Biodistribution and image characteristics of 124 I-positron emission tomography in dogs with neuroendocrine neoplasia.

Radioactive iodine is frequently used for staging of human thyroid carcinomas. Iodine-124 scans performed using position emission tomography (PET) allow for more precise dosimetry of therapeutic radioiodine. The distribution of I-124 has not previously been described in veterinary medicine. The purpose of this prospective, exporatory, descriptive study is to evaluate the whole-body distribution of I-124 in dogs with suspected thyroid carcinoma. Ten dogs with either a cytologic diagnosis of a neuroendocrine neoplasm or biochemical hyperthyroidism were enrolled in a prospective clinical study. Whole-body I-124 PET/CT scans were performed and were evaluated for physiologic and pathologic uptake of I-124. The maximum and mean standardized uptake values (SUVmean) were recorded for several normal and abnormal tissues. Varying degrees of uptake were found in thyroid tumors (SUVmean = 66.37), ectopic thyroid masses (21.44), presumed metastatic lesions in lymph nodes (32.14), and the pulmonary parenchyma (4.50). In most dogs, physiologic uptake above background, measured in maximum SUV, was identified in parotid and mandibular salivary glands (14.00 and 1.57) the urinary tract (1.83), the gastrointestinal tract (19.90 stomach, 6.15 colon), the liver (1.41), and the heart (1.88). Occasionally, uptake was identified in the nasolacrimal duct (3.42), salivary duct (2.73), gallbladder (2.68), and anal gland (2.22). Physiologic uptake was also identified in normal thyroid glands and ectopic thyroid tissue. This study provides a baseline of pathologic and physiologic uptake of I-124 in dogs with thyroid carcinoma, to guide interpretation of future studies.

Papillomavirus DNA not detected in canine lobular orbital adenoma and normal conjunctival tissue.

BACKGROUND: Canine lobular orbital adenomas are benign tumors that arise from orbital glandular tissue and extend into the orbit, conjunctiva, and third eyelid. Surgical excision is challenging and recurrence rates are high following excision alone. Enucleation and exenteration reduces the likelihood of recurrence, but is a radical therapeutic option for an otherwise visual and comfortable eye. Human papillomavirus causes 4.5% of worldwide cancers in people and has been identified in up to 23% of benign salivary gland tumors. To date, the etiology of canine lobular orbital adenomas has not been established and it is reasonable to consider canine papillomaviruses as an associative agent with benign glandular tumors in dogs. Identification of the underlying etiology of these tumors may help establish treatment or preventative measures. The purpose of this study was to evaluate conjunctival and orbital tissue of phenotypically normal dogs and tissue from canine lobular orbital adenomas for the presence of papillomavirus DNA. RESULTS: Thirty seven canine lobular orbital adenoma samples (36 formalin fixed paraffin embedded (FFPE) tissue samples from 33 dogs and one freshly collected sample) were evaluated via polymerase chain reaction for the presence of papillomavirus DNA. Conjunctival tissue samples, from 10 dogs with normal ocular examinations, excised immediately following euthanasia, were used as phenotypically normal controls. Three FFPE and one freshly collected tissue samples previously confirmed to be positive for papillomavirus DNA were used as positive controls. PCR products verified positive controls. Papillomavirus DNA was not detected in fresh conjunctival tissue of the phenotypically normal control dogs or in samples of fresh or FFPE canine lobular orbital adenoma tissue. CONCLUSIONS: An association between papillomavirus and the development of canine lobular orbital adenomas is unlikely. Further research is needed to evaluate if other viruses play a role in the pathogenesis of canine lobular orbital adenomas.

6-Thioguanine and zebularine down-regulate DNMT1 and globally demethylate canine malignant lymphoid cells.

