HLCL61 is primarily used in the development and treatment of autoimmune diseases, particularly systemic lupus erythematosus (SLE). It functions as a selective inhibitor of Bruton's tyrosine kinase (BTK), which plays a critical role in B cell receptor signaling. By inhibiting BTK, HLCL61 helps reduce the activation and proliferation of B cells, thereby decreasing the production of autoantibodies and inflammatory responses associated with autoimmune conditions. It is being investigated in clinical trials for its efficacy in reducing disease activity and improving patient outcomes in lupus and related disorders. Its targeted mechanism offers potential for improved safety and specificity compared to broad immunosuppressive therapies.