ImmTAC/Anti-PD-1 antibody combination to enhance killing of cancer cells by reversing regulatory T-cell-mediated immunosuppression.

Recently, bi-functional molecules that can redirect immune effectors to tumour cells have emerged as potentially robust mediators of tumour regression in clinical trials. Two modalities in particular, bi-specific antibodies for T-cell redirection and activation (BiTe) and immune-mobilizing monoclonal T-cell receptors against cancer (ImmTAC), are being evaluated in efficacy studies as 'off-the-shelf' reagents. Optimal therapy will require an understanding and means to address regulatory mechanisms of limiting efficacy.

Neuroblastoma killing properties of Vδ2 and Vδ2-negative γδT cells following expansion by artificial antigen-presenting cells.

Purpose: The majority of circulating human γδT lymphocytes are of the Vγ9Vδ2 lineage, and have T-cell receptor (TCR) specificity for nonpeptide phosphoantigens. Previous attempts to stimulate and expand these cells have therefore focused on stimulation using ligands of the Vγ9Vδ2 receptor, whereas relatively little is known about variant blood γδT subsets and their potential role in cancer immunotherapy.

Experimental Design: To expand the full repertoire of γδT without bias toward specific TCRs, we made use of artificial antigen-presenting cells loaded with an anti γδTCR antibody that promoted unbiased expansion of the γδT repertoire.

γδ T cells for cancer immunotherapy: A systematic review of clinical trials.

γδ T cells contribute to the front line of lymphoid antitumor surveillance and bridge the gap between innate and adaptive immunity. They can be readily expanded to high numbers in vivo and in vitro, starting from the blood of cancer patients, and a number of Phase I trials have demonstrated that these cells can be employed in cancer immunotherapy. Sufficient patients have received γδ T cell-based immunotherapies in the context of clinical trials to evaluate their utility, and to inform the direction of new trials.

Regeneration of stalled immune responses to transformed and infected cells using γδ T cells.

Manipulation of the human immune system is becoming more of a therapeutic focus as a treatment option or complement. Prominent examples are the increasing use of monoclonal antibodies in combating malignant tumours, and the numerous adoptive immunotherapy trials underway. One important aspect of any use of the human immune system in this regard is to harness the power of professional antigen-presenting cells (pAPC), that is, dendritic cells (DC), to direct immune responses.

Licensing of γδT cells for professional antigen presentation: A new role for antibodies in regulation of antitumor immune responses.

Following activation, γδ T cells display many properties of lymphocytes from the innate immune system, yet how they mediate antigen presentation remains an open conundrum. In humans, circulating γδ T cells that express the Vγ9Vδ2 T-cell receptor become reversibly licensed for professional antigen presentation only upon interaction with a target cell opsonized with IgGs.

Human γδ T lymphocytes are licensed for professional antigen presentation by interaction with opsonized target cells.

Activated human blood γδ T cells have also been previously demonstrated to behave as professional APCs, although the processes that control APC function have not been characterized. n this study, we show that the acquisition of potent APC function by human blood γδ T cells is achieved after physical interaction with an Ab-coated target cell, a process that we refer to as licensing. In cancer models, licensing of γδ T cells by tumor-reactive mAbs promotes the uptake of tumor Ags and professional presentation to tumor-reactive αβ T cells.

Increased PRAME antigen-specific killing of malignant cell lines by low avidity CTL clones, following treatment with 5-Aza-2'-Deoxycytidine.

The cancer testis antigen Preferentially Expressed Antigen of Melanoma (PRAME) is overexpressed in many solid tumours and haematological malignancies whilst showing minimal expression in normal tissues and is therefore a promising target for immunotherapy. HLA-A0201-restricted peptide epitopes from PRAME have previously been identified as potential immunogens to drive antigen-specific autologous CTL responses, capable of lysing PRAME expressing tumour cells. CTL lines, from 13 normal donors and 10 melanoma patients, all of whom were HLA-A0201 positive, were generated against the PRAME peptide epitope PRA(100-108).

Migratory and antigen presentation functions of IFN-producing killer dendritic cells.

The CD11c(int) B220(+) NK1.1(+) CD49(+) subset of cells has recently been described as IFN-producing killer dendritic cells (IKDC), which share phenotypic and functional properties with both dendritic cells and natural killer cells. We have previously shown that IKDCs within murine bone marrow-derived DC preparations are essential for the antitumor activity of unpulsed DCs.

Development of cellular immune responses against PAX5, a novel target for cancer immunotherapy.

PAX5 is a member of the PAX family of developmental transcription factors with an important role in B-cell development. Its expression in normal adult tissue is limited to the hemopoietic system, but it is aberrantly expressed in a number of solid cancers and leukemias where it functions as an oncogene. We therefore hypothesized that anti-PAX5 immune responses could be used to target a number of malignancies without significant toxicity.

MYCN as a target for cancer immunotherapy.

MYCN is a potential target for cancer immunotherapy by virtue of its overexpression in numerous human malignancies and its functional role in tumour progression. Here we show limited expression of MYCN in normal human tissues indicating that anti-MYCN immune responses are unlikely to cross react with self tissues. An HLA-A2 restricted ten amino acid peptide epitope from MYCN, VILKKATEYV, was used to stimulate cytotoxic T cell lines from the peripheral blood of normal blood donors, and from a patient with MYCN amplified neuroblastoma.

Development of anti-PAX3 immune responses; a target for cancer immunotherapy.

PAX3 is overexpressed in several human cancers and is absent from normal adult human tissues. It is known to have an oncogenic function in human malignancy, and is therefore a promising target for cancer immunotherapy. We screened the murine and human PAX3 amino acid sequences for peptides that bind common MHC class I types, and identified murine GVFINGRPL and human KLTEARVQV sequences.

Activation of dendritic cells by human papillomavirus-like particles through TLR4 and NF-kappaB-mediated signalling, moderated by TGF-beta.

Human papillomavirus-like particles (HPV-VLP) are a candidate vaccine for prevention of HPV infection, and also are a candidate for an immunogenic delivery system for incorporated antigen. VLP activate in vitro generated dendritic cells (DC) but not Langerhans cells (LC); however, the mechanism of this activation is unknown. We have shown that uptake and activation of DC by VLP involves proteoglycan receptors and can be inhibited by heparin.

Despite differences between dendritic cells and Langerhans cells in the mechanism of papillomavirus-like particle antigen uptake, both cells cross-prime T cells.

As human papillomavirus-like particles (HPV-VLP) represent a promising vaccine delivery vehicle, delineation of the interaction of VLP with professional APC should improve vaccine development. Differences in the capacity of VLP to signal dendritic cells (DC) and Langerhans cells (LC) have been demonstrated, and evidence has been presented for both clathrin-coated pits and proteoglycans (PG) in the uptake pathway of VLP into epithelial cells. Therefore, we compared HPV-VLP uptake mechanisms in human monocyte-derived DC and LC, and their ability to cross-present HPV VLP-associated antigen in the MHC class I pathway.