Exosome-based liquid biopsies in cancer

The exosome field has gone through a rapid growth phase in parallel with the increasing attention over the potential of liquid biopsies. Despite recent progress of liquid biopsies for late-stage cancers, there remains a need to improve both the accuracy and utility of these tests, especially in earlier stage cancers. This will likely require a combination of approaches that exploit biomarkers released through different processes. Exosomes are released from living cancer cells as an active metabolic process, and carry RNA, DNA and proteins. The paper describes how the use of the multi-analyte component of exosomes either alone or in combination with other types of liquid biopsies will be an important tool to overcome limitations with many of the current liquid biopsies, including low signal to noise ratio.

The inadequacies of tissue biopsy paired with the paradigm shift to molecular analysis, have driven increasing interest in the molecular profiling of biofluids, also known as “liquid biopsy.” This approach offers a significant step forward because of its less invasive nature, lower cost, and real-time insights into tumor status. When treating cancer, early detection is key, and utilizing state-of-the art exosome-based technology provides an exciting alternative, and in some cases a complement to other liquid biopsy forms for better overall diagnostic performances.

ctDNA, Exosomes and CTCs in circulation

The molecular constituents from the tumor are released into biofluids at various stages of the tumor development through very different mechanisms and represent different biological entities. ctDNA is released from the dying tumor cells through apoptosis and/or necrosis, exosomes are actively released from cells at each stage of tumor formation, whereas CTCs are intact cancer cells disseminated from the tumor at later stages. Exosomes are involved in promoting the growth, vascularization and even the dissemination and metastatic process of cancer.

Specifically, exosomes have been implicated in driving key attributes of malignant cell behavior, including stimulation of tumor cell growth, suppression of the immune response, induction of angiogenesis, promotion of tumor cell migration, and establishment of metastases, making them particularly attractive as cancer biomarkers for clinical diagnostics and research.

According to Dr. Johan Skog, Exosome Diagnostics Chief Scientific Officer, “Many liquid biopsy companies today focus on a single analyte, such as cfDNA. Our novel approach to the liquid biopsy field makes it possible to not only selectively enrich disease specific exosomes, but also perform the multi-analyte measurements needed for challenging problems, including early detection.”

Researchers from Bio-Techne provide unique insight into liquid biopsies and the field of exosomes in the context of other liquid biopsies such as cfDNA and CTC analysis.

Source – PRNewswire

Yu W, Hurley J, Roberts D, Chakrabortty S, Enderle D, Noerholm M, Breakefield XO, Skog J. (2021) Exosome-based Liquid Biopsies in Cancer: Opportunities and Challenges. Ann Oncol [Epub ahead of print]. [article]

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