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.

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.

Bacterial infections, especially bloodstream infections (BSIs), compromise the overall survival of patients with hematological malignancies undergoing cellular therapies. The interplay between rectal colonization by different types of multidrug-resistant organisms (MDRO) and subsequent BSIs is not fully determined. We aimed to describe the natural history and risk factors for colonization by MDRO, as well as its impact on subsequent BSIs in patients treated with cellular therapies in an environment of antimicrobial resistance. Retrospective, single-center cohort study of consecutive adult hematological malignancies patients treated with allogeneic or autologous hematopoietic cell transplantation (HCT) or chimeric antigen receptor T-cell therapy between 2021 and 2024 in Attikon University Hospital (Greece), with ≥1 available rectal screening test for carbapenem-resistant gram-negative bacilli (CR-GNB) and vancomycin-resistant Enterococcus faecium (VRE). Univariate and multivariate Cox regression were implemented for identifying predictors of CR-GNB and VRE colonization. We also studied the concordance between rectal colonization and subsequent BSIs. One hundred eighty-two patients were included (male: 64%, mean age: 50.2 ± 13 yr, acute myeloid leukemia/myelodysplastic syndrome diagnosis: 55%, relapsing/refractory disease: 58%, allogeneic HCT: 85%). Median duration of hospitalization and neutropenia was 35 and 15 d, respectively. At baseline, 95% of patients were negative on rectal screening for both CR-GNB and VRE, and of those, 8.4% and 23% were colonized with CR-GNB and VRE during follow-up, respectively. Prior colonization with the same pathogen was independently associated with subsequent CR-GNB (HR: 13.0, 95% CI: 2.83 to 59.3) and VRE (HR: 4.83, 95% CI: 2.28 to 10.2) colonization. Seventy-nine patients had ≥1 BSIs (gram-positive: 60%, gram-negative: 38%), with three concordant CR-GNB BSIs among 16 colonized patients (18.7%) and two CR-GNB BSIs among 153 noncolonized patients (1.3%). Regarding VRE, we identified two concordant BSIs among 45 colonized patients (4.4%). Despite the high MDRO prevalence, we observed low rates of CR-GNB colonization in neutropenic patients treated with cellular therapies, with one patient out of five experiencing a concordant CR-GNB BSI. VRE colonization was more frequent, but it rarely resulted in a concordant BSI. These findings highlight the importance of infection control strategies and support de-escalation approaches in empirical antibacterial treatment of febrile neutropenia in this vulnerable population.