No significant differences
Prior to the trial, annualized attack rates (AARs) and disability, as assessed by change in the Expanded Disability Status Scale (EDSS) scores, were nominally higher in the V allele group from disease onset to trial enrollment.
During the trial’s first 6 months, AARs and annual rates of new/enlarging T2 lesions were nominally lower in inebilizumab-treated V allele participants compared with the F/F allele participants, although the differences were not statistically significant.
The AAR was 0.1 for the V allele group vs. 0.3 for the F/F allele group (hazard ratio, 0.40; P = .17). The annual rate of new/enlarging T2 lesions was 1.4 vs. 1.7 (risk ratio, 0.91; P = .88), respectively.
However, at the end of the randomized controlled period, there were no significant differences between the two genotype groups. There was also little difference in clinical metrics of NMOSD activity or B-cell depletion between the two genotype groups during the open-label period involving the long-term repeated inebilizumab dosing.
“Though greater B-cell depletion was observed in inebilizumab-treated V allele participants, compared with F/F participants during the first 6 months, no significant difference in NMOSD activity was observed during this time period,” the investigators reported.
“No differences in B-cell depletion or NMOSD disease activity were observed after 6 months of inebilizumab treatment,” they added.
Dr. Cree noted the study showed that, overall, inebiluzumab’s efficacy was not adversely affected by a polymorphism in the Fc gamma receptor. “These types of genetic analyses may help inform future screening mechanisms to tailor treatment strategies that can optimize the response rate for each patient,” he said.
Dr. Cree added the higher degree of disease activity among those carrying the alleles at baseline is notable and deserves further investigation. That finding “suggests that the presence of the F/F allele is to some extent protective of the detrimental effects the auto-antibody directed against aquaporin-4 that underlies NMOSD pathogenesis,” he said.
A new era?
Commenting on the study, Marcelo Matiello, MD, assistant professor of neurology at Harvard Medical School and associate director of the Neuromyelitis Optica clinic at Massachusetts General Hospital, both in Boston, said the findings provide valuable insights into risks for key patient subgroups.
“The data is quite important because we know that with other conditions, such as rheumatoid arthritis, people with this particular genotype do have lower response and are more likely to be refractory,” said Dr. Matiello, who was not involved with the research.
He noted that rituximab is the most commonly used medication in the United States for NMOSD. “It’s not FDA approved, but because of extensive experience, and many case series and small prospective studies, most NMO patients are using rituximab,” Dr. Matiello said. However, the drug’s mechanism “can be compromised” by the F/F allele, he added.
The new findings “provide a good understanding that this medication would likely be superior to patients with this genotype,” he said.
“I think it’s a new era,” Dr. Matiello added. “Not only do we have approved medication for this very severe disease, but we can find out who can benefit most. So, I think this is exciting and is a major step in more individualized appropriate use.”
The study was funded by Horizon Therapeutics. Dr. Cree has consulted for Horizon Therapeutics. Dr. Matiello reported no relevant financial relationships.
A version of this article first appeared on Medscape.com.