Ocrelizumab Not Tied to Higher Pregnancy, Infant Risks in Multiple Sclerosis

Exposure to anti-CD20 therapy, ocrelizumab, before or during pregnancy is not associated with an increased risk for adverse pregnancy or infant outcomes in women with multiple sclerosis (MS), according to study results presented at the 2024 Consortium of Multiple Sclerosis Centers (CMSC) Annual Meeting, held in Nashville, Tennessee, from May 29 to June 2, 2024.

Ocrelizumab is used to treat MS and its prescribing information advises women to use contraception during treatment and for 6 months after the last infusion. However, some women become pregnant during use.

Researchers from the University of California, San Francisco and Brigham and Women’s Hospital sourced data for this study from the Roche safety database. Women with MS who had potential in utero ocrelizumab exposure to their fetus up to July 2023 were evaluated for adverse pregnancy and infant outcomes. Potential in utero exposure was defined as receipt of 1 or more ocrelizumab infusion within 3 months of the last menstrual period or during pregnancy. Adverse pregnancy and infant outcomes included fetal death, defined as spontaneous abortion before 22 weeks’ gestation, stillbirth, defined as spontaneous abortion after 22 weeks’ gestation, preterm birth, defined as live birth before 37 weeks’ gestation, and major congenital anomalies (MCAs), defined using the European Registration of Congenital Anomalies and Twins; (EUROCAT) 1.5 classification system.

A total of 3244 pregnancies among women with MS were included in this analysis. The pregnancies were reported prospectively (n=2444), retrospectively (n=793), or unknown (n=7).

Among prospective pregnancies, 35.0% had in utero exposure to ocrelizumab and in 41.5% of pregnancies, it was not clear whether ocrelizumab exposure occurred.

Outcomes were available for 1144 prospective pregnancies. Most pregnancies resulted in live births (83.6%), in which 61.3% of babies were born at full-term, 8.6% preterm, and 30.1% at an unknown gestational week. A minority of pregnancies were ectopic (1.2%), electively terminated (5.1%), resulted in spontaneous abortion (10.1%), or stillbirth (<0.1%).

Among the 855 prospective pregnancies that were exposed to ocrelizumab in utero, 512 had follow-up data available. Most pregnancies resulted in live births (84.2%) with few instances of ectopic pregnancies (0.8%), elective terminations (7.4%), spontaneous abortions (7.4%), and stillbirth (0.2%).

A total of 16 MCAs were reported, of which 9 were exposed to ocrelizumab in utero.

The major limitation of this study was the proportion of missing data.

“This is the largest dataset of pregnancy outcomes for an anti-CD20 therapy in MS. In utero exposure to ocrelizumab did not increase the risk of adverse pregnancy or infant outcomes compared with previous reports as well as with epidemiologic background of both MS and general population,” the researchers concluded.