ORACLE MS
(2014)Objective
Cladribine - To assess the effect of oral cladribine on time to conversion to clinically definite multiple sclerosis (CDMS) in patients with a first clinical demyelinating event (clinically isolated syndrome)
Study Summary
• Cumulative CDMS probability: 15.9% (5.25 mg/kg), 14.0% (3.5 mg/kg) vs 38.0% (placebo)
• Trial terminated early due to sponsor decision; lymphopenia was main safety concern (24% vs 12% vs 0%)
Intervention
Oral cladribine tablets at cumulative doses of 5.25 mg/kg or 3.5 mg/kg vs placebo over 96 weeks (6 treatment courses)
Inclusion Criteria
Age 18-55 years, first clinical demyelinating event within 75 days of screening, ≥2 clinically silent T2 lesions (≥3mm, at least one ovoid/periventricular/infratentorial), EDSS ≤5.0, no MS diagnosis by 2005 McDonald criteria
Study Design
Arms: Cladribine 5.25 mg/kg vs Cladribine 3.5 mg/kg vs Placebo
Patients per Arm: Cladribine 5.25 mg/kg: 204, Cladribine 3.5 mg/kg: 206, Placebo: 206
Outcome
• McDonald MS conversion: HR 0.43 and HR 0.50, both p<0.0001
• ~90% reduction in new Gd+ lesions with cladribine
Bottom Line
Both doses of oral cladribine (5.25 mg/kg and 3.5 mg/kg) significantly delayed conversion to clinically definite MS by 62-67% and to McDonald MS by 50-57% compared to placebo, with robust MRI suppression. However, the trial was terminated early due to sponsor decision to halt cladribine development over safety concerns (malignancy/infection risk related to lymphopenia). Cladribine was later approved in 2017 after additional safety data.
Major Points
- Phase 3 RCT of 616 patients with clinically isolated syndrome (CIS) at 160 centers in 34 countries
- Both cladribine doses significantly reduced risk of conversion to CDMS: HR 0.38 (5.25 mg/kg) and HR 0.33 (3.5 mg/kg), both p<0.0001
- Cumulative CDMS probability at study end: 15.9% (5.25 mg/kg), 14.0% (3.5 mg/kg) vs 38.0% (placebo)
- McDonald MS conversion also significantly delayed: HR 0.43 and HR 0.50, median time 590 days and 338 days vs 120 days
- Dramatic MRI suppression: ~90% reduction in new Gd+ lesions, ~75-79% reduction in new T2 lesions
- First oral therapy trial in CIS population - prior CIS trials used injectable interferons/glatiramer acetate
- Lymphopenia was dose-dependent: 24% (5.25 mg/kg), 12% (3.5 mg/kg), 0% (placebo); median recovery 9-13 weeks
- Trial terminated early (October 2011) due to regulatory concerns about malignancy/infection risk; only 34% completed 96 weeks
- Two malignancies in cladribine 3.5 mg/kg group (thyroid cancer, SCC) vs none in high-dose or placebo
- 37% of patients would have met 2010 McDonald criteria at baseline (more stringent than 2005 criteria used)
Study Design
- Study Type
- Phase 3, randomized, double-blind, three-arm, placebo-controlled, multicenter trial
- Randomization
- Yes
- Blinding
- Double-blind using two-physician model: treating physician (managed AEs, masked to labs) and evaluating physician (assessed neurology, masked to treatment and labs); central blinded MRI assessment
- Sample Size
- 616
- Follow-up
- 96 weeks planned; early termination October 25, 2011
- Centers
- 160
- Countries
- 34 countries across Americas, Western Europe, Eastern Europe, Russia, Asia
Primary Outcome
Definition: Time to conversion to clinically definite MS (CDMS) according to Poser criteria (diagnosis at second clinical event) during the double-blind period
| Control | Intervention | HR/OR | P-value |
|---|---|---|---|
| 71/206 (34%) converted; cumulative probability 38.0% | - | 0.33 (3.5 mg/kg); 0.38 (5.25 mg/kg) (0.21-0.51 (3.5 mg/kg); 0.25-0.58 (5.25 mg/kg)) | <0.0001 for both doses |
Limitations & Criticisms
- Trial terminated early (October 2011) due to sponsor decision to halt cladribine development - reduced power and 2-year completion rate (only 34% completed 96 weeks)
- Regulatory concerns about potential malignancy and infection risk related to lymphopenia mechanism
- Differential follow-up times: placebo group had shorter mean follow-up (66 weeks) than cladribine groups (76-79 weeks) due to higher conversion rates triggering exit from double-blind period
- Two malignancies occurred in cladribine 3.5 mg/kg group vs none in other groups - causality uncertain but concerning
- 37% of patients would have met 2010 McDonald criteria at baseline - some may have already had MS by modern standards
- Unable to assess long-term efficacy or durability of treatment effect due to early termination
- Induction therapy concept (cladribine followed by maintenance DMT) could not be evaluated as planned
- Limited ethnic diversity (94% White)
- Dose-response paradox: 3.5 mg/kg appeared as effective as 5.25 mg/kg for CDMS (HR 0.33 vs 0.38) with fewer adverse events
Citation
Lancet Neurol 2014;13:257-267