Stop-reason taxonomy
Clinical trial stop reasons
See how sponsor-provided stop language is organized into efficacy/futility, safety, operational, regulatory, and other/unknown research signals.
Terminated, withdrawn, and suspended records.
Efficacy/futility and safety classifications.
Distinct rows in the comparison below.
ClinicalTrials.gov API v2
Current dataset
Stop-reason categories in the current dataset
The categories summarize registry language for screening. They do not replace the sponsor's full statement, the protocol, results, publications, or regulatory evidence.
| Stop-reason category | Total stopped | Likely biological | Efficacy / futility | Safety | Operational |
|---|---|---|---|---|---|
| EFFICACY/FUTILITYWeak benefit, endpoint, or futility language | 1,100 | 1,100100% of stopped | 1,100 | 0 | 0 |
| SAFETYSafety, toxicity, or risk-benefit language | 721 | 721100% of stopped | 0 | 721 | 0 |
| OPERATIONALEnrollment, logistics, funding, or execution signals | 12,119 | 00% of stopped | 0 | 0 | 12,119 |
| REGULATORYRegulator or authorization-related language | 91 | 00% of stopped | 0 | 0 | 0 |
| Other / unknownNo reliable specific signal in the compact record | 9,586 | 00% of stopped | 0 | 0 | 0 |
- Biological
- 1,100 (100%)
- Efficacy
- 1,100
- Safety
- 0
- Operational
- 0
- Biological
- 721 (100%)
- Efficacy
- 0
- Safety
- 721
- Operational
- 0
- Biological
- 0 (0%)
- Efficacy
- 0
- Safety
- 0
- Operational
- 12,119
- Biological
- 0 (0%)
- Efficacy
- 0
- Safety
- 0
- Operational
- 0
- Biological
- 0 (0%)
- Efficacy
- 0
- Safety
- 0
- Operational
- 0
How to use the data
What this comparison does and does not show
Efficacy and futility are related, not identical
Lack of efficacy can describe observed insufficient benefit, while futility may follow an interim assessment that continuing is unlikely to achieve the planned objective. The database groups both because they are commonly searched together as biological stop signals.
Safety language needs careful reading
A safety stop may involve toxicity, adverse events, tolerability, risk-benefit review, or a precautionary action. The classification identifies the signal; it does not determine causality or quantify clinical risk.
Operational is not a failed drug
Enrollment, logistics, funding, supply, site execution, and portfolio decisions can stop a study without demonstrating that the intervention lacks efficacy or has an unacceptable safety profile.
Unknown is an honest category
Registry explanations can be missing, generic, or too ambiguous to support a specific classification. Keeping those records in other/unknown is more reliable than forcing every stop into a dramatic narrative.
Method and limitations
Read the classification as a screening signal
The classifier uses structured fields and sponsor-provided stop text from the current dataset. Reason labels are analytical screening categories and can simplify more complex real-world decisions.
Likely biological failure combines efficacy/futility and safety records. Regulatory and operational records are kept separate, while ambiguous language remains other/unknown.
Every high-value conclusion should be checked against the linked NCT record and, where relevant, sponsor disclosures, publications, and regulatory documents.
How classification works →Source-linked examples
Records behind the comparison
Examples are selected from the current ingest and link to the corresponding NCT evidence page.
PDE4 Inhibition in Seborrheic Dermatitis and Papulopustular Rosacea
Icahn School of Medicine at Mount Sinai
The study ended early after interim analysis.
Open source-linked record →A Study to Test the Addition of the Drug Cabozantinib to Chemotherapy in Patients With Newly Diagnosed Osteosarcoma
National Cancer Institute (NCI)
Other - Extend the observation period for current patients
Open source-linked record →Neoadjuvant Inhaled Azacytidine With Platinum-Based Chemotherapy and Durvalumab (MEDI4736) - a Combined Epigenetic-Immunotherapy (AZA-AEGEAN) Regimen for Operable Early-Stage Non-Small Cell Lung Cancer (NSCLC)
National Cancer Institute (NCI)
Placed on voluntary hold to new recruitment pending modification to combination monoclonal antibody treatment.
Open source-linked record →Safety Evaluation of PfSPZ Vaccine in Pregnant Women in Mali (MalVIP1)
National Institute of Allergy and Infectious Diseases (NIAID)
The study remains on hold due to a funding issue after it's been lifted by the FDA.
Open source-linked record →Low-dose Droperidol for Prevention of Postoperative Delirium in Elderly Patients After Non-cardiac Surgery
RenJi Hospital
The trial was terminated on the independent DSMB's recommendation after an interim analysis showed no evidence of benefit and a numerically higher incidence of postoperative delirium in the droperidol group,...
Open source-linked record →FAQ
Questions about this comparison
What are the main reasons clinical trials stop?
The dataset groups stop language into efficacy/futility, safety, operational, regulatory, and other/unknown categories. Operational and unclear explanations are the largest groups.
Is futility the same as a failed endpoint?
Not always. Futility can be based on an interim probability of success, while a failed endpoint usually refers to an observed result. Registry wording and study context determine the interpretation.
Can the classifier determine why a drug failed?
It can surface likely signals from registry language, but it cannot replace clinical, statistical, regulatory, or sponsor-level review.