Novel anti-HER2 ADCs vs dual anti-HER2 antibody for HER2-positive metastatic breast cancer failed to tyrosine kinase inhibitor.

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Both novel anti-human epidermal growth factor receptor 2 (HER2) antibody-drug conjugates (ADCs) and pertuzumab and trastuzumab (HP) combined with chemotherapy(C) regimens are the choice of treatment for HER2 positive metastatic breast cancer (MBC) after tyrosine kinase inhibitors (TKIs). Our team's previous research has shown significant therapeutic effects of novel anti-HER2 ADCs in patients with TKIs treatment failure. Unfortunately, there is currently no data available to compare novel anti-HER2 ADCs with HP combined with chemotherapy regimens. This study was conducted to compare the efficacy and safety of novel anti-HER2 ADCs with that of the HP combined with chemotherapy regimen in patients for whom TKI treatment failed. HER2-positive MBC who used novel anti-HER2 ADCs and HP combined with a chemotherapy regimen from January 2019 to August 2023 were included, and all patients received TKIs. The primary study endpoint was progression-free survival (PFS), while the secondary study endpoints were objective response rate (ORR), clinical benefit rate (CBR), and safety. A total of 150 patients, of which 83 are in the novel anti-HER2 ADCs group and 67 are in the HP combined with chemotherapy. Among these novel anti-HER2 ADCs, 36 patients received treatment with trastuzumab deruxtecan (T-Dxd), and 47 patients received treatment with other new types of ADCs. The median PFS of the novel anti-HER2 ADCs group and HP combined with the chemotherapy group were 7.0 months and 8.9 months, respectively, with ORR of 51.8% and 26.9%, and CBR of 69.9% and 65.7%, respectively. In subgroup, patients receiving T-Dxd showed improvement in PFS compared to the HP combined with chemotherapy group. The most common grade 3-4 adverse events in the novel anti-HER2 ADCs group and the HP combined with chemotherapy group were neutropenia and gastrointestinal symptoms. In HER2-positive MBC for whom TKI treatment has failed, novel anti-HER2 ADCs and the HP combined with chemotherapy regimen both showed moderate efficacy and tolerable toxicity. Novel anti-HER2 ADCs are the preferred treatment recommendation for TKI failure patients. Meanwhile, based on the results of this study, the HP combined with chemotherapy regimen may also be an option, especially for patients with low accessibility.