CAR22 cells expand and persist in vivo and induce complete clinical responses associated with reductions in ctDNA. (A) Maximum-intensity projections (MIPs) and PET-CT composite cross-sectional imaging for primary index lesions at specified assessment time points after infusion of CAR22 therapy. Two-dimensional MIP images are shown on the left of each panel, with blue arrows indicating index lesions shown in the cross-sectional imaging to the right. Response classifications at each time point are according to Lugano criteria. (B) Swimmer plot demonstrating late conversion of PR to CR in P1 and P2, as well as durability compared with prior CAR19 responses of P1 and P3. (C) ctDNA levels were consistently reduced after CAR22 therapy. CAR⁺ T-cell expansion and persistence as measured by flow cytometry (D) and quantitative PCR (E) measurements in all patients. CD8⁺ T cells were the predominant subset expanding in vivo, and CAR⁺ cells remained detectable in circulation up to 6 months. APH, apheresis; D28, day 28 after infusion; M3, day 90 after infusion; M6, day 180 after infusion; M9, day 270 after infusion; PD, progressive disease; PRE, preinfusion/baseline assessment; Pre-LD, pre-lymphodepletion chemotherapy; SD, stable disease.