Feasibility of circulating tumor DNA analysis in dogs with naturally occurring malignant and benign splenic lesions

From shells to sequences: A proof-of-concept study for on-site analysis of hemolymphatic circulating cell-free DNA from sentinel mussels using Nanopore technology

Blue mussels are often abundant and widely distributed in polar marine coastal ecosystems. Because of their wide distribution, ecological importance, and relatively stationary lifestyle, bivalves have long been considered suitable indicators of ecosystem health and changes. Monitoring the population dynamics of blue mussels can provide information on the overall biodiversity, species interactions, and ecosystem functioning. In the present work, we combined the concept of liquid biopsy (LB), an emerging concept in medicine based on the sequencing of free circulating DNA, with the Oxford Nanopore Technologies (ONT) platform using a portable laboratory in a remote area. Our results demonstrate that this platform is ideally suited for sequencing hemolymphatic circulating cell-free DNA (ccfDNA) fragments found in blue mussels. The percentage of non-self ccfDNA accounted for >50 % of ccfDNA at certain sampling Sites, allowing the quick, on-site acquisition of a global view of the biodiversity of a coastal marine ecosystem. These ccfDNA fragments originated from viruses, bacteria, plants, arthropods, algae, and multiple Chordata. Aside from non-self ccfDNA, we found DNA fragments from all 14 blue mussel chromosomes, as well as those originating from the mitochondrial genomes. However, the distribution of nuclear and mitochondrial DNA was significantly different between Sites. Similarly, analyses between various sampling Sites showed that the biodiversity varied significantly within microhabitats. Our work shows that the ONT platform is well-suited for LB in sentinel blue mussels in remote and challenging conditions, enabling faster fieldwork for conservation strategies and resource management in diverse settings.

Noninvasive Blood-Based Cancer Detection in Veterinary Medicine

The past decade has seen incredible advances in blood-based cancer detection in people and in dogs - yet this represents only a glimpse of the benefits these tests can provide to patients. The clinical uses of this technology range from screening asymptomatic individuals for early detection to use as an aid in diagnosis when cancer is suspected, to cancer monitoring both during and after treatment. This article summarizes the benefits of early cancer detection and examines use cases and methods of blood-based cancer detection in dogs, including quantitative, qualitative, and alternative approaches.

Clinical utility of liquid biopsy in canine oral malignant melanoma using cell-free DNA

Introduction

Cell-free DNA (cfDNA), an extracellular free DNA released into the bloodstream by cells, is a potentially useful noninvasive marker to detect human malignancies and monitor response to treatment. In the present study, we evaluated the utility of circulating cfDNA in canine patients with oral malignant melanoma (OMM) in assessing therapeutic response and clinical outcomes.

Methods

Plasma samples were collected from 12 dogs with OMM and 9 healthy controls. cfDNA concentration was quantified by real-time PCR resulting in short (99bp) and long (218bp) fragments of long interspersed nuclear element-1 (LINE-1), and the DNA integrity index (DII) was then calculated (218/99). A follow-up study was conducted on 6 dogs with OMM, and the plasma cfDNA and DII were quantified throughout disease progression.

Results

Although cfDNA levels obtained from dogs with OMM were not significantly different compared to those obtained from healthy controls, the DII was significantly lower in dogs with OMM than in healthy controls. The DII tended to decrease as the disease stage progressed. Moreover, changes in cfDNA concentration and DII along the clinical course were observed when major changes, such as metastasis or apparent tumor progression, were observed.

Discussion

The results of our study suggest that measurements of serum cfDNA and DII using LINE-1 might be valuable new biomarkers for monitoring OMM progression in dogs. This preliminary study demonstrated the potential clinical utility of monitoring plasma cfDNA in canine patients with OMM.

Diagnosis, Prognosis, and Treatment of Canine Hemangiosarcoma: A Review Based on a Consensus Organized by the Brazilian Association of Veterinary Oncology, ABROVET

Hemangiosarcoma is a mesenchymal neoplasm originating in the endothelial cells of blood vessels; they can be classified as non-visceral and visceral types. Non-visceral hemangiosarcomas can affect the skin, subcutaneous tissues, and muscle tissues; visceral hemangiosarcomas can affect the spleen, liver, heart, lungs, kidneys, oral cavity, bones, bladder, uterus, tongue, and retroperitoneum. Among domestic species, dogs are most affected by cutaneous HSA. Cutaneous HSA represents approximately 14% of all HSA diagnosed in this species and less than 5% of dermal tumors, according to North American studies. However, Brazilian epidemiological data demonstrate a higher prevalence, which may represent 27 to 80% of all canine HSAs and 13.9% of all skin neoplasms diagnosed in this species. Cutaneous HSA most commonly affects middle-aged to elderly dogs (between 8 and 15 years old), with no gender predisposition for either the actinic or non-actinic forms. The higher prevalence of cutaneous HSA in some canine breeds is related to lower protection from solar radiation, as low skin pigmentation and hair coverage lead to greater sun exposure. Actinic changes, such as solar dermatosis, are frequent in these patients, confirming the influence of solar radiation on the development of this neoplasm. There are multiple clinical manifestations of hemangiosarcoma in canines. The diagnostic approach and staging classification of cutaneous HSAs are similar between the different subtypes. The definitive diagnosis is obtained through histopathological analysis of incisional or excisional biopsies. Cytology can be used as a presurgical screening test; however, it has little diagnostic utility in cases of HSA because there is a high risk of blood contamination and sample hemodilution. Surgery is generally the treatment of choice for dogs with localized non-visceral HSA without evidence of metastatic disease. Recently, electrochemotherapy (ECT) has emerged as an alternative therapy for the local ablative treatment of different neoplastic types; the use of radiotherapy for the treatment of dogs with cutaneous HSA is uncommon. There is greater consensus in the literature regarding the indications for adjuvant chemotherapy in subcutaneous and muscular HSA; doxorubicin is the most frequently used antineoplastic agent for subcutaneous and muscular subtypes and can be administered alone or in combination with other drugs. Other therapies include antiangiogenic therapy, photodynamic therapy, the association of chemotherapy with the metronomic dose, targeted therapies, and natural products. The benefits of these therapies are presented and discussed. In general, the prognosis of splenic and cardiac HSA is unfavorable. As a challenging neoplasm, studies of new protocols and treatment modalities are necessary to control this aggressive disease.