OncoCan: a liquid biopsy assay for cell-free DNA quantification in canine plasma to support cancer prognosis.

Abstract

Early cancer detection remains a major challenge in veterinary medicine. Cell-free DNA (cfDNA), released into the bloodstream through apoptosis, necrosis, or circulating tumor cells, can be quantified non-invasively via liquid biopsy and is already established in human oncology. In this study, we evaluated OncoCan, a targeted plasma cfDNA assay, by analyzing samples from 83 dogs with various neoplasms and 47 healthy controls to assess diagnostic and prognostic utility. Wilcoxon rank-sum testing revealed significantly higher cfDNA concentrations in neoplastic versus healthy samples (&#x202f;=&#x202f;4.45e-07). ROC curve analysis demonstrated high accuracy for lymphomas/leukemias (AUC&#x202f;=&#x202f;0.95) and moderate accuracy for carcinomas (AUC&#x202f;=&#x202f;0.75), sarcomas (AUC&#x202f;=&#x202f;0.76), and melanomas (AUC&#x202f;=&#x202f;0.69). Stratification by histological grade and clinical stage further supported cfDNA's predictive capability. Three practical thresholds were established: <50&#x202f;pg/&#x3bc;L to distinguish healthy from neoplastic cases; &#x2265;100&#x202f;pg/&#x3bc;L as a "high positive" threshold indicating aggressive disease; and &#x2265;300&#x202f;pg/&#x3bc;L as a "very high positive" threshold strongly associated with systemic dissemination, high-grade histology, and poor survival. The <50&#x202f;pg/&#x3bc;L cut-off showed robust diagnostic performance (AUC&#x202f;=&#x202f;0.808, sensitivity&#x202f;=&#x202f;82%, specificity&#x202f;=&#x202f;73%), confirmed by survival analysis and hazard ratio modeling. These findings suggest that OncoCan provides a noninvasive, clinically applicable tool for cancer prognosis in dogs. Validation in larger cohorts is warranted to support its integration into routine veterinary oncology practice.