**4. Extracellular vesicles and cancer**

This section presents recent studies on EVs' pathological and translational potential in malignancies. Cancer-derived EV payloads preserve their molecular features, and cancer cells actively discharge EVs into easily accessible body fluids [10]. The transport of cancer-associated biomolecules by EVs from cancer cells promotes cancer development and reflects changes in cancer status during treatment. EVs bearing tumor antigens are also studied as cancer vaccines to induce tumor-specific anti-tumor immunity. Tumor cell-derived EVs stimulate immunosuppression, angiogenesis, metastasis, metabolic reprogramming, and other processes in the tumor microenvironment. Tumor-derived exosomes (TEX's) ability to inhibit or boost the immune system is thrilling and intriguing. The occurrence or absence of immunological recipient cells in the TME may affect the outcome of TEX-driven interactions [11]. Transducers that create juxtracrine or paracrine signals may modify immunological

#### *Introductory Chapter: Role of Extracellular Vesicles in Human Diseases and Therapy DOI: http://dx.doi.org/10.5772/intechopen.103865*

recipient cell suppressive pathways, resulting in accelerated tumor development. Due to TEX-based antibody sequestration, immunotherapies may not work fully. TEXinduced immunostimulatory signals may alter the TME to promote immune activation rather than tumor development. TEXs are excellent diagnostic and prognostic biomarkers [12].

The diversity, cargo composition, and molecular mechanism of phenotypic transfer of TEX to recipient cells and vice versa is a critical question. Cancer-derived EV payloads preserve their molecular features, and cancer cells actively discharge EVs into easily accessible body fluids [13]. The transport of cancer-associated biochemicals by EVs from cancer cells promotes cancer development and reflects changes in cancer status during treatment. Moreover, this section discusses the role of EVs in resistance to treatment and diagnostics and being attractive indicators for assessing therapeutic response. EVs produced by disseminated tumor cells chemotactically attract circulating tumor cells (CTCs) and stimulate nearby stromal cells to produce extracellular matrix components like integrins, collagens, and laminin proteins to promote metastatic cell-extracellular matrix remodeling by modulating neighboring tumor cells and stromal cells, promoting tumor invasion and metastasis. Tumorderived EVs carry molecular signatures specific to the tumor's genetic complexity and may be used as minimally invasive cancer immunotherapy biomarkers. Through secretory factors and miRNAs, tumor exosomes have been demonstrated to facilitate distant cell-cell contact, resulting in the creation of pro-tumorigenic microenvironments favorable to metastatic spread. EV-induced fibroblast activation, ECM synthesis, angiogenesis, and immunological regulation are essential for metastatic dissemination. This section presents many aspects of the EV-based mechanism involved in metastasis.

The role of EVs in resistance to cancer treatment and diagnostics and being attractive indicators for assessing therapeutic response. Radiation is now often coupled with immunotherapy [13, 14]. EVs may also reduce chemoresistance by carrying RNA forms, and therefore activity regulation of EVs may overcome immunotherapy resistance. Also discussed many aspects of EVs/exosomes and their potential in targeting chemoresistance, radio-resistance, and cancer management. Tumor-derived EVs serve as excellent diagnostic and prognostic biomarkers. The critical bioactivities of tumor-derived exosomes using examples of their cargo molecules are also presented. EVs are immune cell evaders and are currently being investigated as potential diagnostic biomarkers and drug delivery vehicles. Exosomal immune checkpoint regulators may serve as clinical predictors for treatment response or recurrence in a variety of different malignancies. It may be possible that exosome-based paracrine mediators will be necessary for tailoring immune-based therapies to different tumors.

This section also reviews the role of EVs and the potential to use them in the management of difficult to diagnose and treat cancers, like ovarian cancer and breast cancer. Oncologic malignancies such as ovarian cancer are difficult to diagnose, with dismal results, and critically need new treatments. This section describes EVs' role as a critical player in the spread of ovarian cancer, and EVs may help us learn more about ovarian cancer proliferation and metastasis while also revealing potential new therapeutics. Breast cancer is the most frequent cancer among women, and understanding the role of EVs in facilitating intercellular communication between cancer and stromal cells and its therapeutic possibilities for breast cancer therapy is critical. This book also discussed the information gaps for clinical translation of EVs and pointed out the current research projects on developing EVs as biomarkers or therapeutic delivery systems. The solutions to improve EVs' efficacy as cancer treatments are also

presented. Moreover, the direct and indirect cell surface modification is discussed, emphasizing ongoing and finished clinical studies utilizing naturally generated EVs to treat breast cancer. This book also presents the loopholes for clinical translation of EVs and points out potential future research directions for therapeutic translation and cancer therapy. This anthology of chapters is presented with a broad audience in mind and will serve as a valuable must-have resource to basic biologists, translational scientists, and clinicians.
