Elevated doublecortin-like kinase 1 serum levels revert to baseline after therapy in early stage esophageal adenocarcinoma

Background: Barrett's esophagus (BE) and esophageal adenocarcinoma (EAC) incidence has been increasing in the United States for greater than 30 years. For the majority of EAC patients, treatment is limited and prognosis poor. Doublecortin like kinase-1 (DCLK1) is a cancer stem cell marker with elevated expression in BE patients with high grade dysplasia and/or EAC. This prospective cohort study was designed to compare serum DCLK1 levels before and after EAC treatment with endoscopic mucosal resection (EMR) and/or radio-frequency ablation (RFA). Methods: Barrett's esophagus patients with low or high-grade dysplasia (n = 9) and EAC patients (Stage I/II) eligible for treatment were enrolled (n = 14). Serum was obtained at enrollment and at end of treatment (EoT) where possible (n = 6). Normal control samples (n = 5) were obtained from patients with normal upper endoscopies. Serum was analyzed for DCLK1 protein content by ELISA. Kruskal-Wallis, Mann Whitney U, Pearson correlation, and Receiver Operating Characteristic tests were used to analyze the data. Results: Serum DCLK1 levels were increased by > 50% in Barrett's Esophagus (n = 9) and EAC patients (n = 14) vs controls (n = 5, p = 0.0007). These levels were reduced > 50% at EoT compared to EAC (p = 0.033). Although age was significantly lower in controls, this factor was not statistically related to DCLK1 serum levels (p = 0.66). Conclusions: EAC treatment results in significantly decreased serum DCLK1 levels, suggesting that DCLK1 may be useful as a non-invasive disease regression biomarker following treatment. Impact: Biomarkers for EAC therapeutic response have been poorly studied and no reliable marker has been discovered thus far. These results demonstrate that DCLK1 may have potential as a circulating biomarker of the response to therapy in EAC, which could be used to improve patient outcomes.