Retrospective Analysis of HER2 Testing, Treatment Patterns, and Clinical Outcomes in Patients With Locally Advanced...

HER2 (ERBB2) gene mutations are associated with poor prognosis in non-small cell lung cancer (NSCLC). It is important to identify patients with HER2-mutant (HER2m) NSCLC, as new targeted treatment options are emerging. However, HER2 testing in clinical practice varies across regions, and real-world data on HER2m NSCLC are limited.

This retrospective study included patients from the Epidemio-Strategy and Medical Economics Lung Cancer database (NCT03848052) diagnosed with locally advanced or metastatic (LAM) NSCLC in France (January 1, 2015-December 31, 2020); patients were followed up until April 1, 2022. Data were extracted on April 2, 2022. Primary objectives were to describe the frequency of HER2 testing and test results. Secondary objectives included describing patient characteristics, treatment patterns, and clinical outcomes (stratified by HER2 testing status/results; landmark analyses were conducted to avoid immortal time bias).

Of 18,069 patients with nonsquamous LAM NSCLC, or squamous LAM NSCLC and no history of smoking, 7530 (41.7%) underwent HER2 testing. Median (interquartile range) time between LAM NSCLC diagnosis and first HER2 test result was 28 days (18-49). Of those tested, 152 (2.0%) had a HER2 mutation (HER2m cohort). In the HER2m cohort, 62.5% (n/N = 85/136) of patients received their first HER2 test result prior to first-line treatment; platinum-based chemotherapy was the most frequently received first-line treatment (52.9%, n/N = 72/136), followed by immunotherapy in the second-line setting (29.2%, n/N = 26/89). At 6-month landmark analysis, median (95% confidence interval) overall survival was 18.6 months (14.3-22.5) in the HER2m cohort.

This real-world study demonstrates the low frequency of HER2 testing and potential poor prognosis for patients diagnosed with LAM HER2m NSCLC in France between 2015 and 2020. Despite the low prevalence of HER2m NSCLC, these data highlight the importance of routine HER2 testing to enable patients with HER2m NSCLC to receive treatments that can improve clinical outcomes.