Supporting evidence in phase 2 cancer trial protocols: a content analysis
Bibliographic record
Abstract
BACKGROUND: Phase 2 trials are instrumental for designing definitive efficacy trials or attaining accelerated approval. However, high attrition of drug candidates in phase 2 trials raises questions about their supporting evidence. METHODS: We developed a typology of supporting evidence for phase 2 cancer trials. We also devised a scheme for capturing elements that enable an assessment of the strength of such evidence. Using this framework, we content analyzed supporting evidence provided in protocols of 50 randomly sampled phase 2 cancer monotherapy trials between January 2014 and January 2019, available on ClinicalTrials.gov. RESULTS: Of the 50 protocols in our sample, 52% were industry funded. Most invoked supporting evidence deriving from trials against different cancers (n = 28, 56%) or preclinical studies (n = 48, 96%) but not from clinical studies involving the target drug-indication pairing (n = 23, 46%). When presenting evidence from models, only 1 (2%) protocol explained its translational relevance. Instead, protocols implied translatability by describing molecular (86%) and pathophysiological (84%) processes shared by model and target systems. Protocols often provided information for assessing the magnitude, precision, and risk of bias for supporting trials (n = 43; 93%, 91%, 47%, respectively). However, such information was often unavailable for preclinical studies (n = 49; 53%, 22%, 59%, respectively). CONCLUSIONS: Supporting evidence is key to justifying the commitment of scientific resources and patients to a clinical hypothesis. Protocols often omit elements that would enable critical assessment of supporting evidence for phase 2 monotherapy cancer trials. These gaps suggest the promise of more structured approaches for presenting supporting evidence.
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How this classification was reachedexpand
Direct model labels (unvalidated)
Per-model category and study-design labels from the labeling rounds. They are machine output, unvalidated, and the disagreement between models ships as data. No study design here is MEDLINE-validated yet.
| Model arm | Categories | Study design | Confidence |
|---|---|---|---|
| gemma | Metaresearch Domain: Reporting · Genre: Empirical About the Canadian research system: no · About a Canadian topic: no | Observational | low |
| gpt | Metaresearch Domain: Reporting · Genre: Empirical About the Canadian research system: no · About a Canadian topic: no | Observational | low |
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.008 | 0.094 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedLabeled directly by 2 models reading the full record.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".