Palbociclib

The Basics

What is Palbociclib?

Used in combination with letrozole (an aromatase inhibitor) to treat postmenopausal women with estrogen receptor (ER) positive, HER2 negative advanced breast cancer.

Brand names for Palbociclib

Ibrance

How Palbociclib is classified

Antineoplastic Agents, Enzyme Inhibitors, Protein Kinase Inhibitors, Signal Transduction Inhibitors

Palbociclib During Pregnancy

Palbociclib pregnancy category

Category Not AssignedNote that the FDA has deprecated the use of pregnancy categories, so for some medications, this information isn’t available. We still think it’s useful to list historical info, however, given what a common proxy this has been in the past.

What we know about taking Palbociclib while pregnant

Based on findings from animal studies and its mechanism of action, IBRANCE can cause fetal harm when administered to a pregnant woman [see CLINICAL PHARMACOLOGY]. There are no available data in pregnant women to inform the drug-associated risk. In animal reproduction studies, administration of palbociclib to pregnant rats and rabbits during organogenesis resulted in embryo-fetal toxicity at maternal exposures that were ‚â•4 times the human clinical exposure based on AUC (see Data). Advise pregnant women of the potential risk to a fetus. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2%-4% and 15%-20%, respectively. Data Animal Data In a fertility and early embryonic development study in female rats, palbociclib was administered orally for 15 days before mating through to Day 7 of pregnancy, which did not cause embryo toxicity at doses up to 300 mg/kg/day with maternal systemic exposures approximately 4 times the human exposure (AUC) at the recommended dose. In embryo-fetal development studies in rats and rabbits, pregnant animals received oral doses of palbociclib up to 300 mg/kg/day and 20 mg/kg/day, respectively, during the period of organogenesis. The maternally toxic dose of 300 mg/kg/day was fetotoxic in rats, resulting in reduced fetal body weights. At doses ‚â•100 mg/kg/day in rats, there was an increased incidence of a skeletal variation (increased incidence of a rib present at the seventh cervical vertebra). At the maternally toxic dose of 20 mg/kg/day in rabbits, there was an increased incidence of skeletal variations, including small phalanges in the forelimb. At 300 mg/kg/day in rats and 20 mg/kg/day in rabbits, the maternal systemic exposures were approximately 4 and 9 times the human exposure (AUC) at the recommended dose, respectively. CDK4/6 double knockout mice have been reported to die in late stages of fetal development (gestation Day 14.5 until birth) due to severe anemia. However, knockout mouse data may not be predictive of effects in humans due to differences in degree of target inhibition.

Taking Palbociclib While Breastfeeding

What are recommendations for lactation if you're taking Palbociclib?

No information is available on the clinical use of palbociclib during breastfeeding. Because palbociclib is 85% bound to plasma proteins, the amount in milk is likely to be low. However, its half-life is about 29 hours and it might accumulate in the infant. It is also given in combination with letrozole or fulvestrant, which may increase the risk to the infant. The manufacturer recommends that breastfeeding be discontinued during palbociclib therapy and for 3 weeks after the last dose.

Maternal / infant drug levels

No information is available on the clinical use of palbociclib during breastfeeding. Because palbociclib is 85% bound to plasma proteins, the amount in milk is likely to be low. However, its half-life is about 29 hours and it might accumulate in the infant. It is also given in combination with letrozole or fulvestrant, which may increase the risk to the infant. The manufacturer recommends that breastfeeding be discontinued during palbociclib therapy and for 3 weeks after the last dose.

Possible effects of Palbociclib on milk supply

Relevant published information was not found as of the revision date.

Possible alternatives to Palbociclib

None listed