BACKGROUND & AIMS:Patients with non-cirrhotic non-tumoral portal venous system thrombosis (NCNT-PVT) require long-term anticoagulation to prevent rethrombosis (either splanchnic or at any site, referred to as overall rethrombosis - oRT) when there is an underlying high-risk thrombophilic disorder or history of previous thrombotic episodes. However, up to 25% of patients without such indications still develop oRT. Elevated factor VIII (≥150%), D-dimer (≥500 ng/ml) or the presence of high molecular risk (HMR) variants have been proposed as risk predictors for oRT in these patients. This study aimed to compare the prognostic value of these three biomarkers in a cohort of patients with NCNT-PVT. METHODS:We performed a multicenter, retrospective, observational study including 123 patients with NCNT-PVT without an indication for long-term anticoagulation. RESULTS:During a median follow-up of 89.3 months (IQR 36-129), 33 patients (27%) developed venous oRT, with a cumulative incidence of 7%, 17% and 26% at 1, 5 and 10 years. Factor VIII ≥150% and HMR were associated with oRT risk (hazard ratio 5.92, 95% CI 2.67-13.15, p <0.01; and hazard ratio 2.07, 95% CI 1.01-4.24, p = 0.04, respectively) while D-dimer ≥500 ng/ml showed a non-significant trend. Multivariate analysis confirmed factor VIII and HMR as independent predictors. CONCLUSIONS:Patients with unprovoked or local factor-associated PVT have a clinically relevant long-term risk of recurrence, with a 25% cumulative incidence of oRT at 10 years. Elevated factor VIII (≥150%) identifies a subgroup at particularly increased risk, and its combination with HMR variants may further refine risk stratification. IMPACT AND IMPLICATIONS:This study addresses an important clinical gap by evaluating whether prothrombotic and genetic biomarkers can help identify patients with non-cirrhotic, non-tumoral portal vein thrombosis who remain at risk of recurrent thrombosis despite the absence of classical thrombophilia. Our results show that persistently elevated factor VIII levels, alone or combined with high molecular risk variants, are strong predictors of rethrombosis in this population. These findings may help refine recurrence-risk stratification in patients traditionally considered low risk and could support more individualized decisions regarding long-term anticoagulation and follow-up intensity.

Despite red blood cell (RBC) immunization being a frequent complication of chronic transfusion in myelodysplastic syndromes (MDS), its prognostic significance remains unclear. We analysed 486 transfused patients diagnosed with MDS. Prognostic impact of RBC immunization (allo- or autoantibodies) was evaluated as a time-dependent covariate. Competing risk methods were applied to estimate the cumulative incidence of immunization. Sixty-nine patients (14.2%) developed RBC immunization, most commonly anti-K and anti-E, which was more frequent in patients transfused before MDS diagnosis (subhazard ratio [SHR]: 2.9, 95% confidence interval [CI]: 1.6-5.4; p = 0.001) and Rh(D)-negative blood group (SHR: 1.9, 95% CI: 1.1-3.2; p = 0.026). RBC immunization was associated with a significant and independent reduction in remaining survival (hazard ratio: 11.9, 95% CI: 7.3-19.6; p = 0.001), without differences between auto- and alloantibodies. RBC immunization was followed by increased transfusion intensity, but transfusion requirements also rose in non-immunized patients over time. RBC immunization did not predict progression to acute myeloid leukaemia (AML). A trend towards fewer new antibodies was observed during hypomethylating therapy. RBC immunization is independently associated with reduced survival in transfusion-dependent patients with MDS, irrespective of AML progression. These findings highlight the potential prognostic relevance of RBC antibodies and call for further investigation into the mechanisms linking immunization, transfusion burden and survival outcomes.

