Used in the treatment of autoimmune diseases such as systemic lupus erythematosus (SLE), particularly targeting patients with active lupus nephritis. It functions by selectively inhibiting Bruton's tyrosine kinase (BTK), a key enzyme in B cell receptor signaling, thereby reducing the activation and proliferation of B cells involved in autoimmune responses. This helps decrease autoantibody production and inflammation, leading to improved clinical outcomes in patients with refractory or persistent disease activity. Currently under clinical investigation to evaluate long-term efficacy and safety in various B cell-mediated disorders.