Cerebellar and Middle Ear Metastases of Canine Transmissible Venereal Tumor Following Vincristine Therapy: A Rare Cause of Vestibular Dysfunction with a Review of Pathogenesis

Cerebellar and Middle Ear Metastases of Canine Transmissible Venereal Tumor Following Vincristine Therapy: A Rare Cause of Vestibular Dysfunction with a Review of Pathogenesis | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Case Report Cerebellar and Middle Ear Metastases of Canine Transmissible Venereal Tumor Following Vincristine Therapy: A Rare Cause of Vestibular Dysfunction with a Review of Pathogenesis Diana Bochynska, Ethan Saleh, John Grose, Andrea Peda This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7851673/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 12 You are reading this latest preprint version Abstract Background Canine transmissible venereal tumor (TVT) is a contagious neoplasm that primarily affects the external genitalia of dogs and is typically transmitted through direct physical contact. While TVT frequently metastasizes to regional lymph nodes, distant organ involvement remains rare. This case describes an unusual presentation of a dog with a history of genital TVT treated with Vincristine that presented with vestibular signs due to a metastatic TVT within cerebellum and inner ear. This report highlights the importance of understanding vincristine use in dogs and its limited penetration into the central nervous system. The findings emphasize the potential lymphatic and venous routes of tumor dissemination, along with secondary chemotherapy-related complications such as thymic hyperplasia and vagus nerve enlargement. Case Presentation A 5-year-old intact male dog presented with a history of progressive neurological deficits following confirmed TVT diagnosis and treatment with vincristine. Despite a full regression of genital and internal lesions, the patient developed ataxia and cranial nerve dysfunction, with worsening vestibular signs. Necropsy revealed a mass within the cerebellum and numerous hemorrhages in the inner ear. Additionally, the oral cavity presented with a severe papillomatosis. Histopathology and immunohistochemistry of the cerebellar mass and inner ear revealed a densely cellular, round cell neoplasm, PCR analysis detected LINE-1 insertion within the c-MYC oncogene, confirming TVT origin. Additionally, significant thymic hyperplasia and bilateral vagus nerve enlargement were observed. Conclusions This case represents first reported tympanic bulla and rare cerebellar metastasis of TVT, with evidence supporting both lymphatic and hematogenous dissemination. The findings emphasize the necessity for thorough neurological evaluations in TVT cases presenting with atypical clinical signs, due to inability of Vincristine to cross the blood-brain barrier. Additionally, this report raises important considerations regarding the impact of Vincristine-induced immunosuppression on viral co-infections and tumor behavior. Canine transmissible venereal tumor Vincristine chemotherapy Metastasis Cerebellum Middle ear Vestibular dysfunction Blood–brain barrier Immunohistochemistry Chemotherapy complications Figures Figure 1 Background Canine transmissible venereal tumor (TVT) is a unique allogeneic round cell neoplasm primarily affecting the external genitalia of sexually active dogs that spreads between hosts through direct physical contact [1]. The tumor commonly metastasizes to regional lymph nodes, but distant dissemination to organs such as the liver, spleen, and lungs occurs infrequently [2]. TVT typically follows a well-documented growth pattern, often regressing spontaneously or responding favorably to vincristine chemotherapy [1]. Metastases of TVT to the central nervous system (CNS) are exceedingly rare, with only a few reported cases in the literature [3].The mechanisms underlying CNS involvement in TVT remain poorly understood, as the blood-brain barrier (BBB) generally limits hematogenous tumor spread [4, 5]. However, alternative metastatic pathways, including lymphatic dissemination, may provide routes for tumor cells to bypass the BBB [5, 6]. This case describes an atypical presentation of TVT with cerebellar and middle ear metastasis, along with concurrent thymic hyperplasia and vagus nerve enlargement. Given the patient’s history of vincristine treatment and a severe canine papillomavirus infection, this report also explores the interplay between chemotherapy-induced immunosuppression, viral proliferation, and tumor progression within the CNS despite the administered treatment. Through histopathology, immunohistochemistry, and molecular diagnostics, this case provides insights into TVT’s potential for CNS metastasis and the role of systemic factors in tumor progression. Case presentation A 5-year-old intact male mixed breed dog with a history of severe oral papillomatosis with fully regressed genital and multiorgan TVT and Vincristine treatment presented for necropsy following progressive neurological deterioration with obtundation, opisthotonus, torticollis, vertical to rotary nystagmus, urinary incontinence, and anorexia/prehension difficulty. The patient was euthanized following sedation with dexmedetomidine (0.005 mg/kg) and butorphanol (0.2 mg/kg) IM. Euthanasia was performed using pentobarbital sodium administered at a dosage of 100 mg/kg IV. Investigation The postmortem examination was carried out according to standard procedures. The external postmortem examination revealed multiple coalescing, wart-like masses on the oral cavity, lips, tongue, soft palate, and muzzle, consistent with viral papillomatosis (Fig. 1 A). Additionally, a similar mass was identified on the skin overlying the left testicle. The heart appeared moderately rounded, with areas of pallor in the right atrium and ventricle. The thymus was abnormally present, large and demonstrated multifocal pinpoint hemorrhages. The bilateral vagus nerves exhibited diffuse mild enlargement. The right cerebellum was unilaterally compressed by a spherical, gray 23mm diameter, firm mass (Fig. 1 C). Within the tympanic bullae, multifocal areas of moderate acute hemorrhage were observed bilaterally (Fig. 1 F). No gross lesions were noted in the cerebrum or spinal cord. Histopathology The histological tissue preparation and examination were conducted according to standard procedures. Histologically the oral cavity lesion represented a classical viral papilloma characterized by neoplastic cells arranged in broad folds and papillary projections supported on thin fibrovascular stroma. The epithelium showed rare koilocytes. Examination of the cerebellar mass revealed densely packed round cells arranged in sheets, exhibiting distinct cell borders, moderate amounts of basophilic cytoplasm, and stippled chromatin (Fig. 1 D). The neoplastic cells demonstrated moderate anisocytosis and anisokaryosis, with 21 mitotic figures per 2.37 mm² (10 high power fields). Surrounding the neoplasm, the adjacent cerebellar vermis showed compression with marked vacuolization of the white matter and atrophy of the granular layer sand Purkinje cell. In the tympanic bullae, histology identified a round cell neoplasm showing densely packed round cells with round nuclei, stippled chromatin, and moderate eosinophilic cytoplasm (Fig. 1 F). Occasional mitotic figures were observed. Additionally, vascular congestion was present in the surrounding tissue, correlating with the grossly observed red pinpoint lesions. These histological features were consistent with metastatic round cell neoplasm. Immunohistochemistry (IHC) Immunohistochemical evaluation of cerebellar and inner ear neoplastic cells was performed externally (MSU). No immunolabelling with CD18, CD45, CD204, CD3, CD20, KIT, GFAP, and neurofilament antibodies were reported. Molecular Diagnostics Fourteen unstained slides containing cerebellar tissue were submitted for PCR analysis (MSU).. The PCR targeted the long interspersed nuclear element (LINE) insertion sequence within the c-MYC oncogene, a characteristic genetic alteration in TVT. The results confirmed the presence of the LINE insertion, supporting the diagnosis of TVT in the cerebellum. Discussion Canine transmissible venereal tumor (CTVT) is a round cell neoplasm that most commonly arises on the external genitalia or facial mucosa of dogs [7]. Clinically, CTVT typically presents as solitary or multiple ulcerated, friable nodules, with females being more frequently affected than males [8]. In males, the lesions are