BACKGROUND: The antimetabolite 6-thioguanine (6-TG) has been used to treat both human and canine lymphoid malignancies. 6-TG has been shown to be epigenetically active as a demethylating agent in a human lymphoma cell line, causing downregulation of DNA methyltransferase 1 (DNMT1) through ubiquitin-targeted degradation. Zebularine (Zeb), a similar cytidine analog, also has demethylating activity as well as oral bioavailability. The hypothesis of the present study was that 6-TG and Zeb would cause downregulation of DNMT1 and globally demethylate the genomic DNA of canine lymphoma cells. The secondary hypothesis was that these agents would cause a dose-dependent decrease in cell proliferation in canine lymphoma cells. Canine CLGL-90 malignant T cells and CLL 17-7 cells were incubated in modified RPMI media. They were treated with 6-TG, Zeb, or control media at biologically relevant concentrations. RESULTS: Following treatment with each agent, DNMT1 protein and global DNA methylation were significantly decreased. A dose-dependent decrease in cell survival was also observed, with apoptosis being the primary mode of cell death in the CLGL-90 cell line. CONCLUSIONS: These results confirm the demethylating action of 6-TG and Zeb in canine cells which is similar to that shown in human cell lines. Confirmation of this mechanism supports the clinical application of these compounds as demethylating drugs in veterinary patients.

Effects of neoadjuvant zoledronate and radiation therapy on cell survival, cell cycle distribution, and clinical status in canine osteosarcoma.

Introduction: Zoledronic acid (ZOL) is a third-generation bisphosphonate with a higher affinity for bone resorption areas than earlier bisphosphonates (i.e., pamidronate, PAM). In human medicine, ZOL provides improved bone pain relief and prolonged time to skeletal-related events compared to its older generational counterparts. Preclinical studies have investigated its role as an anti-neoplastic agent, both independently and synergistically, with radiation therapy (RT). ZOL and RT act synergistically in several neoplastic human cell lines: prostate, breast, osteosarcoma, and fibrosarcoma. However, the exact mechanism of ZOL's radiosensitization has not been fully elucidated. Methods: We investigated ZOL's ability to induce apoptosis in canine osteosarcoma cell lines treated with various doses of megavoltage external beam radiotherapy. Second, we evaluated cell cycle arrest in ZOL-treated cells to assess several neo-adjuvant time points. Finally, we treated 20 dogs with naturally occurring appendicular OS with 0.1 mg/kg ZOL IV 24 h before receiving 8 Gy of RT (once weekly fraction x 4 weeks). Results: We found that apoptosis was increased in all ZOL-treated cell lines compared to controls, and the combination of ZOL and RT resulted in dissimilar apoptosis between Abrams and D-17 and HMPOS cell lines. Cell cycle arrest (G2/M phase) was minimal and variable between cell lines but perhaps greatest at 48 h post-ZOL treatment. Only 10% of dogs treated with ZOL and RT developed pathologic fractures, compared to 44% of dogs historically treated with PAM and RT (p = 0.027). Discussion: ZOL and RT appear to be a well-tolerated combination treatment scheme for non-surgical candidates; future studies must elucidate the ideal timing of ZOL.

Clinical validation of a blood-based liquid biopsy test integrating cell-free DNA quantification and next-generation sequencing for cancer screening in dogs.

OBJECTIVE: To validate the performance of a novel, integrated test for canine cancer screening that combines cell-free DNA quantification with next-generation sequencing (NGS) analysis. SAMPLE: Retrospective data from a total of 1,947 cancer-diagnosed and presumably cancer-free dogs were used to validate test performance for the detection of 7 predefined cancer types (lymphoma, hemangiosarcoma, osteosarcoma, leukemia, histiocytic sarcoma, primary lung tumors, and urothelial carcinoma), using independent training and testing sets. METHODS: Cell-free DNA quantification data from all samples were analyzed using a proprietary machine learning algorithm to determine a Cancer Probability Index (High, Moderate, or Low). High and Low Probability of Cancer were final result classifications. Moderate cases were additionally analyzed by NGS to arrive at a final classification of High Probability of Cancer (Cancer Signal Detected) or Low Probability of Cancer (Cancer Signal Not Detected). RESULTS: Of the 595 dogs in the testing set, 89% (n = 530) received a High or Low Probability result based on the machine learning algorithm; 11% (65) were Moderate Probability, and NGS results were used to assign a final classification. Overall, 87 of 122 dogs with the 7 predefined cancer types were classified as High Probability and 467 of 473 presumably cancer-free dogs were classified as Low Probability, corresponding to a sensitivity of 71.3% for the predefined cancer types at a specificity of 98.7%. CLINICAL RELEVANCE: This integrated test offers a novel option to screen for cancer types that may be difficult to detect by physical examination at a dog's wellness visit.

