Nikolaos Spyridis

Background: Treosulfan combined with fludarabine (FluTreo) has emerged as a reduced-toxicity alternative to conventional myeloablative conditioning in allogeneic hematopoietic cell transplantation (allo-HCT) for acute myeloid leukemia (AML) and related myeloid malignancies. Purpose: This study evaluates the safety, engraftment kinetics, and long-term outcomes of the FluTreo FT14 regimen in a real-world adult cohort. Materials and Methods: We conducted a prospective cohort study of 186 consecutive adults (18–70 years) undergoing allo-HCT between January 2015 and December 2024. Eligible diagnoses included de novo or secondary AML, myelodysplastic syndrome, and myelofibrosis. All received peripheral blood stem cells from matched or mismatched unrelated donors, HLA-matched siblings, or haploidentical relatives. The FT14 protocol comprised fludarabine 150 mg/m² over five days and treosulfan 42 g/m² over three days, with rabbit antithymocyte globulin (5 mg/kg) for unrelated grafts. Primary endpoints were neutrophil and platelet engraftment, donor chimerism, incidence of acute and chronic graft-versus-host disease (GVHD), overall survival (OS), disease-free survival (DFS), relapse, and treatment-related mortality (TRM). Kaplan–Meier, Cox regression, and Fine and Gray models were applied. Results: Median age was 59 years; diagnoses included de novo AML (43%), secondary AML (16%), MDS (25%), and MF (16%). Neutrophil and platelet engraftment medians were 10 and 12 days, respectively. Full donor chimerism (≥99%) was achieved by day 31. Grade III conditioning-related toxicity occurred in 3.2% of cases. Five-year cumulative incidences of grade II–IV acute GVHD and moderate/severe chronic GVHD were 37.6% and 30.6%. Median follow-up was 16.3 months; relapse occurred in 25.3%. Five-year OS and DFS were 71% and 49% overall (75.8% and 59% in CR1), with TRM of 15.3%. Disease relapse and acute GVHD independently predicted inferior OS, and acute GVHD predicted TRM. Conclusions: The FluTreo FT14 regimen achieves rapid engraftment, universal high donor chimerism, low severe toxicity, and durable survival, supporting its use as a myeloablative, reduced-toxicity conditioning option in myeloid malignancies.

Endothelial injury indices, such as Endothelial Activation and Stress Index (EASIX), modified EASIX (m-EASIX), and simplified EASIX (s-EASIX) scores, have been previously associated with chimeric antigen receptor-T (CAR-T) cell immunotherapy complications. Soluble urokinase-type plasminogen activator receptor (suPAR), growth differentiation factor-15 (GDF-15), and soluble C5b-9 (sC5b-9) have been described as markers of endothelial injury post-hematopoietic stem cell transplantation. In the current study, we examined whether suPAR, GDF-15, and sC5b-9 levels were associated with endothelial injury indices in adult CAR-T cell recipients. The levels of these markers were measured in patients before CAR-T cell infusion and in healthy individuals with immunoenzymatic methods. We studied 45 CAR-T cell recipients and 20 healthy individuals as the control group. SuPAR, GDF-15, and sC5b-9 levels were significantly higher in the patients’ group compared to the healthy control group (p < 0.001, in all comparisons). SuPAR levels at baseline were associated with the m-EASIX scores calculated at the same time point (p = 0.020), while suPAR and GDF-15 concentrations were correlated with EASIX scores at day 14 post-infusion (p < 0.001 in both comparisons). Moreover, sC5b-9 levels were correlated with the s-EASIX scores at infusion (p = 0.008) and the EASIX scores at day 14 (p = 0.005). In our study, sC5b9, suPAR, and GDF-15 levels were found to reflect endothelial injury in CAR-T cell recipients.

Background/Objectives: Despite novel biological agents, steroid-dependent or -refractory graft-versus-host disease (GvHD) remains a severe complication of allogeneic hematopoietic cell transplantation (allo-HCT). Extracorporeal photopheresis (ECP) is an alternative, non-immunosuppressive treatment for patients with acute (aGvHD) or chronic (cGvHD) GvHD. The aim of this study was to investigate the safety and efficacy of ECP in the treatment of acute and chronic GvHD; Methods: We prospectively studied 112 patients with cGvHD who received one or more previous lines of treatment and 28 patients with steroid-dependent or refractory grade II-IV aGvHD post-alloHSCT. Results: In terms of severe aGvHD, most of the patients (19/28) responded to ECP treatment, while the five-year overall survival (OS) was 34%. After adjustment for several confounder factors, the reduction in immunosuppression (p = 0.026) and number of ECP sessions (p < 0.001) were associated with improved OS. Regarding chronic GvHD, only 19 patients failed to respond to ECP treatment; though significantly lower rates of response were presented in patients with visceral involvement (p = 0.037) and earlier post-transplant GVHD diagnosis (p = 0.001). Over a follow-up period of 45.2 [interquartile range (IQR): 5.6–345.1] months, the 5-year cumulative incidence (CI) of cGvHD-related mortality was 21.2% and was significantly reduced in patients with ECP response (p < 0.001), while the 5-year OS was 65.3%. Conclusions: Our results confirm the safety and efficacy of ECP in patients with GvHD and provide sufficient data for further investigation and the best combination drugs needed such that GvHD will not be the major barrier of allo-HCT in the near future.

Hematopoietic stem cell transplantation-associated thrombotic microangiopathy (HSCT-TMA) and graft-versus-host disease (GvHD) represent life-threatening syndromes after allogeneic hematopoietic stem cell transplantation (allo-HSCT). In both conditions, endothelial dysfunction is a common denominator, and development of relevant biomarkers is of high importance for both diagnosis and prognosis. Despite the fact that soluble urokinase plasminogen activator receptor (suPAR) and growth differentiation factor-15 (GDF-15) have been determined as endothelial injury indices in various clinical settings, their role in HSCT-related complications remains unexplored. In this context, we used immunoenzymatic methods to measure suPAR and GDF-15 levels in HSCT-TMA, acute and/or chronic GVHD, control HSCT recipients, and apparently healthy individuals of similar age and gender. We found considerably greater SuPAR and GDF-15 levels in HSCT-TMA and GVHD patients compared to allo-HSCT and healthy patients. Both GDF-15 and suPAR concentrations were linked to EASIX at day 100 and last follow-up. SuPAR was associated with creatinine and platelets at day 100 and last follow-up, while GDF-15 was associated only with platelets, suggesting that laboratory values do not drive EASIX. SuPAR, but not GDF-15, was related to soluble C5b-9 levels, a sign of increased HSCT-TMA risk. Our study shows for the first time that suPAR and GDF-15 indicate endothelial damage in allo-HSCT recipients. Rigorous validation of these biomarkers in many cohorts may provide utility for their usefulness in identifying and stratifying allo-HSCT recipients with endothelial cell impairment.