Characterizing the Shifting Real-World Treatment Landscape by PD-L1 Testing Status and Expression Level in Advanced Non-Small Cell Lung Cancer.

INTRODUCTION: Contemporary real-world data on advanced non-small cell lung cancer (aNSCLC) treatment patterns across programmed cell death-ligand 1 (PD-L1) expression levels and testing status are limited. METHODS: A retrospective cohort was selected of adults newly diagnosed with aNSCLC between January 1, 2018, and July 31, 2021, who initiated first-line treatments, which were described by PD-L1 status and expression levels (≥ 50%, 1-49%, < 1%). Treatment received before and after PD-L1 test results were described for patients initiating first-line treatment before PD-L1 results. For patients who initiated chemotherapy alone before PD-L1 results, the probability of receiving immune checkpoint inhibitors (ICIs) after PD-L1 results was estimated by PD-L1 level and associated factors were explored. RESULTS: Among 12,202 patients with aNSCLC initiating first-line treatment [54.7% male, mean (standard deviation) age 69.2 (9.4) years], the most common therapies were ICI-based regimens across PD-L1 levels, and chemotherapy alone among PD-L1-untested patients. Use of chemotherapy alone decreased between 2018 and 2019 and stabilized thereafter, accounting for 21-29% of first-line treatments across PD-L1 levels and 48% of untested patients in 2021. Of 1468 patients initiating first-line treatment before PD-L1 results, treatments remained unchanged in most patients after PD-L1 results. Among patients initiating chemotherapy alone before PD-L1 results, the probability of receiving ICIs within 45 days after test results was 40.5% [95% confidence interval (CI) 31.6-48.3%], 28.6% (95% CI 20.3-36.0%), and 22.9% (95% CI 16.9-28.4%) at PD-L1 ≥ 50%, 1-49%, and < 1%, respectively. CONCLUSION: While ICI-based regimens accounted for most first-line treatments across PD-L1 levels, chemotherapy alone was initiated in > 20% of patients tested for PD-L1 and 48% of untested patients in 2021. Patients who initiated chemotherapy alone had a low probability of receiving ICIs after PD-L1 test results. These results highlight the need for understanding the role and timing of PD-L1 test results for informing treatment decisions for patients with aNSCLC.