Prevalence of EGFR and PDL1 testing in a population-based lung cancer surgical resection cohort from 2018-2022.
Authors: Smeltzer Matthew , Akinbobola Olawale , Ray Meredith , Fehnel Carrie , Saulsberry Andrea , Dortch Kourtney , Faris Nicholas R. , Pimenta Kelly , Matthews Anberitha T. , Osarogiagbon Raymond U. 
Published: June 2023

e20585 Background: Most long-term survivors of lung cancer had surgery for early stage disease, but long-term survival rates are about 50%. In 2020 and 2021 the ADAURA and IMpower010 trials established adjuvant Osimertinib and Atezolizumab therapy for stage IB-IIIA non-small cell lung cancer. Eligibility for these treatments depends on specific biomarkers. We evaluated biomarker testing patterns and prevalence in a population based surgical resection cohort. Methods: In the prospective observational Mid-South Quality of Surgical Resection cohort, we evaluated EGFR and PDL1 testing from 2018-2022, spanning time before (2018-2020) and after (2021-2022) FDA approval of adjuvant Osimertinib and Atezolizumab therapy. We estimated the prevalence of EGFR mutations and PDL1 expression ( > 0%) using the binomial distribution with exact 95% confidence intervals (CI). We compared demographic characteristics using Wilcoxon and Fishers Exact tests. Results: From 2018-2022, 1687 patients had surgical resection across 12 institutions (1045 from 2018-2020; 642 from 2021-2022). They were 21% black and 77% white, 49% male and 51% female, with a median age of 69 years. From 2018-2020 11% had EGFR testing, compared to 38% in 2021-2022 (p < 0.0001). There were no differences in testing by age (p = 0.79), sex (p = 0.99), race (p = 0.69), or insurance type (p = 0.45). In 132 ADAURA eligible individuals (stage IB-IIIA, non-squamous, R0, > 4cm tumor), EGFR was tested in 13% in 2018-2020 and 56% in 2021-2022 (p < 0.0001) with no differences by demographic factors (all p > 0.20). 15% (53 of 360) of EGFR tests were next-generation sequencing, increasing from 4% in 2018-2020 to 20% in 2021-2022 (p < 0.0001). The prevalence of EGFR mutations was 8.1% (95% CI: 5.5% to 11.4%) overall; 9% in males vs. 7% in females (p = 0.57); 12% in black persons vs. 7% in white persons (p = 0.40). From 2018-2020 8% of patients received PDL1 testing, compared to 20% in 2021-2022 (p < 0.0001). There were no differences in testing by age (p = 0.47), sex (p = 0.41), and race (p = 0.51), but a trend for insurance type (p = 0.07). In 791 Impower010 eligible patients (Stage IB-IIIA, R0), PDL1 was tested in 8% in 2018-2020 and 23% in 2021-2022 (p < 0.0001) with no significant differences by demographic factors (all p > 0.10). Among all 207 PDL1 tests, PDL1 was > 0% in 143, for a prevalence of 69% (95% CI: 62% to 75%). It was 69% in males, 70% in females (p = 0.88); 68% in black persons, 69% in white persons (p = 0.99). Testing differed significantly by institution for both EGFR and PDL1 testing (p < 0.001). When EGFR was not evaluated, PDL1 was evaluated 2% of the time but when EGFR was evaluated, PDL1 was evaluated 51% of the time. Conclusions: With the advent of biomarker-directed adjuvant therapy, EGFR and PDL1 testing are rising but testing levels are sub-optimal. Institutional factors influence testing.