Characterize patient reported pain in neuromyelitis optica spectrum disorder (NMOSD) in the N-MOmentum study of inebilizumab.

Pain is one of the chief factors responsible for decreased quality of life in NMOSD patients.

The 11-point Pain Numeric Rating Scale (NRS) was reported by patients across 5 body areas (Eyes, Arms, Legs, Upper Back, Lower Back) every 4 weeks during the 6-month randomized controlled period plus during suspected NMOSD attacks.

At baseline, 22% of NMOSD patients reported severe pain (NRS ≥7); 47% reported moderate pain (NRS ≥4).

During an adjudicated attack 22/35 (63%) of patients experienced at least a 3-point worsening in NRS in ≥1 body area; 36% of them retained the 3-point worsening at the following visit. Additionally, 90/162 (55%) of patients who reported no worsening NMOSD symptoms reported a total of 389 episodes of 3-point NRS worsening during the RCP, 35% of which persisted for more than one visit.

Less inebilizumab treated participants reported NRS increases ≥3 relative to placebo. In total, 77% of placebo treated subjects vs. 56% of inebilizumab treated subjects reported 3-point NRS increases during the RCP (OR: 0.34; 95% CI: 0.17-0.81). This trend towards less 3-point NRS increases was also observed in patients who reported no worsening NMOSD symptoms (53% inebilizumab vs. 67% placebo; OR: 0.56; 95% CI: 0.22-1.38).

A subgroup of patients reported chronic pain at all study time points. Chronic moderate-to-severe pain (19% inebilizumab, 25% placebo) was reported similarly between treatment groups. NRS scores, when averaged across all body areas, did not differ significantly between treatment groups over the RCP.

Study participants reported NRS increases ≥3 during attacks and independent of attack. Less inebilizumab treated participants reported NRS increases ≥3 relative to placebo. Further investigation is required to investigate the mechanisms underlying the development of acute pain vs. chronic pain experienced by NMOSD patients.