PTHrP is a well-known factor for malignancy-induced hypercalcemia and tumor-bone interactions in breast cancer bone metastasis30,31; thus, anti-PTHrP antibodies have long been used to suppress cancer progression and metastasis.32–35 However, anti-PTHrP antibodies have never been tested in combination with immune checkpoint inhibitors in cancer patients or murine tumor models, which is an important direction for further studies. Here, PTHLH is linked to breast cancer.