Metagenomic Analysis of DNA Viruses with Targeted Sequence Capture of Canine Lobular Orbital Adenomas and Normal Conjunctiva.

Our study aims are: (1) to evaluate phenotypically normal canine conjunctival and orbital tissue and tissue from canine lobular orbital adenomas (CLOAs) for the presence of viral genomic material and (2) phylogenetically classify detected DNA viruses to determine if a DNA virus is associated with CLOAs. A total of 31 formalin fixed paraffin embedded CLOA tissue samples, 4 papillomas or sarcoid, and 10 fresh clinically normal conjunctival tissues were included in this study. Genomic DNA was isolated from all samples and sequencing libraries were prepared. The libraries were molecularly indexed and pooled and viral DNA was enriched via targeted sequence capture utilizing ViroCap. The libraries were sequenced on the Illumina HiSeq platform and compared to known viral DNA reference genomes to identify viral DNA. Carnivore parvovirus was identified in 6.4% and 20% of CLOA tissue and normal conjunctival samples, respectively. This study showed that conjunctival tissue from healthy dogs and CLOAs uncommonly harbor DNA viruses, and no DNA virus was associated with these tumors. Further studies are needed to evaluate the etiologic cause of CLOAs.

Next-generation sequencing-based liquid biopsy may be used for detection of residual disease and cancer recurrence monitoring in dogs.

OBJECTIVE: The purpose of this study was to evaluate the performance of a next-generation sequencing-based liquid biopsy test for cancer monitoring in dogs. SAMPLES: Pre- and postoperative blood samples were collected from dogs with confirmed cancer diagnoses originally enrolled in the CANcer Detection in Dogs (CANDiD) study. A subset of dogs also had longitudinal blood samples collected for recurrence monitoring. METHODS: All cancer-diagnosed patients had a preoperative blood sample in which a cancer signal was detected and had at least 1 postoperative sample collected. Clinical data were used to assign a clinical disease status for each follow-up visit. RESULTS: Following excisional surgery, in the absence of clinical residual disease at the postoperative visit, patients with Cancer Signal Detected results at that visit were 1.94 times as likely (95% CI, 1.21 to 3.12; P = .013) to have clinical recurrence within 6 months compared to patients with Cancer Signal Not Detected results. In the subset of patients with longitudinal liquid biopsy samples that had clinical recurrence documented during the study period, 82% (9/11; 95% CI, 48% to 97%) had Cancer Signal Detected in blood prior to or concomitant with clinical recurrence; in the 6 patients where molecular recurrence was detected prior to clinical recurrence, the median lead time was 168 days (range, 47 to 238). CLINICAL RELEVANCE: Next-generation sequencing-based liquid biopsy is a noninvasive tool that may offer utility as an adjunct to current standard-of-care clinical assessment for cancer monitoring; further studies are needed to confirm diagnostic accuracy in a larger population.

Safety of TCMCB07, a melanocortin-4 antagonist peptide, in dogs with naturally occurring cachexia.

