Little or no certolizumab pegol (CZP) crosses into the placenta, making it safe for women who take this medication to continue it during pregnancy, according to a study from the U.S. and Europe. The findings were reported online in Annals of the Rheumatic Diseases.

Most chronic inflammatory diseases are more prevalent in women than men, the report notes, and disease onset tends to overlap with peak reproductive age. Adequate control of such diseases ensures the best fetal and maternal health.

“Women of childbearing age with chronic inflammatory diseases are a patient population in need of reliable treatment options and guidance,” lead author Dr. Xavier Mariette reported, noting that women often discontinue their treatment with an anti-tumor necrosis factor (anti-TNF) drug, such as CZP, throughout pregnancy.

In what Mariette et al.  call “the first industry-sponsored study designed to evaluate the placental transfer of CZP from mothers to infants,” they evaluated 16 women who were at least 30 weeks pregnant and were receiving CZP for rheumatoid arthritis, Crohn’s disease, psoriatic arthritis, or axial spondyloarthritis/ankylosing spondylitis.

Gestational ages and birth weights of the 16 babies were within the expected range for healthy infants. The median maternal CZP plasma level at the time of delivery was 24.4 micrograms/mL (within the therapeutic range).

Of the 15 samples of umbilical cord blood evaluated, only three had quantifiable levels of CZP. Of the 14 infants for whom at-birth samples were available, 13 did not have quantifiable plasma CZP levels – and no infants had quantifiable levels four or eight weeks after birth.

These findings, the authors conclude, “support the continuation of CZP treatment throughout pregnancy when considered necessary to control disease activity.”

Given the study’s findings, Mariette characterized CZP as “the only available anti-TNF treatment that is clinically proven to show the minimal placental transfer from mother to infant, during pregnancy.”

Dr. Bharat Kumar, of the Division of Immunology, University of Iowa Hospitals and Clinics, Iowa City, reported that this study “provides real-world evidence for what we rheumatologists and immunologists have been thinking for some time.” 

As CZP lacks an immunoglobulin G fragment crystallizable region, which allows antibodies to go from the mother to the fetus, the drug has been attractive for controlling disease during pregnancy, but until now, he said, “that idea was mostly just theory.”

“With the publication of this study, we have a clearer idea to help guide our decisions about which TNF inhibitor may be best to use in a young woman who may go on to become pregnant,” Dr. Kumar said.

He cautioned that the research looked at only 16 mothers, “which makes it a little difficult to generalize the findings to all patients taking certolizumab.” Besides, the study assessed CZP levels only at delivery, whereas they could have been higher earlier during pregnancy.

Dr. Kumar added, “We don’t have a clear idea about the longer-term impacts of TNF inhibitors, like certolizumab, on the growth of the immune system in babies.” Overall, however, he is satisfied with how the researchers structured their study.

“There needs to be more research on the treatment of immune diseases during pregnancy, but this is an important step in that direction.”