Measurable residual disease (MRD) monitoring has become a critical component in the management of acute myeloid leukemia (AML), to inform prognosis, guide therapy, and serve as a key end point in clinical trials. The 2025 update of the MRD guideline provides a comprehensive and refined framework for MRD assessment, aligned with the European LeukemiaNet (ELN) 2022 genetic risk classification. Developed by members of the ELN AML MRD Working Party, the guidelines incorporate expert consensus determined through a 2-stage Delphi round. They address the clinical implementation of MRD methodologies, technical considerations, integration into clinical trials, and future directions. Importantly, MRD recommendations are tailored to individual prognostic and genetic subgroups. A new qualitative MRD response category, designated as optimal, warning, or high risk of treatment failure, has been introduced to facilitate contextual interpretation of the MRD burden and its clinical relevance. Notably, ultrahigh-sensitivity next-generation sequencing–based MRD assessment is now recommended for FLT3 internal tandem duplication–mutated AML after intensive chemotherapy and before allogeneic hematopoietic cell transplantation. A total of 56 recommendations were formulated, with 53 achieving a high level of consensus (≥90%). These updated guidelines represent a major step forward toward harmonizing MRD assessments in AML and enhancing its clinical utility across diverse treatment settings.

The significance of measurable residual disease (MRD) in hematopoietic stem cell transplantation (HSCT) is well recognized in different hematological malignancies, but the evidence indicate that pre-transplant MRD status is of particular importance in acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). In ALL, inadequate response at the level of MRD is a commonly accepted risk factor for relapse and thus an indication for allogeneic HSCT. Similarly, growing evidence from the literature strongly suggest that MRD detected by multiparameter flow cytometry or molecular techniques should be also used for risk stratification in AML at the time of HSCT. Despite the well-defined association of MRD and outcomes of HSCT in acute leukemias, there are still many open issues such as the role of additional pre-transplant consolidation for MRD eradication, the ability of HSCT to overcome negative influence of MRD positivity on survival, the impact of conditioning regimen intensity on MRD clearance post HSCT, and transplantation outcomes or the selection of optimal donor with regards to MRD status. In addition, the role of MRD assessment in guiding post-transplant maintenance treatment should also be addressed in prospective trials. These open issues mostly awaiting further clinical studies will be discussed in our current review.

Allogeneic hematopoietic cell transplantation (alloHCT) with myeloablative conditioning based on total body irradiation (TBI) is widely used for the treatment of adults with acute lymphoblastic leukemia (ALL). TBI is most frequently administered in combination with either cyclophosphamide (Cy/TBI) or etoposide (Vp/TBI). The goal of this study was to retrospectively compare these two regimens. Adult patients with Ph‐negative ALL treated with alloHCT in first or second complete remission who received Cy/TBI (n = 1346) or Vp/TBI (n = 152) conditioning were included in the analysis. In a univariate analysis, as compared to Cy/TBI, the use of Vp/TBI was associated with reduced incidence of relapse (17% vs. 30% at 5 years, P = .007), increased rate of leukemia‐free survival (60% vs. 50%, P = .04), and improved “graft versus host disease (GVHD) and relapse‐free survival” (GRFS, 43% vs. 33%, P = .04). No significant effect could be observed in terms of the incidence of nonrelapse mortality or acute or chronic GVHD. In a multivariate model, the use of Vp/TBI was associated with reduced risk of relapse (HR = 0.62, P = .04) while the effect on other study end‐points was not significant. In conclusion, conditioning regimen based on Vp combined with TBI appears more effective for disease control than the combination of Cy with TBI for adult patients with Ph‐negative ALL treated with alloHCT.

