Effect Of EGFR Exon 20 Insertion Different Subtypes And Co-occurring EGFR Amplification On EGFR Tyrosine Kinase Inhibitors

BackgroundEpidermal growth factor receptor exon 20 insertion(EGFR ex20ins)mutation is the third most common type of EGFR mutation in non-small cell lung cancer(NSCLC).Most EGFR ex20ins are generally refractory to the 1st and 2nd generation EGFR tyrosine kinase inhibitors(EGFR-TKIs)and associated with poor prognosis.Preclinical studies revealed that EGFR ex20ins has multiple subtypes,of which EGFR p.A763_Y764insFQEA is sensitive to EGFR-TKIs,whether other TKI-sensitive subtypes exist is worth investigating.At the same time,EGFR ex20ins are often co-occurring with EGFR amplification,but there is a lack of studies on patients with EGFR ex20ins and EGFR amplification.Chemotherapy is still the standard treatment for patients with EGFR ex20ins.Although several clinical trials of targeted therapy are ongoing,their efficacy on EGFR ex20ins is limited.How to improve the efficacy of EGFR ex20ins has become an urgent issue.The purpose of this study was to investigate the sensitivity of different EGFR ex20ins subtype and co-occurring EGFR amplification to differences EGFR-TKIs.MethodsThis study is divided into three parts:the first part analyzes the prevalence,clinical and genetic characteristics of EGFR ex20ins patients;the second part is a cytological study of the sensitivity of different EGFR ex20ins subtype to differences EGFR-TKIs;the third part is the predictive effect of EGFR ex20ins with EGFR amplification on the efficacy of EGFR-TKIs.1.The study included a cohort of NSCLC patients with activating EGFR mutations were selected from database of Guangdong Provincial People’s Hospital from December 2016 to February 2019.Among them,patients with an EGFR ex20ins mutation were retrospectively analyzed for prevalence,clinical and genetic characteristics.2.Using Erlotinib,Osimertinib,Poziotinib and a new EGFR ex20ins inhibitor(a new clinical research drug,inhibitor N)to treat Ba/F3 cell carrying EGFR ex20ins exogenous gene(p.N771_H773dup and p.S768_D770dup).verify the sensitivity of different subtypes of EGFR ex20ins to different EGFR-TKIs.3.For the cohort of EGFR ex20ins patients in Part 1,who had tissue sample and were referred to the same genetic company for targeted next generation sequencing(NGS)test were selected.they were divided into amplified and non-amplified groups based on whether they have co-occurring EGFR amplification.Clinical and genetic data were compared between the two groups to explore the characteristics of patients harboring EGFR ex20ins with EGFR amplification.And the patients were followed up for progression-free survival(PFS)and overall survival(OS)to analysis predictive effect on EGFR-TKIs.Results1.There were 70 patients with EGFR ex20ins,accounting for 2.1%of all 3350 NSCLC patients.18 different subtypes of EGFR ex20ins were identified.The most frequent subtypes is p.A767_D770dup(20%),followed by p.S768_D770dup(19%),and p.A763_Y764insFQEA(7%).The most Common co-mutations were TP53 mutations(63.8%),EGFR amplification(34.5%),CDK4 amplification(15.5%),and PDGFRA amplification(10.3%).2.Four different EGFR-TKIs(erlotinib,ositinib,Poziotinib,and drug N)were used to treat two different subtypes of EGFR ex20ins cells(p.N771_H773dup and p.S768_D770dup)in vitro.We found that among the four drugs,Poziotinib has a relatively good inhibitory effect,inhibitor N and Osimertinib have a relatively moderate inhibitory effect,and Erlotinib has a relatively poor inhibitory effect.3.31 patients were included in the analysis of clinical characteristics.Patients with EGFR ex20ins were divided into non-amplified and amplified groups according to whether they had co-occurring EGFR amplification.There were no significant differences in clinical characteristics between the two groups.Survival analysis included 26 patients with treatment data.The median OS of the non-amplified group and the amplified group were 451 and 715 days,respectively,with no significant difference(P=0.912).The chemotherapy group included patients who received chemotherapy.In the chemotherapy group,the PFS of the unexpanded group and the expanded group were 112 days and 206 days,respectively,with no significant difference(P=0.425).The EGFR-TKIs group included patients who received EGFR-TKIs.In the EGFR-TKIs group,the PFS in the non-amplified group was significantly longer than that in the amplified group,with PFS of 110 days and 31 days,respectively(P=0.030).Conclusions1.The three most common subtypes of EGFR ex20ins are p.A767_D770dup,p.S768_D770dup and p.A763_Y764insFQEA.EGFR ex20ins is often co-occurring with EGFR amplification.2.Different subtypes of EGFR ex20ins demonstrated diverse sensitivity to different EGFR-TKIs.However,the overall inhibitory effect is relatively weak.In the future,better EGFR ex20ins inhibitors need to be explored.3.EGFR ex20ins with EGFR amplification is a poor predictor of EGFR-TKIs.