961PFirst results of safety profile of nivolumab (NIVO) in combination with stereotactic body radiotherapy (SBRT) in II and III line of patients (pts) with metastatic renal cell carcinoma (mRCC) in NIVES study

Abstract Background NIVO is an anti-programmed cell death-1 (PD-1) monoclonal antibody; it might work even better when combined with SBRT improving clinical outcomes with a phenomenon known as abscopal effect. To date there are limited data on safety profile of combined SBRT and NIVO in mRCC. We report for the first time the toxicities occurred in phase II NIVES Study. Methods This is a phase II, single arm, multicentre study in pts with mRCC with progression disease after≤2 prior anti-angiogenic therapies and with measurable non-brain metastatic sites, at least one of which potentially suitable for SBRT. The pts included received hypofractionated radiation in one lesion at dose of 10 Gy/3 fractions after 7 days from the first infusion of NIVO. NIVO will be given as flat dose of 240 mg on day 1 every 14 days for 6 months, then switch to 480 mg q4-weekly in responding pts until PD or unacceptable toxicity. Descriptive statistics are reported for patient/tumor/treatment characteristics and observed severe Adverse Events (AEs) graded by CTCAE v. 4.03. Results Sixty-nine pts were enrolled from July 2017 to March 2019 in 11 Italian centers. 79.7% of pts had clear cell histology, median age was 67 years (range 43-85), 82.6% were male. ECOG PS was 0 in 57 pts (82.6%), only 18.8% pts had received 2 previous lines of therapy. The most frequent sites of SBRT were lung (39.4% of pts), lymphonodes (16.7%) and bone (10.6%). Toxicities of grade (G) 3-4 related to NIVO were experienced in 13 pts (18.8%); all G3-4 toxicities were outside of the irradiated area. The most frequently observed G3-4 treatment-related AEs included diarrhea (5.8%), fatigue (4.3%), anemia (2.9%) and increase of amylase/lipase (2.9%). To date no G3-4 pneumonitis were observed. Six pts (8.7%) were hospitalized due to treatment-related SAEs. Overall, 5 of 69 treated pts (7.2%) discontinued therapy because of G3-4 AEs. At the time of this analysis 32/69 pts (46%) are still on treatment. Conclusions Concurrent NIVO plus SBRT is generally well tolerated, without increased rates of common severe toxicity. Definitive data of toxicities and efficacy of the combination of immunotherapy and radiotherapy are not yet mature. Clinical trial identification NCT03469713. Legal entity responsible for the study GOIRC. Funding GOIRC. Disclosure C. Masini: Travel / Accommodation / Expenses: BMS, Janssen, Astellas, Bayer; Advisory / Consultancy: Pfizer, Novartis, Sanofi. U.F.F. De Giorgi: Research grant / Funding (ins