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OA 13 - Immuno-Biology (ID 677)
- Event: WCLC 2017
- Type: Oral
- Track: Immunology and Immunotherapy
- Presentations: 1
- Moderators:Hiroyuki Suzuki, Scott N. Gettinger
- Coordinates: 10/18/2017, 11:00 - 12:30, Room 301 + 302
OA 13.05 - Immune, Molecular and T Cell Repertoire Landscape of 235 Resected Non-Small Cell Lung Cancers and Paired Normal Lung Tissues (ID 8766)
11:00 - 12:30 | Author(s): C. Wu
Non-small cell lung cancer (NSCLC) is characterized by a high mutational load. Accordingly, it is also among the tumor types responding to immune checkpoint blockade, likely through harnessing of the anti-tumor T cell response. However, the lung is continuously exposed to the outside environment, which may result in a continuous state of inflammation against outside pathogens unrelated to the tumor microenvironment. Therefore, further investigation into the T cell repertoire and T cell phenotypes across normal lung and tumor is warranted.
We performed T cell receptor (TCR) sequencing on peripheral blood mononuclear cells (PBMC), normal lung, and tumor from 225 NSCLC patients, among which, 96 patients were also subjected to whole exome sequencing (WES) of PBMC, tumor and normal lung tissues. We further performed Cytometry by Time-of-Flight (CyTOF) on 10 NSCLC tumors and paired normal lung tissues to phenotype immune and T cell subsets.
Comparison of the T cell repertoire showed 9% (from 4% to 15%) of T cell clones were shared between normal lung and paired tumor. Furthermore, among the top 100 clones identified in the tumor, on average 57 (from 0 to 95) were shared with paired normal lung tissue. Interestingly, T cell clonality was higher in the normal lung in 89% of patients suggesting potential differences in the immune response and immunogenicity. A substantial number of somatic mutations were also identified not only in NSCLC tumors (average 566; from 147 to 2819), but also in morphologically normal lung tissues (average 156; from 50 to 2481). CyTOF demonstrated striking differences in the immune infiltrate between normal lung and tumor, namely a lower frequency of PD-1+CD28+ T cells (both CD4+ and CD8+) in the normal lung (2.7% versus 3.0% in tumor). In addition, a unique GITR+ T cell subset (0.96%) was entirely restricted to the normal lung. Conversely, increases in regulatory T cell frequency (CD4+FoxP3+) were observed in the tumor (10.4% vs 1.7% in normal lung), further highlighting the differences in T cell phenotype and response across normal lung and tumor.
These results suggest that a substantial proportion of infiltrating T cells in NSCLC tumors may be residential T cells associated with response to environmental factors. However, normal lung and NSCLC tumors carry T cells of distinct phenotypes including increases in immunosuppressive T cells within the tumor which may further highlight the differences in the anti-tumor immune response.
P2.02 - Biology/Pathology (ID 616)
- Event: WCLC 2017
- Type: Poster Session with Presenters Present
- Track: Biology/Pathology
- Presentations: 1
- Coordinates: 10/17/2017, 09:30 - 16:00, Exhibit Hall (Hall B + C)
P2.02-013 - Investigation of Genomic and TCR Repertoire Evolution of AAH, AIS, MIA to Invasive Lung Adenocarcinoma by Multiregion Exome and TCR Sequencing (ID 9192)
09:30 - 16:00 | Author(s): C. Wu
Carcinogenesis may result from accumulation of molecular aberrations (molecular evolution) and escaping from host immune surveillance (immunoediting). It has been postulated that atypical adenomatous hyperplasia (AAH) represents preneoplastic lesion that may progress to adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA) and further to frankly invasive adenocarcinoma (ADC). However, due to lack of appropriate study materials, the molecular and immune landscape of AAH, AIS or MIA have not been well studied and the definition and management of these lesions remain controversial.
With the intent to delineate the pivotal molecular and immune events during early carcinogenesis of lung adenocarcinoma, we have collected 119 resected pre- and early neoplastic lung lesions including AAH (N=24), AIS (N=27), MIA (N=54) and ADC (N=14) from 53 patients including 41 patients presenting with multifocal lesions and 25 patients carrying more than one type of pathology. Two to five spatially separated regions from each lesion were subjected to whole exome sequencing and T cell receptor sequencing.
Mutation burden (average SNVs) was found to progressively increase from 1.32/Mb in AAH to 2.55/MB in AIS, 5.42/MB in MIA and 15.38/MB in ADC. Genomic heterogeneity has also become more complex with neoplastic progression with mean Shannon index of 1.53 in AAH, 1.78 in AIS, 1.56 in MIA and 1.79 in ADC. An increase in C>A transversions coincident with a decrease in A>G transitions and progressively increasing APOBEC enrichment scores (4.13 in AAH, 5.63 in AIS, 6.02 in MIA and 6.59 in ADC) were observed with neoplastic disease progression. Furthermore, phylogenetic analysis revealed varying evolutional processes in AAH, AIS, MIA and ADC with canonical cancer gene mutations in KRAS, ATM, TP53 and EGFR etc. as key drivers in a subset of patients. TCR sequencing demonstrated a progressive decrease in T cell density (average percent T cells among all nuclear cells: 12% in AAH, 8% in AIS, 7% in MIA and 4% in ADC) and a progressive decrease in productive TCR clonality (average productive TCR clonality: 0.0434 in AAH, 0.0427 in AIS, 0.0399 in MIA and 0.0395 in ADC) suggesting suppressive T cell repertoire in more advanced diseases.
Our results provide molecular evidence supporting the model of early lung carcinogenesis from AAH, to AIS, MIA and ADC and demonstrated that with disease progression, genomic landscape of lung neoplastic lesions has become progressively more complex along with progressive immunosuppressive TCR repertoire.