Biomarker studies in a phase I trial of DKN-01 in advanced esophageal cancer.

161Background: DKK1 is a modulator of Wnt signaling that is frequently overexpressed in tumors and such expression has been associated with worse survival. Preclinical studies have shown that DKK1 can promote tumor growth by increasing angiogenesis and contributing to an immunosuppressive tumor microenvironment. DKN-01 is a humanized IgG4 monoclonal antibody against DKK1 that has shown encouraging efficacy signals in patients (pts) with advanced esophageal (EC) or esophagogastric junction (EGJ) cancer when administered in combination with paclitaxel. Correlative studies are evaluating DKK1 expression and genetics in archived tumor specimens and baseline and on-treatment plasma levels of angiogenesis and inflammation biomarkers as predictors of response. Methods: Formalin fixed paraffin embedded (FFPE) archived tumor tissue was evaluated for DKK1 expression by immunohistochemistry (IHC) and scored for fraction of positive cells, intensity, and localization of DKK1. Genetics were collected if known and/or p...