PMEL and melanoma: To develop a more in-depth understanding of the immunological mechanism of action of NKTR-214, we selected a tumor model that allowed for detailed analysis of tumor-specific T-cell responses, hence the pmel-1/B16.F10 melanoma model that employs trackable, CD90.1 congenically marked gp100 melanoma antigen-specific CD8+ T cells was used19–21.