14193, 14577, and 14739)

14193, 14577, and 14739). clinical trials evaluating the safety and efficacy of adoptive transfer of CAR+T cells into patients with advanced B cell malignancies are under way or have been completed [1, 2]. We have previously generated a CAR that recognizes CD19, a B cell TAA. This CAR consists of a human CD19-specific scFv fused to modified IgG4 Fc and hinge regions, the CD28 intracellular domain, and the CD3- intracellular domain. Gene transfer of this CD19-specific CAR into T cells redirects specificity towards CD19+tumors [3]. To help resolve safety and cost-related issues associated with retroviral- or lentiviral-mediated transduction of T cells with CARs, we recently evaluated theSleeping Beauty(SB) transposon/transposase system and electro-transfer of associated DNA plasmids to achieve non-viral genomic integration. CD19-specific CAR+T cells were numerically expanded on K562-derived artificial presenting cells (aAPC) co-expressing human CD19 and an array of co-stimulatory molecules including CD86, CD137L, as well as a membrane-bound mutein of interleukin (IL)-15. CD19 served to specifically propagate the genetically modified T cells, leaving those cells that did not integrate the transposon to die from neglect. This method of expansion resulted in the outgrowth of sufficient numbers of CD19-specifc CAR+T cells for clinical applications [4, 5]. Thus, we have initiated three US Food and Drug Administration-sanctioned clinical trials to adoptively transfer autologous [6] and allogeneic clinical-grade CAR+T cells into patients with B cell malignancies after hematopoietic stem-cell transplantation (HSCT). Accurate assessment of infused T cell persistence and targeting to tumors in a clinical setting is an essential component of managing effective adoptive immunotherapy. Current methods of assessing infused T cell persistence and function employ polymerase chain reaction to amplify specific gene markers (e. g., CAR (persistence), interferon- (IFN-; function)) from infused T cells serially sampled from peripheral blood and tumor tissue [7]. Other PKCA techniques include the assessment of biomarkers (e. g., CAR-specific antibodies) via immunohistochemical analysis of tissue sections, flow cytometry analysis of peripheral blood or tumor biopsies, and assessment of TAA-mediated stimulation of IFN- production [8, 9]. These methods of assessing T cell function and frequency, however , carry inherent limitations. They present intermittent data obtained from longitudinal sampling events and do not provide a comprehensive whole-body view of the temporal and spatial distribution of infused T cells. Genetic modification of T cells with CD19-specific CAR and a co-reporter suitable for whole-body non-invasive imaging provides a method for repetitive monitoring that can inform on the therapeutic potential of adoptive T cell therapy for CD19+B cell malignancies. Positron emission tomography (PET) is an established imaging technology currently employed in the clinic that relies on the detection of radioactive tracers which incorporate within the cells of interest. Herpes simplex virus (HSV)-1 thymidine kinase (TK) and its variants, such as sr39 [10], can be employed as PET reporter genes because they phosphorylate radiolabeled purine or pyrimidine nucleoside analogs such as 9-(4-[18F]fluoro-3-hydroxymethylbutyl)guanine ([18F]FHBG; approved for clinical use [11]) and 2-deoxy-2-[18F]fluoro-5-ethyl-1–D-arabinofuranosyl-uracil ([18F]FEAU), the latter of which is a more sensitive radiotracer [12]. Intracellular TK-mediated phosphorylation entraps these radiotracers and the foci of the radiotracer accumulation can be spatially delineated using positron emission tomography (PET) [13]. PET has been successfully used to detect TK+tumor-specific T cells in mouse tumor models [1315], TK+polyclonal T cells intravenously injected into non-human primates [16], and TK+T cells intracranially 25-Hydroxy VD2-D6 infused into the site of tumor resection in a patient with glioblastoma multiforme [11]. In the present study, we demonstrate that human T cells can be genetically modified by single transposition or triple transposition achieved by electroporation of one or three SB transposons coding for CAR or CAR, TK, and ffLuc transgenes to generate T cells that are (a) CD19 specific 25-Hydroxy VD2-D6 and (b) detectable using bioluminescent imaging (BLI) 25-Hydroxy VD2-D6 and PET following adoptive transfer into immuno-deficient mice and administration of the radiotracer [18F]FEAU. == Materials and Methods == == Plasmids == One SB transposon plasmid CD19RCD28/pSBSO expresses the human codon-optimized (CoOp), second-generationCoOpCD19RCD28 CAR in the SB transposon DNA plasmid pSBSO under the control of the human elongation factor-1 hybrid promoter and flanked by inverted/direct repeats [5]. Another SB transposon plasmid ffluc-neo/pSBSO expresses myc-tagged firefly luciferase (ffLuc) fused toCoOpneomycin phosphotransferase (Neo) for bioluminescent imaging (BLI). A cytoplasm-retargeted mutant of wild-type HSV1-derived TK was.