The U.S. Food and Drug Administration approved palbociclib (Ibrance) in combination with fulvestrant for the treatment of patients with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced or metastatic breast cancer who have experienced disease progression following endocrine therapy.1
Approval is based on findings from an international, double-blind, placebo-controlled study that compared palbociclib plus fulvestrant to placebo plus fulvestrant in women with disease progression on or after prior adjuvant or metastatic endocrine therapy.
Results showed that among 521 patients, median progression-free survival was 9.5 months with palbociclib compared with 4.6 months with placebo (HR, 0.46; 95% CI, 0.36 – 0.59; P < .0001).
Participants were randomly assigned 2:1 to receive palbociclib 125 mg orally daily on days 1-21 of each 4-week cycle or placebo, plus fulvestrant 500 mg intramuscularly on days 1, 15, 29, and once monthly thereafter.
In terms of safety, the most common adverse events associated with palbociclib were neutropenia, leukopenia, infections, fatigue, nausea, anemia, stomatitis, headache, diarrhea, thrombocytopenia, constipation, vomiting, alopecia, rash, decreased appetite, and pyrexia. The most common grade 3 to 4 adverse reactions were neutropenia and leukopenia.
Frequently reported serious adverse reactions in patients receiving palbociclib plus fulvestrant include infections, pyrexia, neutropenia, and pulmonary embolism. About one-third of patients required a dose reduction due a treatment-related adverse event and 6% required permanent treatment discontinuation.
The recommended dose and schedule of palbociclib is 125 mg daily taken with food for 21 consecutive days followed by 7 days off treatment. Fulvestrant should be administered at a dose of 500 mg intramuscularly on days 1, 15, 29 and once monthly thereafter. Treatment should be continued until disease progression or unacceptable toxicity.
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Palbociclib is also indicated for the treatment of postmenopausal women with HR-positive, HER2-negative advanced breast cancer in combination with letrozole as initial endocrine-based therapy.
- Palbociclib (Ibrance capsules). U.S. Food and Drug Administration website. February 19, 2016. http://www.fda.gov/Drugs/InformationOnDrugs/ApprovedDrugs/ucm487080.htm. Accessed February 22, 2016.