Year: 2007
Type: article
Abstract: Genetic introduction of chimeric antigen receptors (CARs) redirects the specificity of T cells for tumor antigens such as CD19 on B-lineage malignancies. Adoptive transfer of donor-derived CD19-specific CAR+ T cells may be used to augment graft-versus-leukemia/lymphoma (GVL)-effect after allogeneic hematopoietic stem-cell transplantation in general, and umbilical cord blood transplantation in particular. To help assess the therapeutic potential of this adoptive immunotherapy we have generated the genetic tools to non-invasively image CAR+ T cells in vivo. A four-function reporter transgene has been developed for co-expression with a CAR to achieve (i) in vitro selection of CAR+ T cells in cytocidal concentrations of hygromycin B, (ii) in vivo ganciclovir-dependent conditional ablation and (iii) in vivo simultaneous bioluminescence imaging (BLI) with (iv) in vivo positron emission tomography (PET). For imaging, the plasmid expressing the 2nd-generation CD19-specific CAR (CD19RCD28) was modified to encode the reporter gene ffLucHyTK, which fuses Firefly Luciferase (ffLuc), hygromycin (Hy) phosphotransferase and HSV1-derived thymidine kinase (TK). We show that CD19-specific T cells expressing the HyTK- fusion transgene take up PET-tracer in vitro and can be tracked in vivo in mice by BLI and microPET imaging after intravenous injection of d-luciferin and [18F]FEAU, respectively. This is among the first reports demonstrating that HyTK fusion gene can be used not only for selection and suicide, but also for PET. Since the HyTK transgene is currently used in clinical trials, and co-expression of a TK suicide gene may be necessary to ensure safety of initial protocols infusing T cells expressing second-generation CARs (which can activate T cells through chimeric CD3-ζ and CD28), this report should encourage investigators to undertake PET imaging of adoptively transferred HyTK+ cells. The imaging modalities used in this project can be readily translated, and we expect that the clinical application of T-cell-PET will help physicians and their patients dissect the benefits of allogeneic adoptive immunotherapy of CAR+ T cells with respect to toxicity (e.g., graft-versus-host-disease) and efficacy (GVL). Indeed, developing methodologies that are capable of generating quantitative, non-invasive, longitudinal, and spatial in vivo information about the dynamic process of infused T cells will be critical to our general understanding of adoptive immunotherapy in humans.
Language: English
Topic: CAR-T cell therapy research
Subfield: Oncology
Field: Medicine
Domain: Health Sciences
Open Access status: hybrid
Estimated APC paid: $3,650
OpenAlex ID: W2089093791