Impact of sarcopenia indexes on survival and severe immune acute toxicity in metastatic non-small cell lung cancer patients treated with PD-1 immune checkpoint inhibitors

Sarcopenia has long been associated with higher toxicity induced by anti-cancer treatments and shorter survival in patients with solid tumors. The creatinine-to-cystatin ratio (CC ratio, serum creatinine/cystatin C × 100) and the sarcopenia index (SI, serum creatinine × cystatin C (CysC)-based glomerular filtration rate (eGFRCysC)) are have been reported to be correlated with skeletal muscle mass. The aim of this study is to assess primarily whether the CC ratio and the SI could predict mortality in metastatic non-small cell lung cancer (NSCLC) patients treated with PD-1 inhibitors, and secondarily their impact on severe immune-related adverse effects (irAEs). From the prospective CERTIM cohort, we analyzed retrospectively stage IV NSCLC patients, who received PD-1 inhibitors between June 2015 and November 2020 in Cochin Hospital (Paris, France). We assessed sarcopenia measuring skeletal muscle area (SMA) by computed tomography and handgrip strength (HGS) by a hand dynamometer. In total, 200 patients were analyzed. The CC ratio and the IS were significantly correlated with SMA and HGS: rCC/SMA = 0.360, rSI/SMA = 0.407, rCC/HGS = 0.331, rSI/HGS = 0.370. In multivariate analysis of overall survival, a lower CC ratio (HR 1.73, P = 0.033) and a lower SI (HR 1.89, P = 0.019) were independent predictors of poor prognosis. In univariate analysis of severe irAEs, CC ratio (OR 1.01, P = 0.628) and SI (OR 0.99, P = 0.595) were not associated with a higher risk of severe irAEs. In metastatic NSCLC patients treated with PD-1 inhibitors, a lower CC ratio and a lower SI are independent predictors of mortality. However, they are not associated with severe irAEs.