Background: Advanced Non-Small Cell Lung Cancer (aNSCLC) treatment has advanced considerably after introduction of immune checkpoint inhibitors. We track changes in first-line aNSCLC treatment since 2011 and provide an early assessment of regimens (including chemotherapy + PD-(L)1 inhibitors) and treatment duration using data from prior authorization (PA) systems linked to the health plan’s claims data. Methods: A cohort of patients treated for aNSCLC was identified from the OptumLabs® Data Warehouse, using clinical information from the health plan’s cancer registries and prior authorization (PA) systems then linked to medical claims data. Patients were included if they were diagnosed stage IIIB, IIIC, or IV NSCLC and initiated treatment with chemotherapy and/or PD-(L)1 inhibitor between 1/2011 and 5/2018. First line regimen was identified based on all agents received within 30 days following the day of first infusion. Time to discontinuation (TTD) was defined as days from treatment initiation to the date the patient discontinues frontline treatment. Kaplan-Meier methods were used to estimate distribution of TTD. Results: We identified 3,783 eligible patients of which 2,591 received a regimen of interest. In this commercially enrolled population, age was similar across regimens (median=60 years; IQR=55 to 63), 54% were male, and 84% diagnosed stage 4. First-line aNSCLC has changed following approval of PD-(L)1 inhibitors with fewer patients receiving doublet chemotherapy alone. We found duration of first-line to be greater among patient receiving PD-(L)1 monotherapy (median 190 days) or PD-(L)1 + doublet (247 days) compared to doublet chemotherapy (106 days). The proportion of patients receiving a subsequent line of treatment was greatest in the doublet chemotherapy regimen (47%). These results are consistent over time. Conclusions: Data collected as part of electronic PA and linked to claims data can enable head-to-head comparisons of contemporary cancer treatments used according to NCCN guidelines in routine clinical practice. While doublet chemotherapy is still used as first-line treatment, it is becoming more common to combine chemotherapy with a PD-(L)1. Newer regimens appear to be well tolerated relative to traditional doublet chemotherapy regimens. While we focus on aNSCLC treatment, and how they change over time, concurrent research focuses on comparison of adverse events and effectiveness (e.g., OS).