most often located on the penile shaft, whereas in females, they commonly affect the vulva or vestibule of the vagina [9]. Transmission occurs through direct contact, primarily during coitus, but may also result from licking, sniffing, or fighting among canines [8]. CTVT is globally distributed, with increased prevalence reported in tropical and subtropical regions [7]. The higher incidence in these areas has been attributed to larger populations of sexually intact, free-roaming dogs, such as those observed in St. Kitts, compared to more industrialized countries [7]. The etiologic agent of TVT is the implanted tumor cell itself, acting as a clonal allograft. These neoplastic cells are believed to have originated from a single ancestral dog and have since been transmitted between individuals through direct contact. The tumor cells are characterized by a stable, species-specific aneuploid karyotype, typically containing 57–59 chromosomes—distinct from the normal canine diploid number of 78—which supports their long-term evolutionary adaptation and transmissibility [7]. Genetic mutations, potentially induced by viral, chemical, cellular, or radiation-related stimuli, are thought to have contributed to the initial transformation and persistence of these cells [7]. CTVT exhibits distinctive genetic diagnostic features that confirm its origin as a transmissible allograft rather than a de novo neoplasm in the affected host. One hallmark finding is the presence of a long interspersed nuclear element-1 (LINE-1) insertion within the tumor genome, including a characteristic insertion near the c-myc oncogene, that is consistently identified across tumor samples from different animals [7]. These molecular signatures, along with the stable aneuploid karyotype of 57–59 chromosomes, provide compelling evidence that the tumor originates from an external host rather than arising spontaneously in each individual [7]. There are three main stages of tumor development in a new host following cellular transplantation. First stage is identified as Progression phase, during which the tumor rapidly grows while evading the host immune system through the secretion of transforming growth factor-β1 (TGF-β1). This factor inhibits natural killer (NK) cell activity, blocks cytotoxic lymphocyte infiltration, and reduces MHC I expression, allowing the tumor to grow readily by evading the immune system [7]. Additionally, transforming growth factor-β1 (TGF-β1) will induce B-lymphocyte apoptosis, hindering dendritic cell activity by promoting the expression of a pro-apoptosis protein BIM, which is necessary for initiating apoptosis in various cell lineages, including B-lymphocytes [10]. Transforming growth factor-β1 will then enhance the transcription of BIM while also stabilizing the protein to prevent degradation, which results in a sustained pro-apoptotic signal affecting B-lymphocytes [10]. At the same time Transforming growth factor-β1 can inhibit the migration of dendritic cells from the tumor itself, which will result in decreased antigen presentation of tumor cells promoting metastasis of tumor cell line [11]. After the Progression phase, the tumor enters the Stable phase, characterized by slower tumor growth [7]. Depending on the humoral immune response of the affected animal and the associated production of cytotoxic materials such as perforin and granzymes by the NK cells and cytotoxic T cells, which will ultimately slow tumor growth, the tumor can remain in this phase for weeks, months, or indefinitely [7]. Lastly, studies have shown that in approximately 80% of cases experimentally transplanted cases, the tumor enters the Regressive phase lasting between 2 and 12 weeks. During this phase, the tumor may begin to shrink and potentially fully regress. This process is associated with an increase in tumor-infiltrating lymphocytes (TILs), primarily of T Cells, which secrete IFN-γ and IL-6[12]. These cytokines counteract TGF-β, restore MHC expression, promote tumor apoptosis, and facilitate infiltration by host immune cells such as T-lymphocytes, plasma cells, and macrophages allowing appropriate tumor recognition and immune response [7]. Two forms of TVT have been described: the naturally occurring form, which arises through direct transmission between dogs under natural conditions, and the experimentally transplanted form, which is established through deliberate inoculation of tumor cells under controlled settings [7]. The naturally occurring form of TVT rarely undergoes spontaneous regression [7]. When regression does occur, it has been linked to the action of cytokines such as C-C motif chemokine ligand 5 (CCL5), which recruits immune cells to the tumor microenvironment and facilitates tumor clearance [7]. Elevated erythropoietin (EPO) levels and associated erythrocytosis have been reported predominantly in experimentally transplanted tumors, but this phenomenon is typically absent in naturally occurring cases [7, 13]. The precise role of EPO in tumor biology and its potential contribution to regression remains incompletely understood [7]. Reported metastasis rates differ between the two forms of TVT. The naturally occurring form has been associated with a metastasis rate of 5–25%, while the experimentally transplanted form shows a slightly lower rate of 2–20% [7]. Despite these figures, metastasis remains an uncommon outcome and is generally observed in younger or immuno-compromised individuals. When present, metastases most frequently involve regional lymph nodes, though other sites including the brain, liver, and eye have also been documented [9, 14]. Space-occupying lesions involving the cerebellum and middle ear are frequently associated with vestibular disease [15]. Cerebellar neoplasms and the resulting mass effect can induce a range of central nervous system (CNS) signs, including seizures, head tilt, nystagmus, and tremors [15]. Importantly, compression of the cerebellum may lead to ischemia or cerebrovascular accidents, resulting in acute onset of neurologic symptoms [15]. In the present case, a left-sided head tilt and vertical nystagmus were noted. Middle ear neoplasms are similarly associated with vestibular dysfunction, primarily due to the secondary effects of the expanding lesion [15]. These may involve compression of adjacent neuroanatomical structures or components of the vestibular apparatus, as well as secondary infections that can result in localized trauma and inflammation, further exacerbating or precipitating vestibular signs [15]. Diagnosis of TVT is commonly based on clinical presentation and cytological and histopathological findings. A typical history, as observed in this case, describes an intact canine in a subtropical region, exhibiting a cauliflower-like mass on the external genitalia or face. This clinical presentation prompts the clinician to consider TVT as a differential diagnosis. Following a physical examination, a supportive diagnosis can be reached through cytological evaluation via fine-needle aspiration (FNA)[7]. Fine-needle aspirates of TVT typically exhibit round cells with intact cytoplasmic borders and a finely granular vacuolated acidophilic cytoplasm [7]. Typical histological findings in TVT cases, show round cells, with prominent cell borders, lightly eosinophilic vacuolated cytoplasm, and round centrally located nuclei with vesicular chromatin and variable mitotic activity [7]. In this case, the diagnosis was confirmed using multiple diagnostic modalities. At postmortem examination, all external masses had regressed except for the intracranial lesion. The patient was euthanized due to progressive vestibular dysfunction and severe oral papillomatosis. The immunohistochemical analysis showed that the neoplastic cells surprisingly did not immunolabel with any of the attested antibodies. CD18, which plays a critical role in leukocyte adhesion and migration, serves as a common leukocyte antigen associated with integrin β2, primarily confirming histiocytic origin, and is usually positively identified in TVTs. CD45, which plays a crucial role in T-cell activation by modulating signaling thresholds, particularly through the activation of Src family kinases, is another essential marker, expressed on all nucleated hematopoietic cells, which aids in differentiating hematopoietic tumors from non-hematopoietic tumors [16]. The CD204 marker is a pattern recognition receptor predominantly expressed on macrophages and is involved in lipid metabolism, innate immunity, and the clearance