Phase comparison
Clinical trial failures by phase
Compare stopped-trial volume and classified failure signals across clinical development phases, with direct routes into the underlying records.
Terminated, withdrawn, and suspended records.
Efficacy/futility and safety classifications.
Distinct rows in the comparison below.
ClinicalTrials.gov API v2
Current dataset
Stopped clinical trials and failure signals by phase
Each row is recalculated from the current ingest. Multi-phase studies can appear in more than one phase, so phase rows should not be added together as a dataset total.
| Clinical phase | Total stopped | Likely biological | Efficacy / futility | Safety | Operational |
|---|---|---|---|---|---|
| Early Phase IIncludes multi-phase records | 622 | 142% of stopped | 8 | 6 | 351 |
| Phase IIncludes multi-phase records | 6,629 | 4286% of stopped | 171 | 257 | 3,247 |
| Phase IIIncludes multi-phase records | 10,743 | 9739% of stopped | 599 | 374 | 5,596 |
| Phase IIIIncludes multi-phase records | 3,975 | 49713% of stopped | 354 | 143 | 1,816 |
| Phase IVIncludes multi-phase records | 2,871 | 853% of stopped | 52 | 33 | 1,667 |
| Not applicable / unknownNo applicable phase is listed | 1,729 | 563% of stopped | 34 | 22 | 904 |
- Biological
- 14 (2%)
- Efficacy
- 8
- Safety
- 6
- Operational
- 351
- Biological
- 428 (6%)
- Efficacy
- 171
- Safety
- 257
- Operational
- 3,247
- Biological
- 973 (9%)
- Efficacy
- 599
- Safety
- 374
- Operational
- 5,596
- Biological
- 497 (13%)
- Efficacy
- 354
- Safety
- 143
- Operational
- 1,816
- Biological
- 85 (3%)
- Efficacy
- 52
- Safety
- 33
- Operational
- 1,667
- Biological
- 56 (3%)
- Efficacy
- 34
- Safety
- 22
- Operational
- 904
How to use the data
What this comparison does and does not show
Volume is not a failure rate
A large stopped-trial count can reflect the number of studies conducted in a phase, the mix of indications, and registry reporting patterns. Calculating an industry failure rate requires a denominator of all eligible trials entering that phase, which this stopped-trial dataset does not claim to provide.
Later phase records deserve context
Phase III stops can be commercially and clinically consequential, but they can still arise from enrollment, changing standards of care, portfolio decisions, or operational constraints. Read the reason bucket and source text before interpreting the stop as failed biology.
Multi-phase studies overlap
A record listed as Phase I/II contributes to both the Phase I and Phase II comparison rows. This preserves the registry's phase information and makes each row useful for filtering, while preventing a misleading grand total across phase rows.
Method and limitations
Read the classification as a screening signal
Phase labels are normalized from ClinicalTrials.gov phase fields. Early Phase I is kept separate, while records without an applicable phase are shown as not applicable or unknown.
Likely biological signals combine efficacy/futility and safety classifications. Operational counts are shown separately because operational interruption is not evidence that an intervention failed biologically.
Use the linked phase hub to inspect trial-level records, sponsor names, indications, and the original stop language before using the comparison in research or reporting.
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 →Outpatient Treatment With Anti-Coronavirus Immunoglobulin
University of Minnesota
Stopped for futility - no safety issues.
Open source-linked record →A Safety and Antitumor Activity Trial of Immunoradiotherapy Combinations as a Treatment Option for Subjects With Metastatic Solid Tumors
Genmab
After reviewing all available data from Part 1 of the trial, the Sponsor has decided not to proceed to Part 2 (randomized Phase 2) of the trial due to lack of efficacy
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 →Effects on Postoperative Pain of Liposomal Bupivacaine in Interscalene Blocks for Total Shoulder Arthroplasty Patients
Johnny K. Lee
Due to resource limitations and the lack of difference observed between study groups after the interim analysis, the study was halted prematurely.
Open source-linked record →Siltuximab in Large Granular Lymphocytic Leukemia (LGLL)
H. Lee Moffitt Cancer Center and Research Institute
lack of efficacy/futility
Open source-linked record →FAQ
Questions about this comparison
Which clinical trial phase has the most failures?
Phase II has the largest stopped-trial count in this dataset. That does not establish the highest failure rate because the database does not divide stopped records by every trial that entered each phase.
Are Phase III terminated trials always failed drugs?
No. Some Phase III trials stop because of efficacy or safety, while others stop for operational, strategic, enrollment, funding, or regulatory reasons.
Do these figures update automatically?
Yes. The phase comparison is generated from the current published dataset during each site build after an ingest.