Before the availability of CAR T cell therapy and other biological treatments such as BTK- and other inhibitors, relapsed and refractory DLBCL patients had very limited therapy options, e.g., high-dose platin-containing regiments followed by autologous stem cell transplantation and, in rare cases, allogeneic stem cell transplantation where available for fit patients. This evidence concerns the gene BTK and diffuse large B-cell lymphoma.