Paroxysmal nocturnal hemoglobinuria is a rare blood disease involving uncontrolled complement-mediated destruction of red blood cells. Regeneron is testing its investigational pozelimab and cemdisiran combination in the ACCESS-1 Phase 3 programme.
What is known.
Regeneron reported positive data from an exploratory lead-in cohort and said the pivotal cohort was fully enrolled with data expected late in 2026. The pivotal comparison is against eculizumab and has two coprimary measures: control of hemolysis and avoidance of transfusions.
Why it is a possibility.
The lead-in signal and a completed pivotal enrolment give a plausible path to a positive year-end readout, supporting the provisional 55% estimate.
The smaller earlier cohort did not settle the head-to-head result. Both coprimary endpoints must be met and announced by the deadline; success on just one would not satisfy this forecast.
What could prevent it.
The trial may miss either endpoint, or results may not be announced before year-end.
How it will be assessed.
Resolves YES if Regeneron reports by 31 December 2026 that the ACCESS-1 Phase 3 trial's cohort B met both coprimary endpoints versus eculizumab: adequate control of hemolysis from week 8 through week 26 and transfusion avoidance from day 1 through week 26. A positive result on only one endpoint does not count.
Sources and primary records
Probabilities are provisional editorial estimates, not guarantees. Sources document the present evidence and resolution rule. Read the full disclaimer.