Clinical Management in NSCLC Patients With EGFR Mutation After Osimertinib Progression With Unknown Resistance Mechanisms

Abstract

Background: Osimertinib is approved as a standard treatment for non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutation by FDA. However, the mechanisms of resistance for nearly half of patients after osimertinib progression are still unknown, and the optimal therapies for these patients are still controversial. In this retrospective study, we compared efficacy and safety between immunotherapy + chemotherapy, chemotherapy alone, and osimertinib + bevacizumab in NSCLC patients after osimertinib progression with unknown resistance mechanisms.

Methods: Advanced NSCLC patients with unknown resistance mechanisms after osimertinib progression were retrospectively reviewed and divided into immunotherapy + chemotherapy, chemotherapy alone, and osimertinib + bevacizumab treatment groups according to the treatment they received after osimertinib progression. Clinicopathological features, objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) were compared between groups.

Results: A total of 121 patients were enrolled in this study, 22 in the immunotherapy + chemotherapy group, 72 in the chemotherapy group, and 27 in the osimertinib + bevacizumab group. The ORR was much higher in the immunotherapy + chemotherapy group compared with chemotherapy or osimertinib + bevacizumab group (55.56% vs. 14.81% vs. 0% in patients after progression on 1st line osimertinib treatment; 30.77% vs. 6.67% vs. 13.33% in patients after progression on 2nd/3rd line osimertinib treatment). Median PFS was also significantly longer in the immunotherapy + chemotherapy group compared with other groups (8.2 months vs. 4.0 months vs. 6.0 months in all patients, p = 0.0066). The median OS did not reach remarkable difference among groups, although osimertinib + bevacizumab group had a numerically longer median OS (37.0 months vs. 37.0 months vs. 47.6 months in all patients, p = 0.6357). Compared with immunotherapy + chemotherapy and chemotherapy, treatment-related adverse events (AEs) of osimertinib + bevacizumab were milder, especially in AEs related to gastrointestinal and bone marrow suppression.

Conclusion: Our study provides clinical evidence that NSCLC patients after osimertinib progression with unknown resistance mechanisms may benefit from immunotherapy + chemotherapy, with higher ORR and longer PFS compared with osimertinib + bevacizumab or chemotherapy groups. Osimertinib + bevacizumab treatment was also an optional option for patients because OS was numerically longer and safer in this group.

Keywords: EGFR mutation; NSCLC; chemo‐immunotherapy; osimertinib; resistance.