Abstract 7666: Type XVII collagen as potential biomarker of epithelial damage in patients with atopic dermatitis and patients with metastatic colorectal cancer

Abstract Background Type XVII collagen is a membrane-associated collagen with interrupted triple-helices (MACIT) facilitating adhesion between the basement membrane (BS) and epithelial cells. Mutations in COL17A1 lead to junctional epidermolysis bullosa (JEB), while autoimmunity against type collagen XVII ectodomain can cause bullous pemphigoid (BP). In multiple epithelial cancers, both type XVII collagen and its shed ectodomain are associated with cancer development and invasiveness. This study aims to assess the potential of type XVII collagen as an epithelial damage biomarker in patients with metastatic colorectal cancer (mCRC) and in patients with skin diseases like atopic dermatitis (AD) and psoriasis. Methodology Type XVII collagen ectodomain levels were measured in serum using a competitive ELISA (nordicPRO-C17). The study included two cohorts: cohort 1 comprised 212 patients with mCRC and 28 healthy controls and cohort 2 included patients with AD (n=8) or psoriasis (n=3). PRO-C17 levels in mCRC patients were compared to 28 healthy controls using a t-test. The association between PRO-C17 levels and overall survival (OS) was evaluated by categorizing patients into low PRO-C17 levels (tertiles 1+2) and high PRO-C17 levels (tertile 3). Kaplan-Meier curves and the log-rank test were used to assess differences in survival between the two groups. The independent predictive value of PRO-C17 was evaluated using multivariate Cox analysis. PRO-C17 levels in AD and psoriasis patients were compared to 15 healthy controls using one-way ANOVA, followed by multiple comparisons with Dunn's test. Results PRO-C17 levels were elevated (p0. 05) in mCRC patients treated with bevacizumab compared to healthy controls. Patients with high PRO-C17 levels had a shorter overall survival (390 days) compared to those with low levels (539 days) (p=0. 007). High levels of the biomarker were associated with an increased risk of mortality and PRO-C17 levels were independent of other risk factors, such as the number of drugs in the treatment regimen, tumor location, synchronous metastatic disease, primary tumor resection, performance status, and the number of metastatic sites (HR=1. 43, 95% CI 1. 01-2. 01, p=0. 044). Further, patients with AD had increased PRO-C17 levels (p=0. 0057), while patients with psoriasis showed no significant differences in biomarker levels compared to healthy controls (p=0. 58). Conclusions This study demonstrated that high PRO-C17 levels were independently associated with shorter OS and an increased risk of mortality in patients with mCRC. Additionally, elevated levels of PRO-C17 were observed in patients with AD. These findings suggest that type XVII collagen may serve as a reflection of epithelial damage in the invasive front during tumor metastasis. The role of this biomarker in other cancer types and skin diseases warrants further exploration. Citation Format: Marina Crespo-Bravo, Neel Nissen, Rasmus Pedersen, Mogens Boisen, Maria Liljefors, Astrid Johansen, Julia Johansen, Morten Karsdal, Nicholas Willumsen. Type XVII collagen as potential biomarker of epithelial damage in patients with atopic dermatitis and patients with metastatic colorectal cancer abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 7666.