Dickkopf-1 (DKK1) is a secreted modulator of Wnt signaling that is frequently overexpressed in tumors and is associated with poor clinical outcomes. DKN-01 is a humanized monoclonal therapeutic antibody that binds to DKK1 with high affinity and has demonstrated clinical activity in gastric / gastroesophageal junction (G / GEJ) patients with elevated tumor expression of DKK1. Here we report on the validation of an RNAscope DKK1 chromogenic in situ hybridization assay to assess DKK1 expression in G / GEJ tumor tissue.
To reduce pathologist time, potential pathologist variability of manual scoring, and support pathologist decision making, a digital image analysis algorithm was developed that identifies tumor cells and quantifies the DKK1 signal. Following CLIA guidelines, the DKK1 RNAscope chromogenic in situ hybridization assay and digital image analysis algorithm have been successfully validated for sensitivity, specificity, accuracy, and precision.
The DKK1 RNAscope Assay in conjunction with the Digital Image Analysis Solution is acceptable for the prospective detection of G / GEJ adenocarcinoma patients. The work described here will further advance the companion diagnostic development of our DKK1 RNAscope assay and could generally be used as a guide for the validation of RNAscope assays with digital image quantification.