IL6 and neoplasm: Factors like hypoxia, heterogeneous blood supply, and the presence of various cytokines (IL-1, IL-6, TNF-α, and IFN-γ) and enzymes can affect the activity or expression level of the therapeutic enzyme cytochrome P450, the distribution of the prodrug and its metabolites within the tumor (Fradette and Du Souich, 2004; Stipp and Acco, 2021).