Targeting the aminopeptidase ERAP enhances antitumor immunity by disrupting the NKG2A-HLA-E inhibitory checkpoint
Hsiao‐Wei Tsao, Seth Anderson, Kenneth J. Finn, Jonathan Perera, Lomax F. Pass, Emily M. Schneider, Aiping Jiang, Rachel A. Fetterman, Cun Lan Chuong, Kaiya Kozuma, Marcia Stickler, Marc Creixell, Susan Klaeger, Kshiti Meera Phulphagar, Suzanna Rachimi, Eva K. Verzani, Niclas Olsson, Juan Dubrot, Matthew F. Pech, Whitney Silkworth, Sarah Kate Lane-Reticker, Peter M. Allen, Kyrellos Ibrahim, Nelson H. Knudsen, Andrew Y. Cheng, Adrienne H. Long, Hakimeh Ebrahimi-Nik, Sarah Kim, Peter P. Du, Arvin Iracheta‐Vellve, Emily Robitschek, Juliette S. M. T. Suermondt, Thomas Davis, Clara Wolfe, Trisha Atluri, Kira E. Olander, Jason S. Rush, Thomas B. Sundberg, Fiona E. McAllister, Jennifer G. Abelin, Ari J. Firestone, David Stokoe, Steven A. Carr, Fiona Harding, Kathleen B. Yates, Robert T. Manguso
Abstract
The aminopeptidase, endoplasmic reticulum aminopeptidase 1 (ERAP1), trims peptides for loading into major histocompatibility complex class I (MHC class I), and loss of this activity has broad effects on the MHC class I peptidome. Here, we investigated the impact of targeting ERAP1 in immune checkpoint blockade (ICB), as MHC class I interactions mediate both activating and inhibitory functions in antitumor immunity. Loss of ERAP sensitized mouse tumor models to ICB, and this sensitivity depended on CD8 + T cells and natural killer (NK) cells. In vivo suppression screens revealed that Erap1 deletion inactivated the inhibitory NKG2A-HLA-E checkpoint, which requires presentation of a restricted set of invariant epitopes (VL9) on HLA-E. Loss of ERAP altered the HLA-E peptidome, preventing NKG2A engagement. In humans, ERAP1 and ERAP2 showed functional redundancy for the processing and presentation of VL9, and loss of both inactivated the NKG2A checkpoint in cancer cells. Thus, loss of ERAP phenocopies the inhibition of the NKG2A-HLA-E pathway and represents an attractive approach to inhibit this critical checkpoint.