BRAF and MEK inhibitors increase PD1-positive melanoma cells leading to a potential lymphocyte-independent synergism with anti-PD1 antibody

BRAF and MEK inhibitors (BRAF/MEKi) favor melanoma-infiltrating lymphocytes, providing the rationale for current combinatorial trials with anti-PD1 antibody. A portion of melanoma cells may express PD1, and anti-PD1 antibody could have a direct anti-tumor effect. Here, we explore if BRAF/MEKi modulate rates of PD1+ melanoma cells, supporting an additional - lymphocyte-independent - basis for their therapeutic combination with anti-PD1 antibody.