LUMINESCE
(2025)Objective
To assess the safety and efficacy of satralizumab, a humanised monoclonal antibody targeting the IL-6 receptor, in patients with seropositive generalised myasthenia gravis
Study Summary
• Improvement observed as early as week 4 and sustained through week 24, but effect size was modest
• Satralizumab was well-tolerated with a safety profile similar to placebo; no deaths or adverse events of special interest
Intervention
Satralizumab 120 mg (≤100 kg) or 180 mg (>100 kg) subcutaneously at weeks 0, 2, 4, then every 4 weeks vs placebo
Inclusion Criteria
Age ≥12 years, seropositive gMG (AChR-IgG, MuSK-IgG, or LRP4-IgG), MGFA Class II-IV, MG-ADL ≥5 (>50% non-ocular), stable background therapy
Study Design
Arms: Satralizumab vs Placebo
Patients per Arm: Satralizumab: 96, Placebo: 92 (mITT: 86 vs 80 AChR-IgG+)
Outcome
• QMG change at week 24: −3.41 vs −1.78 (difference −1.63; p=0.0062)
• MG-QoL15r: No significant difference (p=0.11)
Bottom Line
Satralizumab was well tolerated and resulted in statistically significant but small improvements in MG-ADL and QMG scores at week 24 in AChR-IgG-positive generalised myasthenia gravis patients. However, the effect size was modest, and no difference was seen in quality of life measures. The sponsor halted further development for this indication.
Major Points
- Primary endpoint met: Satralizumab significantly improved MG-ADL score vs placebo at week 24 (difference −1.02; 95% CI −1.88 to −0.16; p=0.020)
- QMG score also showed significant improvement (difference −1.63; p=0.0062)
- Response observed as early as week 4 and sustained through week 24
- No significant difference in MG-QoL15r total score (p=0.11), breaking the hierarchical testing
- 48% of satralizumab patients achieved ≥3-point QMG reduction vs 29% placebo
- Safety profile similar to placebo with no deaths or adverse events of special interest
- Open-label extension terminated early due to sponsor's decision to halt further development
- IL-6 receptor occupancy >95% achieved across bodyweight ranges
Study Design
- Study Type
- Randomized, double-blind, placebo-controlled, multicentre, phase 3 trial
- Randomization
- Yes
- Blinding
- Double-blind; sponsor, investigators, and patients masked; prefilled syringes identical in appearance; dual-assessor approach with separate treating (safety) and examining (efficacy) investigators
- Sample Size
- 188
- Follow-up
- 24 weeks double-blind period (plus optional 2-year open-label extension, terminated early)
- Centers
- 105
- Countries
- Multiple countries across Europe, North America, South America, Australia, Asia
Primary Outcome
Definition: Mean change from baseline in total MG-ADL score at week 24 in AChR-IgG-positive patients (modified intention-to-treat population)
| Control | Intervention | HR/OR | P-value |
|---|---|---|---|
| −2.57 (SE 0.35; 95% CI −3.25 to −1.88) | −3.59 (SE 0.29; 95% CI −4.15 to −3.02) | - (−1.88 to −0.16) | 0.020 |
Limitations & Criticisms
- Effect size was small (MG-ADL difference of −1.02 points) with uncertain clinical meaningfulness
- MG-QoL15r endpoint not significant (p=0.11), breaking the hierarchical testing and limiting inferences for downstream endpoints
- No further improvement observed during open-label extension beyond week 24 effect
- Imbalance in refractory MG at baseline (52% placebo vs 38% satralizumab)
- Underpowered for MuSK-IgG-positive and LRP4-IgG-positive subgroups
- Only 3 adolescent patients enrolled, precluding efficacy/safety assessment in this age group
- Limited North American representation (10 patients total) with only 2 Black patients
- Sponsor terminated open-label extension and halted further development for this indication
- Cross-trial comparisons with C5 inhibitors and FcRn antagonists difficult due to design differences
- 24-week duration may not capture long-term efficacy and durability of response
Citation
Lancet Neurol 2025; 24: 117–27