Hereditary spherocytosis (HS) is the most common congenital red blood cell membrane disorder, characterized by structural protein defects that lead to hemolytic anemia. Although several diagnostic tests exist, including osmotic fragility tests (OFTs), acidified glycerol lysis test (AGLT), and the EMA-binding test (EMA), each presents specific limitations regarding sensitivity, specificity, or technical requirements. Flow cytometric osmotic fragility testing (OFT-FCM) emerges as a promising complementary assay, offering a standardized workflow and rapid turnaround time. We conducted a retrospective study including 106 subjects (20 HS patients and 86 healthy controls) recruited at Hospital Clínic de Barcelona between September 2024 and September 2025. Clinical and laboratory data were collected, and all participants underwent OFT, AGLT, EMA, and OFT-FCM using two acquisition protocols (300 and 214 s). Logistic regression and receiver operating characteristic curve analysis were performed to evaluate diagnostic performance and determine optimal cut-off values. HS patients exhibited significantly altered hematologic parameters compared with controls, including higher reticulocyte counts, red cell distribution width, and mean corpuscular hemoglobin. The EMA-binding test demonstrated high specificity (100%) but lower sensitivity (57.9%). OFT achieved high sensitivity (>97%) but low specificity (<47%). AGLT showed balanced accuracy (sensitivity 68.4%, specificity 96.1%). OFT-FCM yielded areas under the curve of 0.85 for both protocols, with optimal thresholds providing specificities of 95-100% and sensitivities of 57-59%. No significant differences were observed between OFT-FCM and EMA performance. OFT-FCM effectively discriminates HS patients from healthy controls and showed diagnostic performance comparable to EMA and favorable relative to classical OFT and AGLT in this cohort, while offering practical advantages in terms of workflow simplicity and turnaround time, and supporting its use as a complementary flow-cytometric assay within the diagnostic work-up of HS.

Background JAK2V617F-mutated myeloproliferative neoplasms (MPN) exhibit abnormal proliferation of bone marrow progenitors and increased risk of thrombosis, specifically in splanchnic veins (SVT). The contribution of the endothelium to the development of the prothrombotic phenotype was explored. Material and methods Plasma and serum samples from JAK2V617F MPN patients with (n=26) or without (n=7) thrombotic debut and different treatments, were obtained (n=33). Cultured endothelial cells (ECs) were exposed to serum samples from these patients and from healthy donors as controls. Changes in markers of inflammation (VCAM-1, ICAM-1), cell permeability (VE-cadherin), production of VWF, extracellular matrix (ECM) reactivity, and activation of intracellular signaling pathways related to stress, proliferation, inflammation (Akt, p44/42, IkBa), and JAK2/STAT3 pathway, were assessed by immunofluorescence, flow adhesion, SDS-PAGE and immunoblot. Additionally, circulating markers of endothelial activation and damage (VWF, sVCAM-1, sTNFRI, thrombomodulin, angiopoietin-2, a2-antiplasmin activity, PAI-1) were evaluated in Patients' plasma. Results The in vitro studies showed that EC exposure to MPN thrombotic patients' sera resulted in increased VCAM-1 and ICAM-1, and reduced VE-cadherin expression (p<0.05) at the cell surface. Production and release of VWF to the ECM were higher (p<0.05), with increased platelet adhesion after perfusing whole blood, being more noticeable in response to sera from non-treated patients. Furthermore, intracellular activation of Akt, p44/42, IkBa and JAK2/STAT3 was observed. Moreover, plasma levels of VWF, TNF-R1, VCAM-1, thrombomodulin, and angiopoietin-2 were higher in JAK2V617F+ MPN patients with thrombosis. Conclusion The present findings suggest that circulating factors in MPNs with SVT debut induce endothelial proinflammatory and prothrombotic phenotypes, which are modulated in vitro with MPN treatment.

