Real-world outcomes of atypical EGFR-mutated metastatic non-small cell lung cancer (mNSCLC) treated with osimertinib (osi) vs. Afatinib or erlotinib

Objectives

Limited data are available comparing the efficacy of osi versus earlier generation TKIs for mNSCLC with atypical EGFR mutations (AMs) such as L861Q, G719X, S768I and exon20.

Methods

We performed a single-institution retrospective analysis of patients with EGFR-mutated mNSCLC treated from 2007 to 2023 with 1L TKIs, comparing outcomes for AM patients treated with osi, afatinib, and erlotinib. Baseline demographics, disease characteristics, treatment history, toxicity, and clinical outcomes were abstracted from the electronic medical record and compared between TKIs using independent sample t-tests and chi-square analyses. Median progression free survival (mPFS) and overall survival (mOS) were compared via Kaplan-Meier log-rank analysis and Cox multivariable regression.

Results

Among 355 patients with EGFR-mutated mNSCLC, 36 (10 %) harbored AMs in G719X (N=21; 6 %), Exon 20 (N=11; 3 %), L861Q (N=7; 2 %), S768I (N=4; 1 %), C797S (N=1; 0.3 %); 6 patients had compound mutations. Patients with classical mutations (CMs) vs AMs had similar baseline demographic and disease characteristics and usage of TKIs (p = 0.124). Among AM patients, osi yielded superior mPFS (22 m) vs afatinib (12 m; p = 0.005) or erlotinib (9 m; p = 0.001). mOS was likewise superior for osi (32 m) vs afatinib (21 m; p = 0.032) or erlotinib (17 m; p = 0.011). Dose-reduction rates due to AEs were lower for osi (19 %) vs afatinib (24 %; p = 0.003) or erlotinib (23 %; p = 0.002). Discontinuation rates due to AEs were lower for osi vs afatinib (1 % vs 2 %; p < 0.001) or erlotinib (2 %; p = 0.004).

Conclusions

In a large real-world analysis, osi demonstrated superior progression-free and overall survival and improved tolerability compared to afatinib or erlotinib for atypical EGFR-mutated mNSCLC.