Trastuzumab administration during pregnancy: an update

Area of Science:

• Oncology
• Maternal-Fetal Medicine
• Pharmacology

Background:

• Pregnancy-associated breast cancer (PABC) often presents as HER2-positive.
• Trastuzumab is a standard treatment for HER2-positive breast cancer but is contraindicated in pregnancy (FDA Category D).
• Limited data exists on trastuzumab's safety and efficacy during gestation.

Purpose of the Study:

• To review and synthesize existing data on trastuzumab use during pregnancy.
• To evaluate the impact of trastuzumab on fetal and maternal outcomes.
• To provide an updated perspective on managing HER2-positive breast cancer in pregnant patients.

Main Methods:

• Systematic review of eligible studies identified through MEDLINE and ClinicalTrials.gov up to September 1, 2020.
• Search terms included "breast", "cancer", "trastuzumab", and "pregnancy".
• Study adhered to PRISMA guidelines.

Main Results:

• 28 studies involving 30 patients and 32 fetuses were analyzed.
• Oligohydramnios/anhydramnios occurred in 58.1% of cases, significantly less when trastuzumab was given only in the first trimester (P=0.026).
• Healthy neonates were born in 43.3% of all cases; 41.7% for second/third trimester exposure vs. 75.0% for first trimester only. Maternal mortality was 0%, with 10% experiencing cardiotoxicity.

Conclusions:

• Trastuzumab administration during pregnancy is linked to significant risks, particularly oligohydramnios.
• Exposure limited to the first trimester appears associated with better fetal outcomes.
• Postponing trastuzumab treatment until after delivery is advised, with close maternal and fetal monitoring if treatment is unavoidable during pregnancy.