The goal of this clinical trial is to learn if tinengotinib combined with fulvestrant works to treat patients with HR-Positive and HER-2-Negative or low-expressing advanced breast cancer. It will also learn about the safety of combination therapy. The main questions it aims to answer are:
1. Does tinengotinib combined with fulvestrant reduce the tumor burden in participants?
2. What medical problems do participants have when taking the combination therapy?
Participants will:
Take tinengotinib and fulvestrant to find the optimal dose of tinengotinib for the combination therapy in Part A.
In Part B, will take tinengotinib at the optimal dose with fulvestrant or tinengotinib alone to see if the combination therapy works better than tinengotinib monotherapy.