of apoptotic cells, serves as an indicator of histiocytic and macrophage lineages and typically yields a negative result in the case of TVT [17]. This finding is particularly noteworthy since TVT is classified as a round cell tumor of suspected histiocytic origin. The negative outcome for IHC testing of CD204 in TVT can be attributed to the variable expression of the marker, influenced by several factors, including the tumor cell environment, and the tumor cells lacking specific macrophage lineages commonly expressed on other round cell tumors namely histiocytic sarcomas [17]. To rule out lymphomas CD3 and CD20 antibodies were utilized. CD3 is a protein complex associates with the T-cell receptor (TCR) to form the TCR complex which is essential for T-cell activation and signal transduction [18]. CD20 is a membrane-embedded surface molecule expressed on B-cells, which is involved in B-cell development and differentiation [19]. CD3 is used to mark mature T-lymphocytes, while CD20 is associated with mature B-lymphocytes. Furthermore, KIT receptor (CD117), which is a type III receptor tyrosine kinase expressed on hematopoietic stem cells and other cell types and is associated with signaling pathways that regulate cell proliferation, differentiation, and survival, is frequently expressed in TVT cells and was tested to help further distinguish this sample from other round cell tumors, specifically mast cell tumors in which positive KIT testing is diagnostic [20]. In contexts of the central nervous system, markers including Glial Fibrillary Acidic Protein (GFAP), which is a type of intermediate filament positive in astrocytes, and neurons, and Neurofilament were used in order to exclude neoplasms of glial or neurogenic origin, [21, 22]. Although all above mentioned antibodies did not immunolabel cerebellar mass from this patient it is important to note limitations of immunohistochemistry which is why PCR is commonly used as the confirmatory diagnostic strategy and more reliable testing method for TVT [23]. Considering these findings and to provide a definitive molecular confirmation of TVT, a PCR test was conducted on cerebellar mass sample. As previously noted, TVT is commonly linked to the rearrangement of the c-MYC oncogene, which occurs due to the insertion of a transposable genetic element known as LINE at the 5' region relative to the first exon of the c-MYC gene. Given this specific characteristic, the PCR methodology targeted the LINE sequence along with the upstream c-MYC sequences. According to studies, PCR testing of the Line sequence is associated with a sensitivity rate of 100% and a specificity rate of 80% [23]. The analysis confirmed the presence of the LINE insertion in the samples. Consequently, a diagnosis of transmissible venereal tumor (TVT) was deemed most appropriate based on these results. This case underscores the importance of selecting appropriate chemotherapeutic agents with adequate penetration of the blood-brain barrier in cases of widespread TVT. There are three main treatment options for TVT: surgery, radiotherapy, and chemotherapy [24]. Surgery has been linked to a high recurrence rate of nearly 70%. However, treatment with agents such as vincristine has been associated with a favorable prognosis, often resulting in full tumor regression [25]. Vincristine is a vinca alkaloid antineoplastic drug that is commonly used for the treatment of hematopoietic neoplasms, hemangiosarcoma, and transmissible venereal tumors in dogs [26]. Vincristine is administered as an intravenous (IV) agent and shows a rapid distribution in most tissues with the exception of the CNS [26]. It is important to note that vincristine cannot cross the blood-brain barrier. Therefore, TVT metastasis affecting the central nervous system, as observed in this case with primary nodules on the prepuce and internal organs successfully treated with vincristine, represents a unique therapeutic challenge. This finding highlights the need for alternative agents capable of effectively targeting CNS metastases, as supported by the present and previously reported cases [27]. Following its absorption and distribution, vincristine is metabolized by the liver and excreted primarily through bile and feces, as well as a small amount of excretion in the urine [26]. Vincristine's inability to cross the blood-brain barrier (BBB) is primarily attributed to its molecular structure, C46H56N4O10, and pharmacokinetic properties associated with its absorption, distribution, and excretion [26]. Vincristine is a chemotherapeutic agent characterized by its extensive volume of distribution (2.3 to 8 L/kg in adults and 1.5 to 4.9 L/kg in children), as well as a protein binding percentage of 44% primarily to albumin in the blood [26]. The BBB is a highly selective barrier comprised of endothelial cells that function to prevent solutes in the bloodstream from entering the extracellular fluid of the central nervous system, where neurons reside [28]. Vincristine is a relatively large molecule with hydrophilic characteristics, making it poorly soluble in lipids, which are a key component of the BBB [26]. Furthermore, because of that and lack of a specific transporter that would facilitate its crossing of the BBB, it cannot effectively penetrate brain tissue to provide any form of therapy [26]. This limited ability to permeate the BBB poses significant challenges in clinical settings, particularly since vincristine is not suitable for treating cancers located within the central nervous system, as demonstrated in this case [26]. Lastly, because this drug cannot cross the BBB, it explains why systemic metastasis was cleared while cerebellar lesions remained unaffected [26]. This case presents a novel metastatic pathway of TVT to the cerebellum, with additional involvement of the tympanic bullae, providing new evidence for alternative metastatic pathways beyond the commonly observed routes. The findings emphasize the biological plasticity of TVT, demonstrating its capacity to adapt and disseminate to previously undocumented anatomic locations. Furthermore, the case highlights the limitations of vincristine chemotherapy in treating CNS metastases, underscoring the need for further research into therapeutic strategies capable of crossing the blood-brain barrier as well as the importance of pre-treatment imaging to promote better patient prognosis. This report not only expands the scientific understanding of TVT pathology, but also raises critical considerations for early detection, alternative treatment modalities, and the broader implications of transmissible cancers in veterinary oncology. Abbreviations BBB Blood–brain barrier BIM Bcl-2-like protein 11 CCL5 C-C motif chemokine ligand 5 CD3 Cluster of differentiation 3 CD18 Cluster of differentiation 18 CD20 Cluster of differentiation 20 CD45 Cluster of differentiation 45 CD117 (KIT) Stem cell factor receptor tyrosine kinase CD204 Cluster of differentiation 204 CNS Central nervous system CTVT Canine transmissible venereal tumor c-MYC Cellular myelocytomatosis oncogene DNA Deoxyribonucleic acid EPO Erythropoietin FNA Fine-needle aspiration GFAP Glial fibrillary acidic protein H&E Hematoxylin and eosin IHC Immunohistochemistry IFN-γ Interferon gamma IL-1 Interleukin-1 IL-2 Interleukin-2 IL-6 Interleukin-6 IL-10 Interleukin-10 IM Intramuscular IV Intravenous LINE-1 Long interspersed nuclear element-1 MHC I Major histocompatibility complex class I MRI Magnetic resonance imaging NK cells Natural killer cells PCR Polymerase chain reaction RNA Ribonucleic acid Src Proto-oncogene tyrosine-protein kinase Src TCR T-cell receptor TGF-β1 Transforming growth factor beta-1 TILs Tumor-infiltrating lymphocytes TVT Transmissible venereal tumor Declarations Acknowledgements The authors acknowledge all the technical support in RUSVM. Funding Not applicable Ethics approval and consent to participate. The owner provided informed consent for the euthanasia, postmortem examination, subsequent diagnostic testing, and the dissemination of knowledge derived from this case. Consent for publication Consent for publication has been sought and provided by the patients’ owners. Competing interests The authors declare no competing interests. References De Sanctis Augusto P, Dinau FC, González-Zambrano CM, Montoya-Flórez LM, Araújo JP, Rocha NS: Pilot study: Understanding canine transmissible venereal tumor through its transcriptional profile . Veterinary Immunology and Immunopathology 2024, 276 :110818. Alidadi S: Disseminated Transmissible Venereal Tumour in the Mammary Glands of a Dog: A Histopathological and Immunohistochemical Case Report . Vet Med Sci 2025, 11 (3):e70229. 