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Labeling for Human Epidermal Growth Factor Receptor 2 (HER2) antagonist products includes a boxed warning describing embryo-fetal toxicity associated with oligohydramnios. The FDA initiated this study to determine the real-world exposure rates to HER2 antagonists in pregnancy to better understand the scope of risk for the labeled adverse outcomes. The Merative™ MarketScan® Research Database was utilized to assess how many people have been exposed to HER2 antagonists in pregnancy. Results identified 24 pregnancy episodes with HER2 antagonist exposure among 1,737,836 live births in the Merative™ MarketScan® Database from January 1, 2012, to September 30, 2019. The proportion of exposed pregnancies does not surpass those reported in other post-marketing data and previous literature.
This analysis was also used to inform the feasibility of assessing the risk of oligohydramnios after HER2 antagonist exposure during pregnancy using the Sentinel System. Given the low exposure rate, the Active Risk Identification and Analysis (ARIA) System was found to be insufficient for studying oligohydramnios after HER2 use during pregnancy.