Endpoints
Ask whether the study measured a biomarker, an image, symptoms, daily function, hospitalization, or another outcome that matters to patients.
Independent public peptide educationEditorial and review policy
Evidence literacy
Clinical evidence is a ladder, not a yes-or-no badge
A mechanism, an animal result, a registered trial, a positive phase 2 finding, and an FDA approval answer different questions. This center keeps those stages visible.
| Stage | Typical setting | What it can show | What it cannot yet show |
|---|---|---|---|
| Preclinical | Cells and animals | Can reveal mechanisms and early safety signals. | Cannot establish human benefit or a safe human plan. |
| Phase 1 | Early human exposure | Often examines tolerability, pharmacokinetics, and biomarker activity. | Usually too small or short to establish broad clinical benefit. |
| Phase 2 | Early efficacy | Tests a clinical hypothesis and helps refine study design. | Can overestimate effects and miss uncommon or long-term harms. |
| Phase 3 | Confirmatory trials | Uses larger populations and clinically relevant comparisons. | Still applies to the studied population, product, and endpoint. |
| Regulatory review | Benefit-risk decision | Evaluates a specific product for a specific indication and label. | Does not approve every formulation, seller, dose, or off-label claim. |
Current examples
See how the ladder changes the conclusion
Semaglutide
Substantial human evidence for specific approved uses
FDA-approved products exist
Tirzepatide
Substantial human evidence for specific approved uses
FDA-approved products exist
Retatrutide
Encouraging human evidence; confirmatory development continues
Investigational, not FDA-approved
BPC-157
Primarily preclinical evidence; human outcome evidence is not established
Not FDA-approved; clinical research is emerging
TB-500
Insufficient human evidence
Not FDA-approved
CJC-1295
Limited early human evidence focused on biomarkers
Not FDA-approved
MOTS-c
Primarily preclinical and observational human evidence
Not FDA-approved
Elamipretide (SS-31)
Limited human evidence supporting a narrow accelerated approval
FDA accelerated approval for a specific rare-disease use
Comparators
A change from baseline is not the same as a randomized comparison with placebo or standard care.
Generalizability
Age, diagnosis, severity, geography, duration, and exclusions determine how far a result can travel.