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Serum GFAP may indicate disease severity in NMOSD



Serum levels of glial fibrillary acidic protein (GFAP) may indicate disease severity and risk of attack in patients with neuromyelitis optica spectrum disorder (NMOSD), according to research presented at the meeting held by the Americas Committee for Treatment and Research in Multiple Sclerosis. Treatment with inebilizumab decreases serum GFAP concentrations and reduces the risk of an NMOSD attack, the investigators said.

In NMOSD, autoantibodies often target aquaporin-4, a protein expressed on astrocytes. This immune response destroys astrocytes and increases levels of GFAP in cerebrospinal fluid and serum. In the N-MOmentum trial, inebilizumab reduced the risk of attacks by 73%, compared with placebo, in patients with NMOSD. Bruce Cree, MD, PhD, professor of neurology at the University of California, San Francisco, Weill Institute for Neurosciences and colleagues analyzed the data from this trial to examine the relationship between serum GFAP concentrations and disease activity.

In the study, the investigators prospectively collected 1,260 serum samples from 215 participants, 25 healthy donors, and 23 patients with relapsing-remitting multiple sclerosis (MS). Serum GFAP concentration was measured using a single-molecule array assay. The researchers and an independent adjudication committee evaluated attacks during the 28-week randomized controlled study period using predefined criteria.

The median serum GFAP concentration was higher in patients with NMOSD (128.3 pg/mL) than in patients with relapsing-remitting MS (97.5 pg/mL) and healthy controls (73.3 pg/mL). At baseline, 29% of patients with NMOSD and 9% of patients with MS had a serum GFAP concentration that was three or more standard deviations above the mean level in healthy donors.

During the study, patients with a high baseline concentration of serum GFAP were three times more likely to have an adjudicated NMOSD attack than patients with lower serum GFAP concentrations. Concentrations of serum GFAP increased within 1 week of an adjudicated attack during the randomized controlled period. Furthermore, serum GFAP concentration was significantly higher in patients with major adjudicated attacks, compared with those who had minor adjudicated attacks. This finding was true for all organ domains, including for attacks that affected only the optic nerve.

Compared with placebo, inebilizumab reduced the risk of an adjudicated attack by 79% in patients with a normal baseline serum GFAP concentration and by 61% in patients with an elevated baseline serum GFAP concentration. The increase in serum GFAP concentration following an adjudicated attack was significant in patients receiving placebo, but not in patients receiving inebilizumab. Seven samples taken during an adjudicated attack from patients receiving inebilizumab had serum GFAP concentrations within the normal range. One sample taken during an attack from a patient receiving placebo had a serum GFAP concentration within the normal range. In addition, serum GFAP concentrations decreased from baseline among patients receiving inebilizumab who did not have an adjudicated attack.

“These observations suggest that serum GFAP could be a clinically useful biomarker of disease activity and increased attack risk in NMOSD,” said Dr. Cree and colleagues.

Viela Bio, which is developing inebilizumab, and MedImmune sponsored the study. Dr. Cree has received compensation for consulting services that he provided to Alexion, Atara, Biogen, EMD Serono, Novartis, and TG Therapeutics.

SOURCE: Hartung H et al. ACTRIMS 2020, Abstract P205.

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