A Real-World Analysis of Immune Checkpoint Inhibitor-Based Therapy After Osimertinib Treatment in Patients With EGFR-Mutant NSCLC

Introduction: The use of immune checkpoint inhibitors (ICIs) with chemotherapy has increased the survival of patients with advanced NSCLC. Nevertheless, the efficacy of ICI treatment for NSCLC with EGFR mutations is limited. Previous studies have not evaluated the efficacy of ICI treatment after osimertinib treatment in real-world settings. Methods: This study performed a retrospective analysis of the association between clinical characteristics and ICI efficacy in patients with EGFR-mutant NSCLC treated with ICIs after osimertinib treatment at 12 institutions in Japan from March 2016 to March 2021. Results: Among 80 patients with EGFR-mutant lung cancer, 42 received ICI monotherapy and 38 received chemoimmunotherapy. In the chemoimmunotherapy group, the progression-free survival (PFS) was significantly longer in the group that exhibited PFS more than 10 months with osimertinib than in the group that exhibited PFS less than or equal to 10 months with osimertinib (8.4 mo versus 3.8 mo, p = 0.026). Nevertheless, there was no significant difference in PFS in the ICI monotherapy group (1.7 mo versus 1.5 mo, p = 0.45). Regardless of the EGFR mutation subtype, PFS of osimertinib treatment was a predictor of the PFS of chemoimmunotherapy (exon 19 deletion mutation: p = 0.03 and exon 21 L858R mutation: p = 0.001). Conclusions: The PFS of osimertinib might be a predictor of PFS of chemoimmunotherapy in patients with EGFR-mutant NSCLC. Further clinical investigations on the predictors of efficacy of administering ICIs after osimertinib treatment are required.