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13:40:59","extension":"html","order_by":7,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":59420,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7851673/v1/3e55f2dfef875133fcc60d9f.html"},{"id":94663465,"identity":"a5726ad3-49b9-4789-a8fb-a1a9aba9794e","added_by":"auto","created_at":"2025-10-29 12:11:35","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":157331,"visible":true,"origin":"","legend":"\u003cp\u003eA- Severe multifocal oral papillomatosis. B- Histology of oral papilloma showing an exophytic growth with marked epithelial hyperplasia. C- Cerebellum is unilaterally compressed by a focally extensive, round, metastatic TVT. D- Histology of the cerebellar metastatic mass showing sheets of round neoplastic cells. E- Both tympanic bullae showing pinpoint red areas. F- The tympanic bulla contains sheets of round neoplastic cells (asterisk).\u003c/p\u003e","description":"","filename":"fig1resized170mm.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7851673/v1/1f82dacd82bde8a80c98fc2f.jpg"},{"id":94674057,"identity":"016b390b-4c59-4531-9b4a-35edbea3da5c","added_by":"auto","created_at":"2025-10-29 13:42:27","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1658289,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7851673/v1/7cc552ac-0b00-479f-9a82-70a7745e6b68.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Cerebellar and Middle Ear Metastases of Canine Transmissible Venereal Tumor Following Vincristine Therapy: A Rare Cause of Vestibular Dysfunction with a Review of Pathogenesis","fulltext":[{"header":"Background","content":"\u003cp\u003eCanine transmissible venereal tumor (TVT) is a unique allogeneic round cell neoplasm primarily affecting the external genitalia of sexually active dogs that spreads between hosts through direct physical contact [1]. The tumor commonly metastasizes to regional lymph nodes, but distant dissemination to organs such as the liver, spleen, and lungs occurs infrequently [2]. TVT typically follows a well-documented growth pattern, often regressing spontaneously or responding favorably to vincristine chemotherapy [1].\u003c/p\u003e\u003cp\u003eMetastases of TVT to the central nervous system (CNS) are exceedingly rare, with only a few reported cases in the literature [3].The mechanisms underlying CNS involvement in TVT remain poorly understood, as the blood-brain barrier (BBB) generally limits hematogenous tumor spread [4, 5]. However, alternative metastatic pathways, including lymphatic dissemination, may provide routes for tumor cells to bypass the BBB [5, 6].\u003c/p\u003e\u003cp\u003eThis case describes an atypical presentation of TVT with cerebellar and middle ear metastasis, along with concurrent thymic hyperplasia and vagus nerve enlargement. Given the patient\u0026rsquo;s history of vincristine treatment and a severe canine papillomavirus infection, this report also explores the interplay between chemotherapy-induced immunosuppression, viral proliferation, and tumor progression within the CNS despite the administered treatment. Through histopathology, immunohistochemistry, and molecular diagnostics, this case provides insights into TVT\u0026rsquo;s potential for CNS metastasis and the role of systemic factors in tumor progression.\u003c/p\u003e"},{"header":"Case presentation","content":"\u003cp\u003eA 5-year-old intact male mixed breed dog with a history of severe oral papillomatosis with fully regressed genital and multiorgan TVT and Vincristine treatment presented for necropsy following progressive neurological deterioration with obtundation, opisthotonus, torticollis, vertical to rotary nystagmus, urinary incontinence, and anorexia/prehension difficulty. The patient was euthanized following sedation with dexmedetomidine (0.005 mg/kg) and butorphanol (0.2 mg/kg) IM. Euthanasia was performed using pentobarbital sodium administered at a dosage of 100 mg/kg IV.\u003c/p\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eInvestigation\u003c/h2\u003e\u003cp\u003eThe postmortem examination was carried out according to standard procedures. The external postmortem examination revealed multiple coalescing, wart-like masses on the oral cavity, lips, tongue, soft palate, and muzzle, consistent with viral papillomatosis (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eA). Additionally, a similar mass was identified on the skin overlying the left testicle. The heart appeared moderately rounded, with areas of pallor in the right atrium and ventricle. The thymus was abnormally present, large and demonstrated multifocal pinpoint hemorrhages. The bilateral vagus nerves exhibited diffuse mild enlargement. The right cerebellum was unilaterally compressed by a spherical, gray 23mm diameter, firm mass (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eC). Within the tympanic bullae, multifocal areas of moderate acute hemorrhage were observed bilaterally (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eF). No gross lesions were noted in the cerebrum or spinal cord.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eHistopathology\u003c/h3\u003e\n\u003cp\u003eThe histological tissue preparation and examination were conducted according to standard procedures. Histologically the oral cavity lesion represented a classical viral papilloma characterized by neoplastic cells arranged in broad folds and papillary projections supported on thin fibrovascular stroma. The epithelium showed rare koilocytes. Examination of the cerebellar mass revealed densely packed round cells arranged in sheets, exhibiting distinct cell borders, moderate amounts of basophilic cytoplasm, and stippled chromatin (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eD). The neoplastic cells demonstrated moderate anisocytosis and anisokaryosis, with 21 mitotic figures per 2.37 mm\u0026sup2; (10 high power fields). Surrounding the neoplasm, the adjacent cerebellar vermis showed compression with marked vacuolization of the white matter and atrophy of the granular layer sand Purkinje cell.\u003c/p\u003e\u003cp\u003eIn the tympanic bullae, histology identified a round cell neoplasm showing densely packed round cells with round nuclei, stippled chromatin, and moderate eosinophilic cytoplasm (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eF). Occasional mitotic figures were observed. Additionally, vascular congestion was present in the surrounding tissue, correlating with the grossly observed red pinpoint lesions. These histological features were consistent with metastatic round cell neoplasm.\u003c/p\u003e\n\u003ch3\u003eImmunohistochemistry (IHC)\u003c/h3\u003e\n\u003cp\u003eImmunohistochemical evaluation of cerebellar and inner ear neoplastic cells was performed externally (MSU). No immunolabelling with CD18, CD45, CD204, CD3, CD20, KIT, GFAP, and neurofilament antibodies were reported.\u003c/p\u003e\n\u003ch3\u003eMolecular Diagnostics\u003c/h3\u003e\n\u003cp\u003eFourteen unstained slides containing cerebellar tissue were submitted for PCR analysis (MSU).. The PCR targeted the long interspersed nuclear element (LINE) insertion sequence within the c-MYC oncogene, a characteristic genetic alteration in TVT. The results confirmed the presence of the LINE insertion, supporting the diagnosis of TVT in the cerebellum.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eCanine transmissible venereal tumor (CTVT) is a round cell neoplasm that most commonly arises on the external genitalia or facial mucosa of dogs [7]. Clinically, CTVT typically presents as solitary or multiple ulcerated, friable nodules, with females being more frequently affected than males [8]. In males, the lesions are most often located on the penile shaft, whereas in females, they commonly affect the vulva or vestibule of the vagina [9].\u003c/p\u003e\u003cp\u003eTransmission occurs through direct contact, primarily during coitus, but may also result from licking, sniffing, or fighting among canines [8]. CTVT is globally distributed, with increased prevalence reported in tropical and subtropical regions [7]. The higher incidence in these areas has been attributed to larger populations of sexually intact, free-roaming dogs, such as those observed in St. Kitts, compared to more industrialized countries [7].