Human Data vs Preclinical Data
The two evidence categories are not interchangeable. This page lays out, in a comparison table, what each can and cannot establish.
Educational research-literacy content only. Not medical advice, not dosing guidance, not sourcing advice, and not a protocol for human or animal use. See our responsible information policy.
| Question | Preclinical | Human |
|---|---|---|
| Does the compound bind a receptor? | Yes | Usually unnecessary |
| Is there a measurable downstream effect? | Yes (in model) | Yes (in body) |
| Is the effect dose-related? | Yes (in model) | Yes (in body) |
| Does this dose work in humans? | No | Yes (if studied) |
| What is the human safety profile? | No | Partial |
| What is the long-term safety? | No | Usually no |
| Does it improve a clinical outcome? | No | Yes (if measured) |
| Is human translation likely? | Suggestive only | — |
The hierarchy is not optional
Human evidence wins. Preclinical evidence is essential for mechanism and for justifying a first-in-human trial — but it does not, by itself, establish that a compound works in humans or is safe in them.
Why “works in mice” is not a substitute
The translational failure rate from animal model to clinic is high. A compound that produces large effects in rodent models routinely produces small effects, no effects, or harms in humans. The fact that some peptides have crossed this gap (e.g. GLP-1 agonists) does not make the gap small for other peptides.