Posts in Category: Papers

SCIB2, an antibody DNA vaccine encoding NY-ESO-1 epitopes (2016)

SCIB2, an antibody DNA vaccine encoding NY-ESO-1 epitopes (2016)

Wei Xue, Rachael L. Metheringham, Victoria A. Brentville, Barbara Gunn, Peter Symonds, Hideo Yagita, Judith M.  Ramage and Lindy G. Durrant

ABSTRACT: Checkpoint blockade has demonstrated promising antitumor responses in approximately 10–40% of patients. However, the majority of patients do not make a productive immune response to their tumors and do not respond to checkpoint blockade. These patients may benefit from an effective vaccine that stimulates high-avidity T cell responses in combination with checkpoint blockade. We have previously shown that incorporating TRP-2 and gp100 epitopes into the CDR regions of a human IgG1 DNA (ImmunoBody®: IB) results in significant tumor regression both in animal models and patients. This vaccination strategy is superior to others as it targets antigen to antigen-presenting cells and stimulates high-avidity T cell responses. To broaden the application of this vaccination strategy, 16 NY-ESO-1 epitopes, covering over 80% of HLA phenotypes, were incorporated into the IB (SCIB2). They produced higher frequency and avidity T cell responses than peptide vaccination. These T cells were of sufficient avidity to kill NY-ESO-1-expressing tumor cells, and in vivo controlled the growth of established B16-NYESO-1 tumors, resulting in long-term survival (35%). When SCIB2 was given in combination with Treg depletion, CTLA-4 blockade or PD-1 blockade, long-term survival from established tumors was significantly enhanced to 56, 67 and 100%, respectively. Translating these responses into the clinic by using a combination of SCIB2 vaccination and checkpoint blockade can only further improve clinical responses.

Autophagy, citrullination and cancer (2016)

Autophagy, citrullination and cancer (2016)

Lindy G. Durrant, Rachael L. Metheringham and Victoria A. Brentville

ABSTRACT: A cell needs to maintain a balance between biosynthesis and degradation of cellular components to maintain homeostasis. There are 2 pathways, the proteasome, which degrades short-lived proteins, and the autophagy/lysosomal pathway, which degrades long-lived proteins and organelles. Both of these pathways are also involved in antigen presentation or the effective delivery of peptides to MHC molecules for presentation to T cells. Autophagy (macroautophagy) is a key player in providing substantial sources of citrullinated peptides for loading onto MHC-II molecules to stimulate CD4+ T cell responses. Stressful conditions in the tumor microenvironment induce autophagy in cancer cells as a mechanism to promote their survival. We therefore investigated if citrullinated peptides could stimulate CD4+ T cell responses that would recognize these modifications produced during autophagy within tumor cells. Focusing on the intermediate filament protein VIM (vimentin), we generated citrullinated VIM peptides for immunization experiments in mice. Immunization with these peptides induced CD4+ T cells in response to autophagic tumor targets. Remarkably, a single immunization with modified peptide, up to 14 days after tumor implant, resulted in long-term survival in 60% to 90% of animals with no associated toxicity. These results show how CD4+ cells can mediate potent antitumor responses against modified self-epitopes presented on tumor cells, and they illustrate for the first time how the citrullinated peptides produced during autophagy may offer especially attractive vaccine targets for cancer therapy.

Citrullinated Vimentin presented on MHC-II in Tumor Cells is a target for CD4þ T-cell-mediated antitumor immunity (2016)

Citrullinated Vimentin presented on MHC-II in Tumor Cells is a target for CD4þ T-cell-mediated antitumor immunity (2016)

Victoria A. Brentville, Rachael L. Metheringham, Barbara Gunn, Peter Symonds, Ian Daniels, Mohamed Gijon, Katherine Cook, Wei Xue and Lindy G. Durrant 

ABSTRACT: Stressful conditions in the harsh tumor microenvironment induce autophagy in cancer cells as a mechanism to promote their survival.However, autophagy also causes post-translational modification of proteins that are recognized by the immune system. In particular, modified self-antigens can trigger CD4+ T-cell responses that might be exploited to boost antitumor immune defenses. In this study, we investigated the ability of CD4 cells to target tumor-specific self-antigens modified by citrullination, which converts arginine residues in proteins to citrulline. Focusing on the intermediate filament protein vimentin, which is frequently citrullinated in cells during epithelial-tomesenchymal transition of metastasizing epithelial tumors, we generated citrullinated vimentin peptides for immunization experiments in mice. Immunization with these peptides induced IFNγ- and granzyme B-secreting CD4 T cells in response to autophagic tumor targets. Remarkably, a single immunization with modified peptide, up to 14 days after tumor implant, resulted in long-term survival in 60% to 90% of animals with no associated toxicity. This antitumor response was dependent on CD4 cells and not CD8+ T cells. These results show how CD4 cells can mediate potent antitumor responses against modified self-epitopes presented on tumor cells, and they illustrate fort he first time how the citrullinated peptides may offer especially attractive vaccine targets for cancer therapy. Cancer Res; 76(3); 548–60. 2015 AACR.

