CPI-203 is primarily used in biomedical research as a potent and selective inhibitor of the bromodomain and extra-terminal (BET) family of proteins, particularly targeting BRD4. Its main application lies in oncology research, where it demonstrates antitumor activity by suppressing the expression of key oncogenes such as MYC. It has been studied in hematologic malignancies, including multiple myeloma and leukemia, to disrupt cancer cell proliferation and induce apoptosis. In preclinical studies, CPI-203 enhances the effectiveness of other anticancer agents, such as proteasome inhibitors and kinase inhibitors, suggesting its potential in combination therapies. It is also used as a tool compound to investigate the role of BET proteins in gene transcription, inflammation, and epigenetic regulation. Due to its ability to cross the blood-brain barrier, it is being explored in models of central nervous system diseases involving aberrant epigenetic signaling.