Citations

43 Background: Human leukocyte antigens (HLA) are crucial for cytotoxic T cell responses to cancer. Loss of HLA expression is a mechanism of tumor immune escape and may contribute to resistance to immunotherapy. In patients with non-small cell lung cancer (NSCLC) treated with immune checkpoint inhibitors we have observed discordant responses between brain metastases and extracranial disease and reported on differential PD-L1 expression and clonal T cell infiltration between paired primary lung lesions and brain metastases. In this project we sought to evaluate whether HLA expression was retained in metastatic NSCLC. Methods: Adult patients with paired primary NSCLC and brain metastases were identified from our institution’s tissue registry. HLA-A cell membrane expression on tumor cells was determined by immunohistochemistry with an anti-HLA-A antibody. Tumors with greater than 10% HLA expression were considered positive. Agreement statistics (κ) and Fisher’s exact test were used for analysis. Results: 51 patients with paired primary NSCLC and brain lesions were identified. The median HLA expression was 20% in the primary tumors (IQR 0-65%) and 10% in the brain metastases (IQR 5-40%). 27 primary tumors and 24 brain metastases were positive for HLA expression. There was disagreement in HLA positivity between paired lesions in 11 patients (22%, 95% CI 12-35%)(κ = 0.57, 95% CI 0.35-0.79)(p = 0.0001). There was no significant difference in the time between the primary tumor and brain metastasis resections in patients with HLA expression disagreement compared to those with HLA expression agreement. None of the patients received immune checkpoint inhibitors for treatment of these lesions. Conclusions: We found significant differences in HLA-A expression on tumor cells in nearly one quarter of paired primary lung cancers and brain metastases. Differences in HLA expression may help explain the discrepancies in response to immune checkpoint inhibitors at different sites of disease and warrants further study.

Abstract Background: Adenocarcinoma of the lung is the most common type of non-small cell lung cancer and is the subtype found in approximately 50% of all lung cancer cases. Adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) are thought to be precursor lesions of invasive disease. It has been hypothesized that there is a step-wise progression to lung adenocarcinoma, but little is known about genomic alterations in these precursor lesions. Methods: Genomic analysis including whole genome and exome sequencing, and SNP array analysis were performed on 9 AIS and 18 MIA pathologically confirmed samples to identify single nucleotide variants (SNVs), structural variations and copy number variations. Mutation significance and signature analysis were determined by MutSig and NMF analyses. Altered pathways were determined by Ingenuity variant effect pathway analysis. Results: The tumor mutation burden (TMB) for AIS and MIA ranged from 0.8 to 23.1 mut/Mb with a median of 3.0mut/Mb and a mean of 5.1mut/Mb. Highly mutated genes identified in AIS and MIA were RPL10, NBPF1, KRAS, GPR52, CAMK2A, ATOX1, STK11, TP53, MET and EGFR. Genes with recurrent mutations included SPTA1, USH2A, CACNA1E, EGFR, KRAS, MUC16, MUC17, OTOG, RYR2, COL20A1, CSMD3, RFX6 and XIRP2, which implicated pathways involving the EGFR-KRAS-TP53-MAPK axis. Somatic mutations were characterized by a C>T, T>C transitions and C>A transversion signature. There were comparable structural variations in the AIS cases compared to MIA. Conclusion: In contrast to hypothesized models of tumor progression, AIS and MIA can harbor significant genomic alterations and tumor mutation burden, which suggests an intriguing concept of immunotherapeutic options for either treatment or chemoprevention. Deregulation of EGFR-KRAS-TP53-MAPK pathway indicates a role in early events of carcinogenesis. Citation Format: Michael K. Asiedu, Nanette R. Reed, Marie Christine Aubry, Anja C. Roden, Dennis A. Wigle. Genomic alterations in lung adenocarcinoma precursor lesions [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 728.

Abstract Introduction: While most small cell lung cancer (SCLC) patients die within a few months, a sub-group of patients survive for many years. Factors determining long-term survivorship remain largely unknown. We present the first comprehensive comparative genomic and tumor microenvironment analyses of small cell lung cancer (SCLC) between patients with long term (LTS) and expected (EXS) survival times. Methods: We compared surgically resected tumors of 23 LTS (survival > 4 years) and 18 EXS (survival ≤ 2 years). There were no differences in clinical variables including TNM staging and curative versus non-curative intend surgery between the groups. Gene expression profiling was performed by microarrays and tumor microenvironment analyses were by IHC of prominent immune related markers. Results: Immune related genes and pathways represented the majority of the differentially overexpressed genes in LTS compared to the EXS. The differences in the immunological tumor-microenvironment were confirmed by quantitative immuno-staining. Increased numbers of tumor infiltrating and associated lymphocytes were present throughout tumors of LTS. Several differentiating patterns of enhanced anti-tumor immunity were identified. While some areas of LTS tumors also harbored higher numbers of suppressive immune cells (monocytes, regulatory lymphocytes, and macrophages), ratios of these suppressive cells to CD3+ lymphocytes were generally lower in LTS tumors indicating a more tumor suppressive microenvironment. Conclusions: Our data demonstrate that long-term survivorship of SCLC patients is strongly influenced by the presence of anti-tumor immune cells in the tumor microenvironment. Characterization of the anti-tumor immune responses may identify opportunities for individualized immunotherapies for SCLC. Citation Format: Farhad Kosari, Prasuna Muppa, Simone Terra, Anurag Sharma, Aaron Mansfield, Marie Christine Aubry, Nafiseh Janaki, Aqsa Nasir, Tobias Peikert. Anti-tumor immunity is a key determinant of small cell lung cancer survivorship [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4577.