\u003c/p\u003e\u003cp\u003eThe etiologic agent of TVT is the implanted tumor cell itself, acting as a clonal allograft. These neoplastic cells are believed to have originated from a single ancestral dog and have since been transmitted between individuals through direct contact. The tumor cells are characterized by a stable, species-specific aneuploid karyotype, typically containing 57\u0026ndash;59 chromosomes\u0026mdash;distinct from the normal canine diploid number of 78\u0026mdash;which supports their long-term evolutionary adaptation and transmissibility [7]. Genetic mutations, potentially induced by viral, chemical, cellular, or radiation-related stimuli, are thought to have contributed to the initial transformation and persistence of these cells [7].\u003c/p\u003e\u003cp\u003eCTVT exhibits distinctive genetic diagnostic features that confirm its origin as a transmissible allograft rather than a de novo neoplasm in the affected host. One hallmark finding is the presence of a long interspersed nuclear element-1 (LINE-1) insertion within the tumor genome, including a characteristic insertion near the c-myc oncogene, that is consistently identified across tumor samples from different animals [7]. These molecular signatures, along with the stable aneuploid karyotype of 57\u0026ndash;59 chromosomes, provide compelling evidence that the tumor originates from an external host rather than arising spontaneously in each individual [7].\u003c/p\u003e\u003cp\u003eThere are three main stages of tumor development in a new host following cellular transplantation. First stage is identified as Progression phase, during which the tumor rapidly grows while evading the host immune system through the secretion of transforming growth factor-β1 (TGF-β1). This factor inhibits natural killer (NK) cell activity, blocks cytotoxic lymphocyte infiltration, and reduces MHC I expression, allowing the tumor to grow readily by evading the immune system [7]. Additionally, transforming growth factor-β1 (TGF-β1) will induce B-lymphocyte apoptosis, hindering dendritic cell activity by promoting the expression of a pro-apoptosis protein BIM, which is necessary for initiating apoptosis in various cell lineages, including B-lymphocytes [10]. Transforming growth factor-β1 will then enhance the transcription of BIM while also stabilizing the protein to prevent degradation, which results in a sustained pro-apoptotic signal affecting B-lymphocytes [10]. At the same time Transforming growth factor-β1 can inhibit the migration of dendritic cells from the tumor itself, which will result in decreased antigen presentation of tumor cells promoting metastasis of tumor cell line [11].\u003c/p\u003e\u003cp\u003eAfter the Progression phase, the tumor enters the Stable phase, characterized by slower tumor growth [7]. Depending on the humoral immune response of the affected animal and the associated production of cytotoxic materials such as perforin and granzymes by the NK cells and cytotoxic T cells, which will ultimately slow tumor growth, the tumor can remain in this phase for weeks, months, or indefinitely [7]. Lastly, studies have shown that in approximately 80% of cases experimentally transplanted cases, the tumor enters the Regressive phase lasting between 2 and 12 weeks. During this phase, the tumor may begin to shrink and potentially fully regress. This process is associated with an increase in tumor-infiltrating lymphocytes (TILs), primarily of T Cells, which secrete IFN-γ and IL-6[12]. These cytokines counteract TGF-β, restore MHC expression, promote tumor apoptosis, and facilitate infiltration by host immune cells such as T-lymphocytes, plasma cells, and macrophages allowing appropriate tumor recognition and immune response [7].\u003c/p\u003e\u003cp\u003eTwo forms of TVT have been described: the naturally occurring form, which arises through direct transmission between dogs under natural conditions, and the experimentally transplanted form, which is established through deliberate inoculation of tumor cells under controlled settings [7].\u003c/p\u003e\u003cp\u003eThe naturally occurring form of TVT rarely undergoes spontaneous regression [7]. When regression does occur, it has been linked to the action of cytokines such as C-C motif chemokine ligand 5 (CCL5), which recruits immune cells to the tumor microenvironment and facilitates tumor clearance [7]. Elevated erythropoietin (EPO) levels and associated erythrocytosis have been reported predominantly in experimentally transplanted tumors, but this phenomenon is typically absent in naturally occurring cases [7, 13]. The precise role of EPO in tumor biology and its potential contribution to regression remains incompletely understood [7].\u003c/p\u003e\u003cp\u003eReported metastasis rates differ between the two forms of TVT. The naturally occurring form has been associated with a metastasis rate of 5\u0026ndash;25%, while the experimentally transplanted form shows a slightly lower rate of 2\u0026ndash;20% [7]. Despite these figures, metastasis remains an uncommon outcome and is generally observed in younger or immuno-compromised individuals. When present, metastases most frequently involve regional lymph nodes, though other sites including the brain, liver, and eye have also been documented [9, 14].\u003c/p\u003e\u003cp\u003eSpace-occupying lesions involving the cerebellum and middle ear are frequently associated with vestibular disease [15]. Cerebellar neoplasms and the resulting mass effect can induce a range of central nervous system (CNS) signs, including seizures, head tilt, nystagmus, and tremors [15]. Importantly, compression of the cerebellum may lead to ischemia or cerebrovascular accidents, resulting in acute onset of neurologic symptoms [15]. In the present case, a left-sided head tilt and vertical nystagmus were noted. Middle ear neoplasms are similarly associated with vestibular dysfunction, primarily due to the secondary effects of the expanding lesion [15]. These may involve compression of adjacent neuroanatomical structures or components of the vestibular apparatus, as well as secondary infections that can result in localized trauma and inflammation, further exacerbating or precipitating vestibular signs [15].\u003c/p\u003e\u003cp\u003eDiagnosis of TVT is commonly based on clinical presentation and cytological and histopathological findings. A typical history, as observed in this case, describes an intact canine in a subtropical region, exhibiting a cauliflower-like mass on the external genitalia or face. This clinical presentation prompts the clinician to consider TVT as a differential diagnosis. Following a physical examination, a supportive diagnosis can be reached through cytological evaluation via fine-needle aspiration (FNA)[7]. Fine-needle aspirates of TVT typically exhibit round cells with intact cytoplasmic borders and a finely granular vacuolated acidophilic cytoplasm [7]. Typical histological findings in TVT cases, show round cells, with prominent cell borders, lightly eosinophilic vacuolated cytoplasm, and round centrally located nuclei with vesicular chromatin and variable mitotic activity [7]. In this case, the diagnosis was confirmed using multiple diagnostic modalities. At postmortem examination, all external masses had regressed except for the intracranial lesion. The patient was euthanized due to progressive vestibular dysfunction and severe oral papillomatosis.\u003c/p\u003e\u003cp\u003eThe immunohistochemical analysis showed that the neoplastic cells surprisingly did not immunolabel with any of the attested antibodies. CD18, which plays a critical role in leukocyte adhesion and migration, serves as a common leukocyte antigen associated with integrin β2, primarily confirming histiocytic origin, and is usually positively identified in TVTs. CD45, which plays a crucial role in T-cell activation by modulating signaling thresholds, particularly through the activation of Src family kinases, is another essential marker, expressed on all nucleated hematopoietic cells, which aids in differentiating hematopoietic tumors from non-hematopoietic tumors [16]. The CD204 marker is a pattern recognition receptor predominantly expressed on macrophages and is involved in lipid metabolism, innate immunity, and the clearance of apoptotic cells, serves as an indicator of histiocytic and macrophage lineages and typically yields a negative result in the case of TVT [17]. This finding is particularly noteworthy since TVT is classified as a round cell tumor of suspected histiocytic origin. The negative outcome for IHC testing of CD204 in TVT can be attributed to the variable expression of the marker, influenced by several factors, including the tumor cell environment, and the tumor cells lacking specific macrophage lineages commonly expressed on other round cell tumors namely histiocytic sarcomas [17]. To rule out lymphomas CD3 and CD20 antibodies were utilized. CD3 is a protein complex associates with the T-cell receptor (TCR) to form the TCR complex which is essential for T-cell activation and signal transduction [18]. CD20 is a membrane-embedded surface molecule expressed on B-cells, which is involved in B-cell development and differentiation [19]. CD3 is used to mark mature T-lymphocytes, while CD20 is associated with mature B-lymphocytes. Furthermore, KIT receptor (CD117), which is a type III receptor tyrosine kinase expressed on hematopoietic stem cells and other cell types and is associated with signaling pathways that regulate cell proliferation, differentiation, and survival, is frequently expressed in TVT cells and was tested to help further distinguish this sample from other round cell tumors, specifically mast cell tumors in which positive KIT testing is diagnostic [20].