Establishment and Drug Screening of Patient-Derived Extrahepatic Biliary Tract Carcinoma Organoids

Abstract Background: Patient-derived organoids (PDO) have been proposed as a novel in vitro method of drug screening for different types of cancer. However, to date, extrahepatic biliary tract carcinoma (eBTC) PDOs have not yet been fully established. Methods: We collected six samples of gallbladder carcinoma (GBC) and one sample of extrahepatic cholangiocarcinoma (eCCA) from seven patients in order to attempt to establish eBTC PDOs for drug screening. Eventually, we successfully established five GBC PDOs and one eCCA PDO. Histological staining was used to compare the structural features of original tissues and cancer PDOs. Then, whole exome sequencing (WES) was used to analysed the genetic profiles of original tissues and cancer PDOs. Drug screening, including gemcitabine, 5-fluorouracil, cisplatin, paclitaxel, infigratinib, and ivosidenib, was measured and verified by some cases. Results: Different PDOs were found to have different growth rates during in vitro culture. Hematoxylin and eosin staining demonstrated that the structures of most cancer PDOs are able to retain the original structures of adenocarcinoma. Immunohistological staining and periodic acid-schiff staining were then discovered that marker expression in cancer PDOs were similar to those of the original specimens. Genetic profiles of the four original specimens, as well as paired cancer PDOs, were measured using whole exome sequencing. Three of the four PDOs exhibited a high degree of similarity, compared to the original specimens, except GBC2 PDO, which only had a concordance of 74% in the proportion of single nucleotide polymorphisms in the coding sequence. In general, gemcitabine was found to be the most efficient drug for treatments of the eBTCs, as it showed moderate or significant inhibitory impact on the growth of cancers. Results from the drug screening can be verified by three clinical cases, to a certain extent. Conclusions: Our study successfully established a series of eBTC PDOs, which helped fill in gaps in the field of eBTC PDOs. Additional measures should be explored to improve the growth rate of PDOs, and to preserve their immune microenvironment.