Abstract: Mutations in oncogenes and tumor suppressors contribute to the development and progression of cancer. The methods described herein can detect and quantify the ability of a therapeutic agent to reconform a mutant conformation of mutant p53 to a conformation that possesses physiological activity of wild type p53. The disclosed method can be used as a companion diagnostic to detect and quantify the efficacy of a therapeutic agent in reducing the progression of cancers that contain a p53 mutation.