BTLA and melanoma: Another interesting apoptosis-related biomarker is BTLA, which is a ligand for CD79A and TNFRSF14. Binding of BTLA to TNFRSF14 (also known as HVEM) is an immune checkpoint that has been generally associated with negative immune responses,80 although there is also evidence that this binding promotes survival of CD8+ T cells in melanoma.81