FAS and neoplasm: Further studies found that the activation of the immune system by chemotherapeutic agents leads to a two-pronged tumor eradication process: first, chemotherapeutic agents rely on cytotoxicity to directly destroy tumor cells (Casares et al., 2005); and second, the anti-tumor immune response produced by effector lymphocytes, such as cytotoxic T lymphocytes (CTLs), by secreting cytotoxic molecules and expressing ligands (Fas/TRAIL) that can bind to cell death receptors (Minute et al., 2020).