Choong-Kun Lee1, Sora Kim2, Jae Seok Lee3, Jeong Eun Lee4, Sung-Moo Kim5, In Seok Yang2, Hye Ryun Kim1, Jeong Ho Lee4, Sangwoo Kim6, Byoung Chul Cho7. 1. Division of Medical Oncology, Department of Internal Medicine, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, Korea. 2. Severance Biomedical Science Institute, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul, Korea. 3. Department of Pathology, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, Korea. 4. Graduate School of Medical Science and Engineering, KAIST, Daejeon, Korea. 5. JE-UK Laboratory of Molecular Cancer Therapeutics, Yonsei Cancer Institute, Yonsei University College of Medicine, Seoul, Korea. 6. Severance Biomedical Science Institute, Brain Korea 21 PLUS Project for Medical Sciences, Yonsei University College of Medicine, Seoul, Korea. Electronic address: SWKIM@yuhs.ac. 7. Division of Medical Oncology, Department of Internal Medicine, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, Korea; JE-UK Laboratory of Molecular Cancer Therapeutics, Yonsei Cancer Institute, Yonsei University College of Medicine, Seoul, Korea. Electronic address: cbc1971@yuhs.ac.
Abstract
OBJECTIVES: Despite initial responses to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) in EGFR mutant non-small cell lung cancer, patients invariably develop acquired resistance. In this study, we performed next-generation sequencing in pre- and post-EGFR-TKI tumor samples to identify novel resistance mechanisms to EGFR-TKIs. MATERIAL AND METHODS: We collected tumor tissues before EGFR-TKI treatment and after progression from 19 NSCLC patients to analyze genomic alterations in 409 cancer related genes. Bioinformatics analyses were used to identify mutations in which the allele frequencies are significantly changed, or newly appeared after progression. RESULTS: Overall, mutation rates and compositions were similar between pre- and post-EGFR-TKI tumors. We identified EGFR T790M as the most common mechanism of acquired resistance (63.2%). No pre-EGFR-TKI tumor had a preexisting T790M mutation, suggesting that tumors acquired T790M mutations following progression on EGFR-TKIs. Compared to T790M-positive tumors, T790M-negative tumors showed relatively high tumor mutation burden and shorter survival, suggesting T790M-negative patients as a potential candidate for immune checkpoint inhibitors. TP53 mutation was also significantly enriched in the T790M-negative tumors. Finally, we described here for the first time a novel missense mutation (T263P), which occurred concurrently with an activating G719A mutation, in the extracellular domain II of EGFR in a patient with poor response to erlotinib. Ba/F3 cells harboring EGFR T263P/G719A mutation showed higher sensitivity to afatinib, compared to gefitinib due to inhibition of EGFR/HER2 heterodimerization. CONCLUSION: Comprehensive genomic analysis of post-EGFR-TKI tumors can provide novel insight into the complex molecular mechanisms of acquired resistance to EGFR-TKIs.
OBJECTIVES: Despite initial responses to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) in EGFR mutant non-small cell lung cancer, patients invariably develop acquired resistance. In this study, we performed next-generation sequencing in pre- and post-EGFR-TKI tumor samples to identify novel resistance mechanisms to EGFR-TKIs. MATERIAL AND METHODS: We collected tumor tissues before EGFR-TKI treatment and after progression from 19 NSCLCpatients to analyze genomic alterations in 409 cancer related genes. Bioinformatics analyses were used to identify mutations in which the allele frequencies are significantly changed, or newly appeared after progression. RESULTS: Overall, mutation rates and compositions were similar between pre- and post-EGFR-TKI tumors. We identified EGFRT790M as the most common mechanism of acquired resistance (63.2%). No pre-EGFR-TKI tumor had a preexisting T790M mutation, suggesting that tumors acquired T790M mutations following progression on EGFR-TKIs. Compared to T790M-positive tumors, T790M-negative tumors showed relatively high tumor mutation burden and shorter survival, suggesting T790M-negative patients as a potential candidate for immune checkpoint inhibitors. TP53 mutation was also significantly enriched in the T790M-negative tumors. Finally, we described here for the first time a novel missense mutation (T263P), which occurred concurrently with an activating G719A mutation, in the extracellular domain II of EGFR in a patient with poor response to erlotinib. Ba/F3 cells harboring EGFRT263P/G719A mutation showed higher sensitivity to afatinib, compared to gefitinib due to inhibition of EGFR/HER2 heterodimerization. CONCLUSION: Comprehensive genomic analysis of post-EGFR-TKI tumors can provide novel insight into the complex molecular mechanisms of acquired resistance to EGFR-TKIs.