Abstract 5002: Premalignant squamous cell lung carcinoma lesions have distinct molecular subtypes associated with histologic progression
Authors: Beane Jennifer E. , Mazzilli Sarah , Campbell Joshua , Moy Christopher , Schaffer Michael , Perdomo Catalina , Jenkins David , Liu Gang , Zhang Sherry , Liu Hanqiao , Vick Jessica , Johnson Evan , Platero Suso , Lenburg Marc , Reid Mary , Dhillon Samjot S. , Spira Avrum 
Published: July 2017

Background: Squamous cell carcinoma (SCC) of the lung is a leading cause of cancer mortality in the US due to late stage diagnosis and lack of effective treatments. Lung SCC arises in the epithelial layer of the bronchial airways and is often preceded by the development of premalignant lesions (PMLs). The molecular events involved in the progression of PMLs to lung SCC are not clearly understood, and not all PMLs go on to form carcinoma. By molecularly characterizing PMLs and non-lesion areas in the airway of individuals with PMLs, we hypothesize that we will be able to identify subgroups of PMLs that are more likely to progress.

Methods: We used mRNA sequencing to profile biopsies obtained from high-risk smokers undergoing lung cancer screening by auto-fluorescence bronchoscopy and CT at the Roswell Park Cancer Institute in Buffalo, NY. For each subject (n=30), we sampled bronchial biopsies repeatedly over time (394 +/- 170 days) with serial bronchoscopies (6 +/- 5 biopsies/subject) as the biopsied area progressed towards or regressed away from frank malignancy. mRNA-Seq (n=197 biopsies) data was aligned to hg19 using STAR, and gene/transcript levels were summarized using RNA-Seq using RSEM and Ensembl 74 annotation. Immune, stromal, and epithelial cells content were inferred using the ESTIMATE algorithm and pathway activity of in vitro derived oncogenic signatures was estimated using GSVA for each sample. Molecular subtypes were derived using non-negative matrix factorization (NMF) and consensus clustering. Linear modeling was used to associate PML outcome metrics and pathway activity scores with subtype membership.

Results: We identified six distinct molecular subtypes of bronchial biopsies using NMF across the 10% most variable genes (n=2,322 gene). One subtype contained samples with stable high-grade histology (p&lt;0.01). This subtype was also enriched for basal epithelial cell content and oncogenic pathway activity including AKT and EGFR (p&lt;0.01). Another subtype was enriched for immune cell content and had elevated expression of immune-related pathways including chemokine, cytokine, and T-cell receptor signaling. Increased immune infiltrate was also observed in H&E stains from biopsies taken adjacent to the sequenced biopsy.

Conclusions: Molecular classification of premalignant lesions may lead to biomarkers of disease progression that could be used to stratify patients into prevention trials and to monitor efficacy of the treatment. Additionally, the results suggest that personalized interventions targeting specific cancer-related pathways or the immune system may be have potential therapeutic benefits.

Citation Format: Jennifer E. Beane, Sarah Mazzilli, Joshua Campbell, Christopher Moy, Michael Schaffer, Catalina Perdomo, David Jenkins, Gang Liu, Sherry Zhang, Hanqiao Liu, Jessica Vick, Evan Johnson, Suso Platero, Marc Lenburg, Mary Reid, Samjot S. Dhillon, Avrum Spira. Premalignant squamous cell lung carcinoma lesions have distinct molecular subtypes associated with histologic progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5002. doi:10.1158/1538-7445.AM2017-5002