The success of checkpoint blockade therapy revolutionized cancer treatment. However, we need to increase the fraction of responding patients and overcome acquired resistance to these therapies.... Show moreThe success of checkpoint blockade therapy revolutionized cancer treatment. However, we need to increase the fraction of responding patients and overcome acquired resistance to these therapies. Recently, the inhibitory receptor NKG2A received attention as a new kid on the block of immune checkpoints. This receptor is selectively expressed on cytotoxic lymphocytes, including natural killer cells and CD8 T cells, and NKG2A+ T cells are preferentially residing in tissues, like the tumor microenvironment. Its ligand, HLA-E, is a conserved non-classical HLA class I molecule that binds a limited peptide repertoire and its expression is commonly detected in human cancer. NKG2A blockade as a standalone therapy appears poorly effective in mouse tumor models, however in the presence of activated T cells, for example induced by PD-1/PD-L1 blockade or cancer vaccines, displays strongly enhanced efficacy. Clinical trials demonstrated safety of the humanized NKG2A-blocking antibody monalizumab and first results of phase II trials demonstrate encouraging durable response rates. Further development of this axis is clearly warranted. Show less
Borst, L.; Sluijter, M.; Sturm, G.; Charoentong, P.; Santegoets, S.J.; Gulijk, M.; ... ; Hall, T. van 2021
The surface inhibitory receptor NKG2A forms heterodimers with the invariant CD94 chain and is expressed on a subset of activated CD8 T cells. As antibodies to block NKG2A are currently tested in... Show moreThe surface inhibitory receptor NKG2A forms heterodimers with the invariant CD94 chain and is expressed on a subset of activated CD8 T cells. As antibodies to block NKG2A are currently tested in several efficacy trials for different tumor indications, it is important to characterize the NKG2A(+) CD8 T cell population in the context of other inhibitory receptors. Here we used a well-controlled culture system to study the kinetics of inhibitory receptor expression. Naive mouse CD8 T cells were synchronously and repeatedly activated by artificial antigen presenting cells in the presence of the homeostatic cytokine IL-7. The results revealed NKG2A as a late inhibitory receptor, expressed after repeated cognate antigen stimulations. In contrast, the expression of PD-1, TIGIT and LAG-3 was rapidly induced, hours after first contact and subsequently down regulated during each resting phase. This late, but stable expression kinetics of NKG2A was most similar to that of TIM-3 and CD39. Importantly, single-cell transcriptomics of human tumor-infiltrating lymphocytes (TILs) showed indeed that these receptors were often coexpressed by the same CD8 T cell cluster. Furthermore, NKG2A expression was associated with cell division and was promoted by TGF-beta in vitro, although TGF-beta signaling was not necessary in a mouse tumor model in vivo. In summary, our data show that PD-1 reflects recent TCR triggering, but that NKG2A is induced after repeated antigen stimulations and represents a late inhibitory receptor. Together with TIM-3 and CD39, NKG2A might thus mark actively dividing tumor-specific TILs. Show less
Hall, T. van; Andre, P.; Horowitz, A.; Ruan, D.F.; Borst, L.; Zerbib, R.; ... ; Vivier, E. 2019
