Everolimus and tacrolimus

The mammalian target of rapamycin (mTOR) protein complex functions as a key protein for proliferation, cell survival, and angiogenesis in intracellular signaling pathways. Everolimus (RAD001), which is one of the mTOR inhibitors, is applied to treat patients with unresectable or metastatic renal cell cancers as second-line treatment for those refractory to sorafenib or sunitinib. Tacrolimus (FK506), which is one of the calcineurin inhibitors, is a strong immunosuppressive agent. Tacrolimus is known as an immunosuppressive agent greatly increasing the risk of malignancy by impairing cancer surveillance, and the drug enhances the production of transforming growth factor β1 (TGF-β1). In cytoplasm, everolimus and tacrolimus bind to the same target, which is called FK506 binding protein 12 (FKBP12), and the complexes play different roles in the cell. We here describe the mechanism of action, the side effects, biomarker, and the role of the two drugs in the future.