mTOR-inhibitors are part of targeted agents and are already in use in the clinic, especially for treatment of metastatic renal cell carcinoma. Distinct from conventional chemotherapeutics, targeted agents imply chronic treatment, which has changed our perspective on the commerce of adverse events (AE). In principle, mTOR-inhibitors are associated with a broad number of AEs. The occurrence of stomatitis, infection, pneumonitis, hyperlipidemia and hyperglycemia are considered major class effects of mTOR-inhibitors. However, severe adverse events remain scarce among mTOR-inhibitors and support chronic use of these agents. Based on their good clinical tolerability mTOR-inhibitors are prone to be developed in combinational therapies. However, the hepatic metabolism of these agents may limit their use to partners with a distinct metabolism in order to avoid drug interaction. Meanwhile about 40 different trials use mTOR-inhibitors in different tumor entities. The use of mTOR-inhibitors in neuroendocine tumors of the intestine, mantle cell lymphoma and sarcomas has hereby shown to be very promising. The mainstay of therapy already incorporates the use of everolimus in second line and temsirolimus in first line treatment in patients with metastatic renal cell carcinoma.
