Effect of vincristine on intraocular pressure and tear fluid oxidative stress biomarkers in canine transmissible venereal tumor.

BACKGROUND: The ocular side effects of cancer chemotherapeutic drugs are relatively uncommon. Nonetheless, the ocular system has a potentially high sensitivity to toxic substances. This study proposed a framework to assess the effect of vincristine chemotherapy on intraocular pressure, tear protein, and oxidative stress in canines with transmissible venereal tumor (TVT). METHODS: The study group comprised 10 dogs with TVT, whose diagnosis was based on cytology, and all dogs were treated with vincristine for 4 weeks. Each animal was given a complete ophthalmic examination, followed by a standard Schirmer tear test. Before and 20 min after administering vincristine, intraocular pressure (IOP) was measured in the eyes with a noncontact tonometer. At any of the times mentioned, tear samples were collected using the Schirmer test procedure and were subjected to protein analysis-oxidative stress index (OSI), total antioxidant capacity (TAC), total oxidant status (TOS), nitric oxide (NO), and malondialdehyde (MDA) were determined, and standard statistical analysis was applied. RESULTS: No significant differences were found in protein in tears, but mean Pre and Postinjection IOP revealed a significant decrease in the eyes each week. Also, results indicated significant differences in oxidative stress markers: increased OSI, NO, and MDA, and reduced TAC. CONCLUSION: The importance of an increase in oxidative stress levels in the tears of vincristine-treated patients should be taken seriously, as it appears to play a role in the pathogenesis of eye disease. Therefore, during the treatment weeks prior to prescribing vincristine, eye diseases should be evaluated and considered.

Vincristine-associated total antioxidant and oxidant status of ovaries and in vitro nuclear oocyte maturation in dogs with canine transmissible venereal tumor.

The aim of this study is to evaluate the effects of scheduled vincristine sulfate therapy on canine oocyte quality and nuclear oocyte maturation, associated with total antioxidant and oxidant status of ovaries and Anti-Müllerian Hormone (AMH) concentrations in dogs with Canine Transmissible Venereal Tumor (CTVT). Six bitches suffering from CTVT and six healthy bitches were included in the study. Hemogram was carried out weekly. AMH measurements and ovariohysterectomy operations were performed after the termination of vincristine sulfate therapies. Tissue samples from ovaries were utilized for Malondialdehyde (MDA), reduced Glutathione (GSH), Superoxide Dismutase (SOD), Total Anti-oxidative Status (TAS), Total Oxidative Status (TOS) measurements, and Oxidative Stress Index (OSI) was calculated. Collected oocytes were evaluated for meiotic competence, after In Vitro Maturation (IVM) and parthenogenetic activation. No difference between the two groups was observed in hematologic parameters (P > 0.05). Meiotic stages of Germinal Vesicle Break Down (GVBD), Metaphase I (MI), and Metaphase II (MII) were significantly different between groups (P < 0.05). The number of oocytes reaching MII and meiotic resumption was lower in the CTVT group. Furthermore, AMH concentrations, oxidant parameters (OSI, TOS, and MDA), and antioxidant parameters (GSH, SOD, and TAS) were also statistically different between groups (P < 0.05). The results of this study show that vincristine sulfate application in the treatment of CTVT could alter oxidant/antioxidant status in ovaries. Apart from these, oocyte quality and IVM rates seem to decline related to gonadotoxicity. Moreover, AMH could be an important marker in the evaluation of oocyte qualities in bitches, as it is in women.

Transmission of canine transmissible venereal tumour between two dogs in the UK.

Canine transmissible venereal tumour (CTVT) is a contagious cancer spread by transfer of living cancer cells. Occasional cases are observed in the UK in dogs imported from endemic regions. Here, we report a case of imported canine transmissible venereal tumour that was transmitted to a second dog within the UK. Transmission of genital canine transmissible venereal tumour occurred despite neutered status of the second dog. The aggressive course of disease in both cases, which included metastasis, resistance to therapeutic interventions and ultimate euthanasia of both dogs, is described. The diagnosis of canine transmissible venereal tumour was made using a combination of cytology, histology, immunohistochemistry and PCR to detect the LINE-MYC rearrangement. Practitioners unfamiliar with canine transmissible venereal tumour are reminded of this disease of concern, particularly when imported dogs are placed in multi-dog households, irrespective of neuter status.

