*Extracellular Vesicles for Cancer Immunotherapy: Biomarkers and Beyond DOI: http://dx.doi.org/10.5772/intechopen.103783*

in drug resistance. EVs are unique and can serve as a valuable tool to aid in cancer detection, prognosis, and tracking therapeutic efficacy. EVs circulate in bodily fluids, making them an ideal candidate for non-invasive testing [22]. In addition, the lipid bilayer shields the biomacromolecules like RNA, proteins, and enzymatic activity, EVs constitute a safe vehicle for evaluating genetic sequences. Liquid biopsy is an emerging technique, that requires implying the circulating tumor cells (CTCs), cell-free DNA (cfDNA), and EVs, which has brought new understanding and aspects to the field of cancer therapeutic interventions [23]. CTCs are cancer cells that are slough off from the primary or metastatic sites through the circulation. According to a few recent studies, molecular profiling of CTCs can be used to monitor patients who are receiving therapies [24].

The foremost difficulty in examining CTCs such as rarity of the cells in circulation (one CTC is found in per billion blood cells). Up to date, cell search, targeting epithelial cell adhesion molecule, EpCAM to procure cell CTCs is the most prominent cell CTC enumeration assay. There are other biomarkers such as cfDNA known as short fragments of nucleic acids which are seen in body fluids, like blood or urine. It is demonstrated to be produced by the apoptotic degeneration of cellular DNA [25], and a fragment of cfDNA is procured from the tumor cells and is explained as circulating tumor DNA, which is known to imitate the genetic and epigenetic alterations of the initial tumor and its possible to be used as a diagnostic and prognostic biomarker for cancers. Also, NGS is the most common method for examination of the genetic information of the cfDNA [26]. As compared to NGS, digital PCR can only do the screening for the known variants and has the capability for the limited sample in one reaction. But NGS is a high cost and relatively time-consuming technique, which also necessitates bioinformatics skills for data analysis and interpretation.

EVs have great attention as like another kind of biopsy. EVs are mostly found in different kinds of body fluids such as blood, saliva, urine, bronchoalveolar fluid, breast milk, and semen. They reproduce the disease type by taking the molecules from benign cells, like miRNAs, proteins, long noncoding RNAs, and lipids. Out of

**Figure 1.**

*Extracellular vesicles - body fluids as biomarkers and therapeutic clinical applications [28].*

the components of EVs, the associated proteins and RNA of EVs are demonstrated to be used as a tumor biomarker for detecting cancer and observing the progression of cancer [27]. **Figure 1** and **Table 1** show the development of novel exosome-based biomarkers that could benefit cancer patients in a variety of ways.


#### **Table 1.**

*Exosomes from different types of cancer patients—body fluids as biomarkers.*
