De novo design of highly selective miniprotein inhibitors of integrins αvβ6 and αvβ8

The RGD (Arg-Gly-Asp)-binding integrins alpha v beta 6 and alpha v beta 8 are clinically validated cancer and fibrosis targets of considerable therapeutic importance. Compounds that can discriminate between homologous alpha v beta 6 and alpha v beta 8 and other RGD integrins, stabilize specific conformational states, and have high thermal stability could have considerable therapeutic utility. Existing small molecule and antibody inhibitors do not have all these properties, and hence new approaches are needed. Here we describe a generalized method for computationally designing RGD-containing miniproteins selective for a single RGD integrin heterodimer and conformational state. We design hyperstable, selective alpha v beta 6 and alpha v beta 8 inhibitors that bind with picomolar affinity. CryoEM structures of the designed inhibitor-integrin complexes are very close to the computational design models, and show that the inhibitors stabilize specific conformational states of the alpha v beta 6 and the alpha v beta 8 integrins. In a lung fibrosis mouse model, the alpha v beta 6 inhibitor potently reduced fibrotic burden and improved overall lung mechanics, demonstrating the therapeutic potential of de novo designed integrin binding proteins with high selectivity.

Automated summary

The RGD-binding integrins, alpha v beta 6 and alpha v beta 8, are important therapeutic targets for cancer and fibrosis treatment. This study presents a computational design method for creating RGD-containing miniproteins that specifically bind to a single RGD integrin heterodimer and conformational state. The designed inhibitors show high affinity and stability, and the cryoEM structures confirm their ability to stabilize specific conformational states of the targeted integrins.