Suspended trial analysis
Suspended clinical trials rarely mean the drug has failed
Only 38 of 596 suspended records (6.4%) carry efficacy/futility or safety signals. Operational and unclear reasons account for 92.8%.
- The current database contains 596 suspended clinical trial records.
- 38 suspended records, or 6.4%, are classified as likely biological failure signals.
- 553 suspended records (92.8%) are operational or other/unknown.
- Safety and efficacy/futility are evenly split at 21 suspended records each.
- Oncology is the largest suspended disease-area slice with 207 records.
The result is more mundane than the label sounds
Suspended is a dramatic word. It can make a trial look as if a safety problem or failed biological hypothesis has already been established. In the current database, however, only 38 of 596 suspended records (6.4%) carry efficacy/futility or safety classifications.
Operational and other/unknown reasons account for 553 records (92.8%). That makes suspended status a useful alert, but a poor conclusion on its own. The reason field is what determines whether a record points toward the intervention, trial execution, or unresolved source language.
Why a suspension can happen
A study can be suspended because of site, supply, staffing, funding, regulatory, recruitment, or administrative problems. Public-health disruptions and temporary pauses can also appear in the source text. None of these explanations proves that the intervention failed to work or created an unacceptable risk.
There are also genuine biological signals in the suspended slice. Safety reviews, adverse events, emerging futility, or insufficient benefit can lead to a halt while investigators or regulators evaluate what happened. Those records deserve immediate attention, but they should be isolated from the much larger operational and unclear group.
Safety and efficacy signals are evenly split
Within the small biological-signal subset, safety and efficacy/futility are evenly split at 21 records each. That balance is different from the full stopped-trial database, where efficacy/futility is the larger biological category.
The distinction matters. A safety suspension raises questions about adverse events, dose, exposure, monitoring, and benefit-risk. An efficacy or futility suspension raises questions about treatment effect, endpoint assumptions, interim evidence, and whether continuing the study remains justified.
The unknown group needs restraint
Other/unknown is the largest reason bucket among suspended records. It contains cases where the registry language is too limited or too generic for a defensible classification. That is not missing work that should be filled with an assumption. It is uncertainty in the source data that should remain visible.
When I see a suspended study in that bucket, I would open the original ClinicalTrials.gov record first. I would then check the update history, sponsor disclosures, regulator notices, publications, and whether the study later resumed, terminated, or changed status.
How I would use suspended records
For screening, suspended trials are useful because they identify programs where something interrupted execution. I would filter them by reason category, then compare phase, disease area, sponsor context, and the exact source language. A safety-tagged Phase I suspension is a different research problem from an operational Phase III pause.
For reporting, I would never write that a drug failed simply because one study is suspended. A more accurate statement names the status, quotes or paraphrases the registered reason, and makes clear whether the classification is biological, operational, regulatory, or uncertain.
What this analysis does not measure
This is an analysis of suspended records inside a stopped-trial database. It does not measure how often all clinical trials become suspended, how often suspended studies restart, or the probability that a suspended program eventually succeeds or fails.
The value is narrower and practical: it shows why status and reason must be separated. Suspended tells us where to look. The source explanation tells us what, if anything, can responsibly be inferred.
Suspended trial reason mix
| Reason classification | Suspended records |
|---|---|
| Other/unknown | 287 |
| Operational | 266 |
| Efficacy/futility | 17 |
| Safety | 21 |
| Regulatory | 5 |
Largest suspended disease-area slices
| Disease area | Suspended records |
|---|---|
| Oncology | 207 |
| Other | 163 |
| Infectious Disease | 52 |
| Cardiovascular | 30 |
| Gastroenterology & Hepatology | 27 |
| Endocrine & Metabolic | 18 |
| Neurology | 18 |
| Psychiatry & Mental Health | 15 |
Largest suspended phase groups
| Phase | Suspended records |
|---|---|
| Phase II | 174 |
| Phase I | 129 |
| Phase I + Phase II | 80 |
| Phase III | 66 |
| Phase IV | 42 |
| Unknown | 38 |
| Phase II + Phase III | 35 |
| Early Phase I | 32 |
Continue from here
FAQ
Does a suspended clinical trial mean the drug failed?
No. Suspended status means the study has been halted and may resume. The registered reason must be reviewed before interpreting the suspension as biological, operational, regulatory, or unclear.
Are suspended trials usually stopped for safety?
No. Only 21 of 596 suspended records in the current dataset are classified as safety signals. Operational and other or unknown explanations account for 553 records.
Can a suspended clinical trial restart?
Yes. Suspension is not necessarily a final status. Researchers should check the current registry record and its update history before relying on an older status snapshot.
Source note: counts are generated from the current ClinicalTrials.gov-derived stopped-trial dataset used by ClinicalTrialFailures.com. These labels are analytical screening signals, not medical advice.