PDCD1 and melanoma: IHC analysis of lung tumors following C215Fab-SEA treatment alone and in combination with anti-PD-1 treatment was shown to promote GrzB+CD8+ T-cell infiltration even into the poorly immunogenic B16F10 melanoma tumors, turning “cold” tumors into immunogenically “hot” tumors (Additional file 4: Fig. S4C, D).