BACKGROUND: The melanocortin 4 antagonist TCMCB07 is safe and effective in reversing cachexia caused by sepsis or cancer in rodents. The safety and pharmacokinetics of TCMCB07 are demonstrated in healthy beagle dogs. HYPOTHESIS/OBJECTIVES: The objectives of this study were to investigate the safety, peak plasma concentrations, and potential for efficacy of TCMCB07 in pet dogs with naturally occurring cachexia over a 4-week time period. ANIMALS: Fourteen dogs with cachexia of any underlying cause, except cancer of the oral cavity or gastrointestinal tract, were eligible for enrollment with informed client consent. METHODS: This study was a prospective, 1-armed open-label trial. Physical examination, complete blood count, chemistry panel, and owner-assessed quality of life surveys were checked at weeks 1, 2, and 4. Due to potential for bradycardia and hypotension, Holter monitoring and blood pressure evaluations were scheduled at pre-enrollment and week 4. RESULTS: Fourteen dogs completed the trial. Significant changes detected included increased mean body weight (18.6-19.5 kg, P < .02), increased body condition score (median Tufts 5-point thin dog scale score P < .004 and WSAVA muscle condition score P < .02) and increased mean blood urea nitrogen (21.79-30.43 mg dL-1 , P < .004). On quality of life surveys, pet owners perceived their dog appeared to be panting less (P < .002) and that the general health improved (P < .03). Four dogs had a change in coat pigmentation. The peak plasma concentration of TCMCB07 in cachectic dogs was similar to that in healthy beagle dogs. CONCLUSIONS AND CLINICAL IMPORTANCE: TCMCB07 was safe and has potential efficacy in pet dogs with cachexia.

Fracture rate and time to fracture in dogs with appendicular osteosarcoma receiving finely fractionated compared to coarsely fractionated radiation therapy: A single institution study.

BACKGROUND: Radiation therapy (RT) is used for local pain alleviation in dogs with appendicular osteosarcoma (OS), especially among dogs that are poor surgical candidates for amputation. However, many historical reports of fractionated protocols lack time to fracture and fracture rates. OBJECTIVES: The primary objectives of this retrospective study were to determine fracture rate and time to fracture of dogs receiving RT (coarse or fine fractionated) for appendicular OS. Secondary objectives were to evaluate tolerability and disease outcome measures. METHODS: Fifty-one dogs that received RT as part of treatment for appendicular OS were available for evaluation. Forty-five received coarse fractionation (C-RT, 8 or 6 Gy per fraction protocols [C-RT8 or C-RT6]) while the remaining six received fine fractionation (F-RT). RESULTS: The overall pathologic fracture rate was 37%. Pathologic fracture rate was significantly higher for dogs that received F-RT (5/6, 83%) compared to dogs that received C-RT (12/40, 30%, p = 0.021). In the 17 dogs that fractured, the overall median time to fracture was 57 days. For all dogs, the median progression free interval (PFI) and median overall survival time (OST) were 90 and 140 days, respectively. In a very small cohort of dogs (n = 7) treated with zoledronate and RT, fracture rate was 0% and extended survival times were noted. CONCLUSIONS: In conclusion, C-RT is recommended over F-RT due to lower risk of pathologic fracture and similar PFI. Prospective evaluation of combined C-RT and zoledronate, especially for dogs with poor surgical candidacy, is warranted for the treatment of canine appendicular osteosarcoma.

Comparative Oncology Assessment of a Novel Inhibitor of Valosin-Containing Protein in Tumor-Bearing Dogs.

