Oral Presentation Australasian Society for Immunology Annual Scientific Meeting 2014

Anti-cancer vaccination using mRNA loaded CMRF-56 immune selected blood dendritic cells (#86)

Michael S Papadimitrious 1 , Sebastien Anguille 2 , Christian Bryant 1 , Fiona Kupresanin 1 , Nirupama Verma 1 , Kevin Lo 1 , Georgina J Clark 1 , Elizabeth Newman 3 , Kenneth F Bradstock 1 , Zwi N Berneman 2 , Phillip D Fromm 1 , Derek NJ Hart 1
  1. ANZAC Research Institute, Concord, NSW, Australia
  2. Centre for Cell Therapy and Regenerative Medicine, Antwerp University Hospital, Antwerp, Belgium
  3. Concord Repatriation General Hospital, Sydney, NSW

Introduction: Anti-cancer vaccines using monocyte derived dendritic cells (MoDC) loaded with mRNA from tumour associated antigens (TAA) have shown encouraging clinical results. Although MoDC are widely used for studying dendritic cells (DC), we and others have described functional differences. The CMRF-56 human IgG4 chimeric monoclonal antibody was engineered for clinical-grade immune selection of blood DC.

Aim: We evaluated hCMRF-56 as an improved clinical preparation for DC immunotherapy by 1) comparing moDC preparations in a preclinical xenograft model testing their capacity to migrate to draining lymph nodes 2) their ability to initiate anti-tumour immune response following loading of mRNA TAA.

Method: Blood DC were prepared from healthy donors and tested the clinical utility of GMP grade CMRF-56 isolated cells for migration, cytokine production, their ability to elicit antigen specific immune responses in preclinical models.

Results: Loading of TAA mRNA by nucleofection displayed stable transgene expression up to 48 hours post nucleofection. Characterisation of the proposed clinical preparation identified up-regulation of CD40 post GM-CSF activation, and CD80 post GM-CSF activation and mRNA nucleofection. Levels of CD54, CD83, CD86 and CCR7 were constitutively high. Nucleofected CMRF-56+ blood DC migrated towards CCL21 in vitro, while contaminating B cells and monocytes appeared to migrate minimally. CMRF-56+ blood DC and MoDC were administered to a SCID mice model to monitor their in vivo migration to draining lymph nodes compared with MoDC. IFNgamma Flu Matrix Protein 1 responses were observed by CD4+ and CD8+ lymphocytes. Stimulation of CMRF-56+ blood DC loaded with Wilms Tumour 1 antigen mRNA was able to induce autologous CD4+ T cell responses but did not result in significant IFNgamma production by allogeneic WT1126-134 specific CD8+ T cell clones.

Conclusion: Our data suggests blood DC can be effectively nucleofected with TAA mRNA. Nucleofection does not impair the ability to process antigens, migrate to lymph nodes and present antigen. This demonstrates the efficacy of mRNA nucleofected blood DC to warrant further clinical investigation.