Phase I dose escalating study of oral cyclophosphamide in tumour-bearing cats.

Cyclophosphamide is an alkylating agent used to treat cats with lymphoma, carcinomas and sarcomas. However, no clear consensus exists regarding the maximum tolerated dose (MTD) of oral cyclophosphamide in cats. Toxicities are rarely reported at published oral dosages of cyclophosphamide (200-300 mg/m2). The primary aim of this prospective study was to determine the MTD of oral cyclophosphamide in tumour-bearing cats via a modified phase I trial. A secondary aim was to define any toxicity. Forty-six client-owned tumour-bearing cats were enrolled. The cyclophosphamide dosage was escalated by approximately 10% (300, 330, 360, 400, 440, 460 and 480 mg/m2) in cohorts of at least six cats. The MTD of oral cyclophosphamide in this study was 460 mg/m2 with an inter-treatment interval of two to three weeks. Haematology is recommended 7 and 14 days after first cyclophosphamide treatment, and immediately before each subsequent dosage of cyclophosphamide or any potentially myelosuppressive chemotherapy agent. The dose-limiting toxicity was neutropenia with nadir at 7-21 days. This higher dosage was considered safe in combination with prednisolone and L-asparaginase. However, the higher dose of oral cyclophosphamide has not been evaluated in combination with other chemotherapy agents and thus should not be administered with these agents.

Biological behaviour of canine mandibular osteosarcoma. A retrospective study of 50 cases (1999-2007).

The purpose of this retrospective study was to describe the biological behaviour of canine mandibular osteosarcoma (OSA) and to examine factors for their impact on metastasis-free interval (MFI) and survival time (ST). Records from dogs treated with mandibulectomy for OSA (1999-2007) were reviewed. Archived tumour samples were evaluated for mitotic index (MI) and tumour grade. Fifty dogs were included, 21 received chemotherapy. Twenty-nine dogs (58%) developed metastatic disease. The median MFI was 627 days, and median ST was 525 days. In univariate analysis MI > 40 was prognostic for decreased MFI and ST. Grade also influenced MFI and ST, with 5/21 (24%) dogs with grade II/III tumours metastasis-free at one year versus 16/22 (72%) dogs with grade I tumours (P = 0.002); and 5/21 (24%) dogs with grade II/III tumours alive versus 17/22 (77%) dogs with grade I tumours (P = 0.001). In multivariate analysis, histological grade and adjuvant chemotherapy were prognostic for MFI and ST.

A prospective evaluation of the impact of second-opinion histopathology on diagnostic testing, cost and treatment in dogs and cats with cancer.

Second-opinion histopathology is a common practice in human medicine to avoid unnecessary procedures, costs and to optimize therapy. Histopathology review has been recommended in veterinary oncology as well. In this prospective evaluation of 52 tumours over a 1-year period, there was diagnostic agreement between first and second opinions in 52% of cases. Twenty-nine percent of cases had partial diagnostic disagreement, most often a change in grade, tumour subtype or margin status. Nineteen percent had complete diagnostic disagreement, including a change in cell of origin or a change from benign to malignant. Minor disagreements, which would not affect treatment or prognosis, were present in 21% of cases. Major disagreements, which would affect either treatment or prognosis, were present in 37% of cases. Costs of ideal staging and treatment recommendations were considerably different between first and second opinions.

Relation of vitamin D status to congestive heart failure and cardiovascular events in dogs.

