Engraftment, persistence, and localization of modified T cells to tumor sites. Quantitative real-time PCR was performed on genomic DNA harvested from study subject PBMCs collected before and at serial time points after T-cell infusions, using primers specific for the transgene. CAR⁺ cells are shown as a percentage of total PBMCs for each of the treated patients over (A) the first month and (B) the first year. The same quantitative PCR assay was used to detect modified cells in genomic DNA harvested from surgically excised lymph nodes (C) or bone marrow aspirates (D) collected 24 to 48 hours after the third T-cell infusion. For patient UPN-03, 2 adjacent lymph nodes were excised and analyzed separately, and an additional bone marrow aspirate was performed 1 month after the third T-cell infusion. Data represent mean values (± SD) of at least 2 assays per time point, with each sample performed in triplicate. Arrows indicate infusions of genetically modified T cells; and black bar, the 14-day period of low-dose IL-2 injections.