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African-American patients undergoing standard anti-CD20 treatment for multiple sclerosis or neuromyelitis optica spectrum disorder appeared to experience more rapid repopulation of B cells than their white counterparts, a retrospective cross-sectional study suggested.

In the 6 to 12 months after undergoing treatment with rituximab (Rituxan) or ocrelizumab (Ocrevus) to deplete B cells, Black patients were more than twice as likely to have B cell repopulation compared with white patients (76% vs 33%; P=0.02), reported Lucia Saidenberg, a fourth-year medical student at NYU Grossman School of Medicine in New York City, at the virtual meeting.

In the 4 to 6 months following treatment, however, repopulation of B cells was about the same in both groups, at roughly 21% in the African-American patients compared with 18% in the white patients.

No patients had B cell repopulation within 4 months of treatment. At 4-6 months, 23% had B cell repopulation and by after 10 months, 90% had repopulation of their B cells.

The study included patients from the NYU Langone Multiple Sclerosis Comprehensive Care Center who had been diagnosed with multiple sclerosis or neuromyelitis optica spectrum disorder. For inclusion, the adult patients had to have undergone at least one infusion of rituximab or ocrelizumab, and also underwent tests to determine B-cell composition.

"Anti-CD20 therapy, including rituximab and ocrelizumab, are highly effective treatments for multiple sclerosis and neuromyelitis optica spectrum disorder and are known to cause a near complete depletion of B cells in the blood soon after infusion," Saidenberg said in her oral presentation during the meeting's program.

"However, repopulation of B cells following anti-CD20 infusion has not been well studied in these patients, particularly not in African-American patients, who are underrepresented in clinical trials for these drugs and tend to have more severe disease and faster disease progression compared to white patients with multiple sclerosis," she added.

The researchers enrolled 168 patients in the study, including 61 African-American patients, 60 white patients, and 47 who identified as other races; about 19% were Hispanic. About 80% of the patients were diagnosed with multiple sclerosis, and 19% had neuromyelitis optica spectrum disorder.

The team also looked at the types of B cells being repopulated and found there were no differences between African Americans and whites in the makeup of the cells, Saidenberg said.

"These results may be clinically relevant for the timing of lab draws and CD20 dosing in African-American patients with multiple sclerosis or neuromyelitis optica spectrum disorder," she explained. "Further research is warranted to determine the clinical impact of this finding."

Asked for his perspective, John Corboy, MD, of the University of Colorado Health Neurosciences Center - Anschutz Medical Campus in Aurora, who was not involved with the study, said: "This is an important question as Black patients are noted to have a more challenging time with multiple sclerosis than white patients, and thus potential treatment differences are important."

A key finding was that there was no difference in repletion between racial groups for those treated by 6 months, the usual retreatment time, he told 番茄社区app. "What does this mean in the bigger picture? That repletion -- and likely depletion -- of B cells in blood while on anti-CD20 agents is variable between patients, based on race and perhaps other features. But the exact relationship between blood depletion and repletion, and clinical effects of the drug, remains unknown."

"Of note, during the SARS-CoV-2 pandemic, when many patients missed or had delayed infusions, we have seen quite a few patients with return of B cells, but have not seen any recurrence of multiple sclerosis disease activity related to the return of B cells," Corboy continued.

"We need to determine which markers in blood or elsewhere are related to disease activity, and long-term prognosis," he added. "If persistent B cell depletion in blood is important to avoid recurrence of disease activity, this study suggests that maintaining the usual 6-month retreatment time frame for anti-CD20 agents may be especially important for Black patients."