LAUSR

e16077 Background: Body mass index (BMI) and inflammation indexes are easily evaluated, predict survival in many tumors, and are potentially modifiable. The "obesity paradox" of longer survival in cancer patients with high BMI has been explained by altered fatty acid pathways, which could have an impact in immune-inflammatory function, and leptin-driven increase in T cell aging resulting in higher PD-1 expression and dysfunction, which leaves tumors notably more sensitive to checkpoint blockade. We evaluated the potential association of inflammatory indexes and BMI with the clinical outcome of metastatic renal cell carcinoma (mRCC) undergoing immune checkpoint inhibitor therapy. Methods: A prospective cohort of patients with mRCC treated with nivolumab enrolled in the Italian Expanded Access Program (EAP) from July 2015 through April 2016 was examined. Reference measures of inflammation were identified for neutrophil to lymphocyte ratio (NLR) < /≥3, systemic immune-inflammation index (SII) < /≥3 and platelet to lymphocyte ratio (PLR) < /≥232. Patients were classified as high BMI (≥25 kg/m2) versus normal BMI ( < 25 kg/m2). Results: Among 313 evaluable patients, 289 (75.1%) were male, median age was 65 years (range, 40 to 84), with 105 (24.9%) ≥70 years. In univariate analysis, age ≥70 years, performance status, BMI, SII, NLR and PLR were able to predict outcome. In multivariate analyses, SII ≥1375, BMI < 25 and age ≥70 years independently predicted OS (HR, 2.96; 95% CI, 2.05-4.27; HR, 1.59; 95% CI, 1.10-2.30 and HR, 1.65; 95% CI, 1.07-2.55, respectively). Under the model of independent effects, a patient with both SII ≥1375 and BMI < 25 was estimated to have much worse OS (HR, 3.37; 95% CI, 2.29-4.95, p < 0.0001) than a patient with neither or only one risk factor. SII changes at 3 months predicted OS (P < 0.0001). Conclusions: BMI combined with inflammation tripled the risk of death, suggesting that these biomarkers are critical prognostic factors for OS in patients with mRCC treated with nivolumab.