Rituximab found effective for NMOSD in racially diverse patients
Therapy seen to work better than immunosuppressives to prevent relapses
In a racially diverse group of people with neuromyelitis optica spectrum disorder (NMOSD), rituximab worked better to prevent relapses than did oral immunosuppressive therapies, a single-center U.S. study showed.
This result was particularly relevant for Black patients — who are usually underrepresented in NMOSD clinical trials but who, the researchers noted, comprised more than half of the study’s 50-plus participants.
“In this real-world study involving a majority of Black NMOSD patients, rituximab was relatively more effective in preventing relapses within 3 years of therapy initiation than [azathioprine] and [mycophenolate],” the scientists wrote, noting that relapses were seen in 24% of individuals given rituximab in that time period versus 57% taking the other therapies.
The study, “Effectiveness of rituximab versus oral immunosuppressive therapies in neuromyelitis optica spectrum disorder in a racially diverse cohort of subjects: A single-center retrospective study,” was published in Multiple Sclerosis and Related Disorders.
Study compared rituximab, mycophenolate mofetil, and azathioprine
NMOSD is an autoimmune disorder that primarily affects the spinal cord and optic nerves, which relay information between the eyes and the brain. It is caused by an immune system dysfunction that results in the production of self-reactive antibodies that mistakenly attack and damage healthy nervous system cells.
People with NMOSD experience recurrent relapses, or episodes of acute neurological symptoms and worsening of the disease, that are associated with increasing disability. As such, the main therapeutic goal in NMOSD is to prevent these relapses.
Despite a higher prevalence of NMOSD in Black and Asian populations, these patient groups are usually underrepresented in NMOSD clinical trials. That has led to “limited knowledge of the effectiveness of disease modifying treatments across racially diverse groups,” the researchers wrote.
While none of them are approved for NMOSD, “rituximab, mycophenolate mofetil (MMF), and azathioprine (AZA) have traditionally been used as first-line immunosuppressive treatments in patients with” the rare disorder, according to the team.
Administered intravenously, or directly into the bloodstream, rituximab is an antibody-based therapy that works by promoting the death of antibody-producing immune B-cells. MMF and AZA are both oral therapies, and while the former also suppresses cell-based immunity and antibody formation, the latter works more as general immunosuppressant agent.
Now, a team of researchers in the U.S. retrospectively analyzed the effectiveness of rituximab versus MMF or AZA in a racially diverse group of NMOSD patients. All were followed at the University of Chicago Medical Center from Jan. 1, 1990, to Dec. 1, 2020.
A total of 52 patients — 43 women and nine men — were included in the analysis. Among them, 56% were Black individuals, 23% were white people, 12% were Hispanic individuals, and 9% were Asian people. Each of the patients was positive for antibodies against AQP4, which are the most common NMOSD-driving self-reactive antibodies.
At disease onset, the patients ranged in age from 7 to 70, and their median age was 34. They started treatment at a median of about six months after onset, and had lived with NMOSD for a median of 7.5 years.
Lowest NMOSD relapse rates seen with rituximab
In terms of first-line therapy, rituximab was given to 29 patients (55.8%), MMF to 19 (36.5%), and AZA to four (7.7%). Those receiving MMF or AZA were grouped into a single oral immunosuppressant group.
The results showed that seven (24%) of the rituximab-treated patients experienced a relapse within the first three years of treatment. That compared with 13 of the total 23 patients — 57% overall — given either MMF or AZA.
Within the first six months of treatment, only two patients (6.9%) in the rituximab group had a relapse, while seven patients (30.4%) in the oral immunosuppressant group experienced a relapse in this time period.
In the rituximab group, 88.8% were relapse-free at one year and 70.9% had not experienced a relapse after three years. Relapse-free rates were lower for patients treated with MMF or AZA — 69.5% at one year and 38.7% at three years.
Statistical analyses adjusted the data for age at disease onset, race, sex, duration of disease, location of lesions, and the presence of additional health conditions, including other autoimmune diseases.
The results showed that the risk of relapse for patients treated with AZA or MMF was seven times higher than for those given rituximab.
In addition, Black patients were found to have an 83% lower risk of relapse compared with white patients.
“The mechanism for this difference in outcomes is not clearly understood but could be in part due to early diagnosis because of clinical presentation of a more fulminant disease in the Black cohort [group], and hence rapid initiation of [disease-modifying therapies] and aggressive treatment of relapses, at least in our cohort,” the team wrote.
Insurance issues cause 3 NMOSD patients to stop rituximab treatment
A total of three patients (10.3%) discontinued rituximab during the study period because of insurance issues, and one patient (3.4%) changed to oral immunosuppressants due to insurance coverage.
In contrast, eight patients (34.8%) treated with oral immunosuppressants changed to rituximab and three patients (13%) transitioned to a new antibody-based therapy within 15 years of oral immunosuppressant initiation.
Two patients (8.7%) started combination therapy within five years of immunosuppressant initiation, namely MMF and rituximab.
In general, rituximab was generally well tolerated without any discontinuation due to adverse events or clinically significant hypogammaglobulinemia, a condition characterized by lower-than-normal levels of antibodies in the blood.
Together these findings indicated that rituximab demonstrated superior benefits over oral immunosuppressive therapies in the management of NMOSD in a racially diverse group of patients. This suggests that rituximab may be a treatment option for NMOSD regardless of racial background.
“Rituximab remains an effective option for treating NMOSD, especially when there are delays in treatment due to access and economic issues associated with newer treatments,” the researchers wrote.