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e23222Background: MEK inhibitors have limited success in cancer treatment because tumors circumvent their action. Here, we report broad proteomic analysis of NSCLC cell lines after treatment with t...

11002 Background: Little is currently known about how the oncogenotype of LUAC shapes its immune micro-environment. We recently identified that major subsets of KRAS-mutant LUAC defined on the basi...

3030 Background: Promising results in the treatment of NSCLC have been seen with agents targeting immune checkpoints, such as programmed cell death 1 (PD-1) or programmed cell death 1 ligand (PD-L1...

6030 Background: The incidence of oropharyngeal cancer (OPC) has increased 5% per year over the past decade due to a rise in human papilloma virus (HPV)-driven OPC. HPV+ OPC is clinically and molecularly distinct from HPV- head and neck squamous cell carcinomas (HNSCC). However, there are currently no validated therapeutic targets for HPV+ HNSCC. Methods: Reverse phase protein array (RPPA) was performed on HNSCC tumors from The Cancer Genome Atlas to measure cancer-associated pathways and targets. Differences in individual markers and proteomic pathway scores between HPV+ and HPV– tumors were assessed by t-test in the overall group and for the subset of OPC. Results: Significant proteomic differences were observed in 14 HPV+ and 186 HPV- HNSCC. Of 160 proteins, the top marker overexpressed in HPV+ HNSCC was p16, an established clinical biomarker of HPV status (p

8104 Background: All NSCLC patients treated with erlotinib (E) eventually develop resistance. Both the epithelial-mesenchymal transition (EMT) and cancer stem cells may contribute to resistance to E. The Notch pathway plays a key role in maintaining stem cell viability and in EMT. Gamma secretase inhibitors such as RO4929097 (R) inhibit Notch activity by preventing cleavage of Notch to its active form. In this CTEP-sponsored study, primary endpoint of phase I was to determine maximum tolerated dose (MTD) of the combination of E and R; primary endpoint of phase II was response rate. Methods: Eligible pts had incurable NSCLC, measurable disease, ECOG PS 0-1, and adequate laboratory parameters. There were no limits on prior therapy. All pts were required to have a tumor biopsy. Patients received E PO daily on a continuous schedule and R PO daily on days 1-3, 8-10, and 14-17 of a 21 day cycle. Dose cohorts (E/R both in mg) were as follows: 100 /20, 150/20, 150/30, 150/45. Imaging was performed every 6 weeks. Patients could remain on therapy until progression. Results: 21 pts were enrolled between 9/2010 and 3/2012. 5 were not eligible and did not receive treatment. For the 16 treated pts: median age was 61 yrs (40-75), 7 (44%) were male, 14 (88%) had adenocarcinoma. All pts had received prior chemotherapy (1-8 regimens); 7 (44%) had prior E. 3 pts had known EGFR mutations; 2 pts had KRAS mutations. Time on therapy ranged from 20 to 248 days. Median PFS was 42 days. Pts with prior progression on E had a median PFS of 64 days. 1 pt (6%) had a partial response, 4 (19%) had stable disease at 6 weeks. Median overall survival is 6.5 months (1.3 to 24.5+ months). Observed dose-limiting toxicity was hypophosphatemia in 1 pt in 150/45 cohort. Other toxicities included rash, neuropathic pain and nausea. MTD was determined to be 150/45. The study was halted early, after completion of the phase I cohort, as production of R was discontinued by the manufacturer. 12 pts (75%) have adequate tumor tissue for analyses. Biomarker studies are pending. Conclusions: Combination of R and E is safe and feasible in pts with NSCLC. Though development of R has been discontinued, other drugs targeting the Notch pathway are in development (NCI R21CA153017). Clinical trial information: NCT01193881.

6011 Background: Epithelial-mesenchymal transition (EMT) has been associated with EGFR inhibitor resistance in preclinical studies of head and neck squamous cell carcinoma (HNSCC). Recently, we developed an EMT signature that predicts EGFR inhibitor resistance in lung cancer. Using this signature, we explored the association between EMT and drug response in HNSCC, focusing on the tyrosine kinase Axl as a potential therapeutic target. Methods: We conducted an integrated molecular and drug response analysis in HNSCC. A 76-gene EMT signature previously developed and validated in lung cancer was tested in HNSCC cell lines (n>50) and patient tumors from The Cancer Genome Atlas (TCGA) (n=113) and a MDACC cohort (n=105). Reverse phase protein array (RPPA) and proliferation assays were used to measure protein expression and sensitivity to erlotinib and the Axl inhibitors SGI-7079 and TP-0930. Results: The EMT signature identified distinct epithelial and mesenchymal subsets of HNSCC among cell lines and patient tumors. RPPA experiments revealed higher protein levels of the receptor tyrosine kinase Axl, vimentin, and N-cadherin and lower expression of E-cadherin and beta-catenin in mesenchymal HNSCC (p-values 10μM); however, we discovered that mesenchymal HNSCC were highly sensitive to two Axl inhibitors, SGI-7079 and TP-0930 (IC50s ≤1.2μM and 0.2uM, respectively). Conclusions: Our EMT gene expression signature identified discrete epithelial and mesenchymal subgroups of HNSCC. Mesenchymal HNSCC cells expressed higher levels of Axl protein and exhibited sensitivity to Axl inhibition, but resistance to erlotinib. These results highlight differences in drug response between epithelial and mesenchymal cancers and support Axl as a potential therapeutic target and predictive marker of EGFR inhibitor resistance in HNSCC. (Funded in part by 5 P50 CA097007-10)

10612 Background: LKB1 is a serine/threonine kinase which is mutated in 20-30% of non-small cell lung cancers (NSCLC) and functions as a tumor suppressor by activating AMPK. Loss of LKB1 by point mutation or deletion suppresses AMPK, leading to increased mTOR signaling. We investigated the signaling pathways modulated by LKB1 mutations and by mTOR inhibition in NSCLC. Methods: Protein expression in cell lines was measured by reverse phase protein array. Differences in protein expression at baseline in LKB1 wild-type versus mutant cell lines and the effects of protein modulation by treatment were assessed by ANOVA. Results: LKB1 mutant cell lines had lower expression of phosphorylated AMPK and TSC (p

5524 Background: We have reported that DNA methyltransferase-3B (DNMT3B) gene expression is a strong predictor of OC dvlpt. Using high-throughput DNA methylation profiles of oral preneoplastic lesions (OPL), we identified 86 candidate genes that were hypermethylated in patients (pts) developing OC and suggested that a CpG island methylation phenotype may occur early during OC dvlpt. Our aim was to validate some of the candidate genes and to study the value of LINE1 repetitive element methylation, a surrogate of global DNA methylation, as biomarkers of risk to develop OC. Methods: Validation cohort included 40 pts with a median follow-up of 4.2 years, including 14 pts who developed OC. None of them were used in the discovery phase. Frozen OPL were collected prospectively and subject to DNA extraction. We performed a quantitative analysis of the degree of methylation of LINE1, and AGTR1, FOXI2, PENK, and HOXA9 promoters CpG sites using pyrosequencing. Results: The degree of methylation of AGTR1 (Mann-Whitney P