ibrance with an aromatase inhibitor is for postmenopausal women or for men with hr+/her2- metastatic breast cancer, as the first hormonal based therapy. ibrance plus letrozole significantly delayed disease progression versus letrozole, and shrank tumors in over half of patients. patients taking ibrance can develop low white blood cell counts, which may cause serious infections that can lead to death. ibrance may cause severe inflammation of the lungs that can lead to death. tell your doctor right away if you have new or worsening symptoms, including trouble breathing, shortness of breath, cough, or chest pain. before taking ibrance, tell your doctor if you have fever, chills, or other signs of infection, liver or kidney problems, are pregnant, breastfeeding, or plan to become pregnant. common side effects include low red blood cell and low platelet counts, infections, tiredness, nausea, sore mouth, abnormalities in liver blood tests, diarrhea, hair thinning or loss, vomiting, rash, and loss of appetite. be in your moment. ask your doctor about ibrance.