Liquid biopsy - a narrative review with an update on current US governmental clinical trials targeting immunotherapy

Abstract

Aim: This study aims to present a comprehensive international analysis of the existing techniques used in liquid biopsies and their use in isolating tumor markers to detect, predict, and monitor the results of cancer treatment.

Materials and methods: We conducted a narrative review using a scoping review model based on three databases, including PubMed/Medline, Scopus, and Cochrane. The search criteria included all articles on liquid biopsy of the last five years (June 30th, 2023-Oct 30, 2024) ((liquid Biopsy) AND (("2023/06/30"[Date - Publication]: "2024/10/30"[Date - Publication]))). We also approached gray literature on this topic. We focused on review articles as an eligibility criterion for this narrative review, but we also carried out a United States registered clinical trials review targeting immunotherapy and liquid biopsy with the limitation "recruiting" and/or "not yet recruiting" (updated on March 31, 2025).

Results: We screened 2645 articles from PubMed/Medline, Scopus, and Cochrane and 45 articles from the gray literature. We retrieved the full text for 325 articles. Liquid biopsies involve the extraction of tumor-derived components such as circulating tumor cells, circulating tumor DNA, and tumor extracellular vesicles from the bodily fluids of cancer patients. We found 25 United States registered governmental clinical trials targeting immunotherapy and liquid biopsy, of which 20 trials are recruiting and five trials are not yet recruiting.

Discussion: Developments in medicine have led to a more comprehensive understanding of tumor features, including tumor load, tumor staging, heterogeneity, gene mutations, and clonal evolution. The utilization of liquid biopsies from cancer patients has provided novel opportunities for detection and ongoing monitoring, precision medicine-based therapy, and identification of markers for therapeutic resistance.

Keywords: Liquid biopsy; RNA; cancer; circulating tumor DNA; circulating tumor cells; precision medicine; proteomics; tumor extracellular vesicles.

Figure 1.

Microfluidic technology for the molecular characterization of patient-derived circulating tumor cells at the single-cell level. Different procedures are displayed, including (a) a process connected with ClearCell^® FX. Analysis of single-cell genomics: A significant concordance rate of EGFR mutations (T790M and L858R) was observed between NSCLC circulating tumor cells and corresponding primary tumors. In the single-cell transcriptomic study, patient classification for breast cancer and/or NSCLC was conducted via comprehensive mRNA transcriptomic analysis and targeted gene expression profiling. In the single-cell metabolomics investigation, supervised principal component analysis (PCA) demonstrated distinct metabolic patterns between circulating tumor cells (CTCs) and lymphocytes in gastric and colorectal cancer individuals. In (b) single-cell proteome analysis a microfluidic single-cell western blotting (scWB) facilitated the swift examination of an eight-plex protein expression in ER+ breast cancer. In (c) a single cell secretomic analysis is performed. Here the integrated microfluidic on-chip device demonstrated significant heterogeneity in the expression profiles of two secreted proteins (IL-8 and VEGF) in CTCs from patients with lung cancer (Source: Lim SB, Di Lee W, Vasudevan J, Lim WT, Lim CT. Liquid biopsy: one cell at a time. NPJ Precis Oncol. 2019 Oct 2;3:23. doi: 10.1038/s41698-019-0095-0. PMID: 31602399; PMCID: PMC6775080).

Figure 2.

3D Neoplastic Angio-Chemotaxis. A malignant angiomatoid fibrous histiocytoma is seen invading a blood vessel and the 3D representation of the tumor cells approaching and invading (chemotaxis) a blood vessel is shown in the lower inset. A malignant angiomatoid fibrous histiocytoma refers to a rare, low-grade soft tissue neoplasm, also known as “Angiomatoid Fibrous Histiocytoma,” which typically presents as a slow-growing, painless mass, most found in the extremities of children and young adults. This tumor has a low potential for spreading, but chemotaxis has been demonstrated, and the surgical removal alone cannot rule out a subsequent malignant behavior. This tumor requires a biopsy to confirm the diagnosis based on the characteristic microscopic features, but close monitoring is highly recommended because surgical excision cannot predict alone the behavior of this neoplasm.