Of 214 industry IBD trials terminated or withdrawn over three decades, only ~23% stopped for efficacy or safety. The rest ran out of patients, money, or corporate priority — the trial failed, not the biology.
We read the sponsor’s stated reason — the ClinicalTrials.gov whyStopped note — on all 214 terminated or withdrawn industry IBD trials. Business and portfolio decisions are the single largest cause (36%); inability to enroll is next (22%). Lack of efficacy (20%) and safety (4%) together are only ~23% — so when an IBD trial is pulled early, ~77% of the time the reason says nothing about whether the drug worked.
Alnylam's two siRNA drugs hit the same liver target. One failed an FDA review in 2023. Two years later the other was approved for both forms of ATTR amyloidosis. The mechanism didn't change. The trial design did.
In September 2023 an FDA advisory committee voted 9-3 that patisiran's benefit supported approval for cardiac ATTR amyloidosis. The FDA rejected it anyway. Eighteen months later it approved vutrisiran — a near-identical Alnylam siRNA against the same liver target — for both forms of ATTR at once. Patisiran's APOLLO-B was 360 patients, 12 months, a six-minute-walk endpoint (+14.7 m, p=0.0162) with a secondary composite that missed at a win ratio of 1.27. Vutrisiran's HELIOS-B was 655 patients, up to 36 months, a hard mortality-plus-CV-events composite cut by 28%. Same mechanism, opposite verdicts — the molecule never changed, the trial did.
