To describe the baseline characteristics of patients enrolled in LUMINESCE (NCT04963270), a Phase 3 study investigating the efficacy and safety of satralizumab in patients aged ≥12 years with gMG.

gMG, a rare, autoimmune disease of the neuromuscular junction, results in fatigable skeletal muscle weakness. Satralizumab, a humanized anti-IL-6 receptor monoclonal recycling antibody that inhibits IL-6 signalling, has the potential to modulate upstream immunopathogenic mechanisms in gMG.

Eligible participants had a confirmed diagnosis of seropositive gMG (AChR-IgG+, MuSK-IgG+, or LRP4-IgG+), an MGFA severity class II–IV, an MG-ADL score ≥5 with non-ocular contribution >50%, and were receiving stable background therapy. Randomization stratification factors included: autoantibody-type, healthcare geographical region, and background therapy (acetylcholinesterase inhibitor and/or an oral corticosteroid; steroid-sparing immunosuppressive therapy [IST], or steroid-sparing IST with other treatments). Participants were randomized 1:1 to receive subcutaneous satralizumab or placebo at Weeks 0, 2, 4, and Q4W thereafter until Week 24.

As of September 20, 2023, 186 participants have been randomized 1:1 to satralizumab or placebo. Participant autoantibody seropositivity was as follows: AChR-IgG+ (n=165/184, 89.7%), MuSK-IgG+ (n=15/184, 8.2%), and LRP4-IgG+ (n=4/184, 2.2%). The mean age (range) of participants was 46.8 years (15–76) and the majority were female (n=117, 62.9%). The mean (SD) age at diagnosis was 37.7 (17.5) years old, and mean time (SD) since diagnosis was 9.2 (8.5) years. At screening, distribution (n=184, %) across MGFA classes were: 58.2%, 39.1%, and 2.7%, for classes II–IV. Mean (SD) baseline MG-ADL and QMG scores were 8.0 (2.9) and 14.4 (5.3), respectively. 63 participants had a history of thymectomy. Data presented are preliminary and are subject to revision following final analyses.

LUMINESCE, the first study of IL-6R antagonism with satralizumab in gMG, has enrolled 186 participants who are representative of a broad gMG population. LUMINESCE will evaluate the efficacy, safety, and PK/PD profiles of satralizumab in gMG.