Liquid biopsy is classically defined as the detection of biomarkers in bodily fluids. One of these biomarkers can be circulating cell-free DNA (cfDNA) released by healthy or cancer cells during apoptosis. These fragments can be quantified and molecularly characterized by techniques like digital droplet PCR (ddPCR) or next-generation sequencing (NGS). By identifying common genetic and epigenetic alterations associated with specific cancer types, cfDNA or circulating tumor DNA (ctDNA) can serve as robust biomarkers for monitoring tumor initiation and progression. Other biomarkers, such as circulating microRNAs (miRNAs), extracellular vesicles, or circulating tumor cells (CTCs) are also applied in this context. Liquid biopsy has gained attention as a versatile tool for cancer diagnostics, prognosis, therapeutic monitoring, and minimal residual disease (MRD) detection across various malignancies, including hematological cancers like myeloid and lymphoid leukemias. Herein, we present a comprehensive review of liquid biopsy usage in leukemia, with a specific focus on the clinical utility of ctDNA, miRNAs, and exosomes in monitoring treatment response, tracking clonal evolution, and detecting minimal residual disease. Our review emphasizes the translational implications of these tools for improving patient outcomes and outlines current challenges in their integration into clinical practice.

SMYD4 is a member of the SMYD family that has lysine methyltransferase function. Little is known about the roles of SMYD4 in cancer. The aim of this study is to investigate genetic alterations in the SMYD4 gene across the most prevalent solid tumors and determine its potential as a biomarker. We performed an integrative multi-platform analysis of the most common mutations, copy number alterations (CNAs), and mRNA expression levels of the SMYD family genes using cohorts available at the Cancer Genome Atlas (TCGA), cBioPortal, and the Catalogue of Somatic Mutations in Cancer (COSMIC). SMYD genes displayed a lower frequency of mutations across the studied tumors, with none of the SMYD4 mutations detected demonstrating sufficient discriminatory power to serve as a biomarker. In terms of CNAs, SMYD4 consistently exhibited heterozygous loss and downregulation across all tumors evaluated. Moreover, SMYD4 showed low expression in tumor samples compared to normal samples, except for stomach adenocarcinoma. SMYD4 demonstrated a frequent negative correlation with other members of the SMYD family and a positive correlation between CNAs and mRNA expression. Additionally, patients with low SMYD4 expression in STAD and LUAD tumors exhibited significantly poorer overall survival. SMYD4 demonstrated its role as a tumor suppressor in the majority of tumors evaluated. The consistent downregulation of SMYD4, coupled with its association with cancer progression, underscores its potential usefulness as a biomarker.

SETD5 (SET domain-containing 5) is a chromatin-associated regulator increasingly recognized as dysregulated in human malignancies; however, its contribution to tumor biology and tumor–immune interactions remain undefined. We performed an integrative pan-cancer multi-omics analysis to define the landscape of SETD5 dysregulation across cancer types. Transcriptomic, genomic, and epigenetic datasets were integrated to evaluate SETD5 alterations and molecular associations. Protein interaction and pathway enrichment analyses were conducted using STRING, GO, and KEGG, and immunogenomic profiling was used to interrogate associations between SETD5 expression, immune infiltration, and checkpoint programs. SETD5 was overexpressed across multiple malignancies, with low mutation frequency but recurrent copy-number gains. Promoter hypomethylation was detected in a subset of tumors with increased SETD5 expression, suggesting a possible association with epigenetic regulation. Pathway analyses linked SETD5 to macromolecule methylation and transcriptional regulation. SETD5 expression correlated positively with infiltration of macrophages, neutrophils, and dendritic cells, whereas associations with CD8⁺ and CD4⁺ T cells varied by tumor type. Tumor type-specific correlations were observed between SETD5 and immune checkpoints genes, including PD-L1 and TIM-3, suggesting an association with immunoregulatory tumor states. These findings identify SETD5 as a recurrently deregulated epigenetic regulator and highlight its potential role in transcriptional control and tumor immune modulation.