IPM Take
Progressive MS is where therapeutic optimism has often gone to die.
People keep losing function while systems debate whether the evidence is strong enough, the risk acceptable enough or the budget ready enough. Tolebrutinib now sits at the centre of that debate. Europe has authorised it. FDA has rejected the US application in its current form, citing an unfavourable benefit-risk profile driven primarily by severe drug-induced liver injury.
This is not simply regulatory inconsistency. It shows that access to progressive-MS innovation can depend as much on how agencies weigh uncertainty as on what the trial found.
Executive Summary
The European Commission has authorised Cenrifki, tolebrutinib, for adults with secondary progressive MS who have not experienced relapses in the previous two years.
The authorisation is based on the Phase 3 HERCULES study, which included 1,131 participants with non-relapsing secondary progressive MS. The peer-reviewed trial found that tolebrutinib reduced the risk of six-month confirmed disability progression by 31% versus placebo: hazard ratio 0.69; 95% confidence interval 0.55–0.88; p=0.003.
The EU decision contrasts with the United States. FDA issued a complete response letter for the same application in December 2025, stating that it could not establish a favourable benefit-risk profile for any subgroup. The letter identified the risk of severe drug-induced liver injury as a central concern and raised uncertainty over the population most likely to benefit.
European authorisation does not mean automatic national access. Reimbursement decisions, liver-monitoring infrastructure, clinician confidence and patient preferences will determine how quickly the treatment becomes a real option.
Why it matters
- Patients / advocates: People with non-relapsing secondary progressive MS have few options aimed at disability progression. They also need honest information about liver risk and monitoring requirements.
- Clinicians: Treatment decisions will require careful assessment, liver monitoring and clear discussions about uncertain benefit-risk trade-offs.
- Regulators: The EU–US divergence demonstrates how differently agencies can weigh progression benefit against serious safety uncertainty.
- Payers: Authorisation is not the same as reimbursement. Value assessments will shape whether this becomes broadly accessible or selectively available.
Progressive MS has always exposed the limits of medicine’s comfort zone.
There may be no dramatic relapse. No acute event. No single crisis that makes the loss visible. Instead, disability accumulates quietly while people lose walking distance, hand function, energy, work capacity and independence. Systems built around acute activity have never handled that slow theft particularly well.
Tolebrutinib was developed for precisely that space.
Europe has now authorised it for secondary progressive MS without recent relapses, after the HERCULES trial showed delayed disability progression against placebo. For people with few options targeting this stage of disease, that matters.
But the authorisation is shadowed by a major regulatory split.
FDA’s complete response letter did not simply ask for a minor adjustment. It concluded that the submitted evidence did not establish a favourable benefit-risk profile in any subgroup, pointing particularly to severe drug-induced liver injury and uncertainty about who could benefit enough to justify that risk.
Europe has reached a different decision, with formal liver-monitoring requirements now embedded in the product information.
Neither position should be reduced to a simplistic story of bravery or caution. The harder question is what health systems owe people when the alternative is continued disability and the treatment brings a risk that must be actively managed.
The next fight is not only regulatory. It is practical.
Germany, Italy, France, Spain and other European systems will not experience this authorisation in the same way. Reimbursement, specialist capacity and safety-monitoring pathways will decide whether Cenrifki becomes a real option or another authorised medicine delayed by the infrastructure needed to use it responsibly.