\u003c/p\u003e\u003cp\u003eIn contexts of the central nervous system, markers including Glial Fibrillary Acidic Protein (GFAP), which is a type of intermediate filament positive in astrocytes, and neurons, and Neurofilament were used in order to exclude neoplasms of glial or neurogenic origin, [21, 22]. Although all above mentioned antibodies did not immunolabel cerebellar mass from this patient it is important to note limitations of immunohistochemistry which is why PCR is commonly used as the confirmatory diagnostic strategy and more reliable testing method for TVT [23].\u003c/p\u003e\u003cp\u003eConsidering these findings and to provide a definitive molecular confirmation of TVT, a PCR test was conducted on cerebellar mass sample. As previously noted, TVT is commonly linked to the rearrangement of the c-MYC oncogene, which occurs due to the insertion of a transposable genetic element known as LINE at the 5' region relative to the first exon of the c-MYC gene. Given this specific characteristic, the PCR methodology targeted the LINE sequence along with the upstream c-MYC sequences. According to studies, PCR testing of the Line sequence is associated with a sensitivity rate of 100% and a specificity rate of 80% [23]. The analysis confirmed the presence of the LINE insertion in the samples. Consequently, a diagnosis of transmissible venereal tumor (TVT) was deemed most appropriate based on these results.\u003c/p\u003e\u003cp\u003eThis case underscores the importance of selecting appropriate chemotherapeutic agents with adequate penetration of the blood-brain barrier in cases of widespread TVT.\u003c/p\u003e\u003cp\u003eThere are three main treatment options for TVT: surgery, radiotherapy, and chemotherapy [24]. Surgery has been linked to a high recurrence rate of nearly 70%. However, treatment with agents such as vincristine has been associated with a favorable prognosis, often resulting in full tumor regression [25]. Vincristine is a vinca alkaloid antineoplastic drug that is commonly used for the treatment of hematopoietic neoplasms, hemangiosarcoma, and transmissible venereal tumors in dogs [26]. Vincristine is administered as an intravenous (IV) agent and shows a rapid distribution in most tissues with the exception of the CNS [26]. It is important to note that vincristine cannot cross the blood-brain barrier. Therefore, TVT metastasis affecting the central nervous system, as observed in this case with primary nodules on the prepuce and internal organs successfully treated with vincristine, represents a unique therapeutic challenge. This finding highlights the need for alternative agents capable of effectively targeting CNS metastases, as supported by the present and previously reported cases [27]. Following its absorption and distribution, vincristine is metabolized by the liver and excreted primarily through bile and feces, as well as a small amount of excretion in the urine [26]. Vincristine's inability to cross the blood-brain barrier (BBB) is primarily attributed to its molecular structure, C46H56N4O10, and pharmacokinetic properties associated with its absorption, distribution, and excretion [26]. Vincristine is a chemotherapeutic agent characterized by its extensive volume of distribution (2.3 to 8 L/kg in adults and 1.5 to 4.9 L/kg in children), as well as a protein binding percentage of 44% primarily to albumin in the blood [26]. The BBB is a highly selective barrier comprised of endothelial cells that function to prevent solutes in the bloodstream from entering the extracellular fluid of the central nervous system, where neurons reside [28]. Vincristine is a relatively large molecule with hydrophilic characteristics, making it poorly soluble in lipids, which are a key component of the BBB [26]. Furthermore, because of that and lack of a specific transporter that would facilitate its crossing of the BBB, it cannot effectively penetrate brain tissue to provide any form of therapy [26]. This limited ability to permeate the BBB poses significant challenges in clinical settings, particularly since vincristine is not suitable for treating cancers located within the central nervous system, as demonstrated in this case [26]. Lastly, because this drug cannot cross the BBB, it explains why systemic metastasis was cleared while cerebellar lesions remained unaffected [26].\u003c/p\u003e\u003cp\u003eThis case presents a novel metastatic pathway of TVT to the cerebellum, with additional involvement of the tympanic bullae, providing new evidence for alternative metastatic pathways beyond the commonly observed routes. The findings emphasize the biological plasticity of TVT, demonstrating its capacity to adapt and disseminate to previously undocumented anatomic locations. Furthermore, the case highlights the limitations of vincristine chemotherapy in treating CNS metastases, underscoring the need for further research into therapeutic strategies capable of crossing the blood-brain barrier as well as the importance of pre-treatment imaging to promote better patient prognosis. This report not only expands the scientific understanding of TVT pathology, but also raises critical considerations for early detection, alternative treatment modalities, and the broader implications of transmissible cancers in veterinary oncology.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eBBB\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eBlood\u0026ndash;brain barrier\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eBIM\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eBcl-2-like protein 11\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCCL5\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eC-C motif chemokine ligand 5\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCD3\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eCluster of differentiation 3\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCD18\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eCluster of differentiation 18\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCD20\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eCluster of differentiation 20\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCD45\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eCluster of differentiation 45\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCD117 (KIT)\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eStem cell factor receptor tyrosine kinase\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCD204\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eCluster of differentiation 204\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCNS\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eCentral nervous system\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCTVT\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eCanine transmissible venereal tumor\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003ec-MYC\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eCellular myelocytomatosis oncogene\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eDNA\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eDeoxyribonucleic acid\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eEPO\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eErythropoietin\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eFNA\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eFine-needle