Keytruda's Pregnancy Safety Rating
Keytruda (pembrolizumab), a PD-1 inhibitor for cancer treatment, carries a boxed warning from the FDA stating it can cause fetal harm when administered to pregnant women. Animal studies show embryo-fetal toxicity, including increased abortion rates and fetal death in monkeys at doses similar to human levels. Human data is limited, but no adequate controlled trials exist in pregnant women.[1][2]
Recommendations for Pregnant Patients
Keytruda is not recommended during pregnancy due to these risks. Women of childbearing potential must use effective contraception during treatment and for at least 4 months after the last dose. If pregnancy occurs, discontinue Keytruda and evaluate the fetus via ultrasound or amniocentesis.[1][2]
Evidence from Real-World Cases
Postmarketing reports include six cases of neonatal death after maternal Keytruda exposure during pregnancy (three in the third trimester, three unknown timing). Outcomes ranged from preterm birth and low birth weight to immune-related issues like hypothyroidism and pneumonitis in exposed infants. One case involved elective abortion after first-trimester exposure.[2]
Safety for Specific Groups
No subgroups (e.g., by trimester, cancer type, or patient age) are deemed safe. Risks appear consistent across exposures:
- First trimester: Highest concern for structural defects, though data is sparse.
- Second/third trimester: Linked to preterm delivery, low Apgar scores, and neonatal complications.
Breastfeeding is also not advised, as Keytruda passes into milk in animal models.[1][2]
Alternatives During Pregnancy
Options depend on cancer type and stage. Chemotherapy (e.g., certain regimens avoiding teratogens) or surgery may be considered. Immunotherapies like Keytruda are generally avoided; consult oncology guidelines like NCCN for case-specific advice.[3]
Related Patient Questions
What if I become pregnant on Keytruda? Report immediately to your doctor; fetal monitoring is essential, and treatment interruption is standard.
How long after stopping Keytruda can I get pregnant? Wait at least 4 months for contraception, as the drug's half-life supports prolonged exposure risk.[1]
Does Keytruda affect fertility? No direct evidence of infertility, but immune modulation could impact reproductive health indirectly.[2]
[1]: Keytruda Prescribing Information (FDA)
[2]: Drugs.com - Keytruda Pregnancy Warnings
[3]: NCCN Guidelines (Cancer-Specific)