Purpose:Chimeric antigen receptor (CAR) transduced T cells represent a promising immune therapy that has been shown to successfully treat cancers in mice and humans. However, CARs targeting antigens expressed in both tumors and normal tissues have led to significant toxicity. Preclinical studies have been limited by the use of xenograft models that do not adequately recapitulate the immune system of a clinically relevant host. EGFRvIII is a constitutively activated mutant of the naturally occurring epidermal growth factor receptor and is antigenically identical in both human and mouse glioma, but is also completely absent from any normal tissues. Experimental Design:We developed a third-generation, EGFRvIII-specific murine CAR (mCAR), and performed tests to determine its efficacy in a fully immune-competent mouse model of malignant glioma. Results:At elevated doses, infusion with EGFRvIII mCAR T cells led to cures in all mice with brain tumors. Additionally, antitumor efficacy was found to be dependent on lymphodepletive host conditioning. Selective blockade with EGFRvIII soluble peptide significantly abrogated the activity of EGFRvIII mCAR T cells in vitro and in vivo, and may offer a novel strategy to enhance the safety profile for CAR-based therapy. Lastly, mCAR-treated, cured mice were resistant to rechallenge with EGFRvIIINEG tumors, suggesting generation of host immunity against additional tumor antigens. Conclusions: All together, these data support that third-generation, EGFRvIII specific mCARs are effective against gliomas in the brain and highlight the importance of syngeneic, immune-competent models in the preclinical evaluation of tumor immunotherapies.
- Received March 15, 2013.
- Revision received November 4, 2013.
- Accepted November 26, 2013.
- Copyright © 2013, American Association for Cancer Research.