Several phase 3 clinical trials are underway testing the efficacy of BTK inhibitors in treating RRMS and active SPMS, non-active SPMS, and PPMS (RRMS and active SPMS: FENhance/NCT04586010 and NCT04586023, Evolution RMS 1 and 2/NCT04338022 and NCT04338061, GEMINI 1 and 2/NCT04410978 and NCT04410991, NCT05147220; non-active SPMS: HERCULES/NCT04411641; PPMS: PERSEUS/NCT04458051, FENtrepid/NCT04544449). The gene discussed is BTK; the disease is secondary progressive multiple sclerosis.