Theseus Pharmaceuticals, Inc. is the most common form of lung cancer. Activating mutations in EGFR occur in 10-15% of Caucasian and up to 50% of Asian NSCLC patients, with up to 90% of those mutations found in exons 19 and 21. Although patients may initially respond to treatment with a first-, second- or third-generation EGFR tyrosine kinase inhibitor, their tumors eventually develop resistance to therapy.

In patients whose tumors progress on osimertinib, point mutations at the C797 position (C797X) in EGFR have been observed at a frequency of up to approximately 12% after first-line osimertinib and 20% after second-line osimertinib. Patients presenting with these mutations have no available targeted therapy options due to current therapies lacking the necessary activity that can address both activating and resistance mutations. Details for the presentation are as follows: Title: Preclinical characterization of CNS-active, mutant-selective fourth-generation EGFR inhibitors with potent activity against single, double, and triple mutant EGFR variants including T790M and C797S Abstract Number: 236 Session: Molecular Targeted Agents 2 Session Date and Time: Thursday, October 27, 2022: 10:00am-5:00pm Presenter: Sen Zhang, Ph.D. (Theseus Pharmaceuticals, Cambridge, USA) About EGFR-mutant NSCLC Non-small cell lung cancer is the most common form of lung cancer, accounting for approximately 85% of the estimated 2.2 million cases of lung cancer diagnosed globally in 2020.

Activating mutations in EGFR occur in 10-15% of Caucasian and up to 50% of Asian NSCLC patients, with up to 90% of those mutations found in exons 19 and 21. In response to treatment, patients' tumors can develop one or more additional EGFR mutations, causing resistance and rendering current therapies ineffective.