Tissue01 of 3
Potent is not the same as arrives.
A well puts every cell at zero distance from the drug. A tumor does not. A potent compound that never arrives is a failed program with good numbers, and most programs find out in the animal, years and several million dollars late.
The problem
A compound has to cross packed cells and matrix while the mass pushes fluid back and the body clears it the whole time. Potency measured at zero distance says nothing about two hundred micrometers in. The outer few cell layers are treated. The core never sees a therapeutic dose.
What comes back
- Core or rim
- Which of two similar-potency candidates travels further, and by how much
- Whether a dose or schedule change fixes a shortfall, or only raises the total given
- Where the shortfall sits, because failing everywhere and failing only in a poorly perfused core are different problems with different fixes
The decision it changes
You ask on the molecules already on your bench, before the animal work, while a miss costs a redesign and not a program. The edge is not a better molecule. It is knowing which of yours cannot reach the tissue while that is still cheap.