Trop-2-Cells, Their Exosomal Cargo, and the Potential Impact on Diagnostics and Therapeutics in Breast Cancer: The Expanding Frontiers

Recently, an anti-trophoblast surface antigen-2 (Trop-2) antibody-drug conjugate targeting Trop-2 positive cancer cells has been approved for treating patients with unresectable locally advanced or metastatic triple-negative breast cancer, who have failed two or more lines of systemic chemotherapy. This has renewed the interest in translational research of Trop-2 positive breast cancer, the gene TACSTD2 and microRNAs that interact with it, and the signaling networks sparked by Trop-2 mediated signaling. In addition, this opinion paper argues that exosomes, extracellular vesicles that are released from Trop-2 positive cancer cells, could play a significant role in cancer progression. Furthermore, diagnostic applications using Trop-2-released exosomes, the cargo exosomes carry, which could be any genetic information such as specific miRNAs, adhesion molecules such as integrins, and metabolites, are yet to be explored in breast cancer patients. Most of the evidence and data are obtained from studies in epithelial cancers other than breast cancers, which have been introduced in the current paper. Therefore, this article briefly summarizes previously published data on other cancer types, forms some hypotheses, and proposes research questions and directions that may be explored further.