The emergence of tyrosine kinase inhibitors represented a major advance in the fight against cancer, but the ability of tumors to mutate and develop resistance to these therapies remains a challenge. Theseus Pharmaceuticals is developing what it calls “pan-variant” kinase inhibitors in the hopes of outsmarting tumors by anticipating the range of kinases that may drive their spread and growth as they change. We spoke to Tim Clackson, president and CEO of Theseus Pharmaceuticals, about its structural-based approach to drug development, how it determines the appropriate targets for its pan-variant kinase inhibitors, and why it believes its next-generation TKIs can overcome the challenge of drug resistance.