Abstract |
Immune checkpoint blockade (ICB) has improved cancer care, but ICB is only effective in some patients. The molecular mechanisms that influence ICB therapy response are not completely understood. The non-classical MHC class I molecule HLA-E and its mouse ortholog, Qa-1b, present a limited set of peptides in a TAP1-dependent manner to the NKG2A/CD94 heterodimer to transduce an inhibitory signal to natural killer (NK) and CD8+ T cells. However, deficiency of TAP1 allows Qa-1b to present an alternative peptidome to Qa-1b-restricted T-cell receptors of cytotoxic T cells. In this study, we used CRISPR-Cas9 to study the relationship between TAP1, Qa-1b, and response to anti-PD1 therapy. We hypothesized that immunotherapy response in TAP1-deficient tumors would be influenced by Qa-1b. Strikingly, using a syngeneic orthotopic mouse model, we found that although TAP1-deficient tumors were resistant to anti-PD1 treatment, anti-PD1 response was significantly enhanced in tumors lacking both TAP1 and Qa-1b. This increased sensitivity is partially dependent on NK cells. TAP1-deficient tumors were associated with an increase of intratumoral regulatory T cells (Treg) and neutrophils, whereas tumors lacking both TAP1 and Qa-1b exhibited an increased CD8+ T-cell to Treg ratio. These data suggest that direct inhibition of Qa-1b may alter the immune microenvironment to reverse resistance to anti-PD1 therapy, particularly in the context of antigen-processing defects. IMPLICATIONS: This study reveals important functional crosstalk between classical TAP-dependent MHC complexes and Qa-1b/HLA-E, particularly in tumors with impaired antigen-processing machinery. This can dramatically influence immunotherapy efficacy.
|
Authors | Xiao Zhang, Erich Sabio, Chirag Krishna, Xiaoxiao Ma, Jingming Wang, Hui Jiang, Jonathan J Havel, Timothy A Chan |
Journal | Molecular cancer research : MCR
(Mol Cancer Res)
Vol. 19
Issue 6
Pg. 1076-1084
(06 2021)
ISSN: 1557-3125 [Electronic] United States |
PMID | 33674442
(Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
|
Copyright | ©2021 American Association for Cancer Research. |
Chemical References |
- ATP Binding Cassette Transporter, Subfamily B, Member 2
- Forkhead Transcription Factors
- Histocompatibility Antigens Class I
- Immune Checkpoint Inhibitors
- Q surface antigens
|
Topics |
- ATP Binding Cassette Transporter, Subfamily B, Member 2
(genetics, immunology, metabolism)
- Animals
- Antigen Presentation
(drug effects, genetics, immunology)
- Cell Line, Tumor
- Forkhead Transcription Factors
(immunology, metabolism)
- Gene Knockout Techniques
- Histocompatibility Antigens Class I
(genetics, immunology, metabolism)
- Humans
- Immune Checkpoint Inhibitors
(pharmacology)
- Killer Cells, Natural
(drug effects, immunology, metabolism)
- Lymphocyte Depletion
(methods)
- Mice, Inbred C57BL
- Neoplasms
(genetics, immunology, therapy)
- T-Lymphocytes, Regulatory
(drug effects, immunology, metabolism)
- Tumor Burden
(drug effects, genetics, immunology)
- Tumor Microenvironment
(drug effects, genetics, immunology)
- Mice
|