BTK inhibitor 1 (Compound 27) is primarily utilized in the field of oncology and immunology for its ability to target and inhibit Bruton's tyrosine kinase (BTK). This enzyme plays a critical role in the signaling pathways of B-cells, which are often implicated in various B-cell malignancies and autoimmune disorders. By blocking BTK, this compound effectively disrupts the survival and proliferation of cancerous B-cells, making it a promising therapeutic agent for conditions such as chronic lymphocytic leukemia (CLL), mantle cell lymphoma (MCL), and other B-cell-related cancers. Additionally, it has shown potential in treating autoimmune diseases like rheumatoid arthritis by modulating immune responses. Its application extends to research settings, where it is used to study BTK signaling pathways and develop novel treatments for related disorders.