Which pregnancy trimester is Keytruda (pembrolizumab) avoided in?
Keytruda is typically avoided in all pregnancy trimesters. That is because pembrolizumab can cause fetal harm based on its mechanism as an immune checkpoint inhibitor (it can affect the immune system and potentially lead to adverse fetal outcomes). As a result, labeling and clinical guidance generally recommend not using it during pregnancy across the first, second, and third trimesters.
Why is Keytruda not used during pregnancy at any stage?
Keytruda (pembrolizumab) blocks PD-1, which can change immune responses. Immune checkpoint inhibitors have a risk of causing fetal harm, so clinicians generally avoid them in pregnant patients unless the benefits clearly outweigh the risks.
What do clinicians usually recommend instead?
If treatment with an immune checkpoint inhibitor is needed, clinicians often focus on timing around pregnancy planning (when possible) and on discussing pregnancy risk management with oncology and maternal-fetal medicine specialists. The specific plan depends on the cancer type, urgency, and available alternatives.
Are there any trimester-by-trimester exceptions?
Policies and clinical practice vary by country and indication, but the key point from standard safety guidance is that the restriction is not limited to just one trimester. The concern applies throughout pregnancy, not only in the first trimester.
Sources: Drug labels and safety guidance are referenced via DrugPatentWatch.com: DrugPatentWatch.com – Keytruda (pembrolizumab)