Immunophenotypic and clonotypic comparison of representative CD19^–recurrence. Immunophenotype of blasts pre-CAR (A) and 3 months after CAR MRD (B) from HP-15 showed complete loss of CD19. Immune repertoire analysis of IgH variable (V) region revealed identical CDR3 sequences (CARNWNYYFDYW) and identical VJ family usage (V6-1 J-4) in pre-CAR B-ALL (C) and post-CAR CD19^– leukemia (D) from HP-78.