Causal roles of gut microbiota in cholangiocarcinoma etiology suggested by genetic study

Genetic, Epigenetic, and Microenvironmental Drivers of Cholangiocarcinoma

Cholangiocarcinoma (CCA) is an aggressive and heterogeneous malignancy of the biliary tree that carries a poor prognosis. Multiple features at the genetic, epigenetic, and microenvironmental levels have been identified to better characterize CCA carcinogenesis. Genetic alterations, such as mutations in IDH1/2, BAP1, ARID1A, and FGFR2, play significant roles in CCA pathogenesis, with variations across different subtypes, races/ethnicities, and causes. Epigenetic dysregulation, characterized by DNA methylation and histone modifications, further contributes to the complexity of CCA, influencing gene expression and tumor behavior. Furthermore, CCA cells exchange autocrine and paracrine signals with other cancer cells and the infiltrating cell types that populate the microenvironment, including cancer-associated fibroblasts and tumor-associated macrophages, further contributing to an immunosuppressive niche that supports tumorigenesis. This review explores the multifaceted genetic, epigenetic, and microenvironmental drivers of CCA. Understanding these diverse mechanisms is essential for characterizing the complex pathways of CCA carcinogenesis and developing targeted therapies to improve patient outcomes.

New Relevant Evidence in Cholangiocarcinoma Biology and Characterization

Among solid tumors, cholangiocarcinoma (CCA) emerges as one of the most difficult to eradicate. The silent and asymptomatic nature of this tumor, particularly in its early stages, as well as the high heterogeneity at genomic, epigenetic, and molecular levels delay the diagnosis, significantly compromising the efficacy of current therapeutic options and thus contributing to a dismal prognosis. Extensive research has been conducted on the molecular pathobiology of CCA, and recent advances have been made in the classification and characterization of new molecular targets. Both targeted therapy and immunotherapy have emerged as effective and safe strategies for various types of cancers, demonstrating potential benefits in advanced CCA. Furthermore, the deeper comprehension of the cellular and molecular components in the tumor microenvironment (TME) has opened up possibilities for new innovative treatment methods. This review discusses recent evidence in the characterization and molecular biology of CCA, highlighting novel possible druggable targets.

Strategies for treating the cold tumors of cholangiocarcinoma: core concepts and future directions

Cholangiocarcinoma (CCA) is a rare type of digestive tract cancer originating from the epithelial cells of the liver and biliary tract. Current treatment modalities for CCA, such as chemotherapy and radiation therapy, have demonstrated limited efficacy in enhancing survival rates. Despite the revolutionary potential of immunotherapy in cancer management, its application in CCA remains restricted due to the minimal infiltration of immune cells in these tumors, rendering them cold and unresponsive to immune checkpoint inhibitors (ICIs). Cancer cells within cold tumors deploy various mechanisms for evading immune attack, thus impeding clinical management. Recently, combination immunotherapy has become increasingly essential to comprehend the mechanisms underlying cold tumors to enhance a deficient antitumor immune response. Therefore, a thorough understanding of the knowledge on the combination immunotherapy of cold CCA is imperative to leverage the benefits of immunotherapy in treating patients. Moreover, gut microbiota plays an essential role in the immunotherapeutic responses in CCA. In this review, we summarize the current concepts of immunotherapy in CCA and clarify the intricate dynamics within the tumor immune microenvironment (TIME) of CCA. We also delve into the evasion mechanisms employed by CCA tumors against the anti-tumor immune responses. The context of combination immunotherapies in igniting cold tumors of CCA and the critical function of gut microbiota in prompting immune responses have also been annotated. Furthermore, we have proposed future directions in the realm of CCA immunotherapy, aiming to improve the clinical prognosis of CCA patients.