Limitations
Besides, there were several limitations in this study. First, only 30 eligible patients were included in our study, and the subgroup analysis relied on a small number of subjects, which would affect the accuracy of results. Besides, it was of great urgency to explore and unveil alternative treatment option for highly pretreated patients with ER+/HER2- MBC. Hence, only a limited number of clinical cases were involved in this preliminary attempt. Second, this study was a single-arm, single-center, non-blind study with no control group, which could inevitably lead to some biases. Therefore, more clinical cases will be continuously accumulated to conduct larger sample size, multi-center, randomized and controlled clinical trials to provide definitive validation for the use of apatinib plus exemestane as a follow-up strategy against ER+/HER2- MBC.