Ocrelizumab’s Encouraging Treatment Effects Across Conception Delivery and Breastfeeding

Ocrelizumab (Ocrevus; Genentech), a humanized monoclonal antibody designed to target CD20-positive B cells, has been approved for several years as a treatment for relapsing and progressive multiple sclerosis (MS). At the 2025 European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) Congress, held September 24-26, in Barcelona, Spain, Riley Bove, MD, presented new phase 4 data from the MINORE and SOPRANINO studies–two complimentary trials testing the therapy’s exposure in pregnancy and postpartum periods.

The analysis comprised more than 5000 pregnancies from the ocrelizumab pregnancy registry, the largest dataset of pregnancy outcomes for an anti-CD20 therapy in MS. Overall, findings from the phase 4 study revealed that ocrelizumab does not increase the risk of adverse pregnancy or infant outcomes, as well as had an extremely small effect on protective antibody responses to common childhood vaccines.

Following the meeting, NeurologyLive^® sat down with Bove to discuss the findings in greater detail, as well as how SOPRANINO and MINORE differed from each other. Bove, an associate professor of neurology at the University of California, San Francisco, described the reassuring findings across both studies, as well as reflected on the importance of continued research into reproductive health for women with MS. Notably, Bove touched on the findings specific to childhood vaccines and the significance of ocrelizumab’s lack of negative effect.

NeurologyLive: Provide an overview of SOPRANINO and MINORE, how do these studies differ?

Riley Bove, MD: Over the last decade, we’ve learned that B-cell–depleting therapies provide excellent disease control for people with MS. Because so many women with MS are of childbearing age, it’s critical to understand not only the effectiveness of these medications but also their potential risks during pregnancy and the postpartum period.

MINORE and SOPRANINO were each designed to look at different windows of potential exposure. MINORE focused on women treated with ocrelizumab either before conception or in early pregnancy, examining how much of the drug, if any, crosses the placenta and how that might affect the infant. SOPRANINO, on the other hand, looked at the postpartum period—specifically, whether ocrelizumab can be transferred through breast milk to nursing infants. So, in short, MINORE was designed to study placental transfer, while SOPRANINO focused on breast milk transfer.

Can you summarize some of the key findings that were presented at ECTRIMS and what stood out most to you from the data?

Starting with MINORE, we enrolled women who had received ocrelizumab within six months before conception or during the early first trimester. In earlier analyses, we observed that ocrelizumab levels in maternal blood declined steadily over the course of pregnancy. By the time of delivery, more than 95 percent of cord blood samples contained no detectable ocrelizumab, and all but one infant had undetectable drug levels at six weeks of life. Importantly, these babies had normal B-cell counts when measured, which was a major reassuring point.

At ECTRIMS this year, we shared extended findings that followed the infants through their first year of life. We evaluated their responses to age-appropriate vaccines and the occurrence of infections. The vaccine data showed that the infants mounted the expected immune responses, consistent with what we’d see in the general population. Altogether, MINORE provides a very reassuring safety profile through one year of follow-up.

Turning to SOPRANINO, we previously demonstrated that ocrelizumab transfer into breast milk is negligible. Even when trace amounts are detected in milk, the drug is degraded in the infant’s gastrointestinal tract, and none of the infants had measurable ocrelizumab in their blood. Their B-cell counts were normal, and in the latest data presented at ECTRIMS, we again saw expected vaccine responses and no new safety signals. So both studies together are highly reassuring for clinicians and families.

You mentioned vaccine responses, which are often a concern for new parents. Can you talk more specifically about those findings and how they should inform patient counseling?

Yes, this is an area that has generated a lot of interest—especially as vaccine hesitancy and outbreaks like measles have brought immunization back into public discussion. In the MINORE and SOPRANINO studies, we examined humoral responses to several common childhood vaccines. This included the MMR combination vaccine, DTaP—which covers diphtheria, tetanus, and Bordetella pertussis—as well as vaccines for Haemophilus influenzae type b, hepatitis B, and pneumococcus.

Not every infant showed a perfect response, but the proportion achieving protective antibody levels was entirely within what we expect in the general population. There was no evidence that ocrelizumab exposure blunted vaccine responses in any meaningful way. That aligns with what we’d expect biologically because these infants had no circulating ocrelizumab and normal B-cell function.

One caveat was that our pertussis data couldn’t be interpreted due to a technical issue—the wrong assay kit was used—but responses for diphtheria and tetanus were robust. So overall, the vaccine response findings are very reassuring, both for clinicians and for families planning or managing pregnancy while on ocrelizumab.

From your perspective, what are the next steps in this area of research, and how do we continue advancing women’s health in MS during the childbearing years?

I think the biggest thing is continuing to listen to patients. They’re the ones asking the most relevant, practical questions—about timing of treatment, pregnancy planning, breastfeeding, and what’s safest for their babies. Our job as a research community is to keep generating the data that helps answer those questions as precisely as possible.

We need to keep studying how different therapies behave during pregnancy and lactation, because the field and the drugs themselves are constantly evolving. For ocrelizumab, we’ll continue following these infants long term, but there are also broader implications. The telehealth and registry models developed for studies like these can help us collect more real-world data faster.

Ultimately, the goal is evidence-based, individualized guidance for every patient. Every person with MS—at any age or stage—deserves care decisions grounded in good science, and studies like MINORE and SOPRANINO move us closer to that goal.

Transcript edited for clarity. Click here for more ECTRIMS 2025 coverage.