The Role of Microbiota in Primary Sclerosing Cholangitis and Related Biliary Malignancies

Primary sclerosing cholangitis (PSC) is an immune-related cholangiopathy characterized by biliary inflammation, cholestasis, and multifocal bile duct strictures. It is associated with high rates of progression to end-stage liver disease as well as a significant risk of cholangiocarcinoma (CCA), gallbladder cancer, and colorectal carcinoma. Currently, no effective medical treatment with an impact on the overall survival is available, and liver transplantation is the only curative treatment option. Emerging evidence indicates that gut microbiota is associated with disease pathogenesis. Several studies analyzing fecal and mucosal samples demonstrate a distinct gut microbiome in individuals with PSC compared to healthy controls and individuals with inflammatory bowel disease (IBD) without PSC. Experimental mouse and observational human data suggest that a diverse set of microbial functions may be relevant, including microbial metabolites and bacterial processing of pharmacological agents, bile acids, or dietary compounds, altogether driving the intrahepatic inflammation. Despite critical progress in this field over the past years, further functional characterization of the role of the microbiota in PSC and related malignancies is needed. In this review, we discuss the available data on the role of the gut microbiome and elucidate important insights into underlying pathogenic mechanisms and possible microbe-altering interventions.

Current and Future Systemic Therapies in Biliary Tract Cancer

<b><i>Background:</i></b> Despite an increasing incidence, biliary tumors are still considered a rare tumor entity. Due to an often long clinically inapparent course and a lack of early detection strategies, surgical resection is often not possible at the time of diagnosis. Since 2010, chemotherapy with gemcitabine and cisplatin is considered the standard of care in the palliative situation. Only recently, first studies have been published or initiated that expand the treatment options in the first line and, for the first time, also suggest valid systemic approaches in the second line. <b><i>Summary:</i></b> Molecularly targeted therapies in selected patient subgroups are rapidly changing the field. In addition to IDH1 mutations and FGFR2 fusions in patients with intrahepatic tumors, the therapeutic relevance of rare but targetable alterations such as HER2/neu amplification, NTRK fusions, or BRAF mutations should be considered in patients with biliary tract cancers. <b><i>Key Message:</i></b> The current study landscape clearly shows that precision medicine will play an important role in the therapy of biliary malignancies and underlines the importance of early tumor genetic diagnostics. In this article we provide an overview of systemic therapy concepts in the adjuvant and palliative setting.