EGFR gene mutation abundance predicts survival in NSCLC patients

In patients with nonsmall cell lung cancer (NSCLC), plasma epidermal growth factor receptor (EGFR) mutation abundance shows a significant association with survival benefit, reveals a study.

Such finding may be important in predicting the efficacy of EGFR tyrosine kinase inhibitor (TKI) targeted therapy, according to the investigators.

A retrospective analysis was carried out on 120 patients with advanced NSCLC. Fifty-six patients with EGFR-mutation-positive NSCLC who received first-line treatment with osimertinib were screened and included in this study.

The investigators used cSMART to determine the baseline status and abundance of plasma EGFR in NSCLC patients, with the 0.1 ratio as the critical value. They also performed imaging tests every 8‒12 weeks to assess tumour response. Finally, an analysis was conducted on the association of baseline EGFR mutation abundance with the clinical outcomes of TKI therapy.

The objective response rate (ORR) of EGFR-mutant patients was 69.2 percent in the high-abundance group and 40.0 percent in the low-abundance group. ORR was significantly higher in the high- versus low-abundance group (p=0.029).

Patients with high mutation abundance also had a longer median progression-free survival (PFS) than those with low abundance (11.2 vs 7.1 months; p=0.0133). The same trend was observed for the median overall survival (OS) in both groups (15.5 vs 10.7 months; p=0.0028).

Multivariate Cox regression analysis confirmed the independent association of plasma mutation abundance with both PFS (hazard ratio, 0.30; p=0.006) and OS (hazard ratio, 0.35; p=0.004).

“Our study is expected to provide a research basis for screening patients to whom the EGFR-TKI therapy is beneficial,” the investigators said.