Fate of the infused engineered T cells. (A) Expansion of the engineered T cells over time in both patients. Left y-axis shows cell count per microliter of blood (total white blood cell [WBC] count in red; engineered [marked] cells in green). Right y-axis shows the number of copies of DNA used in the engineered T cells as a function of total genomic DNA in peripheral blood mononuclear cells (PBMCs) over time. (B). Distribution of engineered T cells in tissue samples obtained post mortem in both patients. qPCR for vector sequences was performed from total genomic DNA obtained from flash-frozen tissues. Note different scale on y-axis for Case 1 and Case 2.