[Treatment Experience of Palbociclib as a New Checkpoint Inhibitor].

We encountered a case of multiple metastases from breast cancer. The patient was administered palbociclib, which was a new checkpoint inhibitor. The patient received various chemotherapies and endocrine therapies. We observed episode of care, a harm phenomenon, and tolerability. We did not recognize adverse events more severe than Grade 3 during the 6 weeks after initiating palbociclib therapy. Diagnostic imaging showed that the metastatic lesions maintained stable disease during the 6 weeks after initiating palbociclib therapy. This case suggested that palbociclib therapy is useful for patients with metastatic breast cancer.