Biogen reported 52-week findings from the Phase 2 part of its AMETHYST study of litifilimab for cutaneous lupus in October 2026. The company described continued improvement in skin-disease measures and no new safety signal in that part of the study.
What is known.
AMETHYST has a separate, blinded Phase 3 part. Biogen expects that pivotal readout in the first half of 2027, so the decisive trial result is still ahead.
Why it is a possibility.
The earlier clinical signal and a stated first-half readout support the provisional 60% chance that the Phase 3 trial meets its prespecified primary endpoint by 30 June 2027.
Later-stage studies can differ from earlier cohorts in size, patients and endpoints. Improvement in Phase 2 cannot be counted as success in the still-blinded Phase 3 part.
What could prevent it.
Independent pivotal trials often differ; the treatment could miss the prespecified endpoint or read out later.
How it will be assessed.
Resolves YES if Biogen announces by 30 June 2027 that its AMETHYST Phase 3 trial (NCT05531565) of litifilimab in cutaneous lupus erythematosus met its prespecified primary efficacy endpoint. A positive result from a different trial 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.