Effect of obesity on response to checkpoint inhibitors in renal cell cancer.

Abstract

634 Background: Response to checkpoint inhibitors (CPIs) for renal cell cancer (RCC) remains variable, with markers like PDL1 proving unreliable. Preclinical models suggest that obesity could affect CPI outcomes. We conducted a retrospective study on the effect of obesity on outcomes in RCC patients treated with CPIs. Methods: RCC patients treated with nivolumab +/- Ipilimumab at university of Alabama at Birmingham (UAB) and University of Iowa (UIOWA) from 2015 - 2018 were classified according to WHO standard definition of BMI as non-obese (NOB-<30kg/m2) or obese (OB->30Kg/m2). Overall survival (OS) was defined as the interval from the first CPI dose to date of death or to last follow up date if patients were still alive. Progression free survival (PFS) was defined as the interval from the first dose of CPI to date of progression or date of death and censored at last follow-up date if patients were still alive without progression. Multivariable Cox proportional hazard regression model was used to evaluate the association between OS/PFS and obesity status, controlling for age, sex, race and number of prior therapies. All analyses were performed using SAS 9.4. Results: 84 patients with at least 6 months follow-up received a median of 9 doses of CPI with median follow of 72 weeks. 48 patients were NOB while 36 patients were OB, with 40 patients deceased at time of analysis. The most common response was stable disease in 45%, with CR in 5% and PR in 10% for a disease control rate of 63%. The median OS was 30 months in NOB patients and 20 months in the OB group. The 2 yr survival was 59% in the NOB group vs 28 % in the OB group with a HR of 0.60 (0.32-1.14; p=0.12). Median PFS was 13 months in the NOB group vs 7.3 months in the OB group with 2 yr PFS of 28% in the NOB group vs 5.5% in the OB group (HR 0.58 {0.35-0.98}; p=0.04). Conclusions: In this analysis of RCC patients treated with CPI, BMI < 30 predicts better OS and PFS. Further studies are required to better understand the effect of BMI on CPI outcomes in RCC.[Table: see text]