Purpose: The efficacy of checkpoint inhibitor (CPI) immunotherapy in patients with nonesmall cell lung cancer (NSCLC) is limited by a lack of strongly predictive response markers, subjecting patients to potential underutilization of alternative effective treatments, increased risk for futile care, and unnecessary costs. Here, we characterize the extent to which basic molecular tumor-marker testing has been performed for NSCLC therapy selection in the United States, and compare medical resource utilization and costs in CPI-treated patients versus CPI-eligible patients treated with other therapies. Methods: We identified a cohort of CPI-treated patients with NSCLC and a propensity scoreematched cohort of CPI-eligible patients with NSCLC treated with non-CPI therapies (3095 patients in each group), using US administrative claims data covering the pre-and postinitial FDAapproval period for nivolumab, pembrolizumab, and atezolizumab (October 2012 to September 2017). We describe the utilization of recommended baseline molecular testing for CPI selection (preeindex date for CPI or other anticancer therapy), including programmed death ligand 1 (PD-L1) immunohistochemistry, ALK rearrangement and EGFR mutation testing, and pre-and postindex treatment patterns. All-cause medical resource utilization and semiannual total reimbursement (costs) were compared between CPI-treated and non-CPIetreated patients. Findings: At baseline, in the propensity scoreematched CPI-and noneCPI-treated patient cohorts, mean PD-L1 immunohistochemistry test