Inherited thrombocytopenia (IT) with germline variants in RUNX1, ETV6 or ANKRD26 carries a high risk (10%-45%) of developing haematological malignancy (IT-HM). We evaluated the clinical, platelet and molecular characteristics in 37 patients with RUNX1-related thrombocytopenia (RT), 9 with ETV6-RT and 20 with ANRKD26-RT. Genetic diagnosis was delayed by about 20 years from the identification of thrombocytopenia. Bleeding tendency was present in 25%-30% of RUNX1-RT and ANKRD26-RT patients. Platelet aggregation was impaired in 90% of all patients, while reduced activation and granule secretion were heterogeneous. Most RUNX1-RT patients had low glycoprotein Ia (GPIa) levels, which may be a useful disease biomarker. Sixteen distinct genetic variants in RUNX1, four in ETV6 and four in ANKRD26 were identified in patients. The clinical profile showed immune, skin, gastrointestinal and other comorbidities in many patients. One third of the cases developed a malignancy: This included eight RUNX1-RT patients with myelodysplastic syndrome (MDS), five with acute myeloid leukaemia (AML), and one with chronic myeloid leukaemia (CML) Ph+. One patient with ETV6-RT subsequently developed B-cell acute lymphoblastic leukaemia (B-ALL) during childhood. Three cases with ANKRD26-RT demonstrated a multifaceted clinical presentation, including B-ALL Ph+, MDS and breast cancer. The high incidence of HM development highlights the importance of early diagnosis in life.

Introduction: Patients with hemoglobinopathies, such as sickle-cell disease and thalassemia, are associated with higher rates of venous thromboembolism (VTE), including deep vein thrombosis and pulmonary embolism. However, there are currently no data on the risk of VTE recurrence in patients with hemoglobinopathies compared with those without hemoglobinopathies who have already experienced a VTE event. Methods: Data from patients with a VTE event enrolled in the Computerized Registry of Patients with Venous Thromboembolism (RIETE) between January 1, 2001, and June 16, 2025, were extracted. Patients were stratified based on the presence of any hemoglobinopathy. The primary endpoint was 2-year net adverse clinical events (NACE), defined as the composite of all-cause death, VTE recurrence, and any bleeding. Secondary endpoints included the individual components of the primary endpoint and major bleeding. Bleeding events were classified according to the criteria of the International Society on Thrombosis and Haemostasis (ISTH). Clinical outcomes were compared between groups after propensity score matching in a 1:2 ratio to account for baseline differences in age, sex, weight, inpatient evaluation at diagnosis, intensive care unit admission, and use of antiplatelet therapy. Cox regression models were used to calculate hazard ratios (HRs) and corresponding 95% confidence intervals (CIs). Results: From the original sample of 132,679 patients with a VTE event, 309 patients were diagnosed with a hemoglobinopathy. Baseline characteristics were generally similar between groups, although patients with hemoglobinopathies were younger (60.0 [40.0–73.0] vs. 68.0 [54.0–78.0] years). After propensity score matching, 927 patients were included in the analysis, of whom 618 were classified as non-hemoglobinopathy. At 2 years, no significant difference in NACE was observed between groups (54.3% vs. 50.3%; HR 1.04, 95% CI 0.74–1.47, p=0.809). Similarly, there were no significant differences in all-cause mortality (23.2% vs. 26.1%; HR 0.64, 95% CI 0.39–1.05, p=0.078) or VTE recurrence (34.2% vs. 21.6%; HR 1.40, 95% CI 0.80–2.45, p=0.235). Patients with hemoglobinopathies experienced higher rates of any bleeding (24.0% vs. 10.6%; HR 2.52, 95% CI 1.51–4.21, p<0.001) and major bleeding (10.0% vs. 3.5%; HR 2.85, 95% CI 1.38–5.86, p=0.005) compared with those without hemoglobinopathies. Conclusions: Among patients presenting with VTE, those with hemoglobinopathies appear to be younger and have a higher incidence of 2-year bleeding, including major bleeding, without significant differences in NACE, VTE recurrence, or all-cause mortality compared to those without hemoglobinopathies.

