Liquid biopsy detects genomic drivers in NSCLC without EGFR mutations by single-plex testing: WJOG13620L.

Background: Actionable tumor genomic alterations, primarily EGFR mutations, occur in nearly 70% of Japanese advanced nonsquamous non-small cell lung cancer (NSCLC) patients. Standard assessment of tumor tissue includes rapid testing for EGFR mutations, ALK fusions and ROS1 fusions. We conducted a prospective observational study (WJOG13620L) of follow-on next-generation sequencing of circulating tumor DNA (ctDNA) in patients without driver alterations after EGFR testing.

Methods: Patients with untreated advanced (Stage IIIB-IV or relapsed) nonsquamous NSCLC without EGFR mutations according to single-plex testing of tumor tissue, were enrolled into this study. Patients with other known driver mutations or who underwent comprehensive genomic profiling were excluded. Plasma was analyzed by Guardant360, and the primary endpoint was the proportion of patients with pathogenic gene alterations in at least one of nine genes.

Results: Among the 72 patients enrolled, ALK and ROS1 fusions were tested in 86.1% and 65.2%, respectively. Alterations in pre-defined genes were detected in 21 patients (29.2%; 95% confidence interval: 19.0-41.1, p < 0.001 [one-sided null hypothesis proportion of 10%]), including RET fusion (n = 1) and mutations in KRAS (n = 11), EGFR (n = 5), ERBB2 (n = 3), and BRAF (n = 1). Median time from sample submission to results was 8 days (range, 5-17 days).

Conclusion: Rapid follow-on comprehensive testing of ctDNA should be considered prior to first-line treatment for patients with advanced nonsquamous NSCLC when no alterations are detected after single-plex tissue testing.