Background
Immune checkpoint inhibitors (ICI) are dramatically active in a minority of non-small cell lung cancer (NSCLC) patients. We studied here the relationship between patients's metabolism and outcome under ICI.
Methods
Metastatic NSCLC patients underwent a nutritional assessment prior to initiating immunotherapy. Resting energy expenditure (REE) was measured (mREE) using ambulatory indirect calorimetry and compared with the theoretical value (tREE) provided by the Harris and Benedict formula. The primary endpoint was 6-month progression-free survival (PFS). Secondary endpoints included objective response rate (ORR) and disease control rate (DCR) based on investigator review per RECIST v1.1. and overall survival (OS). The association of patient's metabolism with 6-month PFS was first explored in a single-center training cohort to estimate the effect size. The relationship between patient's metabolism and 6-month PFS was then tested in an independent non interventional observational prospective cohort (ELY) of 100 patients recruited in two tertiary university centers. Findings: In the entire cohort, the ORR was 14% for the hypermetabolic group (n = 10/74) vs 38% for the normometabolic group (n = 26/68), respectively (estimated difference 25%, 95CI 9-40%, p = 0.001). The DCR was 28% for the hypermetabolic group (n = 21/74) vs 53% for the normometabolic group (n = 36/68), respectively (estimated difference 25%, 95CI 7-42%, p = 0.005). In the validation cohort (100 patients, 2 centers), normometabolic patients (defined as mREE/tREE < 110%) had increased 6-month PFS (57% versus 22%; odds ratio: 4.76; IC95 [1.87 - 12.89]; p<0.001) and improved overall survival (HR 2.20; IC95: 1.41-3.44; p<0.001). The positive and negative predictive values of normometabolism to identify non-progressive patients at 6 months, were 57% and 78% respectively, sensitivity was 72% and specificity was 66%. In multivariate analysis including PD-L1 tumor status, basal metabolism was an independent predictive factor for 6-month PFS. Interpretation: Normometabolism is a new independent parameter to identify mNSCLC patients who will benefit from ICI, with both improved tumor response, 6-month PFS, and survival. Funding: This work was supported by Baxter (04012016).