This study compared the efficacy of graft-versus-host disease (GVHD) prophylaxis with post-transplantation cyclophosphamide (PTCy) and tacrolimus (Tac) versus other regimens in 272 adults undergoing peripheral blood (PB) allogeneic hematopoietic cell transplantation (allo-HCT) from HLA-matched donors. Of these 272 patients, 95 (34.9%) received PTCy/Tac. The times to neutrophil and platelet engraftment were longer in the PTCy/Tac group (20 days versus 16 days for neutrophils and 19 days versus 12 days for platelets). The day +30 cumulative incidence (CuI) of bacterial bloodstream infection was higher in the PTCy/Tac group (43.2% versus 13.0%; P < .001). The CuIs of grade II-IV and grade III-IV acute GVHD (aGVHD) at day +180 were 14.7% and 4.2%, and the CuI of moderate/severe cGVHD at 2 years was 2.4% in the PTCy/Tac group and 41.8% (hazard ratio [HR], .29; P < .001), 15.8%, (HR, .24; P = .007), and 47.0% (HR, .05; P < .001), respectively, in the no-PTCy group. The duration of immunosuppression was shorter in patients receiving PTCy/Tac (6.2 months versus 9.0 months; P < .001). PTCy/Tac patients had higher OS (2 years: 74.3% versus 60.9%; HR, .54; P = .012), lower NRM (2 years: 8.6% versus 15.8%; HR, .54; P = .11), comparable CuI of relapse (2 years: 26.0% versus 24.4%; HR, 1.03; P = .89), and higher GRFS (2 years: 59.1% versus 16.7%; HR, .32; P < .001). Using PTCy/Tac in HLA-matched PB allo-HCT improved transplantation outcomes at out institution compared with previous prophylactic regimens, including a higher probability of survival despite more delayed engraftment and a higher rate of bacterial infection.

PTCY 50 mg/kg/day on days +3/+4 is an excellent strategy to prevent GVHD. However, its use is associated with adverse outcomes such as delayed engraftment, increased risk of infection, and cardiac complications. This pilot study evaluates the efficacy and toxicity of a reduced dose of PTCY (40 mg/kg/day) combined with tacrolimus in 22 peripheral blood HLA-matched alloHSCT patients. At day +100, the cumulative incidences of grade II-IV and III-IV acute GVHD were 18.2% and 4.5%, respectively. No grade IV acute GVHD or steroid-refractory disease was observed. The cumulative incidences of all-grade and moderate-severe chronic GVHD at 1-year were 11.4% and 6.4%, respectively. No patient died from transplant-related complications. Two-year OS and RFS were 77.1% and 58.3%, respectively. All patients engrafted, with neutrophil and platelet recovery occurring at a median of 15 (IQR 14-16) and 16 days (IQR 12-23), respectively. The cumulative incidences of bloodstream bacterial infections, polyomavirus BK hemorrhagic cystitis, HHV6 reactivation, CMV reactivation, and fungal infections were 13.6%, 9.1%, 9.1%, 4.6%, and 6%, respectively. Only one early cardiac event was observed. These results suggest that PTCY 40 mg/kg/day on a +3/+4 schedule provides adequate immunosuppression to allow for engraftment and prevent clinically significant GVHD with a low toxicity profile.

To elucidate the role of splanchnic vein thrombosis (SVT) and genomic characteristics in prognosis and survival, we compared patients with polycythemia vera (PV) or essential thrombocythemia (ET) presenting SVT at diagnosis ( n = 69, median age 43 years) or during follow-up ( n = 21, median age 46 years) to a sex- and age-matched control group of PV/ET without SVT ( n = 165, median age 48 years). The majority of patients presenting with SVT at diagnosis were classified as myeloproliferative neoplasm with heterozygous JAK2 mutation (87% of cases vs. 69% in PV/ET control group, p < 0.05), characterized by low JAK2 allele burden and no high-risk mutations. Despite this lower molecular complexity, patients presenting with SVT showed a higher risk of death (HR 3.0, 95% CI 1.5-6.0, p = 0.003) and lower event-free survival (HR 3.0, 95% CI 1.9–4.8, p < 0.001) than age- and sex-matched PV/ET controls. In patients presenting with SVT, molecular high-risk was associated with increased risk of venous re-thrombosis (HR 5.8, 95% CI 1.4–24.0, p = 0.01). Patients developing SVT during follow-up were more frequently allocated in molecular high-risk than those with SVT at diagnosis (52% versus 13%, p < 0.05). In the whole cohort of patients, molecular classification identified PV/ET patients at higher risk of disease progression whereas DNMT3A/TET2/ASXL1 mutations were associated with higher risk of arterial thrombosis. In conclusion, clinical and molecular characteristics are different in PV/ET patients with SVT, depending on whether it occurs at diagnosis or at follow-up. Molecular characterization by NGS is useful for assessing the risk of thrombosis and disease progression in young patients with PV/ET.

