Pembrolizumab for the better treatment of EGFR-mutant T790M-negative advanced lung adenocarcinoma patients than dual treatment of pemetrexed plus platinum after tyrosine kinase inhibitor treatment failure

Background: The treatment of lung cancer patients, especially those with epidermal growth factor receptor (EGFR)-mutant T790M-negative adenocarcinoma, after first- or second-line tyrosine kinase inhibitor (TKI) treatment failure is challenging due to the poor prognosis and limited effectiveness of platinum two-drug chemotherapy or chemotherapy plus anti-angiogenesis therapy. It is well-known that Pembrolizumab monotherapy exhibits low toxicity and long-term survival, but it is unknown in these patients. Methods: From September 2018 to March 2021, 460 patients in Jiangmen Central Hospital were included and 82 patients with disease progression in lung adenocarcinoma who remained T790M-negative on the second biopsy were screened. Two groups were divided according to treatment status, and simple random sampling was performed to obtain 32 cases respectively. The safety of the patients was subsequently evaluated by telephone follow-up. Results: The objective response rate (ORR) and disease control rate (DCR) in the pembrolizumab group were 15.63% and 53.13%. In the chemotherapy group, the ORR was 8.33% and the DCR was 25% (P<0.05). In the pembrolizumab group, the progression-free survival (PFS) [14.65 months, 95% confidence interval (CI): 13.03 to 16.28] was significantly higher than that of the control group (9.54 months, 95% CI: 8.43 to 10.65) (P<0.05). In the univariate analysis, programmed cell death protein 1 ligand (PD-L1) expression, smoking status, gender, and whether first-line chemotherapy was associated with survival. In the multivariate analysis, gender [P=0.001; hazard ratio (HR) 10.98, 95% CI: 2.49-46.67], first-line chemotherapy (P=0.037; HR 4.5, 95% CI: 1.1-4.81), and PD-L1 expression (P=0.039; HR 0.16, 95% CI: 0.04-0.68) were correlated with patient survival. Grade 3 or grade 4 treatment-related adverse events were not found in the pembrolizumab group, while 2 cases of grade 3 or 4 treatment-related adverse events occurred in the control group. Conclusions: In advanced lung adenocarcinoma patients with EGFR-mutant T790M-negative after TKI treatment, pembrolizumab had a higher ORR and PFS. Pembrolizumab in women with first-line chemotherapy and PD-L1 >= 25% of those patients may have a good response and a low rate of adverse reactions. A multicenter, prospective, evidence-based study of pembrolizumab salvage therapy in those patients is warranted for posterior line treatment.