Search

Purpose: While adoptive transfer of T cells bearing a chimeric antigen receptor (CAR) can eliminate substantial burdens of some leukemias, the ultimate challenge remains the eradication of large solid tumors for most cancers. We aimed to develop an immunotherapy approach effective against large tumors in an immunocompetent, self-antigen preclinical mouse model. Experimental Design: In this study, we generated dual-specific T cells expressing both a CAR specific for Her2 and a TCR specific for the melanocyte protein (gp100). We used a regimen of adoptive cell transfer incorporating vaccination (ACTIV), with recombinant vaccinia virus expressing gp100, to treat a range of tumors including orthotopic breast tumors and large liver tumors. Results: ACTIV therapy induced durable complete remission of a variety of Her2 + tumors, some in excess of 150 mm 2 , in immunocompetent mice expressing Her2 in normal tissues, including the breast and brain. Vaccinia virus induced extensive proliferation of T cells, leading to massive infiltration of T cells into tumors. Durable tumor responses required the chemokine receptor CXCR3 and exogenous IL2, but were independent of IFNγ. Mice were resistant to tumor rechallenge, indicating immune memory involving epitope spreading. Evidence of limited neurologic toxicity was observed, associated with infiltration of cerebellum by T cells, but was only transient. Conclusions: This study supports a view that it is possible to design a highly effective combination immunotherapy for solid cancers, with acceptable transient toxicity, even when the target antigen is also expressed in vital tissues. Clin Cancer Res; 23(10); 2478-90. ©2016 AACR ., (©2016 American Association for Cancer Research.)

Aim: The aim of the current study was to fully elucidate the functions of T cells genetically modified with an erbB2-specific chimeric antigen receptor (CAR)., Material & Methods: In this study, key functional parameters of CAR T cells were examined following antigen-specific stimulation of the chimeric anti-erbB2 receptor., Results: Gene-modified T cells produced the cytokines IFN-γ, IL-2, IL-4, IL-10, TNF-α and IL-17, and the chemokine RANTES upon CAR ligation. A multifunctional capacity of these CAR T cells was also demonstrated, where 13.7% of cells were found to simultaneously express IFN-γ and CD107a, indicative of cytolytic granule release. In addition, the CAR T cells were able to respond to a greater degree on the second ligation of CAR, which has not been previously shown. IFN-γ secretion levels were significantly higher on second ligation than those secreted following initial ligation. CAR-expressing T cells were also demonstrated to lyze erbB2-expressing tumor cells in the absence of activity against bystander cells not expressing the erbB2 antigen, thereby demonstrating exquisite specificity., Conclusion: This study demonstrates the specificity of CAR gene-engineered T cells and their capacity to deliver a wide range of functions against tumor cells with an enhanced response capability after initial receptor engagement.

Adoptive immunotherapy involving genetic modification of T cells with antigen-specific, chimeric, single-chain receptors is a promising approach for the treatment of cancer. To determine whether gene-modified T cells could induce antitumor effects without associated autoimmune pathology, we assessed the ability of T cells expressing an anti-Her-2 chimeric receptor to eradicate tumor in Her-2 transgenic mice that express human Her-2 as a self-antigen in brain and mammary tissues. In adoptive transfer studies, we demonstrated significant improvement in the survival of mice bearing Her-2(+) 24JK tumor following administration of anti-Her-2 T cells compared with control T cells. The incorporation of a lymphoablative step prior to adoptive transfer of anti-Her-2 T cells and administration of IL-2 were both found to further enhance survival. The reduction in tumor growth was also correlated with localization of transferred T cells at the tumor site. Furthermore, an antigen-specific recall response could be induced in long-term surviving mice following rechallenge with Her-2(+) tumor. Importantly, antitumor effects were not associated with any autoimmune pathology in normal tissue expressing Her-2 antigen. This study highlights the therapeutic potential of using gene-engineered T cells as a safe and effective treatment of cancer.

Activation and expansion of T cells are important in disease resolution, but tumors do not usually satisfy these immune requirements. Therefore, we employed a novel strategy whereby dual-specific T cells were generated that could respond to both tumor and influenza virus, reasoning that immunization with influenza virus would activate and expand tumor-specific cells, and inhibit tumor growth. Dual-specific T cells were generated by gene modification of influenza virus-specific mouse T cells with a chimeric gene-encoding reactivity against the erbB2 tumor-associated antigen. Dual-specific T cells were demonstrated to respond against both tumor and influenza in vitro, and expanded in vitro in response to influenza to a much greater degree than in response to tumor cells. Following adoptive transfer and immunization of tumor-bearing mice with influenza virus, dual-specific T cells expanded greatly in numbers in the peritoneal cavity and spleen. This resulted in a significant increase in time of survival of mice. However, tumors were not eradicated, which may have been due to the observed poor penetration of tumor by T cells. This is the first demonstration that the potent immunogenic nature of an infectious agent can be utilized to directly impact on T-cell expansion and activity against tumor in vivo.