Fig. 2.

Frequency of MCPyV-specific CD8 T cells over the course of anti-PD-1 therapy. MCPyV-specific HLA class I tetramer-positive T cells were detected in pre-treatment PBMC in 6 of 9 (66%) of patients with VP-MCC tumors and appropriate HLA-I types, and in 0 of 8 patients with VN-MCC tumors with appropriate HLA class I types. a) Representative gating strategy for detection of MCPyV-specific T cells as indicated by tetramer binding. b) The frequency of tetramer-positive T cells increased after therapy in patients with a partial response (dashed, n = 3), yet remained similar to baseline or decreased in patients with a complete response (black, n = 2). Two patients subsequently recurred (denoted by * for recurrence on treatment and ** for recurrence after end of treatment)