Getting there is a physical problem.
A well plate holds every cell at zero distance from the drug. Tissue does not. That gap is where a compound with excellent potency quietly becomes a failed programme — and the assay that recommended it cannot see the gap at all.
The blind spot
In a well, every cell is the same distance from the drug: zero. That is what makes the assay reproducible, and it is also what makes it silent about tissue.
A tumour is not a well. The compound has to cross packed cells and matrix while the mass pushes fluid back the other way and the body clears it the whole time. Potency measured at zero distance is not a statement about what happens two hundred micrometres in.
What you get back
LURA treats the tumour as a place with a geometry rather than reasoning about it by analogy, and reports the part the plate cannot produce: how far the compound actually travels in the tissue it is meant to treat.
- Whether a candidate reaches the core of a mass or only its 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 — a compound failing everywhere and one failing only in the poorly perfused core are different problems with different fixes
The decision it changes
Most programmes learn this in vivo, two years and several million dollars after the plate ranked the candidates. It is the same question, and it is answerable before the animal work, on the molecules already on the bench.
The edge is not a better molecule. It is knowing which of yours cannot reach the tissue while that still costs a redesign, rather than a programme.