ESR1 and breast carcinoma: The phase I JAVELIN study was conducted in patients with metastatic breast cancer who were treated with avelumab, an anti-PD-L1 antibody, and the results showed that the ORR was 5.2%, with a higher ORR in PD-L1+ tumors (16.7%) and TNBC (22.2%) compared to HER2+ and ER+ breast cancer (2.6%) [233].