People of African origin are 2 to 3 times more likely than Caucasians to develop neuromyelitis optica spectrum disorder (NMOSD) depending on where they live, though the reasons for this disparity are not fully understood.

Evanthia Bernitsas, MD. Credit: Wayne State University

Evanthia Bernitsas, MD, has spent much of her career trying to unravel this medical mystery.

Dr. Bernitsas directs the Multiple Sclerosis Treatment and Immunology Clinical Research Center at Wayne State University in Detroit, Michigan. There, she heads an 11-member team serving more than 3000 patients with MS, including the nation’s largest group of African Americans with MS being followed by researchers.

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NMOSD, a rare autoimmune disease of the central nervous system, usually affects the optic nerves and spinal cord. The immune system mistakenly targets healthy cells and proteins in the body, causing eye pain and vision loss.

Specifically, the immune system misrecognizes a water channel protein called aquaporin‑4, which is enriched in the central nervous system. That, in turn, kills cells like astrocytes and neurons, which ultimately causes demyelination in the brain and spinal cord, leading—like MS—to paralysis and blindness.

“When I decided to become an MS expert, I was a young woman. MS affects young women, so I felt closer to my patients,” said Dr. Bernitsas, who studied medicine in her native Greece before moving to the United States. At that time, she said, “we thought NMOSD was a variant of MS. However, now we know that it has a separate identity. It’s a very rare disease and can lead to disability and severe attacks.”

Like multiple sclerosis, NMOSD affects women far more frequently than men. Actual numbers are hard to come by, though Michael Yeaman, PhD, chief medical officer at the nonprofit Guthy-Jackson Charitable Foundation, has estimated that 373,000 people worldwide suffer from NMOSD. That compares to about 2.8 million people with MS around the globe.

Among whites, the prevalence is about 1 in 100,000, though in Japan, it’s 3 in 100,000—and one study in the French-speaking Caribbean island of Martinique showed a prevalence of 11 in 100,000.

Dr. Bernitsas says no population-based studies have been conducted in Africa, though 430 of 100,000 patients admitted to one large hospital in Nigeria—the continent’s most populous nation—were eventually diagnosed with NMOSD.

“This has to do with the genetic makeup, which may define the phenotype of the disease. For example, in Blacks, attacks are more severe and the disease is diagnosed earlier, and at a younger age, than Whites. The genes define the severity, the incidence and the prevalence of the disease, and also sometimes the disability.”

An associate professor of neurology, Dr. Bernitsas completed a neurology residency at Case Western Reserve University in Cleveland, Ohio, and neuroimmunology fellowships at the University of Michigan at Ann Arbor as well as Baylor College of Medicine in Houston, Texas. She’s also editor-in-chief of the neuroimaging section of the journal Brain Sciences. 

Her clinical research focuses on aggressive forms of MS, new immunomodulatory therapies, and symptomatic interventions.  

One of those trials involved inebilizumab-cdon (Uplizna®), a therapy developed by Horizon Therapeutics to treat NMOSD. This drug is the first and only anti-CD19 B-cell-depleting humanized monoclonal antibody approved by the US Food and Drug Administration (FDA) to treat adults with AQP4 antibody-positive NMOSD, according to a news release from Horizon.

“NMOSD is a complex and often unpredictable disease that can be challenging to manage, especially in subpopulations that are disproportionally and more severely affected,” Quinn Dinh, MD, Horizon’s vice president for international medical affairs and pipeline launch strategy, said in the news release.

The trial consisted of a 28-week randomized controlled period in which participants received either inebilizumab or placebo, followed by a minimum 2-year period during which everyone received inebilizumab. Of the 20 African Americans in the randomized controlled period, 15 got inebilizumab and 5 received placebo.

The annualized attack rate (AAR) for Black participants taking the medication was 0.06, compared with 0.09 in all patients on inebilizumab, and a median 1.38 rate among African Americans in the 2 years before enrollment. In addition, only 26.7% of the Black participants in the inebilizumab group developed infections during the randomized period, compared to 60% of the African Americans on placebo.

Dr. Bernitas said that, in general, her White patients with NMOSD have a better prognosis and less disability than her Black patients.

“African Americans have more reactive disease based on B-cells. Humoral immunity is more prominent. That means medications that affect the B‑cells may work better for the African American population,” she said. “There are some studies showing that interferons for MS don’t work that well in Blacks compared to Whites. That’s why we believe that inebilizumab, which affects CD‑19 B‑cells, would be a great choice for Black patients.”

Yet for a variety of historical and sociological reasons, African Americans are generally underrepresented in clinical trials, Dr. Bernitsas said, noting that in the Horizon trial, about 9.5% of patients were Black.

“In other studies, it’s probably 3-4%. We need to make Black patients aware that participation in clinical trials can be really beneficial for them,” she said. “At our center at Wayne State, patients trust us. We have a long history conducting clinical trials in the Black population.”