Catheter-related thrombosis (CRT) is a serious complication in hematological patients, but the risk factors for its occurrence are not well established. The study objectives were to estimate the incidence of CRT and to identify the risk factors for developing CRT in hematological patients. In a prospective setting, 104 consecutive patients with 200 insertions of central venous catheters were enrolled into the study. The patients were screened for CRT by compression Doppler ultrasound every 10–14 days. Additionally, ultrasonography was performed in the case of clinical symptoms suggesting CRT. Over the course of 6,098 catheter days of follow-up, the incidence of CRT was 13.5 %. In 18/27 cases (66.6 %), radiological evidence of CRT was preceded by clinical symptoms. However, in 9/27 (33.3 %), CRT was clinically asymptomatic. The median times to symptomatic and asymptomatic CRT were 17 (range 1–49) and 8 (range 1–16) catheter days, respectively. In univariate analysis, the risk factors for CRT were exit-site infection (ESI) (P < 0.001), two or more prior chemotherapy lines (P = 0.015), catheter-related blood stream infection (P < 0.001), and Coagulase-negative staphylococci infection (P = 0.002). In multivariate analysis, ESI (OR 5.0; 95 % CI 1.6–6.3; P = 0.006) and two or more prior chemotherapy lines (OR 3.57; 95 % CI 1.27–10.11; P = 0.015) remained significantly associated with the risk of CRT. The results of our study provide information regarding the characteristic features of the patients who are at high risk of thrombosis, for whom Doppler ultrasound screening should be considered.

Despite the well-defined role of autologous haematopoietic stem cell transplantation (autoHCT) in the treatment of patients with relapsed or refractory Hodgkin lymphoma (HL), relapse remains the main cause of transplant failure. We retrospectively evaluated long-term outcome and prognostic factors affecting survival of 132 patients with refractory (n = 89) or relapsed HL (n = 43) treated with autoHCT following modified BEAM. With a median follow-up of 68 months, the 10-year overall survival (OS) and progression-free survival (PFS) were 76 and 66 %, respectively. The 10-year cumulative incidence of second malignancies was 7 %. In multivariate analysis, age ≥45 years, more than one salvage regimens and disease status at transplant worse than CR were factors predictive for poor OS. In relapsed HL, age at transplant, response duration (<12 vs. ≥12 months) and the number of salvage regimens were independent predictors for PFS. In the refractory setting, disease status at autoHCT and the number of salvage regimens impacted PFS. The number of risk factors was inversely correlated with PFS in both relapsed and refractory HL (p = 0.003 and 1 risk factor in the relapsed and refractory setting was 5 and 11 months, respectively, in comparison with the median PFS not reached for patients with 0–1 risk factor in both settings. We conclude that high proportion of patients with relapsed/refractory HL can be cured with autoHCT. However, the presence of two or more risk factors helps to identify poor prognosis patients who may benefit from novel treatment strategies.

Vaccination against SARS-CoV-2 is currently the best tool in the fight against the COVID-19 pandemic. However, there are limited data on its efficacy and safety after hematopoietic stem cell transplantation (HCT). We present the results of a prospective analysis of the humoral response to two doses of BNT162b2 mRNA vaccine in 93 adult patients, including 29 after autologous HCT (autoHCT) and 64 after allogeneic HCT (alloHCT). Positive anti-SARS-CoV-2 antibodies were detected before vaccination in 25% of patients despite a negative medical history of COVID-19. Seroconversion after vaccination was achieved in 89% of patients after alloHCT and in 96% after autoHCT, without grade 3/4 adverse events. Post-vaccination anti-SARS-CoV-2 antibody level correlated with the time from transplant and absolute B-cell count at the vaccination. In univariate analysis restricted to the alloHCT group, short time since transplantation, low B-cell count, low intensity conditioning, GvHD, and immunosuppressive treatment at the vaccination were associated with lack of seroconversion. In the multivariate model, the only negative predictor of seroconversion remained treatment with calcineurin inhibitor (CNI). In conclusion, the BNT162b2 mRNA vaccine is highly immunogenic in patients after HCT, but treatment with CNI at the time of vaccination has a strong negative impact on the humoral response