S431 Proteomic Assay for Barrett’s Esophagus Progression: A Multi-Institutional Retrospective Study

Abstract

Introduction: Incidence of Esophageal adenocarcinoma (EAC) in the US has increased at a greater rate than any other cancer. EAC arises from pre-malignant metaplastic tissue - Barrett’s Esophagus (BE). Periodic histological assessment of an endoscopic biopsy is used to assess progression along dysplasia-carcinoma sequence. Current surveillance protocols have clinical limitations as 80% of EAC patients present in advanced cancer stages. The aim of this study is to compare 8 proteomic expression patterns to distinguish stable BE patients from those who developed EAC using the STLA101 assay. Methods: After Institutional Review Board approval (Mayo Clinic and KUMC) patients with BE were identified. 2 cohorts were selected: progressors (progressed to EAC at subsequent interval of 0.5-3 years) and non–progressors (who had 10 yrs of f/u surveillance without progression along dysplasia/carcinoma path). 11 normal esophageal mucosa samples were also retrieved for analysis. Serial tissue sections were microdissected to reduce proteomic noise from surrounding stromal cells. Isolated cells underwent a multi-step process where cross-links were reversed, and proteins were digested and reduced into a mass spec-compatible lysate. Isotopically labeled control peptides of the STLA101 panel were spiked in with digested tissue samples to quantify all of the markers simultaneously using a Q-Exactive HFX mass spectrometer in a CAP/CLIA setting. Results: A total of 42 tissues were analyzed. Cohort tissue descriptions can be found in Table 1. 13 BEs progressed to EAC within a mean of 334 days while the remaining 18 BEs did not progress over a 10-yr period. All 8 biomarkers were expressed at a higher level when comparing dysplastic BE tissue that progressed to cancer to BE tissue that remained stable over 10 yrs and normal esophageal mucosa. There was not a significant difference in age, sex and length of BE between the groups. The assay had a 100% technical success rate as no samples yielded “non-detectable” data points. Conclusion: The overexpression of the STLA101 panel in dysplastic BE tissue that progressed to cancer demonstrates the potential predictability of the assay when assessing molecular hallmarks of carcinogenesis. The expression quantities of the non-progressive BE tissues were closer to normal mucosa and may warrant patients with this profile type to be screened less. Patients with high expression quantities of the STLA101 panel may be candidates for a more frequent screening cadence or therapeutic intervention.Figure 1.: Mass spectrometry-based expression patterns of 2 markers in the STLA101 panel demonstrating clear overexpression of proteins involved in the malignant transformation of Barrett’s precancerous tissue into esophageal adenocarcinoma. The expression mean of non-diseased esophageal squamous mucosa, labeled as “normal”, are represented by blue bars. The green bars represent non-progressive BE tissue that remained stable for over 10-years according to collaborating institutional databases. The red bars represent progressive BE tissue retrieved at a mean of 334 days before adenocarcinoma diagnosis.Table 1.: Specimen types analyzed in this study