Pet dogs with naturally occurring cancers play an important role in studies of cancer biology and drug development. We assessed tolerability, efficacy, and pharmacokinetic/pharmacodynamic relationships with a first-in-class small molecule inhibitor of valosin-containing protein (VCP/p97), CB-5339, administered to 24 tumor-bearing pet dogs. Tumor types assessed included solid malignancies, lymphomas, and multiple myeloma. Through a stepwise dose and schedule escalation schema, we determined the maximum tolerated dose to be 7.5 mg/kg when administered orally on a 4 days on, 3 days off schedule per week for 3 consecutive weeks. Adverse events were minimal and mainly related to the gastrointestinal system. Pharmacokinetic/pharmacodynamic data suggest a relationship between exposure and modulation of targets related to induction of the unfolded protein response, but not to tolerability of the agent. An efficacy signal was detected in 33% (2/6) of dogs with multiple myeloma, consistent with a mechanism of action relating to induction of proteotoxic stress in a tumor type with abundant protein production. Clinical trials of CB-5339 in humans with acute myelogenous leukemia and multiple myeloma are ongoing.

Clinical validation of a next-generation sequencing-based multi-cancer early detection "liquid biopsy" blood test in over 1,000 dogs using an independent testing set: The CANcer Detection in Dogs (CANDiD) study.

Cancer is the leading cause of death in dogs, yet there are no established screening paradigms for early detection. Liquid biopsy methods that interrogate cancer-derived genomic alterations in cell-free DNA in blood are being adopted for multi-cancer early detection in human medicine and are now available for veterinary use. The CANcer Detection in Dogs (CANDiD) study is an international, multi-center clinical study designed to validate the performance of a novel multi-cancer early detection "liquid biopsy" test developed for noninvasive detection and characterization of cancer in dogs using next-generation sequencing (NGS) of blood-derived DNA; study results are reported here. In total, 1,358 cancer-diagnosed and presumably cancer-free dogs were enrolled in the study, representing the range of breeds, weights, ages, and cancer types seen in routine clinical practice; 1,100 subjects met inclusion criteria for analysis and were used in the validation of the test. Overall, the liquid biopsy test demonstrated a 54.7% (95% CI: 49.3-60.0%) sensitivity and a 98.5% (95% CI: 97.0-99.3%) specificity. For three of the most aggressive canine cancers (lymphoma, hemangiosarcoma, osteosarcoma), the detection rate was 85.4% (95% CI: 78.4-90.9%); and for eight of the most common canine cancers (lymphoma, hemangiosarcoma, osteosarcoma, soft tissue sarcoma, mast cell tumor, mammary gland carcinoma, anal sac adenocarcinoma, malignant melanoma), the detection rate was 61.9% (95% CI: 55.3-68.1%). The test detected cancer signal in patients representing 30 distinct cancer types and provided a Cancer Signal Origin prediction for a subset of patients with hematological malignancies. Furthermore, the test accurately detected cancer signal in four presumably cancer-free subjects before the onset of clinical signs, further supporting the utility of liquid biopsy as an early detection test. Taken together, these findings demonstrate that NGS-based liquid biopsy can offer a novel option for noninvasive multi-cancer detection in dogs.

A Retrospective Evaluation of Chemotherapy Overdoses in Dogs and Cats.

Chemotherapy overdoses (ODs) are severe complications that can occur following the use of antineoplastics. However, little is known about chemotherapy ODs in veterinary medicine. The goals of this retrospective study were to report the occurrence, type, and cause of known chemotherapy ODs in companion animal medicine. The American College of Veterinary Internal Medicine oncology and internal medicine listservs were solicited for chemotherapy OD cases in dogs and cats. An OD was defined as administration of a chemotherapy dose 10% higher than intended, or at a shorter interval than planned. Twelve non-anthracycline ODs in 11 dogs, and 3 cat ODs, were collected. Overdoses in dogs included carboplatin, cyclophosphamide, L-asparaginase, lomustine, mustargen, vincristine, and vinorelbine. The cat ODs included doxorubicin and vincristine. In dogs, the median OD was 2.1x (range: 1.2-10x) the intended dose. All dogs survived the OD and developed a variety of gastrointestinal and hematologic toxicities of varying grades. Both cats with a 2.4x vincristine OD died despite supportive care. The cat who received a 2x OD of doxorubicin survived the event, experiencing Veterinary Cooperative Oncology Group-common terminology criteria for adverse events (VCOG) grade I thrombocytopenia and anemia, and VCOG grade II neutropenia. Chemotherapy ODs appear to be rare in veterinary medicine and are typically 2-3xs the intended dose. Clinical effects include VCOG grade I and II gastrointestinal distress and VCOG grade III and IV hematologic effects. With appropriate supportive care, most patients will survive the event. Life-threatening events are more common in cats following vincristine ODs.