Relationship between plasma cell-free DNA changes and lysyl oxidase during the treatment and prognosis of canine transmissible venereal tumors.

BACKGROUND: Transmissible venereal tumors (TVT) are a wide range of canine tumors for which there are no effective markers to monitor the therapeutic response in real-time. Circulating biomarkers can be valuable in early cancer diagnosis and prognosis. Accordingly, this study aimed to investigate the significance of the cell-free DNA (cfDNA) and cfDNA integrity index to monitor the response of TVTs to vincristine and compare them with lysyl oxidase activity. Plasma and sera were collected from fifteen male dogs within four weeks before drug administration. The analytical method was mainly based on the quantitative polymerase chain reaction (qPCR) technique for short and long cfDNAs and lysyl oxidase activity was measured in serum. RESULTS: The results of the cfDNA integrity index showed a significant (p < 0.05) difference in the baseline concentration compared to the second and third weeks (with cut-off values of 1.118 and 93.33% specificity). The cfDNA integrity index increased over time due to the reduction of short cfDNAs in the first week after treatment. Lysyl oxidase activity increased during the fourth week (p < 0.001), but there were no significant differences in the other weeks compared to the baseline. The ROC analysis of lysyl oxidase revealed high sensitivity (100%) and specificity (90%) on the second and third weeks compared to the baseline. Multivariate analysis between cfDNA integrity index and lysyl oxidase showed significant correlation (p < 0.05) only in baseline results. CONCLUSIONS: Overall, short cfDNA, the cfDNA integrity index, and lysyl oxidase activity can be proposed as diagnostic biomarkers and putative prognostic candidates in TVT patients. These biomarkers can be combined with cytology to quickly diagnose TVT.

Vincristine sulfate treatment influence on kidney function of female dogs with transmissible venereal tumor / Influência do tratamento com sulfato de vincristina na função renal de cadela com tumor transmissível venéreo

Chemotherapy agents have some undesirable and non-selective cytostatic effects. Considering that kidneys are vulnerable to drug-induced toxicity, this study evaluated renal injury caused by vincristine sulfate (VS) in 12 female dogs diagnosed with transmissible venereal tumor (TVT). The animals were treated with VS (0.025 mg/kg IV) every 7 days for 4 weeks. During treatment, the animals were subjected to clinical examination, blood count, serum measurement of symmetric dimethylarginine (SDMA), blood urea nitrogen (BUN), creatinine, alanine aminotransferase, and alkaline phosphatase. In addition, urinalysis and urinary gamma-glutamyl transferase (GGT) measurements were performed. All parameters were determined three times: before beginning the treatment (T0), after 14 days (T1), and after 28 days (T2). During the study period, there were no changes in serum urea or creatinine levels, urine specific gravity, or persistent proteinuria. Furthermore, urinary GGT measurement did not indicate tubular lesions, and consistent elevation of SDMA was found in only one patient above the reference range. The results showed that weekly therapy with VS as a single agent for 28 days does not induce renal injury in most cases.(AU)

Os agentes quimioterápicos possuem efeitos citostáticos indesejáveis e não seletivos. Considerando a vulnerabilidade renal à toxicidade induzida por drogas, este estudo avaliou a lesão renal causada pelo sulfato de vincristina (VS) em 12 cadelas com diagnóstico de tumor venéreo transmissível (TVT). Os animais foram tratados com VS (0,025 mg / kg IV) a cada sete dias, durante quatro semanas. No transcurso do tratamento, os animais foram submetidos a exame clínico, hemograma, dosagem sérica de dimetilarginina simétrica (SDMA), nitrogênio ureico sanguíneo (BUN), creatinina, alanina aminotransferase e fosfatase alcalina. Além disso, foram realizadas análises de urina e medições de gama-glutamil transferase (GGT) urinária. Todos os parâmetros foram mensurados em três tempos, antes do início do tratamento (T0), aos 14 dias (T1) e aos 28 dias (T2). Durante o período do estudo, não houve alterações nas concentrações de ureia ou creatinina séricas, na gravidade específica da urina ou proteinúria persistente. Além disso, a medição de GGT urinária não indicou lesões tubulares, e elevação consistente de SDMA foi encontrada em apenas um paciente acima do intervalo de referência. Os resultados mostraram que a terapia semanal com VS como agente único por 28 dias não induz lesão renal na maioria dos casos.(AU)

