Spatial colocalization and combined survival benefit of natural killer and CD8 T cells despite profound MHC class I loss in non-small cell lung cancer
Authors: Wessel Remziye E. , Ageeb Nardin , Obeid Joseph M. , Mauldin Ileana , Goundry Kate A. , Hanson Gabriel F. , Hossain Mahdin , Lehman Chad , Gentzler Ryan D. , Wages Nolan A. , Slingluff Craig L. , Bullock Timothy N.J. , Dolatshahi Sepideh , Brown Michael G. 
Published: February 2024

Background

MHC class I (MHC-I) loss is frequent in non-small cell lung cancer (NSCLC) rendering tumor cells resistant to T cell lysis. NK cells kill MHC-I-deficient tumor cells, and although previous work indicated their presence at NSCLC margins, they were functionally impaired. Within, we evaluated whether NK cell and CD8 T cell infiltration and activation vary with MHC-I expression.

Methods

We used single-stain immunohistochemistry (IHC) and Kaplan-Meier analysis to test the effect of NK cell and CD8 T cell infiltration on overall and disease-free survival. To delineate immune covariates of MHC-I-disparate lung cancers, we used multiplexed immunofluorescence (mIF) imaging followed by multivariate statistical modeling. To identify differences in infiltration and intercellular communication between IFNγ-activated and non-activated lymphocytes, we developed a computational pipeline to enumerate single cell neighborhoods from mIF images followed by multivariate discriminant analysis

Results

Spatial quantitation of tumor cell MHC-I expression revealed intra- and inter-tumoral heterogeneity, which was associated with the local lymphocyte landscape. IHC analysis revealed that high CD56+cell numbers in patient tumors were positively associated with disease-free survival (DFS) (HR=0.58,p=0.064) and over-all survival (OS) (HR=0.496,p=0.041). The OS association strengthened with high counts of both CD56+and CD8+cells (HR=0.199,p<1×10-3). mIF imaging and multivariate discriminant analysis revealed enrichment of both CD3+CD8+T cells and CD3−CD56+NK cells in MHC-I-bearing tumors (p<0.05). To infer associations of functional cell states and local cell-cell communication, we analyzed spatial single cell neighborhood profiles to delineate the cellular environments of IFNγ+/-NK cells and T cells. We discovered that both IFNγ+NK and CD8 T cells were more frequently associated with other IFNγ+lymphocytes in comparison to IFNγ−NK cells and CD8 T cells (p<1×10-30). Moreover, IFNγ+lymphocytes were most often found clustered near MHC-I+tumor cells.

Conclusions

Tumor-infiltrating NK cells and CD8 T cells jointly affected control of NSCLC tumor progression. Co-association of NK and CD8 T cells was most evident in MHC-I-bearing tumors, especially in the presence of IFNγ. Frequent co-localization of IFNγ+NK cells with other IFNγ+lymphocytes in near-neighbor analysis suggests NSCLC lymphocyte activation is coordinately regulated.

What is already known on this topic

MHC-I loss occurs frequently in NSCLC and corresponds with waning immunity in the tumor microenvironment (TME). NK cells recognize “missing-self” targets and could be leveraged to target NSCLC tumors with MHC-I loss. While NK cell presence at tumor margins has been documented in NSCLC, they were shown to lose function in this environment.

What this study adds

We developed spatial analysis pipelines leveraging the local heterogeneity of the TME at single cell resolution to test whether NK cells and T cells together contribute antitumoral immunity in NSCLC. We discovered that a high density of tumor-infiltrating NK cells corresponded with DFS, and this association was increased in patients with high coincident CD8 T cells, especially those in central tumor. Intriguingly, both cell types were found clustered together in MHC-I-bearing tumors, especially when both expressed IFNγ, suggesting coordinated lymphocyte activities may enhance immune control of NSCLC.

How this study might affect research, practice, or policy

This study provides a rationale for developing novel immunotherapies that simultaneously increase NK and T cell anti-tumoral immunity. Associations linking NK cells with patient survival and increased immune effector activity in NSCLC, even in MHC-I-deficient tumors, further highlights the need to devise and deploy NK cell activating strategies which may be highly efficacious in CD8 T cell refractory NSCLC.

Graphical Abstract