Background HLA-E is a non-classical HLA molecule that can engage the heteromeric inhibitory receptor NKG2A/CD94 to suppress T-cell/NK-cells. Blockade of NKG2A in combination with other immunostimulatory antibodies shows encouraging clinical activity in a subset of patients with locally advanced non-small cell lung cancer (NSCLC). Despite its possible clinical relevance, the levels, spatial distribution and biomarker potential of the HLA-E/NKG2A pathway in NSCLC remain poorly understood.
Methods Using multiplexed quantitative immunofluorescence (mQIF), we simultaneously measured the levels of HLA-E, NKG2A protein, CD8+ T-cells and cytokeratin (CK)-expressing cancer-cells in three retrospective NSCLC cohorts represented in tissue microarrays. The mQIF analysis included compartment-based measurements based on fluorescence co-localization as well as single-cell segmentation and spatial analysis. The first two cohorts included baseline tumor samples from patients with stages I-IV NSCLC treated with non-immunotherapy regimens (Cohort #1, n=138; Cohort #2, n=248). The third cohort (Cohort #3, n=23 pairs) included paired biopsies before and after chemotherapy +/- radiotherapy in patients with locally advanced NSCLC. Associations between the markers with clinicopathologic variables and outcomes were studied.
Results 94% of NSCLCs showed detectable expression of HLA-E and 98% of NKG2A, but the levels were highly variable across cases. HLA-E protein was predominantly expressed in CK+ cancer cells and NKG2A was higher in (nonmalignant) CK- stromal cells. The levels of the markers were positively associated across the cohorts. Elevated HLA-E or NKG2A were associated with higher local CD8+ T-cell infiltration and longer overall survival, but only HLA-E was independent from CD8+ TILs in multivariable analysis (Cohort #1, HR= 0.16 [95% CI: 0.022 to 0.89]; Cohort 2, HR= 0.074 [95% CI: 0.0042 to 0.87]). No consistent association between the marker levels and major clinicopathologic variables was found. Notably, NKG2A+ immune cells were located more distant from HLA-E-expressing than from HLA-E-negative cancer-cells.
Conclusions The HLA-E/NKG2A pathway is expressed in a large fraction of NSCLCs with a distinct expression pattern in tumor and non-tumor/immune cells. Elevated expression of HLA-E and NKG2A occurs in tumors with increased local adaptive anti-tumor responses and is associated with better outcomes and distinct spatial tumor microenvironment features. The levels and spatial distribution of HLA-E and NKG2A proteins are unaffected by chemoradiotherapy. Collectively, our results support that the HLA-E/NKG2A is a dominant immunomodulatory pathway in a subset of NSCLC with prominent biomarker and therapeutic potential.
Acknowledgements Funding Source: AstraZeneca
This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See http://creativecommons.org/licenses/by-nc/4.0/.
Statistics from Altmetric.com
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.