Rhinoscopic Appearance and Clinical Features of a Nasal Transmissible Venereal Tumor in a Dog.

A 2-year-old male neutered mixed breed dog was referred for evaluation of left-sided unilateral epistaxis and mucoid discharge following adoption from Mexico 2 months prior to presentation. Computed tomography (CT) showed soft tissue that filled the entirety of the left nasal passage with mild turbinate loss. Subsequent rhinoscopy revealed multifocal patches of discrete, white, wispy, vascularized abnormal tissue in the left nasal cavity. Cytology and histopathology procured with rhinoscopic-guidance were suspicious for transmissible venereal tumor (TVT). Confirmation of a TVT diagnosis was made with polymerase chain reaction for the long interspersed element inserted upstream of the c-myc gene. The dog was treated with 4 cycles of vincristine (0.5 mg/m2, IV, once every 7 days) with complete and sustained resolution of clinical signs shortly after the third cycle. Nasal TVT in dogs is an uncommon presentation of a neoplasm that primarily results in genital or oral lesions. There is a void in the veterinary literature regarding the rhinoscopic appearance, as well as limited clinical descriptions of nasal TVT. Therefore, the objectives of this report were to provide a detailed description of the rhinoscopic appearance of a canine nasal TVT, in addition to clinical features, diagnostic findings, CT imaging, and successful therapeutic management.

Nasal transmissible venereal tumours in 12 dogs - a retrospective study.

OBJECTIVE: The aim of this study was a retrospective analysis of clinical manifestation and treatment outcome of the nasal form of transmissible venereal tumours (TVT). MATERIAL AND METHODS: Twelve dogs suffering from nasal TVT were included in this study. Patients with primary genital lesions were excluded from the study. Signalment, physical examination and laboratory findings, results of further diagnostics, and treatment results were recorded in all patients. RESULTS: The study population comprised 9 male and 4 female dogs with an (estimated) age ranging from 3 to 7 years. With one exception all dogs originated from Ukraine. Symptoms of nasal TVT included sneezing, nasal bleeding (all cases), skull infiltration (9 cases), oronasal fistulas (9 cases) and cutaneous fistulas (5 cases). Animals received vincristine sulfate at 0.7 mg/m2 i. v. weekly. The treatment course consisted of 4-9 cycles (median 5 cycles). Complete remission was achieved in all cases. All dogs were disease-free during the follow-up period (median 23.5 months, range 12-56 months). All patients tolerated the treatment very well. CLINICAL SIGNIFICANCE: In conclusion, our data suggest that nasal TVT can have a good response to vincristine treatment. TVT should be considered as a differential diagnosis in sneezing dogs with nasal discharge or bleeding especially in young dogs and in dogs with suspected nasal tumours, even in countries without a stray animal population.

Vincristine and ivermectin combination chemotherapy in dogs with natural transmissible venereal tumor of different cyto-morphological patterns: A prospective outcome evaluation.