A Pilot Study of Cancer-Induced Bone Pain Using Validated Owner Questionnaires, Serum N-Telopeptide Concentration, Kinetic Analysis, and PET/CT.

Cancer-induced bone pain, despite its frequency and severity, is a poorly understood phenomenon in people and animals. Despite excitement regarding translational osteosarcoma studies, there is a lack of attention toward examining cancer pain in dogs. In this pilot study, we used a multimodal pain assessment methodology to evaluate pain relief after therapeutic intervention in dogs with primary bone cancer. We hypothesized that intervention would cause objective evidence of pain relief. Evaluations of 8 dogs with primary bone cancer included 18F-FDG PET/CT scans, kinetic analysis, validated owner questionnaires (Canine Brief Pain Inventory, canine BPI), and serum N-telopeptide (NTx) concentration. Dogs were routinely staged and had 18F-FDG PET/CT scans prior to treatment with day 0, 7, 14, and 28 canine BPI, serum NTx, orthopedic exam, and kinetic analysis. Dogs treated with zoledronate and radiation underwent day 28 18F-FDG PET scans. All clinical trial work was approved by the University of Missouri IACUC. Four dogs underwent amputation (AMP) for their appendicular bone tumors; four received neoadjuvant zoledronate and hypofractionated radiation therapy (ZOL+RT). Canine BPI revealed significant improvements in pain severity and pain interference scores compared to baseline for all dogs. Positive changes in peak vertical force (+16.7%) and vertical impulse (+29.1%) were noted at day 28 in ZOL+RT dogs. Dogs receiving ZOL+RT had a significant (at least 30%) reduction in serum NTx from baseline compared to amputated dogs (p = 0.029). SUVmax (p = 0.11) and intensity (p = 0.013) values from PET scans decreased while tumor uniformity (p = 0.017) significantly increased in ZOL+RT-treated tumors; gross tumor volume did not change (p = 0.78). Owner questionnaires, kinetic analysis, and 18F-FDG PET/CT scans showed improved pain relief in dogs receiving ZOL+RT. Serum NTx levels likely do not directly measure pain, but rather the degree of systemic osteoclastic activity. Larger, prospective studies are warranted to identify the ideal objective indicator of pain relief; however, use of multiple assessors is presumably best. With improved assessment of pain severity and relief in dogs with cancer, we can better evaluate the efficacy of our interventions. This could directly benefit people with cancer pain, potentially decreasing the amount of subtherapeutic novel drugs entering human clinical trials.

A 3D-printed Apparatus for Imaging Multiple Rats Simultaneously.

CT (computerized tomography) is a necessary imaging modality for cancer staging and disease monitoring. Rodent models of cancer are commonly studied prior to human clinical trials, but CT in rodents can be difficult due to their small size and constant movement, which necessitates general anesthesia. Because microCT equipment is not always available, clinical CT may be a viable alternative. Limitations of microCT and clinical CT include biosecurity, anesthesia to limit image distortion due to motion, and cost. To address several of these constraints, we created a 3D-printed apparatus that accommodated simultaneous imaging of as many as 9 rats under gas anesthesia. Rats were anesthetized in series and placed in a 3 × 3 arrangement. To assess differences in attenuation between individual chambers and rows or columns in the device, we first imaged a standardized phantom plug as a control. We hypothesized that attenuation of specific rat organs would not be affected regardless of the location or position in the 3D-printed device. Four organs-liver, kidney, femur, and brain-were evaluated in 9 rats. For both the phantom and kidneys, statistically significant, but clinically negligible, effects on attenuation were noted between rows but not between columns. We attribute this finding to the absence of a top layer of the apparatus, which thus created asymmetric attenuation and beam hardening through the device. This apparatus allowed us to successfully image 9 rats simultaneously in a clinical CT machine, with negligible effects on attenuation. Planned improvements in this apparatus include completely enclosed versions for biosecure imaging.

