A cancer therapy in two halves: harmless apart, powerful only where the tumour is

Most antibody-drug conjugates — medicines that carry a toxic payload to cancer cells — struggle with a trade-off: strong enough to work can mean strong enough to harm healthy tissue. Zurich-based VERAXA Biotech is testing a two-part version that only assembles at the tumour. In animal tests shared at the World ADC Congress in San Diego, a single dose shrank breast-cancer tumours significantly, while versions missing one half did nothing — and treated animals did not lose weight, an early sign the approach may be gentler.