[Analysis of the Efficacy of Immunotherapy on the Posterior Lines of Advanced EGFR Mutant Patients with Non-small cell Lung Cancer].

Background Immune checkpoint inhibitor monotherapy is reported to have little effect in advanced non-small cell lung cancer (NSCLC) patients with driver oncogenes. However, recent studies have shown that some patients with driver genes are still benefit from combination immunotherapy after tyrosine kinase inhibitors (TKIs) drug resistance. The purpose of this study was to analyze the efficacy of posterior line immunotherapy in NSCLC patients with epidermal growth factor (EGFR) sensitive mutation, and to evaluate the value of immunotherapy in posterior line therapy in patients with advanced EGFR mutation. Methods A total of 27 patients with EGFR mutation diagnosed in Beijing Chest Hospital, Capital Medical University from June 2018 to November 2020 were collected. After the progress of targeted therapy, they had received programmed cell death protein 1 (PD-1) checkpoint inhibitor combined with chemotherapy and anti-angiogenic drug therapy. Results Of the 27 advanced NSCLC patients, 19 cases (70.4%) did not have T790M mutation. There were 8 cases (29.6%) with T790M point mutation. The total objective response rate (ORR) was 40.7%. Kaplan-Meier survival analysis showed that there was no statistically significant difference among different EGFR mutations (χ²=4.15, P=0.230). But progression-free survival (PFS) was significantly longer in patients without T790M mutation than in patients with T790M mutation (9.2 mon vs 3.3 mon, χ²=2.808, P=0.041), and the same trend was observed in patients with overall survival treated with the PD-1 inhibitor (12.2 mon vs 7.3 mon, χ²=3.22, P=0.062). ORR of patients without T790M was significantly better than that with T790M (52.63% vs 12.5%, P=0.045). Conclusions Patients with EGFR mutation can benefit from later-line combined immunotherapy. The patients with T790M mutation in the population of EGFR mutation had the worst effect of immunotherapy in the later line. Therefore, the follow-up treatment and whole-course management of these patients need to explore better treatment strategies to improve the benefit.