CMTM6 stabilizes PD-L1 expression and refines its prognostic value in tumors

In the early 1990s, the team of Dr. Honjo identified a new gene that was upregulated during T-cell activation, supposedly as an apoptosis-associated molecule (1). This gene was named programmed cell death-1 (PD-1 or CD279 or PDCD1). The PD-1 protein turned out to be a receptor delivering a co-inhibitory signal, playing a decisive role in maintaining peripheral tolerance and impeding autoimmunity, but with no effect on cell apoptosis. In 2000, Drs. Freeman and Sharpe discovered the natural ligands for the PD-1 receptor, called programmed cell death-1 ligand-1 (PD-L1 or CD274 or PDCD1L1) and programmed cell death-1 ligand-2 (PD-L2 or CD273 or PDCD1L2) (2,3).