Other ongoing clinical trials are testing if Chidamide, an HDACi developed in China, could sensitize breast tumors to the antitumor effects of PD-1 antibody and chemotherapeutic agents such as paclitaxel, carboplatin, or capecitabine in relapsed/metastatic HER2-negative or TNBC (NCT05749575, NCT05438706). This evidence concerns the gene PDCD1 and breast neoplasm.