The development of Human γδ-T Antigen Presenting Cells as a clinical grade cancer vaccine
Mirka Blahova1, Neil M Steven1, Bernhard Moser1, Stuart M Curbishley1*
1NIHR Birmingham Liver Biomedical Research Unit, University of Birmingham, Edgbaston, Birmingham. B15 2TT, 2Cardiff University, Cardiff Institute of Infection and Immunity, Heath Park, Cardiff. CF14 4XN
Introduction: Gamma-delta T Antigen Presenting Cells (γδT-APC) represent a novel type of therapeutic cellular vaccine with potential to mobilize effective anti-tumour immune responses in patients with cancer compared to existing approaches. Here, we describe a manufacturing process compliant with current regulatory guidelines.
Methods: Up to 200 mL peripheral blood was taken from patients with either melanoma, primary liver cancer or healthy controls. Peripheral blood mononuclear cells were isolated and resuspended to 2 x 106 cells/mL in GMP grade culture medium, supplemented with 1% pooled platelet lysate and a generic γδT-cell antigen (zoledronic acid). After 48 hours, cells were stimulated with IL-2 and IL-15 (both 100 IU/mL). All cultures were carried out in gas permeable culture bags or G-Rex culture devices. In addition, after initiation of expansion, cells were transferred to a wave bioreactor (GE Healthcare, Xuri) and cultured for a further 5-9 days. Maintenance of APC function was confirmed in antigen presentation assays.
Results: The frequency of γδT-cells in peripheral blood varied from 0.2% - 6% of all T cells. Following expansion, γδT-cell frequency increased (mean 85%, range 55-93%) with viability of >90%. Expansion in G-Rex chambers was sufficient to yield 2 -3 x 109 cells whilst transfer into the wave bioreactor permitted expansion up to 20 - 30 x 109 cells. Following expansion, APC function was confirmed by expansion of a CD8 reporter line in response to peptide or whole protein loaded γδT-APC.
Conclusion: We have demonstrated the expansion of γδT-APC in a GMP culture system. This data is being compiled into a submission to the regulatory authority to carry out a vaccination study in patients with solid tumours, refractory to standard of care therapy.