Toward Immunotherapy With Redirected T Cells in a Large Animal Model

Abstract

Adoptive transfer of T cells expressing chimeric antigen receptors (CARs) has shown promising anti-tumor activity in early phase clinical studies, especially for hematological malignancies. However, most preclinical models do not reliably mimic human disease. We reasoned that developing an adoptive T-cell therapy approach for spontaneous osteosarcoma (OS) occurring in dogs would more closely reproduce the condition in human cancer. To generate CAR-expressing canine T cells we developed expansion and transduction protocols that allow for the generation of sufficient numbers of CAR-expressing canine T cells for future clinical studies in dogs within 2 weeks of ex vivo culture. To evaluate the functionality of CAR-expressing canine T cells we targeted HER2-positive OS. We demonstrate that canine OS is positive for HER2, and that canine T cells expressing a HER2-specific CAR with human-derived transmembrane and CD28.ζ signaling domains recognize and kill HER2-positive canine OS cell lines in an antigen-dependent manner. To reduce the potential immunogenicity of the CAR we evaluated a CAR with canine-derived transmembrane and signaling domains, and found no functional difference between human and canine CARs. Hence, we have successfully developed a strategy to generate CAR-expressing canine T cells for future preclinical studies in dogs. Testing T-cell therapies in an immunocompetent, outbred animal model may improve our ability to predict their safety and efficacy prior to conducting studies in humans.

Inducible Activation of MyD88 and CD40 in CAR T Cells Results in Controllable and Potent Antitumor Activity in Preclinical Solid Tumor Models

“…The metastatic osteosarcoma cell line, LM7, was kindly provided by Dr. Eugenie Kleinerman (MD Anderson Cancer Center, Houston, TX) in 2011. The MDA-MB-468 cell line expressing human HER2 (MDA-hHER2) was generated as described previously (40). All adherent tumor cell lines were grown in DMEM (Invitrogen) containing 10% heat-inactivated FCS and 1% GlutaMax (Life Technologies) and cultured at 37°C in 5% CO 2 .…”

Understanding and Modeling Metastasis Biology to Improve Therapeutic Strategies for Combating Osteosarcoma Progression

“…The development and clinical assessment of adoptive cell therapies have been piloted in canine OS, providing valuable preclinical data regarding feasibility and activity. For CAR T cells, HER2 has also been explored as a target for canine OS, and Mata and colleagues reported the successful development of HER2-CAR T cells that killed HER2+ canine OS cell lines in an antigen dependent manner (269). Additionally, combining radiation and immunotherapy has been recently explored in a first-in-dog trial of autologous natural killer (NK) adoptive cell therapy (270).…”

Of Mice, Dogs, Pigs, and Men: Choosing the Appropriate Model for Immuno-Oncology Research

“…124,125 Although this genetic manipulation technology remains in its infancy for veterinary medicine, CAR T cells have shown promising results in dogs as a proof-of-concept for the management of both hematopoietic (B-cell lymphoma) and solid (osteosarcoma) tumors. 126,127 Therefore, pet dogs might in the future serve as an important model in elucidating the design of treatment regimens that maximize therapeutic benefit yet minimize adverse events often observed upon CAR T-cell therapy. 128 The establishment of active adaptive immunotherapy through tumor vaccination strategies remains a priority in human cancer patients.…”