Real-World Prevalence of PD-L1 Expression Among Tumor Samples From Patients With Non-Small-Cell Lung Cancer.

Introduction: We analyzed the prevalence of non-small-cell lung cancer (NSCLC) with a programmed cell death ligand 1 (PD-L1) tumor proportion score (TPS) of ≥ 50% and compared the results with the existing data from clinical trials and databases from other countries.

Materials And Methods: The Latin American Cooperative Oncology Group and Grupo Brasileiro de Oncologia Torácica performed a retrospective, cross-sectional study from August 2017 to April 2018. PD-L1 expression was collected from pathology reports from 5 laboratories in Brazil. All tests were sponsored by the pharmaceutical industry on request from the treating medical oncologist. PD-L1 expression was assessed by immunohistochemistry. The variables were summarized as absolute and relative frequencies or the median and interquartile range. Pearson's χ test was used to compare the TPS categories stratified by sex, age, and histologic type. All analyses were performed with SAS, version 9.4, and were deemed statistically significant at P < .05.

Results: A total of 1512 patients were included in the present study. Their median age was 66 years. Most patients were men (56.02%), and the most common histologic type was adenocarcinoma (58.04%); 109 tumors (11.31%) had EGFR mutations and 34 (3.64%) had ALK gene rearrangements. Overall, 56.54% had a PD-L1 TPS < 1%, 25.63% a TPS of 1% to 49%, and 17.83% a TPS of ≥ 50%. The factors associated with PD-L1 expression were histologic type (with adenocarcinoma samples having a greater proportion of TPS < 1%) and the laboratory that performed the test.

Conclusion: The prevalence of high PD-L1 expression among the Brazilian NSCLC samples was lower than previously described in other countries, which could affect the number of patients who might be candidates for immunotherapy alone.