Osimertinib as Second- and ≥Third-Line Treatment in Advanced and Recurrence EGFR-Mutant NSCLC Patients Harboring Acquired T790M Mutation

Background/objectives: Osimertinib is a standard sequential therapy for advanced and recurrent Epidermal Growth Factor Receptor (EGFR)-mutant non-small-cell lung cancer (NSCLC) patients with the T790M mutation, following treatment with first- or second-generation EGFR Tyrosine Kinase Inhibitors (TKIs). This study aims to investigate the differences in clinical outcomes between osimertinib as a 2nd-line treatment and as a ≥3rd-line treatment in this patient population.

Methods: Between September 2014 and March 2023, we enrolled advanced and recurrent T790M + NSCLC patients who had received osimertinib as sequential treatment for analysis. All patients had previously been treated with gefitinib, erlotinib, or afatinib as first-line therapy.

Results: A total of 158 patients who received osimertinib as sequential treatment were included in the final analysis. Of these, 99 patients (62.7%) received osimertinib as a 2nd-line treatment, while 59 patients (37.3%) were treated with osimertinib as ≥3rd-line therapy. The median progression-free survival (PFS) was 10.7 months for the 2nd-line group and 8.9 months for the ≥3rd-line group. The median overall survival (OS) from first-line treatment was 73.2 months in the 2nd-line group and 57.5 months in the ≥3rd-line group. No statistically significant differences in PFS or OS were observed between the two groups.

Conclusions: Our research demonstrated that osimertinib is effective not only as a 2nd-line therapy but also as a ≥3rd-line treatment, offering promising clinical benefits for advanced and recurrent EGFR-mutant NSCLC patients with acquired T790M mutations who have developed resistance to first- and second-generation EGFR-TKI therapy.