Vincristine is the first-line drug for the chemotherapy of canine transmissible venereal tumor (CTVT). Drug resistance is related to tumor cyto-morphological patterns of CTVT. There are anti-cancer properties of ivermectin, thus, a combination of ivermectin and vincristine could be an effective chemo-therapeutic treatment regimen for CTVT. Study aims, therefore, were to (1) assess the frequency of CTVT cyto-morphologies, and (2) evaluate treatment efficacy and possible adverse reactions to vincristine compared with a combination vincristine and ivermectin. Dogs (n = 41) with CTVT were characterized by tumor cyto-morphology and disease severity and of those, 20 were randomly allocated into two groups. There was a control group (G-Vin; n = 10) in which there was treatment with vincristine; and an experimental group (G-Iv/Vin; n = 10) in which there was treatment with the ivermectin/vincristine combination. Although dogs in the G-Iv/Vin group had more severe disease at the beginning of the study (P = 0.0031), the number of weeks and chemotherapy sessions until tumor remission were similar among dogs of the two groups, indicating both treatments were effective. There was a decrease in the leukocyte counts (P = 0.0020), related to neutropenia (P = 0.0371) in the G-Vin but not the G-Iv/Vin treatment group. There was no tumor resistance that developed during the study regardless of the treatment regimen used or tumor cytomorphology. In summary, the use of the vincristine/ivermectin combination was well tolerated and efficacious for CTVT treatment.

The role of the multi-drug resistance 1, p53, b cell lymphoma 2, and bcl 2-associated X genes in the biologic behavior and chemotherapeutic resistance of canine transmissible venereal tumors.

BACKGROUND: Canine transmissible venereal tumors (CTVTs) generally have different cytomorphologic subtypes and phases of progression. Some tumors have variable biologic behavior including a progressive increase in tumor aggressiveness and variable responses to chemotherapy. This behavior is partially due to high p-glycoprotein expression by tumor cells, which leads to the expulsion of chemotherapeutic drugs. Other possible causes include changes in pro- and anti-apoptotic genes from the BCL-2 family and DNA repair systems, which are associated with the p53 gene family. OBJECTIVES: We aimed to determine the relative expression of the multi-drug resistance 1 (MDR1), p53, b-cell lymphoma 2 (BCL2), and bcl 2-associated X (BAX) genes in CTVT before and after therapy and establish a relationship with treatment responses, cytomorphologic patterns, and tumor progression identified with histopathology. METHODS: RT-qPCR was performed on 21 CTVT tumor samples before and after initiating chemotherapy to determine specific gene expression. Normal canine testicular tissue was used as a negative control for all experiments. RESULTS: MDR1 expression was decreased before and after initiating vincristine therapy in CTVT tumor tissues compared with normal canine testicular tissue; p53 and BAX were overexpressed at both time points compared with normal tissue, and no statistical differences were seen between the different morphologic types. However, BAX expression was decreased in the group with quick therapeutic responses but was still overexpressed compared with normal testicular tissue. In the group with the slowest chemotherapeutic responses, BCL2 was overexpressed. CONCLUSION: The findings of this study showed a relative increase in MDR1 gene expression in response to chemotherapy and higher expression in plasmacytoid CTVTs compared with the other cytomorphologic patterns. BCL2 overexpression was related to a favorable prognosis, and p53, BAX, and BCL2 were expressed independent of the cytomorphologic CTVT type. All of the genes were expressed independent of tumor progression, as noted on histopathology.

Canine transmissible venereal tumor: First report of three clinical cases from Tripoli, Libya.

Canine transmissible venereal tumour (CTVT) is frequently reported in dogs and is responsible for high morbidity rates and economic losses. Three clinical cases were presented at the clinic of the Faculty of Veterinary Medicine, University of Tripoli. One male and two female German shepherds were diagnosed with CTVT based on case history and tumor shape. The diagnosis was confirmed by histopathological examination. The dogs were treated with vincristine intravenously at a dose of 0.025 mg/kg and recovered fully within 4 weeks. All three dogs remained alive with no evidence of recurrence. These first cases of CTVT reported from Libya show the importance of combining case history, clinical examination and laboratory confirmation to arrive at a definitive diagnosis and implement effective therapy.

Intratumoral recombinant human interferon alpha-2a and vincristine combination therapy in canine transmissible venereal tumour.

