"Liquid biopsy can also be used to monitor how tumors respond to treatment and to detect the emergence of resistance. Mutations in the KRAS gene are common in colorectal and pancreatic cancers, with G12C being a clinically important subtype now targetable by approved therapies. In a recent study, ctDNA profiling was used to assess how tumors with KRAS G12C mutations respond to treatment. Researchers found that nearly half of the patients had additional mutations that may interfere with the effectiveness of KRAS G12C inhibitors (1082)Jazieh K, et al. (2025) Clin Cancer Res, 31: 899.. These findings underscore the importance of pre-treatment molecular profiling to identify changes in the tumor that might reduce treatment effectiveness."