Theseus Pharmaceuticals, Inc. is a clinical-stage biopharmaceutical company. It is focused on treating cancer patients through the discovery, development, and commercialization of targeted therapies. Its development programs are designed to address drug resistance mutations in key driver oncogenes, which are mutated genes that cause cancer. It also focused on tyrosine kinase inhibitors (TKIs), which is rooted in the critical role that tyrosine kinases play in the development of cancer. It develops pan-variant kinase inhibitors-inhibitors that target cancer-causing and drug resistance mutations in clinically protein kinases. Its product candidate, THE-630, is a pan-variant inhibitor of all classes of activating and resistance mutations of the KIT kinase for the treatment of GIST, a type of cancer often characterized by oncogenic activation of KIT. It is also developing THE-349, a selective epidermal growth factor receptor inhibitor for the treatment of non-small cell lung cancer.