Prospective Registry Investigating Maternal, Infant, and Lactation Outcomes in Anifrolumab Users

PRIMULA Lac is an open-label, open enrollment, post marketing study to assess concentrations of anifrolumab in breast milk and serum in lactating individuals who are receiving anifrolumab therapeutically, and to evaluate exposure on the breastfed infant. Milk collection will occur at a series of 14 timepoints. Maternal serum will be collected Day 1 (pre-dose and 0-4 hours post-dose), Day 12, and approximately Day 29 (immediately preceding subsequent dose). Infant serum will be collected on approximately Day 30 following the next dose and after 24 hours of breast feeding. Maternal and infant adverse events (AEs) will be actively collected for the duration of the study. Total duration of participation for each participant will be approximately 1 month. The objective of this lactation study is to assess presence of anifrolumab in breast milk and serum (maternal and infant) among lactating individuals who receive anifrolumab therapeutically and to evaluate exposure in the breastfed infant. This is a Post Marketing Requirements (PMR) study designed to fulfill the FDA post-marketing requirements.