AimsPulmonary chondromas, which are rare cartilaginous neoplasms that often arise in the setting of Carney triad, are morphologically similar to pulmonary hamartomas, which are much more common. There is evidence that succinate dehydrogenase (SDH) deficiency drives neoplasia in patients with Carney triad, and SDHB immunohistochemistry can be used as a surrogate marker to detect SDH deficiency. The aim of this study was to investigate the utility of SDHB immunohistochemistry in distinguishing pulmonary chondromas from hamartomas.Methods and resultsImmunohistochemistry for SDHB (clone 21A11AE7) was performed on histological sections from six cases of pulmonary chondroma and 33 cases of pulmonary hamartoma. SDHB expression was retained in all 33 pulmonary hamartomas, and lost in the majority of evaluable chondromas (five of six). Of the five patients with chondromas showing SDHB loss, four had definitive Carney triad. Most patients with pulmonary hamartomas were older males with small solitary masses, whereas chondromas often presented as multiple masses in young females.ConclusionLoss of SDHB immunohistochemical expression can be useful for differentiating pulmonary chondromas from hamartomas, and potentially identifying patients with Carney triad.

Abstract Malignant pleural mesothelioma is a disease primarily associated with exposure to the carcinogen asbestos. Consistent with this carcinogenic exposure, cytogenetic analyses have identified multiple recurrent structural chromosomal abnormalities in this malignancy, but more recent high-throughput sequencing evaluations of point mutations suggest that there is a low mutational burden in mesothelioma. Since tumor mutational burden has been correlated with responses to treatment with immune checkpoint inhibitors such as nivolumab, it was not consistent that patients with mesothelioma and low mutation burdens would have similar response rates in clinical trials with immune checkpoint inhibitors as patients with non-small cell lung cancer which is associated with a high mutation burden. In order to reconcile these differences, and given the potential for an improved understanding of the molecular pathogenesis of mesothelioma to improve therapeutic options, we used mate-pair sequencing (MPseq) and RNA sequencing (RNAseq) to understand how structural variants affect the transcriptome. MPseq differs from standard next generation sequencing approaches by tiling the whole genome with larger fragments (2-5kb) to reliably detect structural variants such as insertions, deletions and rearrangements. Amongst 22 mesothelioma specimens there were 1535 chromosomal rearrangements (median 41, range 3-298 per specimen), that resulted in junctions or novel fusions of non-coding DNA or genes. Six-hundred thirty-seven of these rearrangements (median 22, range 5-103 range per specimen) resulted in novel fusions of genes. Many of these inter- or intra-chromosomal rearrangements were consistent with a pattern of chromoanagesis such as chromoplexy or chromothripsis. Chromosomal rearrangements detected by MPseq were used to guide analysis of RNAseq data and revealed that these chromosomal junctions resulted in the expression of 179 novel amino acid sequences (median 5, 0-51 range per specimen). To determine whether transcription of chromosomal rearrangement-related junctions have neoantigenic potential, we used in silico tools to determine whether any of the expressed junctions contained peptides that could be presented by patient-specific HLA molecules. The top candidate rearrangement-related peptides with neoantigenic potential bound patient-specific HLA molecules nearly as well or as well as a positive control in competitive binding assays. Our findings represent the discovery of potential neoantigen expression driven by structural chromosomal rearrangements. These results may have implications for the development of novel therapeutic strategies, the selection of patients to receive immunotherapy, and blood-based treatment monitoring strategies. Citation Format: Aaron S. Mansfield, Tobias Peikert, James B. Smadbeck, Julia B. Udell, Farhad Kosari, Stephen J. Murphy, Hongzheng Ren, Vishnu V. Serla, Janet L. Schaefer Klein, Giannoula Karagouga, Faye R. Harris, Carlos Sosa, Sarah H. Johnson, Wendy Nevala, Svetomir N. Markovic, Aaron O. Bungum, Eric S. Edell, Haidong Dong, John C. Cheville, Marie Christine Aubry, Jin Jen, George Vasmatzis. Rearrangement-related peptides with neoantigenic potential in malignant pleural mesothelioma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5726.

Abstract Purpose: Pulmonary carcinoid tumors account for up to 5% of all lung malignancies in adults, comprise 30% of all carcinoid malignancies, and are defined histologically as typical carcinoid (TC) and atypical carcinoid (AC) tumors. The role of specific genomic alterations in the pathogenesis of pulmonary carcinoid tumors remains poorly understood. We sought to identify genomic alterations and pathways that are deregulated in these tumors to find novel therapeutic targets for pulmonary carcinoid tumors. Experimental Design: We performed integrated genomic analysis of carcinoid tumors comprising whole genome and exome sequencing, mRNA expression profiling and SNP genotyping of specimens from normal lung, TC and AC, and small cell lung carcinoma (SCLC) to fully represent the lung neuroendocrine tumor spectrum. Results: Analysis of sequencing data found recurrent mutations in cancer genes including ATP1A2, CNNM1, MACF1, RAB38, NF1, RAD51C, TAF1L, EPHB2, POLR3B, and AGFG1. The mutated genes are involved in biological processes including cellular metabolism, cell division cycle, cell death, apoptosis, and immune regulation. The top most significantly mutated genes were TMEM41B, DEFB127, WDYHV1, and TBPL1. Pathway analysis of significantly mutated and cancer driver genes implicated MAPK/ERK and amyloid beta precursor protein (APP) pathways whereas analysis of CNV and gene expression data suggested deregulation of the NF-κB and MAPK/ERK pathways. The mutation signature was predominantly C>T and T>C transitions with a minor contribution of T>G transversions. Conclusions: This study identified mutated genes affecting cancer relevant pathways and biological processes that could provide opportunities for developing targeted therapies for pulmonary carcinoid tumors. Clin Cancer Res; 24(7); 1691–704. ©2018 AACR.