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.

Biochemical, functional, and histopathologic characterization of lomustine-induced liver injury in dogs.

OBJECTIVE: To characterize the biochemical, functional, and histopathologic changes associated with lomustine-induced liver injury in dogs. ANIMALS: I0 healthy purpose-bred sexually intact female hounds. PROCEDURES: Dogs were randomly assigned to receive lomustine (approx 75 mg/m2, PO, q 21 d for 5 doses) alone (n = 5) or with prednisone (approx 1.5 mg/kg, PO, q 24 h for 12 weeks; 5). For each dog, a CBC, serum biochemical analysis, liver function testing, urinalysis, and ultrasonographic examination of the liver with acquisition of liver biopsy specimens were performed before and at predetermined times during and after lomustine administration. Results were compared between dogs that did and did not receive prednisone. RESULTS: 7 of the I0 dogs developed clinical signs of liver failure. For all dogs, serum alanine aminotransferase (ALT) and alkaline phosphatase (ALP) activities, bile acid concentrations, and liver histologic score increased and hepatic reduced glutathione content decreased over time. Peak serum ALT (r = 0.79) and ALP (r = 0.90) activities and bile acid concentration (r = 0.68) were positively correlated with the final histologic score. Prednisone did not appear to have a protective effect on histologic score. CONCLUSIONS AND CLINICAL RELEVANCE: In dogs, liver enzyme activities, particularly ALT and ALP activities, should be closely monitored during lomustine treatment and acute increases in those activities may warrant discontinuation of lomustine to mitigate liver injury. Nonspecific ultrasonographic findings and abnormal increases in liver function tests were not detected until the onset of clinical liver failure. Glutathione depletion may have a role in lomustine-induced hepatopathy and warrants further investigation.

Autologous cancer cell vaccination, adoptive T-cell transfer, and interleukin-2 administration results in long-term survival for companion dogs with osteosarcoma.

BACKGROUND: Osteosarcoma (OSA) in dogs is an aggressive bone tumor with frequent chemotherapy failure and translational relevance for human health. HYPOTHESIS/OBJECTIVES: We hypothesized that dogs with OSA could be treated safely by ex vivo activated T-cells that were generated by autologous cancer vaccination and supported by interleukin-2 (IL-2) treatment with survival more than twice that reported for amputation alone. ANIMALS: Osteosarcoma-bearing dogs (n = 14) were enrolled in a single-arm prospective trial after complete staging before amputation. Four healthy dogs also were treated in a safety study. METHODS: Autologous cancer cell vaccinations were administered intradermally and dogs underwent leukapheresis. Mononuclear cell products were stimulated ex vivo with a T-cell-activating agent. Activated product was transfused and 5 SC IL-2 injections were administered q48h. Dogs were monitored for metastasis by thoracic radiography every 3 months. RESULTS: Autologous cancer cell vaccine and activated cellular therapy (ACT) products were successfully generated. Toxicity was minimal after premedicants were instituted before ACT. With premedication, all toxicities were grade I/II. Median disease-free interval for all dogs was 213 days. One dog developed cutaneous metastasis but then experienced spontaneous complete remission. Median survival time for all dogs was 415 days. Five dogs survived >730 days. CONCLUSIONS AND CLINICAL IMPORTANCE: This immunotherapy protocol without cytotoxic chemotherapy is safe and tolerable. Compared to historical amputation reports, survival was notably prolonged in this group of patients. Additional prospective studies are warranted to elucidate active immunologic mechanisms and further improve disease response and survival.