Hemofilia A adquirida tras la infección

INTRODUCTION Hereditary hemochromatosis (HH) is caused by increased intestinal absorption with subsequent deposition in tissues. Eventually, this may result in hepatic cirrhosis (HC), hepatocellular carcinoma (HCC), endocrine dysfunction, arthropathy, and cardiomyopathy. Most patients are homozygous for the C282Y mutation in the HFE gene, with a minority bearing mutations in other genes. Despite many studies on the epidemiology of HH, its current impact on life expectancy and the presenting factors determining prognosis in homozygous C282Y patients remain poorly defined. OBJECTIVE This study aims to characterize the evolution, impact on life expectancy, and initial prognostic factors in a modern series of patients with homozygous C282Y HH, homogeneously managed and closely followed up by the same medical team over three decades. METHODS We retrospectively reviewed the clinical records of individuals diagnosed with HH and treated by phlebotomy or erythrocytapheresis at our hospital from January 1990 to June 2024. HH was diagnosed based on specific genetic abnormalities (C282Y/C282Y), transferrin saturation >45%, and serum ferritin >200 µg/l. RESULTS A total of 125 consecutive patients were included in the study. The median age at diagnosis was 49 years (interquartile range [IQR]: 40-59), and 98 patients (78.4%) were males. In 91 (72.8%) individuals, HH diagnosis was triggered by the incidental finding of abnormal laboratory results, including routine analysis, investigation of symptoms unrelated to HH, or family studies. At diagnosis, 37 patients (29.6%) had some complications of HH: arthralgia in 23 patients, insulin-dependent diabetes mellitus (IDDM) in 4, HC in 4 (2 with superimposed HCC), and dilated cardiomyopathy in one. The median and IQR of serum ferritin and transferrin saturation were 1071 µg/l (676-1518) and transferrin saturation 81% (66-97), respectively. Ferritin levels were significantly lower in patients diagnosed incidentally (p=0.02), those without complications at baseline (p< 0.01), and in women (p<0.01). Ferritin levels were especially high (median 3450 µg/l, IQR: 1865 - 5756) in patients with more advanced initial complications: HC, HCC and cardiomyopathy. After a median follow-up of 18 years (IQR: 10.1 - 24.3), 26 patients had died, and 99 were alive at the study's closing date (June 2024). The overall projected survival at 20 years was 81% (CI 95%: 72%-88%). The ultimate causes of death were malignancies (9 patients), cardiac failure (n=4), infection (n=4), HC (n=2), and others (n=7). Initial factors independently associated with increased mortality were age (HR: 1.06, 95% CI: 1.02-1.10 per year, p=0.002) and ferritin > 1000 µg/l (HR: 10.13, 95% CI: 1.33-76.9, p=0.027). One or more complications not initially present were diagnosed in 33 patients after a median follow-up of 13 years, including HCC in 11 patients (without prior recognized CH in 4). A total of 18 other malignancies were diagnosed in 16 patients (13 solid organ carcinomas, 5 hematological neoplasms). The patients with non-HCC malignancies were more likely to have had initial ferritin levels >1000 µg/l than the remaining patients (94% and 50%, respectively, p<0.01). Life expectancy of patients was not significantly different from the general population matched by age, sex, and year of diagnosis. CONCLUSIONS Homozygous C282Y HH does not reduce life expectancy in patients managed and closely followed up according to current standards. The late appearance of HCC, even among non-cirrhotic individuals, stresses the need for lifelong surveillance. Early diagnosis should be encouraged to avoid complications secondary to iron accumulation and, perhaps, the incidence of associated neoplasms.

