Incidence and risk factors for graft failure in the modern era of cord blood transplantation

Successful treatment of very severe aplastic anemia with double unrelated umbilical cord blood transplantation in a donor-specific antigen positive adult patient: A case report and review

To overcome the cell-dose barrier of cord blood, double unrelated umbilical cord blood transplantation (UCBT) has become increasingly common in adults with severe aplastic anemia (SAA). Pre-existing donor-specific anti-HLA antibodies (DSAs) represent a risk factor for graft failure (GF). Desensitization therapy should be conducted to reduce circulating DSA levels, thereby decreasing the risk of GF. This report details a case of a female patient with acquired SAA and pre-transplantation anti-HLA antibodies. Desensitization with rituximab, intravenous immunoglobulin (IVIG), and plasma exchange (PE) was performed before transplantation with a conditioning regimen of fludarabine (30 mg/m2 for six days) and cyclophosphamide (50 mg/kg/d for four days). DSA titers were significantly reduced; the patient was successfully treated with double unrelated UCBT. Currently, complete remission (CR) status has been maintained for over a year after UCBT, with no signs of graft-vs-host disease. Our findings support the use of double-unit unrelated UCBT in adult patients with SAA when cell doses of single-unit UCB are inadequate. Monitoring and reducing DSA levels before and after UCBT is an efficient way to reduce the risk of GF.

Salvage HLA-haploidentical Peripheral Blood Stem Cell Transplantation Using Post-transplant Cyclophosphamide for Recurrent Hemophagocytic Lymphohistiocytosis-associated Graft Failure after Cord Blood Transplantations: A Case Report

We describe a case of immunological rejection occurring twice after cord blood transplantation (CBT) for mixed phenotype blast phase chronic myeloid leukemia that was successfully salvaged by haploidentical peripheral blood stem cell transplantation (haplo-PBSCT) with post-transplant cyclophosphamide (PT-Cy). Pre-engraftment immune reaction (PIR) and subsequent hemophagocytic lymphohistiocytosis (HLH), likely due to HLA mismatch in the graft-versus-host (GVH) direction, lead to poor graft function (PGF) and graft failure (GF). This case highlights the pathophysiology of PIR, HLH, PGF, and GF, collectively termed "post-transplant cytokine syndrome." PT-Cy haplo-PBSCT, with wide donor availability and reduced infection risk leading to HLH via rapid engraftment, may be a suitable salvage option for post-CBT cytokine syndrome-related GF.

Machine Learning Prediction Model for Neutrophil Recovery after Unrelated Cord Blood Transplantation

Delayed neutrophil recovery is an important limitation to the administration of cord blood transplantation (CBT) and leaves the recipient vulnerable to life-threatening infection and increases the risk of other complications. A predictive model for neutrophil recovery after single-unit CBT was developed by using a machine learning method, which can handle large and complex datasets, allowing for the analysis of massive amounts of information to uncover patterns and make accurate predictions. Japanese registry data, the largest real-world dataset of CBT, was selected as the data source. Ninety-eight variables with observed values for >80% of the subjects known at the time of CBT were selected. Model building was performed with a competing risk regression model with lasso penalty. Prediction accuracy of the models was evaluated by calculating the area under the receiver operating characteristic curve (AUC) using a test dataset. The primary outcome was neutrophil recovery at day (D) 28, with recovery at D14 and D42 analyzed as secondary outcomes. The final cord blood engraftment prediction (CBEP) models included 2991 single-unit CBT recipients with acute leukemia. The median AUC of a D28-CBEP lasso regression model run 100 times was .74, and those for D14 and D42 were .88 and .68, respectively. The predictivity of the D28-CBEP model was higher than that of 4 different legacy models constructed separately. A highly predictive model for neutrophil recovery by 28 days after CBT was constructed using machine learning techniques; however, identification of significant risk factors was insufficient for outcome prediction for an individual patient, which is necessary for improving therapeutic outcomes. Notably, the prediction accuracy for post-transplantation D14, D28, and D42 decreased, and the model became more complex with more associated factors with increased time after transplantation.

Long-term outcome of second allogeneic hematopoietic stem cell transplantation (HSCT2) for primary graft failure in patients with acute leukemia in remission: A study on behalf of the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

Second transplantation (HSCT2) is a potential treatment for primary graft failure (pGF). We assessed the outcome of HSCT2, performed between 2000 and 2021, for pGF in 243 patients with acute leukemia. Median age was 44.8 years. Conditioning at first HSCT (HSCT1) was myeloablative (MAC) in 58.4%. Median time from HSCT1 to HSCT2 was 48 days. Donors for HSCT2 were the same as for HSCT1 in 49%. Engraftment post HSCT2 was achieved by 73.7% of patients. The incidence of acute (a) graft versus host disease (GVHD) grades II-IV and III-IV was 23.2 and 8.1%. 5-year total and extensive chronic (c) GVHD was 22.3 and 10.1%. 5-year nonrelapse mortality (NRM), relapse incidence (RI), leukemia-free survival (LFS), overall survival (OS) and GVHD free, relapse-free survival (GRFS) was 51.6, 18.8, 29.6, 30.7 and 22.4%, respectively. Infections were the main cause of death. In multivariable analysis, being transplanted at second vs. first remission, lower Karnofsky performance status (KPS; <90) and receiving MAC at HSCT1 were adverse prognostic factors for NRM, LFS, OS, and GRFS, as was increased age for NRM, LFS, OS. We conclude that HSCT2 can rescue about a third of the patients who experienced pGF, but NRM is as high as 50%.