High avidity cytotoxic T lymphocytes can be selected into the memory pool but they are exquisitely sensitive to functional impairment (2012)

High avidity cytotoxic T lymphocytes can be selected into the memory pool but they are exquisitely sensitive to functional impairment (2012) 

Victoria A. Brentville, Rachael L. Metheringham, Barbara Gunn and Lindy G. Durrant

ABSTRACT: High avidity cytotoxic T lymphocytes (CTL) are important in viral clearance and anti-tumor immunity, however, mechanisms for their optimal generation and maintenance in vivo remain unclear. Immunizing mice with an antibody-DNA vaccine encoding a single CTL epitope, induces a 100 fold higher avidity response than peptide vaccination with the identical epitope. The high avidity response is retained into memory and can be efficiently reactivated with an antibody-DNA boost. In contrast, reactivation of high avidity CTL with peptide, stimulated responses with a significant drop in avidity, suggesting loss or conversion of the high avidity CTL to lower avidity. Similarly, high avidity T cells maintained ex vivo were exquisitely sensitive to signaling with low doses of peptide (1 ng/ml) giving optimal TCR stimulation and resulting in retained avidity, proliferation and ability to kill specific targets. In contrast, high avidity T cells maintained ex vivo with supraoptimal TCR stimulation (10 μg/ml peptide) resulted in reduced avidity and failure to kill tumor cells. They also failed to proliferate, showed a significant increase in apoptosis and expressed high levels of the exhaustion marker programmed death-1 (PD-1) and low levels of the lymphocyte-activation gene 3 (LAG-3). This suggests high avidity T cells are recruited to the memory pool but can be lost by supraoptimal stimulation in vitro and in vivo. This is characterized by loss of function and an increase in cell death. The remaining CTL, exhibit low functional avidity that is reflected in reduced anti-tumor activity. This could contribute to failure of the immune system to control the growth of tumors and has implications for vaccination strategies and adoptive transfer of T cells.

DNA vaccination with T-cell epitopes encoded within Ab molecules induces high-avidity anti-tumor CD8 T cells (2009)

DNA vaccination with T-cell epitopes encoded within Ab molecules induces high-avidity anti-tumor CD8 T cells (2009)

Victoria A. Pudney, Rachael L. Metheringham, Barbara Gunn, Ian Spendlove, Judith M. Ramage and Lindy G. Durrant

ABSTRACT: Stimulation of high-avidity CTL responses is essential for effective anti-tumor and antiviral vaccines. In this study we have demonstrated that a DNA vaccine incorporating CTL epitopes within an Ab molecule results in high-avidity T-cell responses to both foreign and self epitopes. The avidity and frequency was superior to peptide, peptide-pulsed DC vaccines or a DNA vaccine incorporating the epitope within the native Ag. The DNA Ab vaccine was superior to an identical proteinvaccine that can only cross-present, indicating a role for direct presentation by the DNA vaccine. However, the avidity of CTL responses was significantly reduced in Fc receptor γ knockout mice or if the Fc region was removed suggesting that cross presentation of Ag via Fc receptor was also important in the induction of high-avidity CTL. These results suggest that generation of high-avidity CTL responses by the DNA vaccine is related to its ability to both directly present and crosspresent the epitope. High-avidity responses were capable of efficient anti-tumor activity in vitro and in vivo. This study demonstrates a vaccine strategy to generate high-avidity CTL responses that can be used in anti-tumor and anti-viral vaccine settings

Antibodies designed as effective cancer vaccines (2009)

Antibodies designed as effective cancer vaccines (2009)

R.L. Metheringham, V.A. Pudney, B. Gunn, M. Towey, I. Spendlove and L.G. Durrant

ABSTRACT: Antigen/antibody complexes can efficiently target antigen presenting cells to allow stimulation of the cellular immune response. Due to the difficulty of manufacture and their inherent instability complexes have proved inefficient cancer vaccines. However, anti-idiotypic antibodies mimicking antigens have been shown to stimulate both antibody and T cell responses. The latter are due to T cell mimotopes expressed within the complementarity-determining regions (CDRs) of antibodies that are efficiently presented to dendritic cells in vivo. Based on this observation we have designed a DNA vaccine platform called ImmunoBodyTM, where cytotoxic T lymphocyte (CTL) and helper T cell epitopes replace CDR regions within the framework of a human IgG1 antibody. The ImmunoBodyTM expression system has a number of design features which allow for rapid production of a wide range of vaccines. The CDR regions of the heavy and light chain have been engineered to contain unique restriction endonuclease sites, which can be easily opened, and oligonucleotides encoding the T cell epitopes inserted. The variable and constant regions of the ImmunoBodyTM are also flanked by restriction sites, which permit easy exchange of other IgG subtypes. Here we show a range of T cell epitopes can be inserted into the ImmunoBodyTM vector and upon immunization these T cell epitopes are efficiently processed and presented to stimulate high frequency helper and CTL responses capable of anti-tumor activity