This study investigates early cardiac events (ECEs) occurring during the first 180 days after allogeneic hematopoietic cell transplant (allo-HCT) in 416 adults receiving posttransplant cyclophosphamide (PTCY) (n = 258) or not receiving PTCY (n = 158). Total body irradiation (TBI) was given to 133 (31.9%) patients, of whom 111 (83.4%) received TBI combined with PTCY. The day +180 cumulative incidence function (CIF) of ECEs was 8.4%, with heart failure (n = 13) and pericardial complications (n = 11) being the most prevalent complications. The incidence of ECEs was higher in patients receiving PTCY, and receiving TBI. ECEs were more prevalent in haploidentical HCTs than in matched sibling donor, 10/10 HLA-matched unrelated donor, and 9/10 HLA-mismatched unrelated donor allo-HCTs. As for the ECE risk from the combination of PTCY and TBI, the multivariate analysis reported that patients receiving PTCY without TBI, TBI without PTCY, and TBI with PTCY were at higher risk for ECEs compared with patients receiving neither PTCY nor TBI. Pre-existing cardiac morbidity predicted ECEs. However, using high-dose CY-containing preparative regimens did not increase the risk for cardiac toxicity at +180 days after allo-HCT. ECEs were associated with higher nonrelapse mortality and lower overall survival. Considering that PTCY and TBI were predictors for ECEs, and the impact of this complication on transplant mortality, the implementation of cardiac monitoring plans could be appropriate in patients receiving these medications.

Lysinuric protein intolerance (LPI) is a rare inborn error of metabolism (IEM), classified as an inherited aminoaciduria, caused by mutations in the SLC7A7 gene, leading to a defective cationic amino acid transport. The metabolic adaptations to the demands of pregnancy and delivery cause significant physiological stress, so those patients affected by IEM are at greater risk of decompensation. A 28-year-old woman with LPI had experienced 3 early miscarriages. While pregnancy was finally achieved, diverse nutritional and medical challenges emerged (food aversion, intrauterine growth restriction, bleeding risk, and preeclampsia suspicion), which put both the mother and the fetus at risk. Moreover, the patient requested a natural childbirth (epidural-free, delayed cord clamping). Although the existence of multiple safety concerns rejected this approach at first, the application of novel strategies made a successful delivery possible. This case reinforces that the woman’s wish for a non-medicated, low-intervention natural birth should not be automatically discouraged because of an underlying complex metabolic condition. Achieving a successful pregnancy is conceivable thanks to the cooperation of interdisciplinary teams, but it is still important to consider the risks beforehand in order to be prepared for possible additional complications.

