520 Background: Brain metastases (BMs) are associated with poor prognosis in metastatic renal cell carcinoma (mRCC). Patients with BM were excluded from pivotal studies of nivolumab in mRCC. Therefore, activity of nivolumab in BM is currently unknown. Methods: Data from mRCC patients with BMs, treated at Gustave Roussy with nivolumab, were collected. RECIST 1.1 assessments of both BM and metastatic sites outside the brain have been prospectively centrally reviewed. Treatment for BM: surgery, stereotactic radiation therapy (SBRT), whole brain radiotherapy (WBRT), and systemic treatment were collected. Results: Between February 2016 and September 2016, 62 consecutive patients have been treated with nivolumab in 2nd/3rdline at Gustave Roussy as part of the GETUG-AFU-26 NIVOREN trial (EudraCT 2015-004117). Among those, 8 patients (13%) had baseline non symptomatic BM, either untreated (n=6), or after SBRT (n=2). Among the 8 patients, median follow up from study enrollment is 8.1 months (range: 3.7-8.5). All 8 patients are alive at the time of analysis, only one still receiving nivolumab. 6/6 patients previously untreated required focal therapy to the brain due to early symptomatic disease progression to the brain: SBRT=5; surgery=1; WBRT=1 (one patient had SBRT +WBRT). Disease progression of BM was symptomatic in 8/8 patients and required steroid use as well as nivolumab discontinuation in 7/8 patients due to either brain and/or systemic disease progression. Conclusions: To our knowledge,this is the first experience evaluating BMs from mRCC treated with nivolumab. Our report suggests that BM from mRCC may not derive benefit from nivolumab and that prior focal therapy to the brain may be discussed in patients before nivolumab start. This finding is currently being investigated in the entire GETUG-AFU-26 NIVOREN trial population (n=499 patients, from 27 centers), which included 54 patients (11%) with BM at treatment start, to be presented at ASCO GU.[Table: see text]
