A large real-world study on the effectiveness of the combined inhibition of EGFR and MET in EGFR-mutant advanced non-small cell lung cancer (NSCLC).
Authors: Li Liu , Qu Jingjing , Heng Jianfu , Zhou Chunhua , Xiong Yi , Yang Haiyan , Jiang Wenjuan , Zeng Liang , Zhu Songlin , Zhang Yongchang , Tan Jiarong , Hou Ting , Lizaso Analyn , Chen Zhiqiu , Hu Chengping , Deng Pengbo , Yang Nong 
Published: June 2021

9043 Background: MET amplification is an important mechanism mediating acquired resistance to EGFR tyrosine kinase inhibitors (TKI). Until now, no consensus exists on the standard treatment strategy for this subset of patients due to the lack of clinical data from large cohort or controlled trials. In our clinical practice, three regimens were commonly administered to patients after MET amplification-mediated EGFR-TKI progression: EGFR-TKI and MET-TKI combination therapy, MET-TKI monotherapy, or chemotherapy. Our study aimed to compare the effectiveness of these three regimens. Methods: Seventy patients with EGFR-mutant advanced NSCLC who progressed from prior EGFR-TKI through the acquisition of MET amplification and received treatment between March 2015 and March 2020 were included in this study. Of them, 38 received EGFR-TKI plus crizotinib, 10 received crizotinib monotherapy, and 22 received platinum-based doublet chemotherapy. Somatic mutation profiling was performed on blood and tissue biopsy samples. Resistance mechanisms to the combination targeted therapy were also explored in 12 patients. Results: The objective response rate (ORR) and disease control rate (DCR) were 47.5% and 84.0% for EGFR-TKI+crizotinib group, 40.0% and 70.0% for crizotinib monotherapy group, and 18.2% and 50.0% for chemotherapy group, respectively. The EGFR-TKI+crizotinib group had significantly better ORR (P = 0.026) and DCR (P = 0.016) than the chemotherapy group but was not statistically different from the crizotinib monotherapy group (ORR, P = 0.73; DCR, P = 0.39). Progression-free survival (PFS) was significantly longer for the EGFR-TKI+crizotinib group than those who received crizotinib monotherapy (5.0 vs 2.3 months, P = 0.004) or chemotherapy (5.0 vs 2.9 months, P = 0.036), but overall survival was comparable (10.0 vs 4.1 vs 8.5 months, P = 0.088). TP53 mutation (58.5%) and EGFR amplifications (42.9%) were the two common concurrent mutations in the three cohorts. PFS was significantly longer for patients with either concurrent TP53 mutation (n = 17) (6.0 vs 2.3 vs 2.9 months, P = 0.009) or concurrent EGFR amplification (n = 13) (5.0 vs 1.2 vs 2.4 months, P = 0.016) who received EGFR-TKI+crizotinib. Potential molecular mechanisms of acquired resistance to EGFR-TKI+crizotinib therapy included EGFR T790M (n = 2), EGFR L718Q (n = 1), EGFR S645C (n = 1), MET D1228H (n = 1), BRAF V600E (n = 1), NRAS Q61H (n = 1), and amplifications in KRAS (n = 2), ERBB2 (n = 1), CDK4 (n = 1), and MYC (n = 2). Conclusions: Our study provides real-world clinical evidence, in the largest cohort to date, that simultaneous inhibition of EGFR and MET improves clinical outcomes of patients with EGFR-mutant NSCLC who acquired MET amplification from prior EGFR-TKI therapy, indicating that combinatorial regimen of EGFR-TKI and MET-TKI could be a more effective therapeutic strategy in this subset of patients.