Comparative whole transcriptome analysis of gene expression in three canine soft tissue sarcoma types.

Soft tissue sarcomas are pleiotropic tumors of mesenchymal cell origin. These tumors are rare in humans but common in veterinary practice, where they comprise up to 15% of canine skin and subcutaneous cancers. Because they present similar morphologies, primary sites, and growth characteristics, they are treated similarly, generally by surgical resection followed by radiation therapy. Previous studies have examined a variety of genetic changes as potential drivers of tumorigenesis and progression in soft tissue sarcomas as well as their use as markers for soft tissue sarcoma subtypes. However, few studies employing next generation sequencing approaches have been published. Here, we have examined gene expression patterns in canine soft tissue sarcomas using RNA-seq analysis of samples obtained from archived formalin-fixed and paraffin-embedded tumors. We provide a computational framework for using resulting data to categorize tumors, perform cross species comparisons and identify genetic changes associated with tumorigenesis. Functional overrepresentation analysis of differentially expressed genes further implicate both common and tumor-type specific transcription factors as potential mediators of tumorigenesis and aggression. Implications for tumor-type specific therapies are discussed. Our results illustrate the potential utility of this approach for the discovery of new therapeutic approaches to the management of canine soft tissue sarcomas and support the view that both common and tumor-type specific mechanisms drive the development of these tumors.

Adjuvant Sirolimus Does Not Improve Outcome in Pet Dogs Receiving Standard-of-Care Therapy for Appendicular Osteosarcoma: A Prospective, Randomized Trial of 324 Dogs.

PURPOSE: The mTOR pathway has been identified as a key nutrient signaling hub that participates in metastatic progression of high-grade osteosarcoma. Inhibition of mTOR signaling is biologically achievable with sirolimus, and might slow the outgrowth of distant metastases. In this study, pet dogs with appendicular osteosarcoma were leveraged as high-value biologic models for pediatric osteosarcoma, to assess mTOR inhibition as a therapeutic strategy for attenuating metastatic disease progression. PATIENTS AND METHODS: A total of 324 pet dogs diagnosed with treatment-naïve appendicular osteosarcoma were randomized into a two-arm, multicenter, parallel superiority trial whereby dogs received amputation of the affected limb, followed by adjuvant carboplatin chemotherapy ± oral sirolimus therapy. The primary outcome measure was disease-free interval (DFI), as assessed by serial physical and radiologic detection of emergent macroscopic metastases; secondary outcomes included overall 1- and 2-year survival rates, and sirolimus pharmacokinetic variables and their correlative relationship to adverse events and clinical outcomes. RESULTS: There was no significant difference in the median DFI or overall survival between the two arms of this trial; the median DFI and survival for standard-of-care (SOC; defined as amputation and carboplatin therapy) dogs was 180 days [95% confidence interval (CI), 144-237] and 282 days (95% CI, 224-383) and for SOC + sirolimus dogs, it was 204 days (95% CI, 157-217) and 280 days (95% CI, 252-332), respectively. CONCLUSIONS: In a population of pet dogs nongenomically segmented for predicted mTOR inhibition response, sequentially administered adjuvant sirolimus, although well tolerated when added to a backbone of therapy, did not extend DFI or survival in dogs with appendicular osteosarcoma.

Development of prednisone resistance in naïve canine lymphoma: Longitudinal evaluation of NR3C1α, ABCB1, and 11ß-HSD mRNA expression.

Prednisone resistance develops rapidly and essentially universally when dogs with lymphoma are treated with corticosteroids. We investigated naturally occurring mechanisms of prednisone resistance in seven dogs with naïve multicentric lymphoma, treated with oral prednisone; four dogs were administered concurrent cytotoxic chemotherapy. Expression of NR3C1α, ABCB1 (formerly MDR1), 11ß-HSD1, and 11ß-HSD2 mRNA was evaluated in neoplastic lymph nodes by real-time RT-PCR. Changes of expression levels at diagnosis and at time of clinical resistance to prednisone were compared longitudinally using a Wilcoxon signed-rank test. Clinical resistance to prednisone was observed after a median of 68 days (range: 7-348 days) after initiation of treatment. Relative to pretreatment samples, prednisone resistance was associated with decreased NR3C1α expression in biopsies of all dogs with high-grade lymphoma (six dogs, p=.031); one dog with indolent T-zone lymphoma had increased expression of NR3C1α. Resistance was not consistently associated with changes in ABCB1, 11ß-HSD1, or 11ß-HSD2 expression. Decreased expression of the glucocorticoid receptor (NR3C1α) may play a role in conferring resistance to prednisone in dogs with lymphoma. Results do not indicate a broad role for changes in expression of ABCB1, 11ß-HSD1, and 11ß-HSD2 in the emergence of prednisone resistance in lymphoma-bearing dogs.

