsewhere. As such this article represents a misuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.

Clinical features, pathophysiology, and therapy of poor graft function post-allogeneic stem cell transplantation

Poor graft function (PGF), defined by the presence of multilineage cytopenias in the presence of 100% donor chimerism, is a serious complication of allogeneic stem cell transplant (alloSCT). Inducers or potentiators of alloimmunity such as cytomegalovirus reactivation and graft-versus-host disease are associated with the development of PGF, however, more clinical studies are required to establish further risk factors and describe outcomes of PGF. The pathophysiology of PGF can be conceptualized as dysfunction related to the number or productivity of the stem cell compartment, defects in bone marrow microenvironment components such as mesenchymal stromal cells and endothelial cells, or immunological suppression of post-alloSCT hematopoiesis. Treatment strategies focused on improving stem cell number and function and microenvironment support of hematopoiesis have been attempted with variable success. There has been limited use of immune manipulation as a therapeutic strategy, but emerging therapies hold promise. This review details the current understanding of the causes of PGF and methods of treatment to provide a framework for clinicians managing this complex problem.

Effect of donor lymphocyte infusion from two types of donors on Mixed Chimerism with Secondary Graft Failure after allogeneic haematopoietic stem cell transplantation

Mixed chimerism (MC) and secondary graft failure (SGF) with recipient-or donor-type chimerism is a major obstacle in allogeneic hematopoietic stem cell transpl- antation (HSCT). Donor lymphocyte infusion(DLI) can eradicate minimal residual disease or be used to rescue a hematologic relapse, being able to induce durable remissions after HSCT.This study aimed to analyse the efficacy and immune mecha- nism of DLI from the original and alternative donor for patients of mixed donor chimerism with SGF . The alternative donor refers to the candidate relative donor who did not initially provide stem cells include HLA-matched sibling donor(MSD) or HLA- haploidentical donor (HID). We conducted a retrospective study of 246 patients with a median age of 37 (9-58) years who were regularly detected MC, complete donor chimera (CC) and regulatory T cells (Treg). The median diagnosis time of SGF was 69 (39-141) days after transplantation . Sixteen patients of SGF received DLI from the alternative donor, including 3 patients who chose DLI from the original donor with no initial response and 13 patients who directly chose DLI from the alternative donor. Sixteen patients with SGF exsisted mixed chimerism synchronously and the rate calculated overall chimerism of MC was 63% (range, 42%-85%) after transplantation. The proportion of Treg decreased significantly in SGF patients from a median of (2.66% ±0.80%) to (0.93%±0.57%) at a time point after transplantation (p=0.02).The DLI of the alternative donor in 14 patients achieved complete response and MC gradually convert to CC state, simultaneously there was significant increase in the Treg fraction [SGF vs CR: (0.93% ± 0.57%) vs (3.61%±0.82%), p=0.01)].For the clinical nonres- ponders from two types of donor there was no significant change in MC and Treg cells. The OS and DFS at 2 years after DLI were 69.7%±3.19 % and 61.3%±4.80%, respectively. DLI from the alternative donor may be an effective treatment for MC with SGF and the mechanism is closely related to the activation of Treg cells level.

Advances in the understanding of poor graft function following allogeneic hematopoietic stem-cell transplantation

Poor graft function (PGF) following allogeneic hematopoietic stem-cell transplantation (allo-HSCT) is a life-threatening complication and is characterized by bilineage or trilineage blood cell deficiency and hypoplastic marrow with full chimerism. With the rapid development of allo-HSCT, especially haploidentical-HSCT, PGF has become a growing concern. The most common risk factors illustrated by recent studies include low dose of infused CD34+ cells, donor-specific antibody, cytomegalovirus infection, graft versus host disease (GVHD), iron overload and splenomegaly, among others. Because of the poor prognosis of PGF, it is crucial to uncover the underlying mechanism, which remains elusive. Recent studies have suggested that the bone marrow microenvironment may play an important role in the pathogenesis of PGF. Deficiency and dysfunction of endothelial cells and mesenchymal stem cells, elevated reactive oxygen species (ROS) levels, and immune abnormalities are believed to contribute to PGF. In this review, we also discuss recent clinical trials that evaluate the safety and efficacy of new strategies in patients with PGF. CD34+-selected stem-cell boost (SCB) is effective with an acceptable incidence of GVHD, despite the need for a second donation. Alternative strategies including the applications of mesenchymal stem cells, N-acetyl-l-cysteine (NAC), and eltrombopag have shown favorable outcomes, but further large-scale studies are needed due to the small sample sizes of the recent clinical trials.

Improved outcomes of allogeneic hematopoietic stem cell transplantation including haploidentical transplantation for childhood myelodysplastic syndrome

This retrospective study aimed to investigate the outcomes of allogeneic hematopoietic stem cell transplantation (HSCT) for childhood myelodysplastic syndrome (MDS). Thirty-six patients (low-grade MDS, 24; advanced MDS, 12) received HSCT at the Asan Medical Center over two decades (early period, 1997-2007; recent period, 2008-2017). The transplantation outcomes were analyzed according to disease status, conditioning regimen, various donor types, and period of HSCT. During a median follow-up of 5.6 (range, 1.4-21.1) years, the probability of overall survival (OS) and failure-free survival was 77% and 69%, respectively. The cumulative incidence of transplantation-related mortality (TRM) was 12%. Significantly reduced TRM and improved OS were observed in patients who received HSCT during the recent period vs. the early period (TRM, 4% vs. 30%, P = 0.021; OS, 87% vs. 50%, P = 0.006). Comparable outcomes were observed for HSCT from haploidentical family donors vs. HLA-identical donors (TRM, 10% vs. 14%, P= 0.837; OS, 86% vs. 79%, P = 0.625). This study identified the improved outcomes of allogeneic HSCT for childhood MDS over time, in addition, the feasible outcomes of haploidentical HSCT suggested its use as an attractive alternative in the future procedures.

Acquired Aplastic Anemia: What Have We Learned and What Is in the Horizon?

Acquired aplastic anemia (aAA) characterized by peripheral pancytopenia and bone marrow aplasia is a rare and serious disorder. Differential diagnosis includes constitutional bone marrow failure syndromes and myelodysplastic disorders. Autoimmune reaction to altered hematopoietic stem cells highlights the underlying mechanism. Matched related donor allogeneic hematopoietic stem cell transplantation is the ideal pediatric treatment; alternative approaches include immunosuppressive therapy and use of eltrombopag. Progression to clonal disorders can occur. Recently, alternative donor hematopoietic stem cell transplantation outcomes have significantly improved. Despite advances, aAA continues to be a challenge for hematologists.