Testing Patterns and Detection of Exon 20 Insertions in the United States.

Introduction: exon 20 insertions () are a diverse set of mutations in NSCLC that are refractory to tyrosine kinase inhibitors. We describe real-world detection patterns in patients with advanced NSCLC in the United States.

Methods: Data from 2011 to 2020 were extracted from the Flatiron Health electronic health record-derived deidentified database.

Results: Among 67,281 patients with advanced NSCLC and at least two clinic visits, 66.8% were tested for mutations, of whom 13.9% tested positive. Of these, 4.9% had . The median time from NSCLC diagnosis to the first positive test result was 23 days, including 9 days of laboratory testing time. The were reported in 0.6% to 1.0% of all patients with advanced NSCLC and account for 3.9% to 5.3% of all mutations. During the study period, reverse transcription-polymerase chain reaction testing rates decreased whereas next-generation sequencing rates increased both in overall and among patients with tumors positive for . Tissue was the most common sample type used for and detection (81.1% and 84.9%, respectively), whereas blood sampling for detection increased from 0% (2011) to 37.2% (2020). For 23.7% of patients with , treatment was initiated before receiving the first positive test result, with therapies including immuno-oncology agents as the most common treatment type from 2017 to 2020.

Conclusions: testing and detection of in patients with NSCLC have increased slightly over time with the increasing use of next-generation sequencing. The current late-stage development of -targeted therapy is driving a need for more efficient testing.