Palbocilcib is a first-in-class drug, that demonstrated in several studies, improvements in progression-free-survival, in combination with endocrine therapy. Palbociclib with fulvestrant improved progression-free survival in hormone receptor-positive, HER2-negative advanced breast cancer. The author reports the case of a 63-year-old metastatic breast cancer patient, positive for hormonal receptors, that had received multiple chemotherapy regimens. She was treated with palbociclib plus fulvestrant. Three months later she obtained partial response. However she also experienced side-effects such as grade IV neutropenia and grade III thrombopenia, that led to palbociclib reduction.