Fat mass and survival in immunotherapy-treated metastatic renal cell carcinoma patients

Introduction: Immune checkpoint inhibitors (ICI) are widely prescribed as the first-line treatment for metastatic renal clear-cell carcinoma (mRCC) because of their overall survival benefits. However, ICI are associated with unreliable efficacy and sometimes severe and unpredictable toxicities. There is a lack of biomarkers for efficacy or toxicity beyond the IMDC score. Body composition (fat and muscle mass) may also be a biomarker of interest. The aim of this retrospective study was to analyze the association between body composition, overall survival (OS), and toxicities in patients with RCC treated with ICI as a first-line metastatic treatment. Methods: Body composition parameters - subcutaneous fat index (SFI), visceral fat index (VFI), total fat index (TFI), and skeletal muscle index (SMI)–were measured on computed tomography scans using semi-automated software. Results: In 71 patients, no significant association was found between TFI and OS (adjusted HR 0.70, 95% CI = [0.33–1.48]) or toxicities. The TFI was strongly correlated with BMI (r=0.81), whereas the SFI and VFI were weakly correlated. Conclusion: Larger studies would be valuable to better define the thresholds of different parameters (SFI, VFI, TFI, and SMI) and their association with the efficacy and toxicity of ICI.