Allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the only therapy with a curative potential for a variety of malignant and non-malignant diseases. The major limitation of the procedure is the significant morbidity and mortality mainly associated with the development of graft versus host disease (GVHD) as well as with a series of complications related to endothelial injury, such as sinusoidal obstruction syndrome/veno-occlusive disease (SOS/VOD), transplant-associated thrombotic microangiopathy (TA-TMA), etc. Endothelial cells (ECs) are key players in the maintenance of vascular homeostasis and during allo-HSCT are confronted by multiple challenges, such as the toxicity from conditioning, the administration of calcineurin inhibitors, the immunosuppression associated infections, and the donor alloreactivity against host tissues. The early diagnosis of endothelial dysfunction syndromes is of paramount importance for the development of effective prophylactic and therapeutic strategies. There is an urgent need for the better understanding of the pathogenetic mechanisms as well as for the identification of novel biomarkers for the early diagnosis of endothelial damage. This review summarizes the current knowledge on the biology of the endothelial dysfunction syndromes after allo-HSCT, along with the respective therapeutic approaches, and discusses the strengths and weaknesses of possible biomarkers of endothelial damage and dysfunction.

Transplant-associated thrombotic microangiopathy (TA-TMA) constitutes a significant contributor to the increased morbidity and mortality after allogenic hematopoietic stem cell transplantation (allo-HSCT). TA-TMA is a heterogenous disease, characterized by the triad of endothelial cell activation, complement dysregulation and microvascular hemolytic anemia, which may affect all organs. The lack of consensus diagnostic criteria, along with the common clinical features mimicking other diseases that complicate allo-HSCT, make the diagnosis of TA-TMA particularly challenging. Significant effort has been made to recognize specific risk factors predisposing to the development of TA-TMA and to identify serum biomarkers predicting the development of the disease. With regard to treatment, therapeutic plasma exchange (TPE) has been traditionally used, although with doubtful efficacy. On the other hand, the pivotal role of complement activation in the pathophysiology of TA-TMA has led to the exploration of the therapeutic potential of complement inhibitors in this setting. Eculizumab has been proposed as a first-line therapeutic agent in TA-TMA, owing to the very promising results in both pediatric and adult clinical trials. Pharmacokinetic and pharmacodynamic studies and CH50 levels are of paramount importance in the allo-HSCT setting, as a different dosing schedule (more intensive—in dose and frequency—at the beginning) seems to be required for successful outcomes. Furthermore, Narsoplimab, a MASP-2 inhibitor, recently received a Breakthrough Therapy Designation from the FDA for the treatment of TA-TMA after allo-HSCT. Finally, the decision to withdraw the CNIs, although initially advised by the Bone and Marrow Transplant Clinical Trials Network Committee, remains debatable owing to the controversial results of recent clinical trials. This review summarizes the current updates on pathophysiology, diagnosis and therapeutic approaches and emphasizes future goals and perspectives.

Chronic Kidney Disease (CKD) is a frequent complication in patients with multiple myeloma (MM) and is associated with adverse outcomes. The use of autologous stem cell transplantation (ASCT) has improved disease outcomes, however, the safety and efficacy of ASCT in patients with CKD has been the subject of debate. To investigate this, we conducted a retrospective analysis of 370 MM patients who underwent their first ASCT, including those with mild, moderate and severe CKD as well as normal renal function at the time of transplant. No significant difference in ASCT-related mortality, Progression-Free or Overall Survival was noted between the different renal function groups. A decline in estimated glomerular filtration rate (eGFR) at 1-year of >8.79% was associated with poorer overall survival (p < 0.001). The results of this study show that ASCT is a safe and effective option for myeloma patients with CKD, including those on dialysis. Patients who demonstrate renal deterioration at 1-year post-transplant should be closely monitored as this is a predictor for poor survival.

Background/Objective: The prognostic impact of additional cytogenetic aberrations and molecular abnormalities (such as MDS-related mutations, mutations in myeloid genes and the KRAS/NRAS mutations) in patients with NPM1- and/or FLT3-ITD-mutated AML remains elusive. Methods: This retrospective, multicentre study of real-world data aimed to investigate the impact of these mutations and cytogenetic abnormalities on the prognosis of patients with NPM1- and/or FLT3-ITD-mutated AML, treated with intensive chemotherapy. Results: In a cohort of 161 patients, the only parameters identified to affect the outcomes (EFS and OS) were the age of the patient, primary refractory disease, the presence of a NPM1 mutation and the use of allogenic stem cell transplantation (allo-SCT) within the first complete remission. More specifically, ages below the median conferred significantly improved outcomes, whereas primary refractory disease exhibited a negative correlation with the EFS and OS. Subsequent subgroup analysis, stratifying patients into three groups (Group 1: NPM1^mutated/FLT3^wt; Group 2: NPM1^mutated/FLT3^mutated; Group 3: NPM1^wt/FLT3^mutated). revealed that allo-SCT in CR1 improved the outcomes (EFS and OS) in Groups 2 and 3, but had no additional impact in Group 1. Conclusions: Age, primary refractory disease and allogenic stem cell transplantation in the first complete response were found to have a prognostic impact on outcomes, Interestingly, no significant association was detected between the poor prognostic cytogenetic abnormalities or the presence of additional mutations in myeloid genes, MDS-related genes or KRAS/NRAS genes and the outcomes in any group of patients.

Transplant-associated thrombotic microangiopathy (TMA) occurs in a significant percentage of patients after allogeneic stem cell transplantation (allo-SCT) and is associated with significant morbidity and mortality. The aim of the present study was to examine the association of serum angiopoetin-2 (Ang2) levels and the presence of antibodies against angiotensin II type 1 (AT1R) and ndothelin A Recreptor (ETAR) with the outcome of patients with TMA and/or graft-versus-host disease (GVHD) after allo-SCT. Analysis of our data showed that elevated serum Ang2 levels at the time of TMA diagnosis are significantly associated with increased non-relapse mortality and decreased overall survival. To our knowledge, this is the first study demonstrating an association between raised Ang2 levels and poor outcomes in patients with TMA. Antibodies against AT1R (AT1R-Abs) and ETAR (ETAR-Abs) were detected in 27% and 23% of the patients, respectively, but there was no association between the presence of autoantibodies and the outcome of patients with TMA. However, a significant finding was the strong positive correlation between the presence of AT1R-Abs with the occurrence of chronic fibrotic GVHD, such as scleroderma and cryptogenic organizing pneumonia, raising the possibility of the contribution of autoantibodies in the pathogenesis of fibrotic GVHD manifestations.