Abstract 3136: Discovery of low abundance colorectal cancer related biomarkers by the ADAPT Biotargeting System

Disease biomarkers play an essential role in disease-diagnostics and in monitoring their responses to therapies. Identification of low to medium abundance biomarkers is one of the biggest challenges in the field. We have developed Adaptive Dynamic Artificial Poly-ligand Targeting (ADAPT), a method in which libraries of single-stranded oligodeoxynucleotides (ssODNs) are enriched for sequences that bind to targets existing in samples in various amounts. Pull-downs with enriched libraries followed by LC-MS/MS allows for the enrichment and identification of low abundance biomarkers that cannot be identified by conventional proteomics. A highly diverse library of 1011 ssODNs was subjected to multiple rounds of positive selection against formalin-fixed paraffin-embedded (FFPE) colorectal cancer tissue with negative selection against adjacent non-cancer tissue of the same specimen. An enriched library of ~3x106 ssODNs that bound preferentially to cancer tissue was obtained and used in combination with LC-MS/MS to identify biomarkers related to colorectal cancer. Using this approach, a total of 14 proteins were identified in cancer but not in non-cancer tissue lysates. Their identification was only possible due to their enrichment by binding of the immobilized ssODN library to the cancer sample since the same proteins were undetectable by conventional proteomics. Immunohistochemical staining (IHC) of multiple colorectal cancer cases verified that several of the identified target proteins, including nucleophosmin (NPM1) and synaptotagmin-like protein 2 (SYTL2), showed higher expression in cancer tissue compared to adjacent non-cancer tissue. Our data indicate the potential of the ADAPT platform to profile small differences between cancer affected and unaffected tissue and provide a novel approach for cancer biomarker discovery. Citation Format: Tassilo Hornung, Jelena Zarkovic, Michelle Kassner, Matthew Rosenow, Mark R. Miglarese, Gunter Mayer, Michael Famulok, David B. Spetzler. Discovery of low abundance colorectal cancer related biomarkers by the ADAPT Biotargeting System [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3136.