Cell-Free DNA as a Diagnostic and Prognostic Biomarker in Dogs With Tumors

Abstract

Cell-free DNA (cfDNA) is derived from apoptosis/necrosis, active cellular secretion, and lysis of circulating cancer cells or micrometastases. In humans, cfDNA is widely used in cancer diagnosis, but veterinary research has yet to be actively conducted to establish it as a cancer biomarker. This retrospective study analyzed cfDNA levels in samples collected from dogs with neoplastic disease (n = 38), clinically ill dogs without neoplasia (n = 47), and healthy dogs (n = 35). cfDNA levels and clinical data were compared among groups, and prognostic analyses were performed within the neoplastic group. Furthermore, continual cfDNA measurements were performed during the chemotherapy of six dogs with lymphoma. Dogs with neoplasia showed significantly higher cfDNA concentrations than dogs without neoplasm, and the cfDNA oncentration in the lymphoid neoplasia group was significantly elevated among all neoplastic groups. Dogs with neoplasia and a plasma cfDNA concentration above 1,247.5 μg/L had shorter survival rates than those with levels below this threshold (26.5 vs. 86.1%, respectively, P < 0.05). In cases with complete remission in response to chemotherapy, the cfDNA concentration was significantly decreased compared with the first visit, whereas the cfDNA concentration was increased in cases with disease progression or death. Interestingly, a significant correlation was found between lymph node diameter and cfDNA concentration in dogs with multicentric lymphoma (R2 = 0.26, P < 0.01). These data suggest that changes in cfDNA concentration could be used as a diagnostic biomarker for canine neoplasia. Furthermore, increased plasma DNA levels might be associated with shorter survival time, and cfDNA concentrations may reflect the response to chemotherapy.

Plasma cell‐free DNA in canine lymphoma patients as a novel material for genotyping

“…In previous reports, dogs with malignancies other than lymphoma and dogs with some non-neoplastic diseases have been shown to have significantly higher cfDNA concentrations than healthy dogs. [18][19][20][21][22] Therefore, cfDNA concentration is not a lymphomaspecific marker. In contrast, our pilot study showed that cfDNA concentrations were significantly higher in the malignant tumour group than in the non-neoplastic disease group and were significantly higher in the lymphoma group than in the other malignant tumour groups (median cfDNA concentration in the other malignant tumours were 544 ng/mL and lymphomas were 2626 ng/mL, respectively; p < .01; unpublished data).…”

“…[18][19][20] Two recent studies have reported that plasma cfDNA concentration could be considered a prognostic factor in canine lymphoma. 21,22 Furthermore, attempts have been made to use cfDNA isolated from dog plasma to comprehensively analyse and predict the presence of tumours based on the combination of genetic mutations. 23 However, further research is necessary to establish methods to extract canine cfDNA and its application in genetic analysis in canine lymphomas.…”

Molecular Markers in Urinary Bladder Cancer: Applications for Diagnosis, Prognosis and Therapy

“…Cells, both normal and tumoural, can release DNA into the bloodstream (circulating cell-free DNAs) via processes such as direct secretion, necrosis and apoptosis. Circulating tumour DNAs (ctDNA) contain the same genetic information as the original tumour, and they have been investigated in human and veterinary medicine for various applications, including studying tumour features and monitoring disease progression and response to treatment [ 106 , 107 , 108 , 109 , 110 ].…”

“…Sorafenib is another kinase inhibitor that targets multiple kinases, including RAF, VEGFRs and PDGFR-β, with anti-proliferative and anti-angiogenic activities. It is approved for the treatment of various cancers in humans, and it has been studied in veterinary medicine too, being well tolerated by dogs in preliminary studies [ 66 , 67 , 110 , 181 ].…”

“…Dysuria was well managed, and a decrease in thickness of urethral wall was seen. The patient remained stable for over 3 months of treatment, with few side effects [ 110 ].…”