BTLA and metastatic melanoma: Increased BTLA and PD-1 expression is noted on tumor-specific CD8+ T cells in patients with metastatic melanoma and anti-BTLA and anti-PD-1 immunotherapy has shown to improve tumor-specific CD8+ T cell immune responses with increased frequencies of IFN-γ, TNF, and IL-2 cytokine producing CD8+ T cells [12].