Adoptive transfer of antigen-specific T cells can augment the immune response to prevent and treat opportunistic infections and malignancies. Gene therapy can improve the therapeutic potential of adoptive immunotherapy and as recently published (Science 2006 Aug 31), infusion of genetically modified T cells with redirected specificity for melanoma can treat exert an anti-tumor effect. Building up this clinical experience, we have initiated a first-in-human trial using T cells genetically modified to express a chimeric antigen receptor (CAR) to target CD19 on B-cell malignancies (BB-IND 11411, author LJN Cooper). In this trial sponsored by the NCI (R21CA105824), the CD19-specific T cells are activated via chimeric CD3-??using 1st-generation technology upon CAR-binding to CD19, resulting in antigen-dependent activation and killing of malignant B cells. Co-expression of thymidine kinase (TK) permits in vivo conditional ganciclovir (GCV)-mediated ablation in event of serious toxicity. While this first-in-human clinical trial establishes the safety and feasibility of adoptive transfer of CAR+ CD19-specific T cells, further insight is needed to evaluate the survival and function of infused T cells. In particular, we seek the genetic tools to image T cells which are contributing to the graft- versus-tumor (GVT)-effect. Therefore, we propose non-invasive imaging to determine persistence, distribution, and activation of infused genetically modified T cells and we hypothesize that the temporal-spatial distribution of activated versus quiescent CD19-specific T cells will correlate therapeutic efficacy. The imaging will combine luciferase-dependent biophotonics with TK-dependent micro-positron-emission tomography (PET), the latter being a methodology which can be readily translated to the clinic at the M.D. Anderson Cancer Center. These studies will be undertaken on T cells derived from peripheral blood (PB) and umbilical cord blood (UCB) to generate CD19-specific effector cells which can be infused to augment the GVT-effect, especially after allogeneic hematopoietic stem-cell transplantation in general and UCB transplantation in particular. An in vivo analysis will be used to determine if these CD19-specific T cells, expressing the 2nd- generation CAR, designated CD19RCD28, which can signal through chimeric CD28 and CD3-? are superior in distribution, activation potential and therapeutic efficacy, to T cells expressing the 1st-generation CAR, designated CD19R. To accomplish this, Aim #1 will develop new DNA plasmids based on Sleeping Beauty transposon/transposase to co-express in T cells CD19R or CD19RCD28 CARs as well as Photinus pyralis and Renilla reniformis derived luciferases and human and HSV TK reporter transgenes, under constitutive and activation-dependent promoters, respectively.
Aim #2 will adoptively transfer genetically modified 1st- and 2nd- generation PB- and UCB-derived CD19-specific T cells expressing the luciferase and TK reporter genes into mice bearing CD19+ tumor to noninvasively image distribution and activation of T cells specifically activated through CD19R and CD19RCD28 CARs. This project develops the tools to non-invasively measure the distribution and activation status of infused tumor-specific T cells. This will help investigators gauge the efficacy of T-cell immunotherapies. ? ? ?
