CDA and neoplasm: A previous study suggested bacteria class Gammaproteobacteria (e.g., K. pneumoniae) harbored in PC tumor was able to metabolize the gemcitabine to the inactive 2’, 2’-difluorodeoxyuridine through a long isoform of the enzyme cytidine deaminase (Ertz-Archambault et al., 2017; Geller et al., 2017; Sayin and Mitchell, 2023; Horvat et al., 2024).