MTOR and kidney cancer: In fact, the United States Food and Drug Administration and the European Medicines Agency have approved the mTOR inhibitor temsirolimus as a first-line to treat metastatic ccRCC in 2007 and temsirolimus is listed as a category 1 drug for front-line treatment of poor-risk patients in the National Comprehensive Cancer Network (NCCN) Kidney Cancer Panel, which is based on the phase III NCT0065468 trial for temsirolimus.