Metronomic administration of lomustine following palliative radiation therapy for appendicular osteosarcoma in dogs.

The purpose of this study was to determine if metronomic administration of lomustine following palliative radiation therapy (RT) improved length of palliation and therefore survival in dogs with appendicular osteosarcoma compared to treatment with palliative radiation alone. A search of medical records identified dogs with appendicular osteosarcoma, treated with palliative RT (2 fractions of 8 Gray in a 24 hour time frame, day 0 and day 1; or day 0, 6 hours apart). Data collected included signalment, history, clinical signs, physical examination findings, clinicopathologic abnormalities, extent of disease, response, toxicity, other therapy, survival time, and whether dogs received metronomic lomustine (ML) or not. Of 86 patients, 43 received ML while 43 did not. Median survival time (MST) was not significantly different (P = 0.84), at 184 +/- 17 days for patients which received ML, and 154 +/- 20 days for those which did not. Metronomic lomustine administration was well-tolerated, but it did not improve survival in dogs with palliatively treated osteosarcoma.

Administration métronomique de lomustine après radiothérapie palliative pour le traitement des ostéosarcomes appendiculaires chez le chien. L'objectif de cette étude était de déterminer si l'administration métronomique de lomustine après radiothérapie palliative (RT) améliore la durée de palliation, et par conséquent la durée de vie, des chiens atteints d'ostéosarcome appendiculaire, en comparaison avec la radiothérapie seule. Les dossiers médicaux des chiens atteints d'ostéosarcome appendiculaire traités par radiothérapie palliative (2 fractions de 8 Gray dans un intervalle de 24 heures, jour 0 et jour 1; ou jour 0, à 6 heures d'intervalle) ont été identifiés et évalués. Les données collectées incluaient l'anamnèse, les commémoratifs, les anomalies de l'examen clinique et des analyses de laboratoires, les résultats du bilan d'extension, la réponse au(x) traitement(s), le développement de toxicités, d'éventuelles autres thérapies prodiguées, la durée de vie et si les chiens avaient été traités avec de la lomustine ou non. Sur 86 patients, 43 ont reçu de la lomustine tandis que 43 n'en ont pas reçu. La médiane de survie (MST) n'était pas significativement différente (P = 0.84), 184 +/− 17 jours pour les patients traités avec de la lomustine, et 154 +/− 20 jours pour ceux n'ayant pas reçu de lomustine. L'administration métronomique de lomustine était bien tolérée mais ne prodigua pas d'amélioration de la durée de vie lors de la prise en charge palliative des chiens atteints d'ostéosarcome.(Traduit par les auteurs).

Evaluation of vincristine-associated myelosuppression in Border Collies.

OBJECTIVE: To determine whether Border Collies (ATP binding cassette subfamily B1 gene [ABCB1] wildtype) were more likely than other breeds to develop vincristine-associated myelosuppression (VAM) and, if so, whether this was caused by a mutation in ABCB1 distinct from ABCB1-1Δ. ANIMALS: Phase 1 comprised 36 dogs with the ABCB1 wildtype, including 26 dogs with lymphoma (5 Border Collies and 21 dogs representing 13 other breeds) treated with vincristine in a previous study; phase 2 comprised 10 additional Border Collies, including 3 that developed VAM and 7 with an unknown phenotype. PROCEDURES: For phase 1, the prevalence of VAM in ABCB1-wildtype Border Collies was compared with that for ABCB1-wildtype dogs of other breeds with data from a previous study. For phase 2, additional Border Collies were included. Hematologic adverse reactions were graded with Veterinary Co-operative Oncology Group criteria. Genomic DNA was used to amplify and sequence all 27 exons of the canine ABCB1. Sequences from affected dogs were compared with those of unaffected dogs and dogs of unknown phenotype. RESULTS: 3 of 5 Border Collies with the ABCB1 wildtype developed VAM; this was significantly higher than the proportion of other dogs that developed VAM (0/21). A causative mutation for VAM in Border Collies was not identified, although 8 single nucleotide polymorphisms in ABCB1 were detected. CONCLUSIONS AND CLINICAL RELEVANCE: Breed-associated sensitivity to vincristine unrelated to ABCB1 was detected in Border Collies. Veterinarians should be aware of this breed predisposition to VAM. Causes for this apparent breed-associated sensitivity should be explored.

