HER2 and Folate Receptor Targeted Therapy is Enhanced by NK Cell-Activating Cytokines

The anti-tumor effects of therapeutic monoclonal antibodies (mAb) may depend on immune effector cells that express Fc receptors (FcR) for immunoglobulin G. Natural killer (NK) cells are innate immune effector cells that play a crucial role in cancer rejection and immunosurveillance. Importantly NK cells express the Fcgamma receptor IIIa (FcgammaRIIIa) and various cytokine receptors, which can be activated upon encountering antibody-coated targets and cytokines in the tumor microenvironment. Previous work from our group reported a significant association between elevated IFN-gamma levels in patients receiving Trastuzumab plus the cytokine interleukin-12 (IL-12) and more favorable outcomes in phase I clinical trials. We hypothesized that co-administration of IL-12 with an anti-HER2 mAb (4D5) would enhance the FcR dependent immune mechanisms and IFN-gamma production and contribute to its anti-tumor activity. We aimed to elucidate the cell type responsible for this elevated IFN-gamma production and further determine how this subset affected combination therapy. Treatment with IL-12 and 4D5 significantly inhibited the growth of CT-26HER2, a murine cancer cell line that expresses human HER2. Combination therapy was associated with increased circulating levels of IFN-gamma, MIG and RANTES. IFN-gamma deficient mice demonstrated that this cytokine was necessary for the observed anti tumor effects of therapy with IL-12 plus 4D5. Dual therapy induced tumor necrosis and depletion studies confirmed that NK cells mediated the anti tumor effects of this treatment combination. In an effort to extrapolate our findings with other antibody and cytokine therapies, a novel folate immunoglobulin (F-IgG) construct was created to direct innate immune cells to folate receptor-expressing cancer cells. We hypothesized that F-IgG could bind to tumor cell folate receptors (FR) and mediate NK cell antibody dependent cell-mediated cytotoxicity (ADCC) and cytokine production, an effect that would be enhanced by cytokine therapy. F-IgG bound to both human KB and HeLa and murine L1210JF FR over-expressing cancer cells. Recognition of F IgG by NK cell FcgammaRIIIa receptors led to phosphorylation of the ERK transcription factor and increased NK cell CD69 expression. NK cell lysis of KB tumor cells was synergistically enhanced following treatment with IL-2, IL-12, IL-15 or IL-21. Moreover, NK cell production of IFN-gamma, MIP-1-alpha and RANTES was significantly increased in response to F IgG coated KB target cells in the presence of IL-12. Studies in a murine leukemia model confirmed the anti-tumor activity and intra-tumoral localization of F IgG, an effect that was enhanced by the NK cell activating cytokine IL-12. As was observed with IL-12 and 4D5 dual therapy, the anti-tumor effect of F-IgG and IL-12 was dependent on NK cells, and led to decreased tumor cell proliferation in these studies. Taken together, these data suggest that tumor regression in response to 4D5 or F- IgG plus IL-12 is mediated through the NK cell compartment. These studies indicate that the anti-tumor effects observed with these antibodies can be augmented with various cytokines and provide a rationale for the co administration of NK cell-activating cytokines with therapeutic antibodies. Further understanding of the exact mechanisms of action for these combinatorial approaches may allow for more targeted treatments and decreased detrimental effects of unnecessary therapies.

Name thesis:degree_name

Doctor of Philosophy

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Integrated Biomedical Science Graduate Program

Grantor dc:publisher

The Ohio State University

Year dc:date

2013

Author dc:creator

• Jaime-Ramirez, Alena Cristina

Contributors dc:contributor

• Carson, William

• Biology
• Biomedical Research
• Immunology

Statement dc:rights

• unrestricted
• This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.

Language dc:language

English

Repository record dc:identifier

http://rave.ohiolink.edu/etdc/view?acc_num=osu1364465780

OAI identifier oai:identifier

oai:etd.ohiolink.edu:osu1364465780