{"entity":{"id":"idea-tr1-external-control-rulebook","kind":"idea","name":"A public rulebook for when an external or synthetic control arm is acceptable","aka":[],"tldr":"Sometimes a trial cannot randomise, so the new drug is compared with past patients' records. Clear published rules on when that is allowed, and how it must be done, would replace case-by-case guesswork.","summary":"Regulators publish a binding checklist for externally controlled trials: pre-registration of the comparator cohort and analysis before unblinding; target-trial emulation framing; minimum data quality (endpoint ascertainment, line of therapy, index date); quantitative bias analysis and tipping-point reporting; and the settings where it is acceptable (rare disease, effect size large relative to plausible confounding, randomisation infeasible). Submissions meeting the rulebook receive predictable review.","asOf":"2026-09-08","links":[{"label":"FDA Real-World Evidence programme","url":"https://www.fda.gov/science-research/science-and-research-special-topics/real-world-evidence"}],"tags":[],"related":[],"cancers":[],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":["real-world-evidence","accelerated-approval","hazard-ratio"],"trials":[],"people":[],"bottlenecks":["b-trial-design","b-real-world-evidence","b-rare-cancers"],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"hypothesis":"A published rulebook will increase the share of externally controlled oncology submissions that are accepted without a confirmatory-trial demand, while post-approval confirmatory results will not disagree with the external-control estimate more often than they do today for single-arm accelerated approvals.","rationale":"External controls are already used informally and inconsistently. Cases where the historical comparison misled (later overturned by randomised data) share identifiable features (immortal-time bias, mismatched lines of therapy, endpoint drift) that a rulebook can exclude.","test":"Retrospectively apply the draft rulebook to past single-arm approvals with later randomised confirmation; check whether rulebook-compliant cases had smaller estimate discrepancies. Then pilot prospectively for two years.","maturity":"early-clinical","actor":"regulator","cost":"small","horizonYears":2},"route":"/ideas/idea-tr1-external-control-rulebook/","neighbours":{"term":[{"id":"accelerated-approval","kind":"term","name":"Accelerated approval","route":"/terms/accelerated-approval/"},{"id":"hazard-ratio","kind":"term","name":"Hazard ratio (HR)","route":"/terms/hazard-ratio/"},{"id":"real-world-evidence","kind":"term","name":"Real-world evidence","route":"/terms/real-world-evidence/"}],"bottleneck":[{"id":"b-rare-cancers","kind":"bottleneck","name":"Rare and paediatric cancers without markets","route":"/bottlenecks/b-rare-cancers/"},{"id":"b-trial-design","kind":"bottleneck","name":"Trial design, endpoints and cost","route":"/bottlenecks/b-trial-design/"},{"id":"b-real-world-evidence","kind":"bottleneck","name":"Weak real-world evidence and registries","route":"/bottlenecks/b-real-world-evidence/"}],"roadmap":[{"id":"trial-modernisation-roadmap","kind":"roadmap","name":"Trial modernisation roadmap: the randomised trial → platforms and adaptive designs → decentralised, pragmatic and always-on","route":"/roadmaps/trial-modernisation-roadmap/"}]}}