Adjuvanticity of Plasmid DNA Encoding Cytokines Fused to Immunoglobulin Fc Domains

Abstract

Purpose: Plasmid DNAs encoding cytokines enhance immune responses to vaccination in models of infectious diseases and cancer. We compared DNA adjuvants for their ability to enhance immunity against a poorly immunogenic self-antigen expressed by cancer. Experimental Design: DNAs encoding cytokines that affect T cells [interleukin (IL)-2, IL-12, IL-15, IL-18, IL-21, and the chemokine CCL21] and antigen-presenting cells [granulocyte macrophage colony-stimulating factor (GM-CSF)] were compared in mouse models as adjuvants to enhance CD8 + T-cell responses and tumor immunity. A DNA vaccine against a self-antigen, gp100, expressed by melanoma was used in combination with DNA encoding cytokines and cytokines fused to the Fc domain of mouse IgG1 (Ig). Results: We found that (a) cytokine DNAs generally increased CD8 + T-cell responses against gp100; (b) ligation to Fc domains further enhanced T-cell responses; (c) adjuvant effects were sensitive to timing of DNA injection; (d) the most efficacious individual adjuvants for improving tumor-free survival were IL-12/Ig, IL-15/Ig, IL-21/Ig, GM-CSF/Ig, and CCL21; and (e) combinations of IL-2/Ig + IL-12/Ig, IL-2/Ig + IL-15/Ig, IL-12/Ig + IL-15/Ig, and IL-12/Ig + IL-21/Ig were most active; and (f) increased adjuvanticity of cytokine/Ig fusion DNAs was not related to higher tissue levels or greater stability. Conclusions: These observations support the potential of cytokine DNA adjuvants for immunization against self-antigens expressed by cancer, the importance of timing, and the enhancement of immune responses by Fc domains through mechanisms unrelated to increased half-life.

Tumor-targeted T cells modified to secrete IL-12 eradicate systemic tumors without need for prior conditioning

“…The human CD8 transmembrane domain was fused to the mouse CD3 chain and to either the CD19-specific scFv from 19z1 to generate 19mz, or to the prostate-specific membrane antigen (PSMA) scFv from the Pz1 CAR, 5 to generate the control Pmz CAR. The fusion gene encoding the complete murine IL-12 with a serine-glycine repeat between the p35 and p40 chain-coding domains (mIL12f) was generously provided by Alan Houghton and Jedd Wolchok, 14 and modified to include an hCD8 leader peptide and an internal ribosome entry site (IRES).…”

Transgenic expression of human gp100 and RANTES at specific time points for suppression of melanoma

“…[5][6][7] Furthermore, a number of cytokines (interleukin (IL)-2, -12, -15, -18, -21, and -24) have been tested as adjuvants in combination with DNA vaccines, with varying degrees of enhanced antitumor immunity. 8,9 We earlier reported that granulocyte macrophage colony-stimulating factor (GM-CSF) DNA enhanced antitumor immunity induced by hgp100 DNA vaccination in a mouse melanoma model. 10 However, in general, such adjuvant cytokines have not been shown to confer significant and consistent enhancement of antigen-specific cell-mediated immunity with DNA vaccine approaches, and the ability of tumors to escape the immune system has been a major obstacle to the development of effective tumor immunotherapy.…”

Synergistic antitumor efficacy of combined DNA vaccines targeting tumor cells and angiogenesis

“…Therefore we fuse the antigen mVEGFR2 with GPI signal peptide and Fc fragment, so that the antigen could be anchored on the cell membrane and be recognized by APCs more efficiently [17,18].…”