Introduction PTCY-based prophylaxis is becoming increasingly prevalent across allogeneic hematopoietic cell transplantation (allo-HCT) due to its efficacy on GVHD prevention. However, using PTCY has been associated with delayed engraftment, immune reconstitution, and high infectious complications. Although different studies have investigated how PTCY interacts with infectious risk after allo-HCT, whether the incidences of these complications differ depending on donor type has not been widely investigated. At our institution, PTCY-based prophylaxis has become our institutional prophylaxis irrespectively of the selected donor type. This study explores the incidences of infectious complications and immune cell reconstitution dynamics in patients undergoing allo-HCT with PTCY and according to the donor type selected. Methods This study included the 253 consecutive adults who underwent peripheral blood allo-HCT with PTCY at our institution between 2013 and 2021. Retrospective data was updated in June 2023. All patients received levofloxacin 500mg daily from day +1 until neutrophil engraftment. No patient received letermovir. Cumulative incidences (CI) analyses have been estimated considering death as competing event and reported at day +30, +100, +180, and 1-year. Infection density was calculated by dividing the number of infections of a patient by the observed time period after allo-HCT. Immune reconstitution was evaluated by the measurement of lmmunoglobulin (IgG), CD4+T-cell (CD4) and CD8+T-cells (CD8) levels in alive patients without relapse history. Results The median age was 53 years (range, 18-70 years), with 44 (17.6%) patients older than 65. Acute myeloid leukemia was the most common underlying diagnosis (38%), and 103 (41%) patients received myeloablative conditioning regimens. As reported in Table 1, 120 (47.4%) patients received grafts from HLA-matched donors, 84 (33.2%) from 9/10 HLA mismatched unrelated donors (MMUD) and 49 (19.4%) from haploidentical donors (haplo-HCT). To perform the statistical analysis, the study cohort was divided into 3 groups according to donor type. Baseline characteristics were balanced between these 3 groups, except for the proportion of patients with HCT-CI>3, higher in HLA-matched donor group (p=0.028). As shown in Table 1, 244 (96%) patients engrafted. The median of days to neutrophil and platelet engraftment, and the CIs of clinically relevant acute and chronic GVHD did not differ according to the donor type. Moreover, the duration of the immunosuppression and post-transplant outcomes were similar in all groups. Bacterial bloodstream infections (BSI) were predominantly diagnosed within the first 30 days post allo-HCT, and with a tend to higher incidence in allo-HCT performed from HLA-matched donors (p=0.07). CMV reactivation was the most frequent viral infection in all groups, occurring mostly between days +30 and +100, and with a higher CI in the MMUD group (p=0.033). CMV disease, grade 2-4 BK hemorrhagic cystitis, VHH6 reactivation/disease and fungal infection CIs were not prevalent post-transplant complications generally occurring during the first 100 days after allo-HCT, with comparable CI differences among the 3 groups. The CI of respiratory viral infections increased steadily during the first year after allo-HCT, with similar incidences among the 3 study groups. Infection density analysis showed comparable volume of infections complications in the 3 study groups. As shown in Figure 1, a higher infection density was observed during the first 100 days after allo-HCT (with approximately 1 or 2 number of infections occurring during that time period in most of the patients). After day +100, the number of infections progressively decreased during the post-transplant follow-up. Immune reconstitution was measured in 139 (55%) alive patients. IgG, CD4, and CD8 levels tended to normalize in most patients from day 180 onwards, with median days to normalization of 208, 216, and 203 days, respectively, and with no differences according to donor type. Conclusions Patients undergoing allo-HCT with PTCY-based prophylaxis have a relevant infectious density rate during the peri-engraftment phase with no differences according to donor type. Infectious complications decreased 6 months after allo-HCT, and in parallel with discontinuation of immunosuppression and immune reconstitution with no differences according to donor type.

Transfusion of packed red blood cells (RBCs) produces a myriad of immunologic derangements, from suppressive to stimulatory. Proliferation of human T cells is suppressed in vitro after exposure to processed red blood cells (PRBCs). We hypothesized that this effect would be mitigated by using fresh RBCs. We also hypothesized that this suppressive effect was a generalized effect on lymphocyte proliferation and would be observed in both CD4+ and CD8+ T-cell subpopulations as well as B cells.We isolated human T cells from donor peripheral blood mononuclear cells and exposed them to either blood bank PRBCs or fresh RBCs from volunteer donors and stimulated them with anti-CD3/anti-CD28. Human B cells were stimulated with lipopolysaccharide and exposed to PRBCs or fresh RBCs. We measured proliferation of B cells by thymidine incorporation assays. We also treated RBCs with citrate-phosphate-dextrose (CPD) at different time points before culture them with stimulated T cells to determine the role of this common RBC storage solution in lymphocyte proliferation.In vitro proliferation of CD4+ and CD8+ T cells was suppressed by blood bank RBCs. This suppression is eliminated when fresh RBCs were used. The B cells showed inhibition of proliferation when exposed to similar conditions, which appeared to be consistent over serial dilutions. Fresh RBCs exposed to CPD did not appear suppressive in the first 6 h after exposure.T-cell and B-cell proliferation inhibition by blood banked RBCs suggests a generalized effect of RBCs on cellular proliferation. The lack of suppression by fresh RBCs further suggests that something involved in blood banking alters RBC properties such that they attain a suppressive phenotype. One such blood banking component, CPD, does not appear to affect this suppressive phenotype within the first 6 h.

