Our patient 4 did not respond to CD19 CAR-T treatment despite the fact that he had shown (1) a dramatic expansion of CAR-T in the periphery, (2) an accumulation of CD4+ central memory-type CAR-T cells in the CNS, and (3) continuous surface expression of CD19 on his CNS lymphoma cells. The gene discussed is CD4; the disease is primary central nervous system lymphoma.