Cancer is the leading cause of death in dogs, yet there are no established screening paradigms for early detection. Liquid biopsy methods that interrogate cancer-derived genomic alterations in cell-free DNA in blood are being adopted for multi-cancer early detection in human medicine and are now available for veterinary use. The CANcer Detection in Dogs (CANDiD) study is an international, multi-center clinical study designed to validate the performance of a novel multi-cancer early detection “liquid biopsy” test developed for noninvasive detection and characterization of cancer in dogs using next-generation sequencing (NGS) of blood-derived DNA; study results are reported here. In total, 1,358 cancer-diagnosed and presumably cancer-free dogs were enrolled in the study, representing the range of breeds, weights, ages, and cancer types seen in routine clinical practice; 1,100 subjects met inclusion criteria for analysis and were used in the validation of the test. Overall, the liquid biopsy test demonstrated a 54.7% (95% CI: 49.3–60.0%) sensitivity and a 98.5% (95% CI: 97.0–99.3%) specificity. For three of the most aggressive canine cancers (lymphoma, hemangiosarcoma, osteosarcoma), the detection rate was 85.4% (95% CI: 78.4–90.9%); and for eight of the most common canine cancers (lymphoma, hemangiosarcoma, osteosarcoma, soft tissue sarcoma, mast cell tumor, mammary gland carcinoma, anal sac adenocarcinoma, malignant melanoma), the detection rate was 61.9% (95% CI: 55.3–68.1%). The test detected cancer signal in patients representing 30 distinct cancer types and provided a Cancer Signal Origin prediction for a subset of patients with hematological malignancies. Furthermore, the test accurately detected cancer signal in four presumably cancer-free subjects before the onset of clinical signs, further supporting the utility of liquid biopsy as an early detection test. Taken together, these findings demonstrate that NGS-based liquid biopsy can offer a novel option for noninvasive multi-cancer detection in dogs.

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Circulating cell-free DNA (ccfDNA) sequencing for low-burden cancer monitoring is limited by sparsity of circulating tumor DNA (ctDNA), the abundance of genomic material within a plasma sample, and pre-analytical error rates due to library preparation, and sequencing errors. Sequencing costs have historically favored the development of deep targeted sequencing approaches for overcoming sparsity in ctDNA detection, but these techniques are limited by the abundance of ccfDNA in samples, which imposes a ceiling on the maximal depth of coverage in targeted panels. Whole genome sequencing (WGS) is an orthogonal approach to ctDNA detection that can overcome the low abundance of ccfDNA by supplanting sequencing depth with breadth, integrating signal across the entire tumor mutation landscape. However, the higher cost of WGS limits the practical depth of coverage and hinders broad adoption. Lower sequencing costs may thus allow for enhanced ctDNA cancer monitoring via WGS. We therefore applied emerging lower-cost WGS (Ultima Genomics, 1USD/Gb) to plasma samples at ~120x coverage. Copy number and single nucleotide variation profiles were comparable between matched Ultima and Illumina datasets, and the deeper WGS coverage enabled ctDNA detection at the parts per million range. We further harnessed these lower sequencing costs to implement duplex error-corrected sequencing at the scale of the entire genome, demonstrating a ~1,500x decrease in errors in the plasma of patient-derived xenograft mouse models, and error rates of ~10-7 in patient plasma samples. We leveraged this highly de-noised plasma WGS to undertake cancer monitoring in the more challenging context of resectable melanoma without matched tumor sequencing. In this context, duplex-corrected WGS allowed us to harness known mutational signature patterns for disease monitoring without matched tumors, paving the way for de novo cancer monitoring.

OBJECTIVE To determine the amount of negative pressure generated by syringes of various sizes with and without an attached thoracostomy tube and whether composition of thoracostomy tubes altered the negative pressure generated. SAMPLE Syringes ranging from 1 to 60 mL and 4 thoracostomy tubes of various compositions (1 red rubber catheter, 1 polyvinyl tube, and 2 silicone tubes). PROCEDURES A syringe or syringe with attached thoracostomy tube was connected to a pneumatic transducer. Each syringe was used to aspirate a volume of air 10 times. Negative pressure generated was measured and compared among the various syringe sizes and various thoracostomy tubes. RESULTS The negative pressure generated decreased as size of the syringe increased for a fixed volume across syringes. Addition of a thoracostomy tube further decreased the amount of negative pressure. The red rubber catheter resulted in the least amount of negative pressure, followed by the polyvinyl tube and then the silicone tubes. There was no significant difference in negative pressure between the 2 silicone tubes. The smallest amount of negative pressure generated was −74 to −83 mm Hg. CONCLUSIONS AND CLINICAL RELEVANCE Limited data are available on the negative pressure generated during intermittent evacuation of the thoracic cavity. For the present study, use of a syringe of ≥ 20 mL and application of 1 mL of negative suction volume resulted in in vitro pressures much more negative than the currently recommended pressure of −14.71 mm Hg for continuous suction. Additional in vitro or cadaveric studies are needed.