aspiration\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eGFAP\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eGlial fibrillary acidic protein\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eH\u0026amp;E\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eHematoxylin and eosin\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eIHC\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eImmunohistochemistry\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eIFN-γ\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eInterferon gamma\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eIL-1\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eInterleukin-1\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eIL-2\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eInterleukin-2\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eIL-6\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eInterleukin-6\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eIL-10\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eInterleukin-10\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eIM\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eIntramuscular\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eIV\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eIntravenous\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eLINE-1\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eLong interspersed nuclear element-1\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eMHC I\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eMajor histocompatibility complex class I\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eMRI\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eMagnetic resonance imaging\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eNK cells\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eNatural killer cells\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003ePCR\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003ePolymerase chain reaction\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eRNA\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eRibonucleic acid\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eSrc\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eProto-oncogene tyrosine-protein kinase Src\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eTCR\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eT-cell receptor\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eTGF-β1\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eTransforming growth factor beta-1\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eTILs\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eTumor-infiltrating lymphocytes\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eTVT\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eTransmissible venereal tumor\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors acknowledge all the technical support in RUSVM.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe owner provided informed consent for the euthanasia, postmortem examination, subsequent diagnostic testing, and the dissemination of knowledge derived from this case.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eConsent for publication has been sought and provided by the patients\u0026rsquo; owners.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eDe Sanctis Augusto P, Dinau FC, González-Zambrano CM, Montoya-Flórez LM, Araújo JP, Rocha NS: \u003cb\u003ePilot study: Understanding canine transmissible venereal tumor through its transcriptional profile\u003c/b\u003e. \u003cem\u003eVeterinary Immunology and Immunopathology\u003c/em\u003e 2024, \u003cb\u003e276\u003c/b\u003e:110818.\u003c/li\u003e\n\u003cli\u003eAlidadi S: \u003cb\u003eDisseminated Transmissible Venereal Tumour in the Mammary Glands of a Dog: A Histopathological and Immunohistochemical Case Report\u003c/b\u003e. \u003cem\u003eVet Med Sci\u003c/em\u003e 2025, \u003cb\u003e11\u003c/b\u003e(3):e70229.\u003c/li\u003e\n\u003cli\u003eFaccini LS, Legramanti WM, De Castro LT, Barreto Coelho AC, Caetano Teixeira M, Shild AL, Pereira CM: \u003cb\u003eMultiple Metastases of a Transmissible Venereal Tumor in a Dog\u003c/b\u003e. \u003cem\u003eActa Scientiae Veterinariae\u003c/em\u003e 2019, \u003cb\u003e47\u003c/b\u003e.\u003c/li\u003e\n\u003cli\u003ePinczowski P, Gimeno M, Acena C, Villegas A, de MARTINO A, Lujan L: \u003cb\u003eBrain metastasis in a case of canine transmissible venereal tumor after a supposed successful treatment with vincristine sulfate\u003c/b\u003e. \u003cem\u003eActa Veterinaria-Beograd\u003c/em\u003e 2015, \u003cb\u003e65\u003c/b\u003e(1):137–142.\u003c/li\u003e\n\u003cli\u003eSteindl A, Brastianos PK, Preusser M, Berghoff AS: \u003cb\u003ePrecision medicine biomarkers in brain metastases: applications, discordances, and obstacles\u003c/b\u003e. \u003cem\u003eNeuro-Oncology Advances\u003c/em\u003e 2021, \u003cb\u003e3\u003c/b\u003e(Supplement_5):v35-v42.\u003c/li\u003e\n\u003cli\u003eKeopaseuth S, Pringproa K, Patchanee P, Setthawongsin C, Techangamsuwan S, Chuammitri P: \u003cb\u003eDivergent DNA methylation patterns and gene expression in MYC and CDKN2B in canine transmissible venereal tumors\u003c/b\u003e. \u003cem\u003eVet World\u003c/em\u003e 2024, \u003cb\u003e17\u003c/b\u003e(7):1581–1590.\u003c/li\u003e\n\u003cli\u003eAbeka YT: \u003cb\u003eReview on canine transmissible venereal tumor (CTVT)\u003c/b\u003e. \u003cem\u003eCancer Therapy \u0026amp; Oncology International Journal\u003c/em\u003e 2019, \u003cb\u003e14\u003c/b\u003e(4):86–94.\u003c/li\u003e\n\u003cli\u003eMcGavin MD, Zachary JF: \u003cb\u003ePathologic basis of veterinary disease\u003c/b\u003e: Elsevier Health Sciences; 2006.\u003c/li\u003e\n\u003cli\u003eVermooten MI: \u003cb\u003eCanine transmissible venereal tumor (TVT): a review\u003c/b\u003e. \u003cem\u003eJ S Afr Vet Assoc\u003c/em\u003e 1987, \u003cb\u003e58\u003c/b\u003e(3):147–150.\u003c/li\u003e\n\u003cli\u003eRamesh S, Wildey GM, Howe PH: \u003cb\u003eTransforming growth factor β (TGFβ)-induced apoptosis: the rise and fall of Bim\u003c/b\u003e. \u003cem\u003eCell Cycle\u003c/em\u003e 2009, \u003cb\u003e8\u003c/b\u003e(1):11–17.\u003c/li\u003e\n\u003cli\u003eImai K, Minamiya Y, Koyota S, Ito M, Saito H, Sato Y, Motoyama S, Sugiyama T, Ogawa J-i: \u003cb\u003eInhibition of dendritic cell migration by transforming growth factor-β1 increases tumor-draining lymph node metastasis\u003c/b\u003e. \u003cem\u003eJournal of Experimental \u0026amp; Clinical Cancer Research\u003c/em\u003e 2012, \u003cb\u003e31\u003c/b\u003e:1–9.\u003c/li\u003e\n\u003cli\u003eTiwari K, Verma P, Sharma J, Upadhyay AK: \u003cb\u003eImmune-mediated gene expression of Il-6 and TGF-β1 during progression and regression of canine transmissible venereal tumour\u003c/b\u003e. \u003cem\u003eVeterinarski arhiv\u003c/em\u003e 2021, \u003cb\u003e91\u003c/b\u003e(6):624–634.\u003c/li\u003e\n\u003cli\u003eMartins MM, De Souza F, Ferreira F, Gobello C: \u003cb\u003eThe canine transmissible venereal tumor: etiology, pathology, diagnosis and treatment\u003c/b\u003e. \u003cem\u003eRecent Advances in Small Animal Reproduction\u003c/em\u003e 2005, \u003cb\u003e25\u003c/b\u003e(7):161–167.\u003c/li\u003e\n\u003cli\u003eBirhan G, Chanie M: \u003cb\u003eA review on canine transmissible venereal tumor: from morphologic to biochemical and molecular diagnosis\u003c/b\u003e. \u003cem\u003eAcademic Journal of Animal Diseases\u003c/em\u003e 2015, \u003cb\u003e4\u003c/b\u003e(3):185–195.\u003c/li\u003e\n\u003cli\u003eBongartz U, Nessler J, Maiolini A, Stein VM, Tipold A, Bathen-Nöthen A: \u003cb\u003eVestibular disease in dogs: association between neurological examination, MRI lesion localisation and outcome\u003c/b\u003e. \u003cem\u003eJournal of small animal practice\u003c/em\u003e 2020, \u003cb\u003e61\u003c/b\u003e(1):57–63.\u003c/li\u003e\n\u003cli\u003eAltin JG, Sloan EK: \u003cb\u003eThe role of CD45 and CD45-associated molecules in T cell activation\u003c/b\u003e. \u003cem\u003eImmunology and cell biology\u003c/em\u003e 1997, \u003cb\u003e75\u003c/b\u003e(5):430–445.\u003c/li\u003e\n\u003cli\u003eKato Y, Murakami M, Hoshino Y, Mori T, Maruo K, Hirata A, Nakagawa T, Yanai T, Sakai H: \u003cb\u003eThe class A macrophage scavenger receptor CD204 is a useful immunohistochemical marker of canine histiocytic sarcoma\u003c/b\u003e. \u003cem\u003eJournal of comparative pathology\u003c/em\u003e 2013, \u003cb\u003e148\u003c/b\u003e(2–3):188–196.