Elderly patients with advanced HER2-positive breast cancer with liver metastases benefit from low dose disitamab vedotin (RC48): case series and literature review.

Currently, although some antibody-drug conjugates have been shown to be safe and effective in the treatment of drug-resistant relapsed human epidermal growth factor receptor 2 (HER2)-positive (IHC 3+ or IHC 2+/fluorescence in situ hybridization+) breast cancer, they are already approved for clinical use in China. But the clinical needs of advanced HER2-positive patients cannot be met due to adverse reactions, drug resistance, drug accessibility and other problems, thus affecting the prognosis of patients. In particular, the representation of elderly and frail patients in randomized clinical trials is significantly under-represented. We report on two elderly women with breast cancer who developed recurrent metastatic lesions after breast cancer surgery and were again confirmed HER2-positive by histopathology and immunohistochemistry. They all developed multiple metastases in the liver after second- or third-line anti-HER2 therapy. Subsequent treatment with RC48 produced good responses and tolerable adverse reactions. One patient obtained progression-free survival for more than 7 months. Based on preliminary evidence, this study shows that RC48 in HER2-positive breast cancer with liver metastases can achieve rapid remission, thereby reducing tumor load and improving patients' quality of life. In particular, RC48 has low side effects and can be well tolerated by elderly patients after dose adjustment, providing them with treatment opportunities. It needs to be further discussed in the future research.