Real-world clinical outcomes and toxicity in metastatic breast cancer patients treated with palbociclib and endocrine therapy.

Among patients with HR-positive advanced breast cancer, the estimated PFS in patients treated with fulvestrant and palbociclib was comparable to a previously reported phase 3 trial. However, the median PFS with letrozole and palbociclib was shorter than previously reported data from phase 2 and 3 trials. Palbociclib toxicity was very manageable, with a low drug discontinuation rate.