Defactinib is primarily used in the field of cancer research and treatment, particularly as an inhibitor of focal adhesion kinase (FAK). It is being studied for its potential to disrupt cancer cell survival, proliferation, and metastasis by targeting FAK, which plays a critical role in tumor growth and resistance to therapy. Defactinib is often explored in combination with other anticancer agents to enhance therapeutic efficacy, especially in solid tumors such as ovarian cancer, pancreatic cancer, and mesothelioma. Additionally, it is investigated for its ability to reduce cancer stem cell activity and improve the effectiveness of immunotherapy. Its application extends to preclinical and clinical trials aimed at understanding and combating aggressive and treatment-resistant cancers.