The Cancer Lifetime Assessment Screening Study in Canines (CLASSiC): interim results of the first prospective cancer screening study in dogs using next-generation sequencing-based liquid biopsy

The Cancer Lifetime Assessment Screening Study in Canines (CLASSiC) is a prospective, longitudinal study evaluating serial physical exams plus next-generation sequencing (NGS)-based liquid biopsy for cancer screening in dogs. The goals of the interim analysis presented here were to assess the benefits of using the OncoK9® liquid biopsy test as a cancer screening tool in a clinical setting, and to demonstrate test performance for cancer detection, including preclinical detection. 725 presumed cancer-free client-owned dogs were prospectively enrolled across 24 clinical sites in the US and Canada; most were at high risk by age and/or breed. The analysis included 419 dogs enrolled ≥ 1 year with ≥2 screening visits, or with a definitive or presumptive cancer diagnosis by the interim cut-off. Clinical data and blood were collected at each visit (annual, biannual, or when cancer was suspected). Cell-free DNA extracted from plasma was tested by OncoK9® using NGS technology. 417 dogs were eligible for inclusion in the interim analysis and had classifiable outcomes, with a mean on-study duration of 422 days. Fifty-one dogs were newly diagnosed with cancer (37 definitive, 14 presumptive), an observed incidence of 12% (51/417) during the study. The liver, skin, bone, heart, spleen, lung, and lymph node(s) were the most common anatomic locations for disease. The observed sensitivity (detection rate) of the test was 56.9% (95% CI: 42.3–70.4%) with a specificity of 98.9% (95% CI: 97.0–99.6%). The observed positive predictive value was 87.9% (95% CI: 70.9–96.0%) and the negative predictive value was 94.3% (95% CI: 91.3–96.3%). Adding NGS-based liquid biopsy doubled the overall number of cancer cases detected in this study population (from 25 to 51). Preclinical detection rose from 12% (6/51) by routine care alone to 55% (28/51) when combined with OncoK9®, a 4.6-fold increase. CLASSiC is the first study to prospectively document the incidence of cancer in a predominantly high-risk canine population, and to demonstrate that the addition of NGS-based cancer screening to regularly scheduled wellness visits has the potential to substantially increase preclinical cancer detection in this population.