No B-cell depletion found in children of mothers with MS treated with ocrelizumab

Key takeaways:

• Ocrelizumab was virtually undetectable in mothers, making breastfeeding safe.
• All pregnancies resulted in live births with normal head, height, weight and length measurements.

In pregnant women with MS given ocrelizumab, treatment did not result in infant B-cell depletion after birth, and the drug was virtually undetectable in the bloodstream of mother and child, according to a poster from ECTRIMS 2024.

“Since MS typically starts in the childbearing years and affects 3 times more females than males, many individuals who are starting or using MS medications are women who will, in the future, plan a pregnancy,” Riley M. Bove, MD, a neurologist at the Weill Institute for Neurosciences at the University of California, San Francisco, told Healio in an email.

“Understanding whether this medication could be transferred to their baby through the placenta during pregnancy or breastmilk during lactation is important.”

Bove and colleagues analyzed data from the phase 4 MINORE clinical trial to determine whether exposure to ocrelizumab (Ocrevus, Genentech) affects newborn B cells and impacts subsequent outcomes for mother and child.

The study included 35 women diagnosed with either relapsing-remitting MS or clinically isolated syndrome, who were pregnant at least 30 weeks upon enrollment, with no prior documented history of conditions indicating adverse pregnancy outcomes.

Additionally, the study included enrollees whose last ocrelizumab infusion occurred up to 6 months before their last menstrual period (LMP) or during the first trimester.

The study’s primary endpoint was the proportion of infants with B-cell levels below normal limits, measured at 6 weeks post-birth, with secondary endpoints including serum concentration of ocrelizumab in the umbilical cord blood at birth and at 6 weeks.

A total of 32 women received ocrelizumab before LMP, with a median time between last OCR and LMP of 3.2 months, with three women receiving ocrelizumab during pregnancy, at a median time of 1.9 months after LMP.

According to the study results, ocrelizumab was undetectable in 24 of 35 women (68.6%) during weeks 24 to 30 of pregnancy, undetectable in 32 of 34 women (94.1%) by week 35 and undetectable in 34 of 35 women by the time of their delivery.

Bove and colleagues also found that ocrelizumab was undetectable in umbilical cord serum at birth for 33 of 35 women (94.3%) and within infant serum at week 6 in 32 of 33 children (97%).

All 35 pregnancies resulted in births where the children displayed normal height, weight, length and head measurements, while B-cell levels in all 34 children measured were within age-specific normal parameters from birth to week 6.

Data further showed serious adverse events occurred in six women, with the majority occurring within 10 days post-delivery, while no serious adverse events were recorded prior to labor.

“Data indicate that if a mother receives a usual dose of ocrelizumab, her baby will absorb none of that through the breastmilk,” Bove told Healio. “Clinically, this supports a woman’s ability to both breastfeed — if that is the best decision for her and her baby — and concurrently receive effective treatment during the high-risk postpartum period.”