Cyclin-dependent kinases 4 and 6 (CDK4/6) inhibitors combined with hormonal therapy are the current standard frontline treatment for patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2 (HER-2)-negative metastatic breast cancer (MBC). However, the optimal treatment after progression on CDK4/6 inhibitors remains unknown. Anlotinib is an oral multi-target tyrosine kinase inhibitor (TKI) that strongly inhibits VEGFR, PDGFR, FGFR, and c-kit. This study aimed to evaluate the safety and efficacy of anlotinib-based combination therapy in patients with HR+ MBC previously treated with a CDK4/6 inhibitor.
Female patients aged 18 to 75 years, with an ECOG score of 0-1, and an expected survival of at least 3 months;
Presence of measurable lesions as defined by RECIST 1.1 criteria;
Histopathologically confirmed HR-positive/HER2-negative breast cancer. HER2 negativity is determined by an immunohistochemistry (IHC) result of HER2 (0/1+). If the result is HER2 (++), a FISH or CISH test is required to confirm the absence of HER2 amplification;
Patients who have undergone multiple lines of advanced therapy with no remaining standard treatment options;
Patients with HER2-positive breast cancer confirmed by histology or cytology;
Patients who discontinued therapy due to non-disease progression reasons, such as adverse events or other non-medical factors;
Detection of a second primary malignant tumor at the time of enrollment;
Failure to complete CDK4/6 inhibitor therapy;