The study of cell-free DNA (cfDNA) and other peripheral blood components (known as “liquid biopsies”) is promising, and has been investigated especially in solid tumors. Nevertheless, it is increasingly showing a greater utility in the diagnosis, prognosis, and response to treatment of hematological malignancies; in the future, it could prevent invasive techniques, such as bone marrow (BM) biopsies. Most of the studies about this topic have focused on B-cell lymphoid malignancies; some of them have shown that cfDNA can be used as a novel way for the diagnosis and minimal residual monitoring of B-cell lymphomas, using techniques such as next-generation sequencing (NGS). In myelodysplastic syndromes, multiple myeloma, or chronic lymphocytic leukemia, liquid biopsies may allow for an interesting genomic representation of the tumor clones affecting different lesions (spatial heterogeneity). In acute leukemias, it can be helpful in the monitoring of the early treatment response and the prediction of treatment failure. In chronic lymphocytic leukemia, the evaluation of cfDNA permits the definition of clonal evolution and drug resistance in real time. However, there are limitations, such as the difficulty in obtaining sufficient circulating tumor DNA for achieving a high sensitivity to assess the minimal residual disease, or the lack of standardization of the method, and clinical studies, to confirm its prognostic impact. This review focuses on the clinical applications of cfDNA on the minimal residual disease in hematological malignancies.

This study discusses the importance of minimal residual disease (MRD) detection in acute myeloid leukemia (AML) patients using liquid biopsy and next-generation sequencing (NGS). AML prognosis is based on various factors, including genetic alterations. NGS has revealed the molecular complexity of AML and helped refine risk stratification and personalized therapies. The long-term survival rates for AML patients are low, and MRD assessment is crucial in predicting prognosis. Currently, the most common methods for MRD detection are flow cytometry and quantitative PCR, but NGS is being incorporated into clinical practice due to its ability to detect genomic aberrations in the majority of AML patients. Typically, bone marrow samples are used for MRD assessment, but using peripheral blood samples or liquid biopsies would be less invasive. Leukemia originates in the bone marrow, along with the cfDNA obtained from peripheral blood. This study aimed to assess the utility of cell-free DNA (cfDNA) from peripheral blood samples for MRD detection in AML patients. A cohort of 20 AML patients was analyzed using NGS, and a correlation between MRD assessment by cfDNA and circulating tumor cells (CTCs) in paired samples was observed. Furthermore, a higher tumor signal was detected in cfDNA compared to CTCs, indicating greater sensitivity. Challenges for the application of liquid biopsy in MRD assessment were discussed, including the selection of appropriate markers and the sensitivity of certain markers. This study emphasizes the potential of liquid biopsy using cfDNA for MRD detection in AML patients and highlights the need for further research in this area.

For the treatment of Multiple Myeloma, proteasome inhibitors are highly efficient and widely used, but resistance is a major obstacle to successful therapy. Several underlying mechanisms have been proposed but were only reported for a minority of resistant patients. The proteasome is a large and complex machinery. Here, we focus on the AAA ATPases of the 19S proteasome regulator (PSMC1-6) and their implication in PI resistance. As an example of cancer evolution and the acquisition of resistance, we conducted an in-depth analysis of an index patient by applying FISH, WES, and immunoglobulin-rearrangement sequencing in serial samples, starting from MGUS to newly diagnosed Multiple Myeloma to a PI-resistant relapse. The WES analysis uncovered an acquired PSMC2 Y429S mutation at the relapse after intensive bortezomib-containing therapy, which was functionally confirmed to mediate PI resistance. A meta-analysis comprising 1499 newly diagnosed and 447 progressed patients revealed a total of 36 SNVs over all six PSMC genes that were structurally accumulated in regulatory sites for activity such as the ADP/ATP binding pocket. Other alterations impact the interaction between different PSMC subunits or the intrinsic conformation of an individual subunit, consequently affecting the folding and function of the complex. Interestingly, several mutations were clustered in the central channel of the ATPase ring, where the unfolded substrates enter the 20S core. Our results indicate that PSMC SNVs play a role in PI resistance in MM.

In a large multicenter real‐world cohort, we aimed to evaluate outcomes of FLAG‐Ida salvage therapy for relapsed/refractory (R/R) acute myeloid leukemia (AML) and validated the SALFLAGE prognostic score. We analyzed 1079 adults with R/R AML treated across 112 PETHEMA institutions over 26 years (1998–2024), including patients with primary refractory disease (36.9%) and first relapse episode (63.1%), with a median age of 52 years. Complete remission composite (CRc) was achieved 56.8%, including complete remission (CR) in 51.0%, CR with incomplete recovery in 4.0%, and morphological‐free‐state in 1.8%, enabling 35.2% of patients and 62% of responders to proceed to allogeneic transplantation without morphological disease. With median follow‐up of 50.9 months, median overall survival (OS) was 10.2 months, with 5‐year OS rate of 21.6%. Prior allogeneic transplantation (HR 0.54; p < 0.001) and relapse‐free interval ≥ 1 year (HR 0.75; p = 0.024) independently predicted improved OS, whereas modified high‐risk cytogenetics including t (8; 21) (HR 3.58; p < 0.001), FLT3 ‐ITD mutation at primary diagnosis (HR 1.61; p < 0.001), and age ≥ 60 (HR 1.43; p < 0.001) conferred inferior OS. Validation of the SALFLAGE score demonstrated moderate discrimination (C‐index 0.67), with 5‐year survival of 38.4%, 27.2%, and 12.7% across risk categories ( p < 0.001). Outcomes improved over periods (1998–2005 vs. 2006–2016 vs. 2017–2024): 30‐day mortality was 6.9% vs. 9.3% vs. 5.0%, respectively ( p = 0.030), and median OS was 7.8 versus 9.4 versus 11.1 months, respectively ( p = 0.16). We confirm FLAG‐Ida as a reference salvage regimen in fit R/R AML and validate the SALFLAGE score in this setting.