Long-Term Survival and Glycemic Control with Toceranib Phosphate and Prednisone for a Metastatic Canine Insulinoma.

Canine insulinoma is a highly metastatic neoplasm that is associated with a guarded to poor prognosis in dogs with distant metastases. A median survival of 6 mo has been reported for dogs with metastatic insulinoma. The dog in this report, diagnosed with stage III pancreatic insulinoma, had long-term glycemic control with survival of over 24 mo while receiving prednisone and toceranib phosphate after partial pancreatectomy. Toceranib phosphate has been shown to be an efficacious therapy for canine mast cell tumors with increasing evidence that it may be beneficial in the medical management of neuroendocrine tumors.

Concurrent 5-fluorouracil and carboplatin for the treatment of canine carcinomas.

5-Fluorouracil (5-FU) is used in combination chemotherapy protocols for human head and neck cancer and other epithelial neoplasms. However, a paucity of literature describing use of this drug in veterinary oncology exists, likely due to previous reports of fatal neurotoxicity in both dogs and cats, mainly due to ingestion of human creams. The primary aim of this retrospective study was to report the safety of concurrent 5-FU and carboplatin in canine carcinomas. Secondarily, we aimed to look at the efficacy of the combination using overall response rate in treated dogs. Medical records were searched from 2007 to 2017 for dogs treated with both agents; 24 dogs met inclusion criteria. Carboplatin dosages ranged from 180 to 250 mg/m2 (median 200 mg/m2 ); 5-FU dosage was 150 mg/m2 . Fourteen dogs had myelosuppression, ranging from Grade I to asymptomatic Grade IV; thrombocytopenia was more common than neutropenia. Gastrointestinal upset was uncommon, with only seven dogs having Grade I or II nausea, vomiting or diarrhoea. No cases were hospitalized for any of the above toxicities. One dog had an episode of ataxia, which could not be differentiated between otitis and 5-FU neurotoxicity. This protocol is well tolerated. Response rate in the gross disease setting was 43% (three complete responses, three partial responses). Prospective analysis of this combination protocol, and potentially 5-FU with other platinum agents, is warranted in the treatment of canine carcinomas.

Evaluation of intravenous and subcutaneous administration of a novel, excipient-free, nanoparticulate formulation of paclitaxel in dogs with spontaneously occurring neoplasia.

Carriers used to solubilize taxane chemotherapy drugs cause severe hypersensitivity. Nanoparticle formulations can provide improved dissolution and bioavailability of taxanes. Thus, a nanoparticulate, excipient-free formulation of paclitaxel (CTI52010) was evaluated in tumour-bearing dogs with intravenous and subcutaneous delivery. Tumour-bearing dogs were treated with intravenous CTI52010 using a modified rapid dose escalation scheme. Subcutaneous administration was then planned for a small cohort of dogs for comparison. For both groups, serial blood samples were collected after first dosing for pharmacokinetic analysis by LCMSMS. Tumour response was measured using RECIST criteria. Toxicity was recorded using VCOG-CTCAEv1.1. Fifteen dogs were treated with intravenous delivery at increasing dosages (80-136 mg/m2 ), with one objective response in the urethral component of a prostatic carcinoma (probable transitional cell carcinoma) and four dogs with durable stable disease (two carcinomas, two sarcomas). Pharmacokinetic data indicate a rapid initial clearing of the drug from serum followed by an extended elimination half-life, similar to normal dogs and suggesting reticuloendothelial clearance. Parameters and toxicity were highly variable and a maximally tolerated dosage could not be reliably confirmed. Three dogs were treated with subcutaneous delivery and no drug was detected in circulation, resulting in termination of the study. This novel formulation of paclitaxel is well tolerated in dogs and no unique toxicity or hypersensitivity was noted. The preliminary responses suggest biologic activity. The lack of systemic absorption after subcutaneous administration suggests a possible role for intratumoural anticancer therapy.