Abstract 523: Type XX collagen is elevated in circulation of patients with solid tumors and high levels are associated with higher overall mortality in pancreatic cancer
Authors: Thorlacius-Ussing Jeppe , Jensen Christina , Madsen Emilie A. , Nissen Neel I. , Johansen Astrid Z. , Chen Inna M. , Manon-Jensen Tina , Johansen Julia S. , Diab Hadi M. , Jørgensen Lars N. , Karsdal Morten , Willumsen Nicholas 
Published: June 2022

Abstract
Introduction: The tumor microenvironment has proven to be intricately involved in many aspects of cancer and is a promising place to look for non-invasive biomarkers. The extracellular matrix (ECM) has also been recognized as an important driver for cancer development. The most dominant ECM proteins are the collagens, which are important for tumor stiffness, tumor immunity and cancer metastasis. However, most of the cancer research of collagens has focused on the abundant and already well-described collagens, such as type I, III or IV collagens, whereas many of the more poorly described collagens remain unexplored. Type XX collagen is one such collagen. In this study, we developed an enzyme-linked immunosorbent assay (ELISA) quantifying type XX collagen, named PRO-C20, using a monoclonal antibody raised against its natural C-terminus and quantified circulating type XX collagen in patients with cancer.
Methods: Optimizations to the PRO-C20 protocol included finding the time and temperature of incubation as well as the assay buffer and concentration of assay components that gave the best sensitivity in serum. PRO-C20 was measured in serum of 219 patients with a range of solid cancer types and compared to serum levels in 33 healthy controls. The patients with cancer included 20 patients each of pancreatic-, colorectal-, kidney-, stomach-, breast-, bladder-, lung-, melanoma-, head and neck- and prostate-cancer as well as 19 with ovarian cancer. PRO-C20 was also subsequently measured in a separate cohort comprising 36 patients with pancreatic ductal adenocarcinoma (PDAC) and compared to 20 healthy controls. The biomarker performance of PRO-C20 was evaluated by ANOVA, ROC-curve analysis and cox proportional hazards models.
Results: The PRO-C20 ELISA was optimized and validated to be specific, precise and robust. PRO-C20 was significantly elevated in all cancers tested (p&lt;0.01 - p&lt;0.0001). PRO-C20 could discriminate between cancer and healthy controls with area under the receiver operating characteristic values ranging from 0.76 to 0.92. Elevated levels of PRO-C20 were confirmed in a separate cohort of patients with PDAC when compared to healthy controls (p&lt;0.0001). In addition, high PRO-C20 levels were associated with higher overall mortality (HR: 4.25, 95%CI: 1.52-11.9, p-value: 0.006) after adjusting for age, sex and the presence of metastasis.
Conclusion: An ELISA optimized to measure circulating type XX collagen in serum (PRO-C20) was successfully developed. Type XX collagen was elevated in serum of patients with cancer and high levels were associated with higher overall mortality in PDAC suggesting PRO-C20 has diagnostic and prognostic biomarker potential.
Citation Format: Jeppe Thorlacius-Ussing, Christina Jensen, Emilie A. Madsen, Neel I. Nissen, Astrid Z. Johansen, Inna M. Chen, Tina Manon-Jensen, Julia S. Johansen, Hadi M. Diab, Lars N. Jørgensen, Morten Karsdal, Nicholas Willumsen. Type XX collagen is elevated in circulation of patients with solid tumors and high levels are associated with higher overall mortality in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 523.