There will be a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to mirikizumab during pregnancy. Pregnant women exposed to mirikizumab and health care providers are encouraged to call Eli Lilly and Company at 1-800-Lilly-Rx (1-800-545-5979).1

Available data from case reports of mirikizumab use in pregnant women are insufficient to evaluate for a drug-associated risk of major birth defects, miscarriage, or other adverse maternal or fetal outcomes. Although there are no data on mirikizumab-mrkz, monoclonal antibodies can be actively transported across the placenta, and mirikizumab may cause immunosuppression in the in utero-exposed infant.1

An enhanced prenatal and postnatal development study conducted in pregnant monkeys at a dose 20 times the maximum recommended human dose revealed no adverse developmental effects to the developing fetus, or harm to infant monkeys from birth through 6 months of age. There are risks of adverse pregnancy outcomes associated with increased disease activity in women with inflammatory bowel disease.1

The background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defects, loss, or other adverse outcomes. In clinically recognized pregnancies in the US general population, the estimated background risk of

• major birth defects is 2% to 4%, and
• miscarriage is 15% to 20%.1

An enhanced prenatal and postnatal development study was conducted in cynomolgus monkeys administered mirikizumab by intravenous injection during organogenesis to parturition at a dose of 300 mg/kg twice weekly, which was 20 times the maximum recommended human dose (MRHD) based on exposure comparisons.1

Mirikizumab crossed the placenta in monkeys. No maternal toxicity was noted in this study. No mirikizumab-related effects on morphological, functional, or immunological development were observed in infant monkeys from birth through 6 months of age. However, incidence of embryo or fetal loss were higher in the treated groups compared with controls (6.7% [1 of 15] in controls vs 26.7% [4 of 15]) at 300 mg/kg, which was 20 times the MRHD based on exposure comparisons, but were within the range of historical control data.1 

Following delivery, most adult female cynomolgus monkeys and all infants from the mirikizumab-treated group had measurable serum concentrations up to 28 days postpartum. In the infant monkeys, mean serum concentrations were approximately 4.8 times the respective mean maternal concentrations.1

Developmental toxicity studies in pregnant monkeys revealed no evidence of harm to the fetus or infant. There are insufficient human data to establish the safety of mirikizumab during pregnancy. Mirikizumab should be used in pregnancy only if the potential benefit justifies the potential risk to the mother or fetus.2

There are no data on mirikizumab's

• presence in human milk
• effect on the breastfed infant, or
• effect on milk production.1 

Endogenous maternal immunoglobulin G and monoclonal antibodies are transferred in human milk. The effects of local gastrointestinal exposure and limited systemic exposure in the breastfed infant to mirikizumab are unknown.1

The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for mirikizumab and any potential adverse effects on the breastfed infant from mirikizumab or from the underlying maternal condition.1

Animal studies have not been conducted to evaluate the carcinogenic or mutagenic potential of mirikizumab.1

No organ weight or histopathology effects were observed in the male or female reproductive tract in sexually mature cynomolgus monkeys that received subcutaneous mirikizumab once weekly for 26 weeks, at a dose of 100 mg/kg, at least 2 times the maximum recommended human dose of mirikizumab based on exposure comparisons.1

OMVOH® (mirikizumab-mrkz) injection, for intravenous or subcutaneous use, Lilly