O-Desmethyl Gefitinib is primarily used in the field of medical research and oncology. It serves as a metabolite of Gefitinib, a well-known tyrosine kinase inhibitor used in the treatment of non-small cell lung cancer (NSCLC). Researchers study this compound to better understand the pharmacokinetics and metabolic pathways of Gefitinib, which helps in optimizing dosing regimens and improving therapeutic outcomes. Additionally, O-Desmethyl Gefitinib is investigated for its potential biological activity, as it may retain some of the anti-cancer properties of its parent compound. This makes it valuable in the development of new therapeutic strategies and in assessing drug efficacy and safety profiles. Its role in research also extends to the study of drug resistance mechanisms in cancer cells, providing insights that could lead to more effective treatments.