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Cemiplimab Pregnancy and Breastfeeding Warnings

Medically reviewed by Last updated on Dec 2, 2022.

Cemiplimab is also known as: Libtayo

Cemiplimab Pregnancy Warnings

Use is not recommended.

AU TGA pregnancy category: D
US FDA pregnancy category: Not assigned.

Risk Summary: Based on its mechanism of action, this drug can cause fetal harm when administered to a pregnant woman. Animal studies have demonstrated that inhibition of the PD1/PD-L1 pathway can lead to increased risk of immune-mediated rejection of the developing fetus resulting in fetal death. Human IgG4 immunoglobulins (IgG4) are known to cross the placenta; therefore, this drug has the potential to be transmitted from the mother to the developing fetus.

-Based on its mechanism of action, fetal exposure to this drug may increase the risk of developing immune-mediated disorders or altering the normal immune response.
-Verify negative pregnancy status in females of reproductive potential prior to initiating therapy.
-Advise females of reproductive potential to use effective contraception during therapy and for at least 4 months after.
-If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential harm to the fetus.

Animal studies have not been conducted with this drug. There are no controlled data in human pregnancy.

AU TGA pregnancy category D: Drugs which have caused, are suspected to have caused or may be expected to cause, an increased incidence of human fetal malformations or irreversible damage. These drugs may also have adverse pharmacological effects. Accompanying texts should be consulted for further details.

US FDA pregnancy category Not Assigned: The US FDA has amended the pregnancy labeling rule for prescription drug products to require labeling that includes a summary of risk, a discussion of the data supporting that summary, and relevant information to help health care providers make prescribing decisions and counsel women about the use of drugs during pregnancy. Pregnancy categories A, B, C, D and X are being phased out.

See references

Cemiplimab Breastfeeding Warnings

Because this drug is a large protein molecule, the amount in milk is likely to be very low and absorption is unlikely because it is probably destroyed in the infant GI tract. The manufacturer recommends that breastfeeding be discontinued during therapy and for 4 months after.

Use is not recommended.

Excreted into human milk: Unknown
Excreted into animal milk: Data not available

-Because of the potential for serious adverse reactions in breastfed children, women should not breastfeed during therapy and for at least 4 months after the last dose.

See references

References for pregnancy information

  1. "Product Information. Libtayo (cemiplimab)." Regeneron Pharmaceuticals Inc (2018):

References for breastfeeding information

  1. "Product Information. Libtayo (cemiplimab)." Regeneron Pharmaceuticals Inc (2018):

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.