Difference in adverse-event profiles between mTOR inhibitors, temsirolimus, and everolimus for advanced renal cell carcinoma.

461 Background: Everolimus and temsirolimus have proven their efficacy and are used for patients with metastatic renal cell carcinoma (mRCC). They both are rapamycin derivatives and are categorized as mTOR inhibitors. There have been few reports that examined the difference between these two agents regarding adverse events. Our objective was to investigate the difference in the safety of both agents on the basis of our clinical experience. Methods: We identified patients with mRCC who had been treated with everolimus or temsirolimus at our hospital. Treatment duration, relative dose intensity, laboratory data, and adverse events during treatment with each agent were evaluated. Results: A total of 55 patients were evaluable. 43 of those had been treated with everolimus, 22 with temsirolimus, and 10 with both agents. There was no significant difference in age and gender between the two treatment groups. Median treatment durations of the everolimus and temsirolimus groups were 2.4 months and 1.8 months, respectively. Relative dose intensities of the everolimus and temsirolimus groups were 71.6 % and 75.4 %, respectively. Anemia, hyperglycemia, stomatitis, and interstitial lung disease (ILD) were detected with higher frequency in the everolimus group. In the everolimus group, 31 % of patients developed any grade of ILD including 15 % of grade 3, whereas ILD was reported in only one patient treated with temsirolimus with no grade 3 or higher. Frequencies of adverse events of grade 3 or higher were 49 % in the everolimus group and 26 % in the temsirolimus group. Conclusions: Adverse-event profiles of everolimus and temsirolimus may differ from each other. Respiratory disorders may occur more frequently and severely in patients treated with everolimus than temsirolimus. These findings suggest the difference in the pharmacodynamics, pharmacokinetics, and treatment regimen of these two agents may result in different adverse events even though they target the same molecule.