For patients with MS and neuromyelitis optica spectrum disorder (NMOSD) receiving antiCD20 treatment, B-cell repopulation occurs in more Black than White patients between 6 and 12 months after infusion, according to a study presented at the virtual 2021 annual meeting of the American Academy of Neurology. Investigators retrospectively collected demographics, disease-related information, and anti-CD20 treatment history on patients with MS or NMOSD who had flow cytometry results after infusion of rituximab or ocrelizumab. At a median of 6.8 months following anti-CD20 infusion, 29.8% of the 168 patients (134 with MS; 32 with NMOSD) had detectable B-cell repopulation, defined as any detectable number of CD19+ cells on flow cytometry. None of the patients had B-cell repopulation less than 4 months following anti-CD20 infusion; 23% and 61% of patients had B-cell repopulation between 4 and 6 months and between 6 and 12 months, respectively, following infusion. Black and White patients showed no differences in the frequency of B-cell repopulation at 4-6 months following infusion, while at 6-12 months following infusion, the frequency of B-cell repopulation was significantly higher among Blacks versus Whites (76.2% vs 33.3%). “Our findings raise the question of whether the same therapy dose may be equally effective for all people,” a coauthor said in a statement.”