CD19 and neoplasm: The phenomenon in RJ-31 was reminiscent of a case (Patient-10) reported in the anti-CD19 CAR-T therapy (referred to as the CD19 CAR-T case, hereafter), in which, the CAR-T infused for the second time bore TET2 sequence abnormalities on both alleles, enabling clonal proliferation of CD8+ central memory CAR-T, and rapidly achieving tumor clearance accompanied by high-grade CRS44.