Canine disease is often diagnosed only after clinical signs are apparent and cancer is advanced, with advanced therapeutics being neither readily available nor affordable for most pet owners, underscoring the critical need for frequent monitoring via a stage 1–sensitive test. To address this gap, a new diagnostic approach has been tested, leveraging the fact that tumor cells undergo mutations and epigenetic modifications to their genomic DNA, shedding tumor DNA into peripheral blood and other biospecimens, and enabling noninvasive detection through liquid biopsies.
Despite the development of several blood-based multicancer diagnostic (MCD) tests for both humans and dogs—designed to detect tumor-derived DNA fragments—these assays exhibit low sensitivity and accuracy for stage 1 cancers, limiting their utility for early intervention.
Autoantibodies elicited by tumor-associated self-antigens, though detectable in late-stage patients, are rarely measurable in early-stage samples due to immune tolerance and low antibody affinity. Overcoming this sensitivity barrier is essential for deploying liquid biopsy MCDs in large-scale screening.
To comprehensively capture diverse tumor antigens, including those derived from RNA processing errors (REDNs), conformational variants, and nonproteinaceous molecules, high-density peptide microarrays termed antibody comprehensive effective detection (ACED) arrays were engineered. These arrays, synthesized in situ on silicon wafers, enable unbiased profiling of tumor-induced antibodies, facilitating the sensitive and specific detection of five common stages 1 canine cancer—hemangiosarcoma (HSA), lymphoma (LYM), mast cell tumors (MCT), osteosarcoma (OSA), and soft tissue sarcoma (STS)—from a single blood test.
The ACED immunoassay hinges on two principles: first, that early-stage tumors elicit detectable antibody responses, and second, that peptide arrays can effectively mimic these antigenic targets.
Serum samples were analyzed from 283 dogs, including 30 with hemangiosarcoma, 34 with lymphoma, 60 with mast cell tumors, 41 with osteosarcoma, and 49 with soft tissue sarcomas, along with 69 cancer-free controls.
Peptides with differential antibody-binding activity were identified and used to construct two multiclass models. The first, a simple peptide-scoring model, achieved stage 1 sensitivities of 68%–98% (97%–99% specificity) in 70% peptide resampling tests iterated 50 times, with an 87% multiclass accuracy. The second, a neural network-based algorithm, yielded sensitivities of 60%–88% (92%–99% specificity) in 30% independent sample holdout tests, also iterated 50 times, with an 80% multiclass accuracy. The convergence of results across these divergent methodologies underscores the platform’s robustness.
While some argue that early detection may not improve outcomes under standard care, human data demonstrate that stage shifts from late (stages 3–4) to early (stages 1–2) disease enhance survival even without advanced therapies. Predicting tumor origin could further streamline clinical follow-up for stage 1 cases. Optimal testing frequency would depend on the assay’s ability to detect pre-stage 1 disease, with the ACED test’s minimal blood requirements, lack of pre-test restrictions, and anticipated low cost supporting frequent monitoring.
The ACED arrays hold promise as a stage 1–sensitive diagnostic platform, potentially addressing a key unmet need in canine oncology. Integrating complementary tests like Oncotect and Nu.Q Vet could optimize screening strategies. However, the study’s primary limitation—the scarcity of stage 1 samples, which prolonged recruitment over several years—highlights the need for expanded prospective collections.
Future work will focus on incorporating additional tumor types and stages, with field studies required to validate clinical utility. The research was conducted by Calviri, Inc., a biotech company with inventions and discoveries that enable the development of diagnostics for the early detection of cancer and for vaccines to treat or prevent it. The company is developing a portfolio of fundamentally different products against all cancers for both people and their pets, worldwide.
