Immunophenotypic and clonotypic comparison of representative CD19⁺MRD/relapse. (A) Early reappearance of normal hematogones in the bone marrow at 3 months after infusion in HP-181 who subsequently developed CD19⁺ MRD. Normal maturation pattern of B cells with progressive acquisition of CD45 and CD19 and decrease in CD10 as they mature from stage 1 (blue) to stage 2 (teal) to stage 3 (green) hematogones.³¹  Other markers such as CD34, CD24, CD22, and CD20 (not shown) were also consistent with normal maturation pattern. Events in green also include mature T cells (CD19^– events). Pre-CAR blasts (B) and 12-month post-CAR blasts (C) from HP-6 with identical CD45 dim variable; CD22+,CD10+,CD34 dim variable; CD20 variable; CD24 bright; and CD38 dim phenotype. Immune repertoire analysis showed identical CDR3 sequences (CARRGARIVVVPAAV_RAVAKYYYYGMDVW) and identical variable region (V) joining region (J) family usage (V4-31 J6) in pre-CAR blasts (D) and 12-month post-CAR blasts (E) from HP-51.