Radiation therapy in horses.

Although the diagnosis of cancer is relatively uncommon in horses, tumors do occur in this species. Surgery, radiation, and chemotherapy are traditional cancer treatments in all species. In equine patients, surgery has often been the only treatment offered; however, not all tumors can be controlled with surgery alone. In small animal oncology, newer and better therapies are in demand and available. Radiation therapy is often used to control or palliate tumors locally, especially to satisfy clients who demand sophisticated treatments. The large size of equine patients can make radiation therapy difficult, but it is a valuable tool for treating cancer and should not be overlooked when treating horses.

Granulocytopenia associated with thymoma in a domestic shorthaired cat.

A 5-year-old, spayed female cat was referred because of a mass in the cranial mediastinum noted on thoracic radiographs. A thymoma was diagnosed following ultrasound and biopsy of the mass. Treatment was initiated with coarse-fraction radiation therapy using external-beam therapy (four fractions of 5 Gy). The mass responded, but granulocytopenia developed. Bone marrow examination showed a myeloid to erythroid ratio of approximately 1:1, with a left shift within the myeloid line. These findings, as well as the lack of toxic changes within the peripheral blood neutrophils, suggested immune-mediated destruction of peripheral granulocytes. Immune suppression with prednisone and cyclosporine was instituted. After 7 weeks, the neutrophil count returned to normal. The tumor was removed, and cyclosporine was reduced and eventually discontinued 3 weeks postsurgery.

A nine-day accelerated radiation protocol for feline squamous cell carcinoma.

Nine cats with oral squamous cell carcinoma were treated with an accelerated radiation protocol (14 fractions of 3.5 Gy in 9 days). Radiation was administered twice daily with a 6hour break between treatments. Median overall survival was 86 +/- 110 days. Median survival for cats with a partial response (n=6) was 60 +/- 7 days, while median survival for cats with a complete response (n=3) was 298 +/- 187 days (P = 0.0639). The accelerated protocol was well tolerated and toxicity in the early and late period was manageable in all cats. Further modification of the protocol is warranted to extend survival.

Reevaluation of the University of Wisconsin 2-year protocol for treating canine lymphosarcoma.

This retrospective study investigated a population of 96 dogs with newly diagnosed malignant lymphosarcoma that were treated with the commonly used University of Wisconsin-Madison (UW-M) chemotherapy protocol. Pretreatment characteristics were analyzed to determine prognostic factors. Dogs with higher World Health Organization (WHO) stages (including stage IV) and dogs with hypercalcemia were at significantly higher risk of relapse (P=0.018 and P=0.016, respectively). Dose reduction, treatment delays, and prior therapy with cortico-steroids were not associated with clinical outcome. First remission duration of 270 days was similar to historically reported data. Overall survival time of 218 days was much shorter than historical data.

Intranasal malignant melanoma in a dog.

A 10-year-old, female Newfoundland-cross dog was presented for evaluation of chronic intermittent unilateral epistaxis, nasal stertor, and sneezing. Nasal magnetic resonance imaging revealed a 3 x 5-cm mass in the left nasal cavity. Histopathological evaluation of nasal biopsies determined that the mass was a malignant melanoma. The mass was surgically resected and treated with bilateral opposed photon-beam radiation. This is the first report to describe the presentation, diagnosis, and treatment of an intranasal malignant melanoma in a dog.