Use of CFTR modulators in special populations, part 1: Pregnancy and lactation.

Safety and efficacy data regarding cystic fibrosis transmembrane conductance regulator (CFTR) modulator use in the setting of pregnancy or breastfeeding remains lacking due to exclusion from key trials and lack of multicenter prospective and retrospective studies in the post-CFTR modulator era. A scoping review of English articles from the period of January 1, 2012, to July 31, 2023, was conducted utilizing PubMed and EmBase databases with the following terms: "special population (pregnancy, lactation, breastfeeding)" AND "ivacaftor OR lumacaftor OR tezacaftor OR elexacaftor"; "cystic fibrosis transmembrane conductance regulator" AND "off label drug use." Search results were reviewed by title and abstract for duplications and relevance. Relative to pregnancy or breastfeeding, a total of 18 publications were included for review. Majority of case reports and surveys concluded maternal and infant health were preserved throughout gestation. Likewise, breastfeeding infant case reports show possible changes in liver function and lens opacities, though risk may be increased with both in-utero and breastfeeding exposure. Ivacaftor (IVA) and lumacaftor (LUM) concentrations in fetal cord blood and maternal blood were found to be equivalent. Yet, low concentrations of IVA and LUM were detectable in breastmilk and infant plasma. Current safety data surrounding CFTR modulator use in the setting of pregnancy and lactation is relatively reassuring; however, long-term safety remains unclear, necessitating ongoing observation, and reporting by care teams. As such, treatment decisions should be individualized and coproduced.