The Efficacy And Safety Of Osimertinib In Advanced Non-small Cell Lung Cancer Patients With EGFR T790M Mutation Detected By First And Repeat Rebiopsy

Background Osimertinib could effectively target epidermal growth factor receptor(EGFR)T790M resistance mutations in non-small cell lung cancer(NSCLC),indicating that rebiopsy is particularly important.However,the clinical benefit of repeat rebiopsy in T790M-negative patients with NSCLC detected by the first rebiopsy is still unclear and data on the efficacy and safety of osimertinib in patients with NSCLC who are T790 M positive patients on repeat rebiopsy remain rare.Methods We retrospectively collected the clinical data of advanced non-small cell lung cancer(NSCLC)patients with common EGFR mutation who were treated with 1/2generation EGFR-tyrosine kinase inhibitors(TKIs)in first-line therapy in the respiratory department of Anhui Provincial Cancer Hospital from January 2018 to December 2020.The detection rate of T790 M by first and repeat rebiopsy were recorded,and we also analyzed the efficacy and safety of osimertinib for T790 M positive patients.Results Among 190 common EGFR-mutant patients who received 1/2G EGFR-TKIs with advanced NSCLC in the first-line treatment,141 patients got a progressive disease.110 of 141 accepted the first rebiopsy,and the result shows T790 M prevalence was50.9%(56/110).43 T790 M positive patients who received osimertinib were included in the first rebiopsy group.Of 54 T790 M negative patients detected by the first rebiopsy,28 underwent repeated rebiopsy in subsequent clinical treatment and 10(35.7%)T790M-positive cases were confirmed.8 T790 M positive patients treated with osimertinib were included in the repeat rebiopsy group.Overall,66(60%)of 110 patients got acquired T790 M mutation.In patients with the 790 M mutation discovered by the first and repeat rebiopsy,osimertinib resulted in median progression-free survival(PFS)of 7 [95% confidence interval(CI): 5.3-8.7] and 6(95% CI: 4.7-7.3)months,respectively(P=0.656).The median overall survival(m OS)since osimertinib initiation for T790M-positive patients at first rebiopsy was 20(95% CI:15.1-24.9)months and 19(95% CI:16.9-21.1)months for those at repeated rebiopsy.(P = 0.888).The incidence of serious adverse events were similar in the two groups(25.6% vs.12.5%,P = 0.616).There was no treatment-related death in the two groups.Conclusions Repeat rebiopsy can increase the T790 M mutation cumulative detection rate.osimertinib was shown similar efficacy and safety in T790 M positive patients whether detected by the first or repeat rebiopsy.