INTRODUCTION: Despite improvements in the treatment and outcomes of patients with acute myeloid leukemia (AML), in nearly 10-20% of the cases, a morphological remission (CR) after administrating induction regimens is not achieved. In other cases, and despite initial CR, early disease relapse may occur, with only a minority of patients durably benefiting from salvage regimens. Allogeneic hematopoietic cell transplantation (allo-HCT) is a potentially curative strategy for patients with relapsed / refractory (R/R) AML. However, the prognostic of these patients after allo-HCT remains dismal, with reported survival rates ranging from 20% to 35% in different publications. Allo-HCT using peripheral blood and sequential-based conditioning regimens has been the transplant platform used at our institution for R/R AML during the last decade. During the study period the use of post-transplant cyclophosphamide (PTCY) combined with tacrolimus (TK) has been implemented on this allo-HCT setting. This study evaluates the results obtained from a single institution obtained from using sequential allo-HCT for patients with R/R AML, and the effectiveness of having implemented the use of PTCY in this type of transplant. Very few studies have evaluated the safety of including PTCY-based in sequential-based conditioning allo-HCTs. METHODS: This study includes the 21 patients with R/R AML who underwent allo-HCT with sequential-based conditioning regimens at our institution between 2011 and 2022. Retrospective data were collected during June 2023. Sequential regimens combined fludarabine (150 mg/m2), cytarabine (2 g/m2 x 5 days), and idarubicin (12 mg/m2 x 3 days) chemotherapy with low doses of Bu (n=3), melphalan (n=17), or treosulfan (n=1). Six adults transplanted after November 2016 received PTCY (50mg/kg/24h) on day +3 and +4 followed by TK from day +5 to day +90 for GvHD prevention. RESULTS: The main baseline characteristics of the study cohort and according to the GVHD prophylaxis are shown in Table 1 . The median age was 53 years (range 31-68), 11 (52%) patients were males, and all patients had R/R AML after having received at least one line of induction chemotherapy with curative intent. Fourteen (66.7%) patients received grafts from HLA-matched donors, and 7 (33.3%) from 9/10 HLA mismatched unrelated donors (MMUD). Baseline characteristics between patients who received PTCY and those who did not were balanced, except for the proportion of allo-HCT performed from MMUD which was higher in the PTCY group (66.7% vs. 20.0% p=0.03). Post-transplant results are shown in Table 2. All patients engrafted (100%). Patients who received PTCY experienced similar median of days to neutrophil engraftment (18 vs. 15 days, P=0.103) and a longer median of time to platelet engraftment (25 vs. 13 days, P=0.046). The day +100 cumulative incidences (CI) of grade II-IV and III-IV aGVHD, and 2-year CI of moderate/severe cGVHD were 33.3%, 0% and 0% for patients who received PTCY-TK, and 40% (p=0.823), 33% (p=0.118), and 40.4% (p=0.099) for those who did not. During the first 2-years after allo-HCT, 8 (38%) out of 21 patients died and 7 (21%) relapsed. The main causes of death were relapse (n=4, 19%) and infection (n=2, 9.5%), and the 2-year OS, PFS, NRM and CIR were 61.5%, 51.9%, 14.3%, and 33.3%. As shown in Table 2 patients who received PTCY had comparable rates of OS (2-y: 50.0% vs. 66.7%, p=0.903) and RFS (2-y: 50.0% vs. 53.3%, p=0.873) and those who did not. In addition, and although no patient who received PTCY died secondary to transplant-related toxicity (2-y 0 vs. 20%, p=0.254), a non-significant trend to higher cumulative incidence of relapse (2-y: 50.0% vs. 26.7%, p=0.282) was observed in this group of patients. Lastly, a non-significant trend to higher GRFS was documented in patients who received PTCY (2-y: 50.0% and 25.0%, p=0.266). CONCLUSIONS: At our institution, 50% of the patients with R/R AML going thought allo-HCT performed using sequential-based conditioning regimens survived after two years. The implementation of PTCY as part of the GVHD prophylaxis results decreased rates clinically relevant GVHD and NRM, resulting on a trend to better GRFS. Although the results provided by this analysis suggest that using PTCY in this allo-HCT is safe and effective, caution is still recommended considering the trend to higher relapse rates observed among these patients and the limited sample size.