\u003c/li\u003e\n\u003cli\u003eNgoenkam J, Schamel WW, Pongcharoen S: \u003cb\u003eSelected signalling proteins recruited to the T-cell receptor–CD3 complex\u003c/b\u003e. \u003cem\u003eImmunology\u003c/em\u003e 2018, \u003cb\u003e153\u003c/b\u003e(1):42–50.\u003c/li\u003e\n\u003cli\u003eBoross P, Leusen JH: \u003cb\u003eMechanisms of action of CD20 antibodies\u003c/b\u003e. \u003cem\u003eAmerican journal of cancer research\u003c/em\u003e 2012, \u003cb\u003e2\u003c/b\u003e(6):676.\u003c/li\u003e\n\u003cli\u003eMiettinen M, Lasota J: \u003cb\u003eKIT (CD117): a review on expression in normal and neoplastic tissues, and mutations and their clinicopathologic correlation\u003c/b\u003e. \u003cem\u003eApplied immunohistochemistry \u0026amp; molecular morphology\u003c/em\u003e 2005, \u003cb\u003e13\u003c/b\u003e(3):205–220.\u003c/li\u003e\n\u003cli\u003eYang Z, Wang KK: \u003cb\u003eGlial fibrillary acidic protein: from intermediate filament assembly and gliosis to neurobiomarker\u003c/b\u003e. \u003cem\u003eTrends in neurosciences\u003c/em\u003e 2015, \u003cb\u003e38\u003c/b\u003e(6):364–374.\u003c/li\u003e\n\u003cli\u003eDing EA, Kumar S: \u003cb\u003eNeurofilament biophysics: From structure to biomechanics\u003c/b\u003e. \u003cem\u003eMolecular Biology of the Cell\u003c/em\u003e 2024, \u003cb\u003e35\u003c/b\u003e(5):re1.\u003c/li\u003e\n\u003cli\u003eSetthawongsin C, Techangamsuwan S, Tangkawattana S, Rungsipipat A: \u003cb\u003eCell-based polymerase chain reaction for canine transmissible venereal tumor (CTVT) diagnosis\u003c/b\u003e. \u003cem\u003eJournal of Veterinary Medical Science\u003c/em\u003e 2016, \u003cb\u003e78\u003c/b\u003e(7):1167–1173.\u003c/li\u003e\n\u003cli\u003eSouto EP, Rissi DR, Oliveira AM, Garcia DS, Mota RA, de Souza AP, Galiza GJ, Dantas AF: \u003cb\u003eTransmissible venereal tumour with encephalic metastasis in dogs\u003c/b\u003e. \u003cem\u003eJournal of Comparative Pathology\u003c/em\u003e 2025, \u003cb\u003e216\u003c/b\u003e:25–32.\u003c/li\u003e\n\u003cli\u003eDEN OTTER W, Hack M, Jacobs JJ, Tan JF, Rozendaal L, VAN MOORSELAAR RJA: \u003cb\u003eEffective treatment of transmissible venereal tumors in dogs with vincristine and IL2\u003c/b\u003e. \u003cem\u003eAnticancer research\u003c/em\u003e 2015, \u003cb\u003e35\u003c/b\u003e(6):3385–3391.\u003c/li\u003e\n\u003cli\u003ePlumb DC: \u003cb\u003ePlumb's veterinary drug handbook: desk\u003c/b\u003e: John Wiley \u0026amp; Sons; 2018.\u003c/li\u003e\n\u003cli\u003eHIDALGO GS, GUAJARDO SDCC, PAREDES MDSD, ARECHIGA N, VALENZUELA ML: \u003cb\u003eCerebral metastasis of transmissible venereal tumor after effective chemotherapy in a dog\u003c/b\u003e. \u003cem\u003eTurkish Journal of Veterinary \u0026amp; Animal Sciences\u003c/em\u003e 2020, \u003cb\u003e44\u003c/b\u003e(1):162–166.\u003c/li\u003e\n\u003cli\u003ePeters JJ, Teng C, Peng K, Li X: \u003cb\u003eDeciphering the Blood–Brain Barrier Paradox in Brain Metastasis Development and Therapy\u003c/b\u003e. \u003cem\u003eCancers\u003c/em\u003e 2025, \u003cb\u003e17\u003c/b\u003e(2):298.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"veterinary-oncology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Veterinary Oncology](https://veterinaryoncology.biomedcentral.com/)","snPcode":"44356","submissionUrl":"https://submission.springernature.com/new-submission/44356/3","title":"Veterinary Oncology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Canine transmissible venereal tumor, Vincristine chemotherapy, Metastasis, Cerebellum, Middle ear, Vestibular dysfunction, Blood–brain barrier, Immunohistochemistry, Chemotherapy complications","lastPublishedDoi":"10.21203/rs.3.rs-7851673/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7851673/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cu\u003e\u003cstrong\u003eBackground\u003c/strong\u003e\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003eCanine transmissible venereal tumor (TVT) is a contagious neoplasm that primarily affects the external genitalia of dogs and is typically transmitted through direct physical contact. While TVT frequently metastasizes to regional lymph nodes, distant organ involvement remains rare. This case describes an unusual presentation of a dog with a history of genital TVT treated with Vincristine that presented with vestibular signs due to a metastatic TVT within cerebellum and inner ear. This report highlights the importance of understanding vincristine use in dogs and its limited penetration into the central nervous system. The findings emphasize the potential lymphatic and venous routes of tumor dissemination, along with secondary chemotherapy-related complications such as thymic hyperplasia and vagus nerve enlargement.\u003c/p\u003e\n\u003cp\u003e\u003cu\u003e\u003cstrong\u003eCase Presentation\u003c/strong\u003e\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003eA 5-year-old intact male dog presented with a history of progressive neurological deficits following confirmed TVT diagnosis and treatment with vincristine. Despite a full regression of genital and internal lesions, the patient developed ataxia and cranial nerve dysfunction, with worsening vestibular signs. Necropsy revealed a mass within the cerebellum and numerous hemorrhages in the inner ear. Additionally, the oral cavity presented with a severe papillomatosis. Histopathology and immunohistochemistry of the cerebellar mass and inner ear revealed a densely cellular, round cell neoplasm, PCR analysis detected LINE-1 insertion within the c-MYC oncogene, confirming TVT origin. Additionally, significant thymic hyperplasia and bilateral vagus nerve enlargement were observed.\u003c/p\u003e\n\u003cp\u003e\u003cu\u003e\u003cstrong\u003eConclusions\u003c/strong\u003e\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003eThis case represents first reported tympanic bulla and rare cerebellar metastasis of TVT, with evidence supporting both lymphatic and hematogenous dissemination. The findings emphasize the necessity for thorough neurological evaluations in TVT cases presenting with atypical clinical signs, due to inability of Vincristine to cross the blood-brain barrier. Additionally, this report raises important considerations regarding the impact of Vincristine-induced immunosuppression on viral co-infections and tumor behavior.\u003c/p\u003e","manuscriptTitle":"Cerebellar and Middle Ear Metastases of Canine Transmissible Venereal Tumor Following Vincristine Therapy: A Rare Cause of Vestibular Dysfunction with a Review of Pathogenesis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-29 12:11:30","doi":"10.21203/rs.3.rs-7851673/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-11-17T20:13:26+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-13T22:58:29+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-10-31T21:20:13+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-10-29T13:02:03+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"136588151742879631395509648348280781217","date":"2025-10-24T10:51:31+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"315771413624282531215239500792006041778","date":"2025-10-23T18:58:54+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"242836166391259288378300265464025735278","date":"2025-10-22T12:41:54+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"1809401481695529318226006885553890758","date":"2025-10-21T19:26:45+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-10-14T20:24:38+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-10-14T09:15:57+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-10-14T09:11:53+00:00","index":"","fulltext":""},{"type":"submitted","content":"Veterinary Oncology","date":"2025-10-13T18:14:32+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"veterinary-oncology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Veterinary Oncology](https://veterinaryoncology.biomedcentral.com/)","snPcode":"44356","submissionUrl":"https://submission.springernature.com/new-submission/44356/3","title":"Veterinary Oncology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"d123f640-f2da-4761-a6df-c75f612d09b4","owner":[],"postedDate":"October 29th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-12T18:38:19+00:00","versionOfRecord":[],"versionCreatedAt":"2025-10-29 12:11:30","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7851673","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7851673","identity":"rs-7851673","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}