PPIG and cancer: The goal of gene-directed enzyme prodrug therapy (GDEPT) with the design of CYP enzymes for cancer gene therapy is to leverage this principle, achieving more targeted and effective chemotherapy treatment while also aiming at reducing side effects from undesired toxic metabolites (Waxman et al., 1999; Zanger and Schwab, 2013; Zhang et al., 2015; Mishra et al., 2018).