R428 (BGB324) is primarily used in cancer research as a selective inhibitor of the Axl receptor tyrosine kinase. It shows potential in blocking tumor growth, metastasis, and resistance to therapy in various cancers, including lung, breast, and pancreatic cancers. By targeting Axl signaling, R428 helps restore sensitivity to chemotherapy and immune-based treatments, making it a candidate for combination therapies. It is also being studied for its role in modulating the tumor microenvironment and suppressing cancer cell survival under stress conditions. Most applications remain in preclinical and early clinical development stages.