During the last 5 years, several novel agents have been introduced and approved for the treatment of relapsed and refractory MCL; the immunomodulatory agent lenalidomide, the BTK inhibitor ibrutinib, the BCL2 inhibitor venetoclax, and most recently, brexucabtagene autoleucel, a CAR-T cell product. The gene discussed is BTK; the disease is mantle cell lymphoma.