1 Barrett's esophagus (BE) affects about 3.3 million adults in the United States1. A small subset of patients with 2 BE may sequentially progress from intestinal metaplasia (BIM-P) to low-grade dysplasia (LGD), high-grade 3 dysplasia (HGD) and esophageal adenocarcinoma (EAC). The incidence of EAC has increased greater than 5 4 fold over the past 4 decades in the United States2. Patients with BIM without dysplasia have a much lower 5 EAC risk than those with high-grade dysplasia. For effective health care, identification of molecular markers 6 that predict progression of BIM to HGD/EAC is highly desirable, as BIM-P may be monitored and aggressively 7 treated to inhibit progression to EAC. Our laboratory and others have identified genomic alterations that may 8 drive HGD/EAC development, including point mutations 6 and copy number changes. We found frequent (50%) 9 losses in chromosome 9p areas containing CDKN2A/p16 in BIM-P but not in non-progressors. Inactivation of 10 CDKN2A/p16 by methylation is a frequent event in BE progression to HGD/EAC7-9. Molecular 11 genomic/epigenomic testing of surveillance biopsies may identify candidate high-risk BIM patients for closer 12 surveillance and chemoprevention of HGD/EAC. We propose a combination of demethylating agents to 13 reverse CpG methylation in p16 and other genes that may contribute to neoplastic progression with anti14 inflammatory drugs, which have been shown to reduce HGD/EAC development 13 14. Our hypothesis is that 15 the CDKN2A gene product p16 is key in determining disease progression in a large number of those 16 BE patients who develop dysplasia/EAC and that detection of CDKN2A/p16 alterations and/or 17 molecular genomic, epigenetic and expression alterations that result from CDKN2A/p16 inactivation 18 may be used to direct early therapeutic intervention to prevent EAC development. We will address this 19 hypothesis in three specific aims. Aim 1: To characterize the global transcriptomic alterations that result 20 from CDKN2A/p16 genomic and epigenetic inactivation, leading to evasion from senescence and increased 21 proliferation, in patients with BE who progress to HGD/EAC. These alterations will permit the identification of 22 molecular pathways, potential novel treatment targets and biomarkers of high-risk BIM patients, who are 23 candidates for intervention therapy (such as demethylating and anti-inflammatory drugs) to prevent HGD/EAC. 24 Aim 2: To investigate the role of CDKN2A/p16 in esophageal dysplasia and adenocarcinoma development and 25 progression in mouse models of esophageal Barrett's-like metaplasia progressing to HGD/EAC. Aim 3: To 26 investigate the effect of demethylating and anti-inflammatory drugs in the context of active and inactive 27 CDKN2A/p16, in the development of esophageal dysplasia and adenocarcinoma in the established mouse 28 models. To characterize the comprehensive transcriptomic alterations that result from CDKN2A/p16 29 inactivation, in mice with BE-like lesions that progress to HGD/EAC under effect of treatment vs. no treatment. 30 Transcriptomic mouse data will be compared with data from human tissues tested in aim 1.