Defactinib hydrochloride is primarily used in the field of cancer research and treatment, particularly as an inhibitor of focal adhesion kinase (FAK). It is 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. This compound is being explored in clinical trials for various cancers, including ovarian, pancreatic, and non-small cell lung cancer, often in combination with other therapies to enhance efficacy. Additionally, it is investigated for its role in reducing tumor fibrosis and improving drug delivery to tumor sites. Its application extends to preclinical studies aimed at understanding the mechanisms of FAK inhibition in cancer biology and developing targeted therapeutic strategies.