GEMINI 1 and GEMINI 2
(2025)Objective
Tolebrutinib - To evaluate the efficacy and safety of tolebrutinib, a brain-penetrant BTK inhibitor, compared to teriflunomide in patients with relapsing multiple sclerosis
Study Summary
• Disability worsening ≥6 months appeared lower with tolebrutinib (8.3% vs 11.3%, HR 0.71)
• Safety profiles were similar
Intervention
Double-blind, double-dummy, event-driven phase 3 trials comparing oral tolebrutinib 60mg daily versus oral teriflunomide 14mg daily in patients with relapsing multiple sclerosis
Inclusion Criteria
Age 18-55 years, relapsing multiple sclerosis per 2017 McDonald criteria, EDSS ≤5.5, at least one relapse in past year or two relapses in past 2 years or gadolinium-enhancing brain lesion in past year
Study Design
Arms: Tolebrutinib 60mg daily (n=933) vs Teriflunomide 14mg daily (n=940)
Patients per Arm: 933 tolebrutinib, 940 teriflunomide (pooled across both trials)
Outcome
• Key secondary: 6-month confirmed disability worsening 8.3% vs 11.3% (HR 0.71, 95% CI 0.53-0.95)
• No formal hypothesis testing for secondary endpoints due to primary endpoint failure
Bottom Line
Tolebrutinib was not superior to teriflunomide in reducing annualized relapse rates in patients with relapsing multiple sclerosis. While disability worsening appeared numerically lower with tolebrutinib, formal statistical testing could not be performed due to the failed primary endpoint.
Major Points
- Two identical phase 3, double-blind, double-dummy, event-driven trials (GEMINI 1: n=974, GEMINI 2: n=899)
- Primary endpoint failed: annualized relapse rates were similar between groups (rate ratio 1.06 in GEMINI 1, 1.00 in GEMINI 2)
- Disability worsening ≥6 months numerically favored tolebrutinib (8.3% vs 11.3%, HR 0.71, 95% CI 0.53-0.95) but no formal testing
- Tolebrutinib is brain-penetrant and targets CNS-resident microglia and B cells, unlike peripherally-acting therapies
- Safety profiles were generally similar, though tolebrutinib had higher rates of minor bleeding (petechiae 4.5% vs 0.3%)
- Liver enzyme elevations occurred in both groups (5.6% tolebrutinib vs 6.3% teriflunomide with ALT >3x ULN)
Study Design
- Study Type
- Two multicenter, double-blind, double-dummy, event-driven, active-controlled, randomized phase 3 trials
- Randomization
- Yes
- Blinding
- Double-blind, double-dummy design with matching placebos
- Sample Size
- 1873
- Follow-up
- Median 139 weeks (event-driven design)
- Centers
- GEMINI 1: 162 sites in 24 countries, GEMINI 2: 155 sites in 25 countries
- Countries
- 24-25 countries including US, Europe, and others
Primary Outcome
Definition: Annualized relapse rate (confirmed relapses per participant-year)
| Control | Intervention | HR/OR | P-value |
|---|---|---|---|
| GEMINI 1: 0.12, GEMINI 2: 0.11 | GEMINI 1: 0.13, GEMINI 2: 0.11 | - (Rate ratio 1.06 (0.81-1.39) GEMINI 1, 1.00 (0.75-1.32) GEMINI 2) | P=0.67 GEMINI 1, P=0.98 GEMINI 2 |
Limitations & Criticisms
- Primary endpoint was not met, limiting conclusions about efficacy
- Hierarchical testing procedure prevented formal statistical testing of potentially important disability outcomes
- No direct comparison with other modern high-efficacy DMTs like anti-CD20 therapies
- Event-driven design may have been underpowered for the observed low relapse rates in both groups
- Tolebrutinib showed worse performance on MRI inflammatory markers compared to teriflunomide
- Study population was relatively young (18-55 years) and may not represent full MS population
- 84-86% completion rates suggest some loss to follow-up that could affect results
Citation
N Engl J Med 2025; DOI: 10.1056/NEJMoa2415985