title: mTOR inhibitors and renal allograft: Yin and Yang.
abstract: Mammalian target of rapamycin inhibitors (mTOR-I), everolimus and sirolimus, are immunosuppressive drugs extensively used in renal transplantation. Their main mechanism of action is the inhibition of cell signaling through the PI3 K/Akt/mTOR pathway. This interesting mechanism of action confers to these medications both great immunosuppressive potential and important anti-neoplastic properties. Although the clinical utility of this drug category, as with other antineoplastic/immunosuppressants, is clear, the use of mTOR-I commonly results in the development of several complications. In particular, these agents may determine severe renal toxicity that, as recent studies report, seems clearly correlated to dose and duration of drug use. The mTOR-I-induced renal allograft spectrum of toxicity includes the enhanced incidence of delayed graft function, nephrotoxicity in particular when co-administered with calcineurin inhibitors (CNI) and onset of proteinuria. The latter effect appears highly frequent in patients undergoing mTOR-I treatment and significantly associated with a rapid graft lost. The damage leading to this complication interests both the glomerular and tubular area. mTOR-I cause an inhibition of proliferation in podocytes and the epithelial-to-mesenchymal transition in tubular cells. Interestingly, all these side effects are mostly reversible and dose related. Therefore, it is unquestionable that these particular drugs should be administered at the lowest dose able to maintain relatively low trough levels, in order to maximize their important and specific therapeutic effects while minimizing or avoiding drug toxicities. Utilization of low dosages of mTOR-I should be encouraged not only in CNI-combined schemas, but also when administered alone in a CNI-free immunosuppressive protocol.
authors.affiliation: Renal Unit, Department of Medicine, University-Hospital of Verona, Piazzale A. Stefani 1, 37126, Verona, VR, Italy, gianluigi.zaza@univr.it.
authors.forename: Gianluigi
authors.initials: G
authors.lastname: Zaza
authors.forename: Simona
authors.initials: S
authors.lastname: Granata
authors.forename: Paola
authors.initials: P
authors.lastname: Tomei
authors.forename: Valentina
authors.initials: V
authors.lastname: Masola
authors.forename: Giovanni
authors.initials: G
authors.lastname: Gambaro
authors.forename: Antonio
authors.initials: A
authors.lastname: Lupo
mesh_terms: D064591:Allografts; D000818:Animals; D051799:Delayed Graft Function / Q000139:chemically induced; D006084:Graft Rejection / Q000201:enzymology / Q000276:immunology / Q000517:prevention & control*; D006085:Graft Survival / Q000187:drug effects*; D006801:Humans; D007166:Immunosuppressive Agents / Q000009:adverse effects / Q000627:therapeutic use*; D016030:Kidney Transplantation / Q000009:adverse effects; D061214:Patient Safety; D018579:Patient Selection; D011507:Proteinuria / Q000139:chemically induced; D018570:Risk Assessment; D012307:Risk Factors; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D007166:Immunosuppressive Agents; D058570:TOR Serine-Threonine Kinases