Canine transmissible venereal tumour (CTVT) is a naturally occurring contagious neoplasm of dogs located mainly on the external genitalia of both sexes. The course of vincristine chemotherapy, the most effective and practical therapy, is affected by the immune status of the host. The aim was to investigate recombinant human interferon alpha-2a (rhIFNα-2a) and vincristine for treatment of CTVT. A total of 21 female dogs were included. In group I (n = 9), vincristine (0.025 mg/kg, IV) was administered weekly. In group II (n = 6), dogs were injected intratumorally weekly with 1.5 million IU rhIFNα-2a. In group III (n = 6), rhIFNα-2a and vincristine were combined. No tumour regression was observed after three injections of rhIFNα-2a in group II and weekly vincristine was administered. The number of tumour infiltrating lymphocytes (TILs), mitotic figures and apoptotic cells were counted in subsequent incisional tumour biopsies. The Kaplan-Meier Method was used to analyse survival using complete tumour regression as the outcome and Breslow Test was used for comparison of survival curves. Differences in TILs, cell proliferation and apoptosis between groups were assessed by analysis of covariance. Complete regression was observed in all animals included. Mean duration of vincristine treatment for complete regression was shorter in group II (3.50 weeks, 95% CI, 3.06-3.94, P < 0.05) and group III (3.17 weeks, 95% CI, 2.84-3.49, P < 0.01) compared to group I (5.11 weeks, 95% CI, 4.42-5.80). Vincristine and rhIFNα-2a combination increased TILs in CTVT biopsies compared to vincristine treatment (P = 0.017) and vincristine treatment after rhIFNα-2a (P = 0.049). Vincristine treatment after rhIFNα-2a (Group II; P < 0.001) and rhIFNα-2a and vincristine combination (Group III; P < 0.001) decreased apoptosis. The results indicate that intratumoral rhIFNα-2a treatment alone is not effective in CTVT. However, combination of rhIFNα-2a and vincristine shortens the duration of treatment compared to vincristine therapy.

Pre- and post-treatment computed tomographic findings of a primary intranasal transmissible venereal tumor in a canine patient.

A two-year-old, female intact, cross-breed dog presented with a two-month history of nasal discharge. Computed tomography (CT) demonstrated obliteration of both nasal cavities by soft tissue density, destruction of the nasal and ethmoidal turbinates, and lysis of the frontal and palatine bones and maxilla. Frontal sinuses and maxillary recesses were obscured by soft tissue/fluid density. Histopathological examination of the mass was diagnostic of transmissible venereal tumor. The dog was clinically normal 3 months after treatment initiation with vincristine sulphate and amoxicillin/clavulanate. Six months after the completion of treatment no mass-like lesion was demonstrated in CT sections. Nasal cavities, maxillary recesses and frontal sinuses were filled with air. The reticular turbinate nasal plexus appeared atrophic with focal loss of the nasal turbinates on both sides. The ethmoidal turbinates were well-defined; however, focal loss of turbinates was also seen. Lysis of the frontal and palatine bones were still evident.

Molecular Signatures of Regression of the Canine Transmissible Venereal Tumor.

The canine transmissible venereal tumor (CTVT) is a clonally transmissible cancer that regresses spontaneously or after treatment with vincristine, but we know little about the regression mechanisms. We performed global transcriptional, methylation, and functional pathway analyses on serial biopsies of vincristine-treated CTVTs and found that regression occurs in sequential steps; activation of the innate immune system and host epithelial tissue remodeling followed by immune infiltration of the tumor, arrest in the cell cycle, and repair of tissue damage. We identified CCL5 as a possible driver of CTVT regression. Changes in gene expression are associated with methylation changes at specific intragenic sites. Our results underscore the critical role of host innate immunity in triggering cancer regression.

Does the tumour microenvironment alter tumorigenesis and clinical response in transmissible venereal tumour in dogs?

