• Zhengbo Song, Yuping Li, Shiqing Chen, Shenpeng Ying, Shuguang Xu, Jianjin Huang, Dan Wu, Dongqing Lv, Ting Bei, Shuxun Liu, Xiaoping Huang, Congying Xie, Xiaoyu Wu, Jianfei Fu, Feng Hua, Wenxian Wang, Chunwei Xu, Chan Gao, Shangli Cai, Shun Lu, and Yiping Zhang.
• Department of Clinical Trial, Zhejiang Cancer Hospital, Hangzhou, 310022, China.
• Bmc Med. 2022 Feb 1; 20 (1): 42.

BackgroundThere is currently a lack of effective treatments for non-small cell lung cancer (NSCLC) patients harboring HER2 mutations. We examined the efficacy and safety of, and potential resistance mechanism to, pyrotinib, a pan-HER inhibitor, in advanced NSCLC carrying HER2 mutations.MethodsIn this multicenter, single-arm, phase II trial, stage IIIB-IV NSCLC patients harboring HER2 mutations, as determined using next-generation sequencing, were enrolled and treated with pyrotinib at a dose of 400 mg/day. The primary endpoint was 6-month progression-free survival (PFS) rate, and secondary endpoints were objective response rate (ORR), PFS, overall survival (OS), disease control rate (DCR), and safety. The impact of different HER2 mutation types on sensitivity to pyrotinib and the potential of utilizing mutational profile derived from circulating tumor DNA (ctDNA) to predict disease progression were also explored.ResultsSeventy-eight patients were enrolled for efficacy and safety analysis. The 6-month PFS rate was 49.5% (95% confidence interval [CI], 39.2-60.8). Pyrotinib produced an ORR of 19.2% (95% CI, 11.2-30.0), with median PFS of 5.6 months (95% CI, 2.8-8.4), and median OS of 10.5 months (95% CI, 8.7-12.3). The median duration of response was 9.9 months (95% CI, 6.2-13.6). All treatment-related adverse events (TRAEs) were grade 1-3 (all, 91.0%; grade 3, 20.5%), and the most common TRAE was diarrhea (all, 85.9%; grade 3, 16.7%). Patients with exon 20 and non-exon 20 HER2 mutations had ORRs of 17.7% and 25.0%, respectively. Brain metastases at baseline and prior exposure to afatinib were not associated with ORR, PFS, or OS. Loss of HER2 mutations and appearance of amplification in HER2 and EGFR were detected upon disease progression.ConclusionsPyrotinib exhibited promising efficacy and acceptable safety in NSCLC patients carrying exon 20 and non-exon 20 HER2 mutations and is worth further investigation.Trial RegistrationChinese Clinical Trial Registry Identifier: ChiCTR1800020262.© 2022. The Author(s).

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