Fig. 3

T cell reactivity to MCPyV-specific peptides increased after therapy in a patient who had a robust partial response to pembrolizumab. a) There was a significant reduction in burden of liver metastases (white arrow heads) as visualized by CT scans obtained at baseline and 12 weeks after initiating therapy. b) IFN-γ and IL-2 production by CD8+ cells from circulating PBMC to pools of MCPyV-specific peptides from samples obtained immediately pre-treatment and after 12 weeks of pembrolizumab therapy show a ~15x increase in anti-MCPyV-reactivity to peptide pools 1 and 2 after subtraction of background stimulation by DMSO. c) The frequency of tetramer+ CD8 cells restricted to HLA-B*07:02 ‘APNCYGNIPL’ (an epitope in Pool 1) increased significantly (~7x) after therapy