The canine transmissible venereal tumour (CTVT) is a transmissible cancer that is spread naturally between dogs, with the ability to develop and evade the immune system, despite strict immune surveillance of the host. Furthermore, molecular signalling between cells of the immune system and the tumour microenvironment appear to influence the behaviour and development of the tumour. Thus, this study aimed to quantify the expression of genes related to the immune system such as IL-6, IFN-γ, and TGF-ß, as well as angiogenic factors (VEGF, CXCR4), in CTVT cells in vivo and in vitro (primary culture), correlating with the clinical response of the animals treated with vincristine. As expected, the most prevalent subtype was plasmacytoid cells, although lymphocytic cells were also found, indicating the possibility of polyclonality. When we compared the gene expressions of IFN-γ and IL-6, we mostly found low expression, concluding that MHC expression was probably not occurring in tumour cells, and no activation of immune cells to eliminate the tumour. The TGF-ß gene was normal in the majority of animals but demonstrated decreased expression in vincristine resistant animals, leading to the hypothesis that the concentration of tumour-derived TGF-ß was affecting and even suppressing the real TGF-ß expression, favouring tumour proliferation and progression in these cases. VEGF expression was extremely high, demonstrating its angiogenic role in tumour growth, while CXCR4 was decreased, possibly because of CTVT's low metastatic potential. Thus, we concluded that the tumour microenvironment, together with the immune system of the host, influences CTVT, presumably altering its tumorigenesis and the animal's clinical response to treatment.

Cell cycle kinetics, apoptosis rates and gene expressions of MDR-1, TP53, BCL-2 and BAX in transmissible venereal tumour cells and their association with therapy response.

Transmissible venereal tumour (TVT) generally presents different degrees of aggressiveness, which makes them unresponsive to conventional treatment protocols. This implies a progressive alteration of their biological profile. This study aimed to evaluate the cytotoxicity, cell survival, apoptosis and cell cycle alterations in TVT cell cultures subjected to treatment with vincristine. Similarly, it assessed possible implications of MDR-1, TP53, BCL-2, and BAX gene expressions in eight TVT primary cultures for both resistance to chemotherapy and biological behaviour. When comparing TVT cells receiving vincristine to those untreated, a statistical difference related to increased cytotoxicity and decreased survival rates, and alterations in G1 and S cell cycle phases were found but without detectable differences in apoptosis. Increased MDR-1 gene expression was observed after treatment. The groups did not differ statistically in relation to the TP53, BAX and BCL-2 genes. Although preliminary, the findings suggest that such augmented expression is related to tumour malignancy and chemotherapy resistance.

Canine transmissible venereal tumour: a review.

Canine transmissible venereal tumour (CTVT) is a contagious venereal tumour of dogs, commonly observed in dogs that are in close contact with one another, or in stray and wild dogs that exhibit unrestrained sexual activity. CTVT represents a unique, naturally transmissible, contagious tumour, where the mutated tumour cell itself is the causative agent and perpetuates as a parasitic allograft in the host. Clinical history, signalment and cytological features are often obvious for establishing a diagnosis though biopsy and histological examination may be needed in atypical cases. Most cases are curable with three intravenous injections of vincristine sulphate at weekly intervals. The role of stray and wild dogs makes the disease difficult to control and necessitates sustained animal birth control in stray dogs along with prompt therapy of the affected dogs. This review captures the manifold developments in different areas embracing this fascinating tumour, including its biology, diagnosis and therapeutic alternatives.

Effective Treatment of Transmissible Venereal Tumors in Dogs with Vincristine and IL2.

AIM: To improve treatment of inoperable transmissible venereal tumors (TVTs) in dogs. Recently, we showed that TVT is sensitive to intratumoral treatment with interleukin-2 (IL2). In addition it is known that TVT is sensitive to intravenous treatment with vincristine. In the present study we tried to establish the therapeutic effect of intratumoral treatment with vincristine and IL2. PATIENTS AND METHODS: We treated 12 dogs with TVT with 1-4 intratumoral treatments with vincristine and IL-2. Per treatment we used vincristine (0.5-0.7 mg/m(2)) and IL2 (2×10(6) units). The injections were given at weekly intervals. RESULTS: Early therapeutic effects were: three complete regressions, four partial regressions, three stable disease, and two progressive disease. Late therapeutic effects were established 45-60 months after the first presentation; there were five complete regressions, no partial regressions, nor stable or progressive diseases. Interestingly, all five dogs with late therapeutic effects were in good health. No tumor recurrence was noted. CONCLUSION: Intratumoral treatment of TVT with vincristine and IL2 appears to have impressive therapeutic effects.