e15529 Background: We assessed the incidence and clinical presentation of stomatitis and cutaneous toxicity associated with everolimus in patients (pts) with metastatic renal cell carcinoma (mRCC). Correlation between these toxicities and clinical outcome was also determined. Methods: We retrospectively reviewed the clinical data of pts with mRCC treated with everolimus in two Italian Centers. Clinical evidence of stomatitis and/or cutaneous toxicity inducing a treatment discontinuation or a dose reduction were considered stomatitis-cutaneous toxicity events (SCTE). SCTE were evaluated and corresponding clinical data were reviewed for response and clinical outcome. Response was evaluated according to Response Evaluation Criteria in Solid Tumours (RECIST) criteria. Results: The study population consisted of 79 mRCC pts treated everolimus (57 male, 22 female; median age 69 years, range 44–88). Fifty-two pts (66%) received everolimus as second-line therapy, while 27 (34%) as third-line. SCTE were seen in 20/79 pts (25%) at a median of 30.5 days on everolimus treatment (range 10–270 days). Tumor response was evaluable in 77 of 79 patients (19 of 20 SCTE pts and 58 of 59 non-SCTE). Partial response or stable disease was achieved in 15 of 19 pts with SCTE (79%) compared to 28 of 58 (48%) with no SCTE (p = 0.03). After a median follow-up of 19 months (range, 1 to, 39), the median progression-free survival (PFS) was 5.5 months (95% CI 3.4-7.7) and the median overall survival (OS) was 17.2 months (95% CI 13.2-24.4). A significant difference was found in the median PFS equal to 7.5 months (95% CI 3.4-24.4) in SCTE pts vs 3.7 months (95% CI 2.7-7.5) in non-SCTE, p = 0.047, and in the median OS equal to 30.6 months (95% CI 14.8-not reached) in SCTE pts vs 14.0 months (95% CI 9.9-17.7) in non-SCTE, p = 0.004. Conclusions: These data suggest that SCTE may be a predictive marker of favorable outcome in mRCC treated with everolimus. A prospective observational study with a dermatologic/stomatologic monitoring has been planned in mRCC pts treated with everolimus.