Immunogenicity assessment
ADENOVIRUS, VIRUS, CYTOMEGALOVIRUS
The primary immunogenicity endpoint was defined by the induction of CoVac-1-specific T-cell responses in at least 70% of study patients to one or more of the CoVac-1 peptides or the combination of all six peptides, evaluated on day 7, day 14, and day 28 by IFN-γ ELISPOT assay ex vivo and after in vitro T-cell expansion. For T-cell expansion, peripheral blood mononuclear cells (PBMCs) were pulsed with CoVac-1 peptides (5 μg/mL per peptide) and cultured for 12 days adding 20 U/mL interleukin-2 (IL-2, Novartis) on days 3, 5, and 7. For IFN-γ ELISPOT (ex vivo or after in vitro expansion), cells were stimulated with 2.5 μg/mL of CoVac-1 peptides and analyzed in technical replicates. T-cell responses were considered positive (indicated as median of positive samples) if mean spot count was ≥ three-fold higher than mean spot count of negative control and defined as CoVac-1-induced (indicated as response (%)) if the mean spot count post administration was ≥ two-fold higher than the respective spot count on day 1 (baseline, prior to vaccination). Patients without the general ability to mount antigen-specific T-cell responses (absence of CoVac-1-induced T-cell responses and no T-cell responses to HLA-DR T-cell epitope control panel including Epstein-Barr virus (EBV), cytomegalovirus (CMV) and adenovirus (ADV) peptides as previously described