Galectin-1 is associated with hematopoietic cell engraftment in murine MHC-mismatched allotransplantation.

Haploidentical hematopoietic cell transplantation (haplo-HCT) is associated with an increased risk of allograft rejection. Here, we employed a major histocompatibility complex (MHC)-mismatched allogeneic HCT (allo-HCT) murine model to better understand the role of Gal-1 in immune tolerance. Transplanted mice were classified into either rejected or engrafted based on donor chimerism levels. We noted significantly higher frequencies of CD4+ T cells, CD8+ T cells, natural killer cells, IFN-γ and TNF-α producing CD4+ T cells, and IFN-γ producing dendritic cells and macrophages in rejected mice. Conversely, we found significantly increased frequencies of regulatory T cells (Tregs), predominantly Helios+, IL-10-producing CD4+ T cells, type 1 regulatory (Tr1) cells, and the proportion of Tr1+Gal-1+ cells in engrafted mice. Further, Gal-1 specific blockade in Tregs reduced suppression of effector T cells in engrafted mice. Lastly, effector T cells from engrafted mice were more prone to undergo apoptosis. Collectively, we have shown that Gal-1 may favor HSC engraftment in an MHC-mismatched murine model. Our results demonstrate that Gal-1-expressing Tregs, especially at earlier time points post-transplant, are associated with inducing immune tolerance and stable mixed chimerism after HCT.

Case Report: Approaches for managing resistant cytomegalovirus in pediatric allogeneic hematopoietic cell transplantation recipients.

The instructional case is a pediatric haploidentical TCRαß+/CD19+ depleted allogeneic hematopoietic cell transplantation recipient who developed early onset CMV infection, which was complicated by resistant CMV (both UL97 and UL54) and successfully managed with maribavir and haploidentical CMV-specific T lymphocytes. Novel approaches to resistant CMV infection are reviewed and effective utilization of recent advances in diagnosis and management of resistant CMV in pediatric HCT are highlighted.

Features of Epstein-Barr Virus and Cytomegalovirus Reactivation in Acute Leukemia Patients After Haplo-HCT With Myeloablative ATG-Containing Conditioning Regimen.

Background: Haploidentical donor hematopoietic cell transplantation (haplo-HCT) has become a preferred option for patients without HLA-matched donors, but it increases the risk of viral reactivations. Epstein-Barr virus (EBV) and cytomegalovirus (CMV) are common viruses post-HCT, but limited data have been reported in the setting of haplo-HCT. Methods: We conducted a retrospective study enrolling acute leukemia patients who received haplo-HCT with myeloablative conditioning regimen employing ATG in our center from July 2014 to July 2017. All the patients enrolled were EBV-IgM and EBV-DNA negative but EBV-IgG positive, and so were their donors. The same went for CMV as well. Results: In total, 602 patients were recruited consisting of 331 with acute myeloid leukemia (AML) and 271 with acute lymphoblastic leukemia (ALL). One-year cumulative incidences of EBV (22.9% ± 2.4% vs. 27.4% ± 2.8%, P = 0.169) and CMV (24.7% ± 2.4% vs. 29.4% ± 2.8%, P = 0.190) reactivation were comparable between AML and ALL. EBV and CMV were independent risk factors for each other. In the AML group, male recipients [HR = 1.275, 95% CI (1.001-1.624), P = 0.049] and acute graft-versus-host disease [HR = 1.592, 95% CI (1.001-2.533), P = 0.049] were independent risk factors for EBV reactivation and CMV reactivation, respectively. CMV rather than EBV reactivation was related to a trend of worsened treatment-related mortality (TRM) (15.6% ± 0.1% vs. 10.2% ± 0.0%, P = 0.067) and progression-free survival (PFS) (60.6% ± 4.1% vs. 70.3% ± 2.3%, P = 0.073), while significant impacts were revealed only in the subgroup analysis. CMV reactivation resulted in a remarkable inferior 2-year overall survival (OS) (64.2% ± 5.7% vs. 77.6% ± 3.2%, P = 0.038) and PFS (55.0% ± 5.9% vs. 71.9% ± 3.4%, P = 0.042) in ALL patients. On the other hand, in the EBV+/CMV- subgroup, relapse was lower in ALL patients (8.2% ± 0.2% vs. 32.4% ± 0.8%, P = 0.010) compared with AML patients, which led to a superior 2-year OS (82.0% ± 6.2% vs. 60.3% ± 8.8%, P = 0.016) and PFS (74.5% ± 7.0% vs. 57.5% ± 8.4%, P = 0.036). Conclusion: We concluded that EBV and CMV reactivations were frequent in acute leukemia patients after haplo-HCT, with possibly distinctive risk factors from HLA-matched HCT. There could be a potential interaction between EBV and CMV, but impacts on transplant outcomes remained complex.

Post-transplant cyclophosphamide pharmacokinetics and haploidentical hematopoietic cell transplantation outcomes: an exploratory study.

Pharmacokinetics of cyclophosphamide has been explored to optimize conditioning dosing. We hypothesized that post-transplant cyclophosphamide (PTCy) metabolite carboxy-ethyl phosphoramide mustard (CEPM) pharmacokinetics might impact haploidentical transplantation (haplo-HCT) outcomes. CEPM area under the curve (AUC0-48) was determined by eleven sampling timepoints on day +3/+4 using LC-MS/MS. The median CEPM AUC0-48 in a cohort of 30 patients was 14.2 (14) mg·hr/L. The incidence of severe chronic graft-versus-host disease (GVHD) (73% vs. 11%, p = 0.02), and GVHD-/relapse-free survival (GRFS) was significantly inferior in the CEPM AUC0-48 < 14 mg·hr/L group (54 days vs. 344 days, p = 0.02). There was, however, no difference in grade III-IV acute GVHD (38% vs. 14%, p = 0.12) and overall survival (295 days vs. not reached, p = 0.2). CEPM AUC0-48, is associated with severe chronic GVHD and GRFS post-haplo-HCT in this exploratory study. There is scope for personalizing day + 4 PTCy dose based on day + 3 CEPM AUC0-8.

Cytokine Release Syndrome and Associated Acute Toxicities in Pediatric Patients Undergoing Immune Effector Cell Therapy or Hematopoietic Cell Transplantation.

Immune effector cells (IEC) are a powerful and increasingly targeted tool, particularly for the control and eradication of malignant diseases. However, the infusion, expansion, and persistence of autologous or allogeneic IEC or engagement of endogenous immune cells can be associated with significant systemic multi-organ toxicities. Here we review the signs and symptoms, grading and pathophysiology of immune-related toxicities arising in the context of pediatric immunotherapies and haploidentical T cell replete Hematopoietic Cell Transplantation (HCT). Principles of management are discussed with particular focus on the intersection of these toxicities with the requirement for pediatric critical care level support.