IMMU-02. CMV-EXPANDED T-CELLS IN GLIOBLASTOMA PATIENTS: TRANSLATIONAL RESEARCH

Abstract Human cytomegalovirus (CMV) is a contributing factor to tumour expansion and progression in glioblastoma patients. Patient-derived non-modified CMV-specific T cells can be isolated, ex vivo re-stimulated with CMV and expanded before IV infusion. Adoptive T cell Therapy with expanded CMV-specific T cells and has been shown to improve GBM prognosis. We aimed to develop a CMV-specific T cell expansion protocol. PBMCs were isolated from blood of 12 healthy CMV-antibody positive donors and 9 patients (three glioblastoma patients, four prostate cancer patients, one pancreatic cancer and one rectal cancer patient). CMV-pulsed stimulating and responding PBMC (S:R ratio = 1:2) were cultured in RPMI supplemented with IL-21 and subsequent IL-2 addition for 9 days. Cell quality was ensured via cell surface staining and intracellular cytokine assays. Product sterility was tested with aerobic and anaerobic sterility assays, Endotoxin test and mycoplasma tests. Autologous CMV-specific T cells were successfully isolated from CMV positive donors and cancer patients. Ex vivo analysis of CMV-specific T cells after in vitro CMV restimulation and expansion resulted in 6.81 x 106 to 2.52 x 108 viable cells (Δ1.09 x 108 with Δ90% viability) with antigen-specific active T-cell frequencies ranging from 15.10% to 41.98% (median 38.39%) in healthy donors and 14.78% to 54.75% of total CD8+ T cells (median 31.42%) in cancer patients. A cell culture protocol was developed to expand autologous CMV-specific CD8+ T cells from patients. Product release criteria were defined as 1-2 x 107 cells per m2 body surface area with a >50% viability rate and >15% CMV-specific CD8+ T cells within the total T cell population. The translation of the cell culture protocol within a GMP setting is envisioned. The efficacy of such treatment has to be elaborated once the cell product is approved for medicinal use.