What the evidence shows
Recurring findings across European trials
1
A 90-day planning assumption misses a large share of submissions
Only 39.9% of Phase II immunology trials were authorised within 90 days. Phase III rare-disease trials reached 48.3%, Phase I immunology 48.9%, Phase I haematology 55.2%, and Phase I cell therapy 56.9%. In the immunology and rare-disease cohorts, moving the planning horizon toward 120 days materially improved coverage: 87.0% of Phase II immunology and 81.2% of Phase III rare-disease trials had reached first authorisation by then.
2
End-to-end CTIS and country Part II are different operational clocks
Trial-level medians ranged from 64.5 days in Phase III oncology to 104 days in Phase II immunology, with Phase I cell therapy at 77 days, Phase I immunology at 94 days and Phase III rare disease at 98 days. Country-specific Part II medians were longer in the same broad evidence base: 102 days in Phase III oncology, 128 in Phase I immunology, 139 in Phase II immunology, 159.5 in Phase III rare disease and 189 in Phase I cell therapy. Country Part II should therefore not be treated as a country attribution of the trial-level end-to-end metric.
3
More countries and more sites repeatedly align with slower review
In Phase II immunology, submissions covering five or more countries had a 113-day median versus 80 days for single-country submissions. Trials with 21 or more sites had a 112-day median versus 82 days for trials with three or fewer sites. Larger country and site footprints were also among the clearest delay signals in Phase III oncology and Phase I cell therapy.
4
Country Part II has a pronounced long-delay tail
The Part II median reached 270.5 days in Phase I haematology, 189 days in Phase I cell therapy and 159.5 days in Phase III rare disease. Standard deviations above 200 days in these cohorts show why a single median can understate the operational risk of late country decisions. In Phase III rare disease, only 51.6% of country Part II records were completed within 180 days.
5
Submission timing can matter, but the pattern is cohort-specific
Late-year submission was one of the strongest delay signals in Phase III oncology. In Phase I cell therapy, October submissions clustered with faster outcomes while December submissions clustered with slower ones. These are observational associations rather than a universal calendar rule, but they are strong enough to justify checking month effects in indication-specific planning.
6
Trial complexity matters more than any single headline median
First-in-human status, modality, randomisation, planned recruitment intensity and broader site networks each separated faster and slower groups in at least one cohort. The practical implication is not to copy a global CTIS benchmark, but to benchmark a planned trial against cohorts that resemble its phase, modality, country footprint and site footprint.
What this changes in trial planning
- Use trial-level first authorisation and country Part II as separate planning variables.
- Treat 90 days as an optimistic scenario in many cohorts; test a 120-day base case against the closest comparable trials.
- Model the incremental timing risk of adding countries and sites before finalising the operational footprint.
- Use cohort-specific month and modality effects as risk signals, not as universal causal rules.
Scope note. This page synthesizes findings from separate Trial Agents analyses of European CTIS cohorts. Each statistic remains tied to the phase, disease, modality and time window of its underlying analysis. Cross-cohort patterns are used as planning signals, not pooled estimates or causal claims.
Underlying evidence
Read the analyses behind these findings
More evidence
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