BACKGROUND: Vitamin D plays a pivotal role in cardiac function, and there is increasing evidence that vitamin D deficiency is associated with the development of congestive heart failure (CHF) in people. HYPOTHESIS: Serum vitamin D concentration is lower in dogs with CHF compared with unaffected controls and serum vitamin D concentration is associated with clinical outcome in dogs with CHF. ANIMALS: Eighty-two client-owned dogs. METHODS: In this cross-sectional study, we examined the association between circulating 25-hydroxyvitamin D [25(OH)D], a measure of vitamin D status, and CHF in dogs. In the prospective cohort study, we examined whether 25(OH)D serum concentration was associated with clinical outcome in dogs with CHF. RESULTS: Mean 25(OH)D concentration (100 ± 44 nmol/L) in 31 dogs with CHF was significantly lower than that of 51 unaffected dogs (123 ± 42 nmol/L; P = .023). The mean calculated vitamin D intake per kg of metabolic body weight in dogs with CHF was no different from that of unaffected dogs (1.37 ± 0.90 µg/kg metabolic body weight versus 0.98 ± 0.59 µg/kg body weight, respectively, P = .097). There was a significant association of serum 25(OH)D concentration on time to clinical manifestation of CHF or sudden death (P = .02). CONCLUSION AND CLINICAL RELEVANCE: These findings suggest that low concentrations of 25(OH)D may be a risk factor for CHF in dogs. Low serum 25(OH)D concentration was associated with poor outcome in dogs with CHF. Strategies to improve vitamin D status in some dogs with CHF may prove beneficial without causing toxicity.

Use of adjuvant carboplatin for treatment of dogs with oral malignant melanoma following surgical excision.

Melanoma is the most common oral malignancy in dogs. This retrospective study evaluated adjuvant carboplatin chemotherapy (with or without radiation therapy) in 17 dogs with malignant oral melanoma following surgical resection. The median dosage and number of doses of carboplatin administered to the 17 dogs was 300 mg m(-2) (range, 150-300 mg m(-2)) and 4 (range, 2-11), respectively. The overall median progression-free survival for all dogs was 259 days [95% confidence interval (CI95), 119-399 days]. The first progression-free survival event was local recurrence in seven dogs (41%) and metastases in seven dogs (41%). The median overall survival for all dogs was 440 days (CI95, 247-633 days). The tumour was the cause of death in 10 dogs (59%). On the basis of this study, systemic therapy with carboplatin may be an appropriate adjunct to local treatment for canine malignant melanoma, although future prospective controlled studies are needed to compare treatment modalities for this aggressive neoplasia.

Prospective evaluation of biweekly streptozotocin in 19 dogs with insulinoma.

BACKGROUND: Administration of streptozotocin (STZ) at a 21-day interval has been described in dogs with stage II and III insulinoma. Myelosuppression was not observed, suggesting the possibility of increasing dose intensity by decreasing the interval between doses. OBJECTIVE: To describe the tolerability of a biweekly STZ protocol. A secondary objective was to describe the outcome of dogs treated with this protocol. ANIMALS: Nineteen dogs with residual local, metastatic, or recurrent insulinoma. METHODS: After surgery for insulinoma, or at the time of recurrence, dogs were treated with a previously described STZ and saline diuresis protocol. Treatments were administered every 14 days. All dogs received antiemetic treatment. Adverse events (AEs) were recorded and graded. Outcome endpoints assessed were progression-free survival (PFS) and survival. RESULTS: None of the dogs experienced neutropenia or thrombocytopenia. Mild to moderate gastrointestinal toxicity was the most common AE. Diabetes mellitus was observed in 8 dogs and, in 6, resulted in euthanasia or death. Two dogs developed nephrotoxicity manifested as Fanconi syndrome in 1 and nephrogenic diabetes insipidus in the other. Six dogs developed increased alanine amino transferase activity. Hypoglycemia at the end of the STZ infusion, resulted in collapse in 1 dog and a generalized seizure in another. The median overall PFS and survival time were 196 and 308 days, respectively. CONCLUSIONS AND CLINICAL IMPORTANCE: Streptozotocin can be safely administered to dogs with insulinoma, but serious AEs are possible. Additional investigation is required to better define the role of STZ in managing dogs with insulinoma.

Immunohistochemical characterization of feline mast cell tumors.

Expression of histamine, serotonin, and KIT was evaluated in 61 archived feline mast cell tumors (MCTs) from the skin (n = 29), spleen (n = 17), and gastrointestinal (GI) tract (n = 15) using immunohistochemistry. Twenty-eight percent of cutaneous MCTs, 18% of splenic MCTs, and 53% of GI MCTs displayed histamine immunoreactivity. Serotonin immunoreactivity was detected in 3 GI and 1 cutaneous MCT. Sixty-nine percent of cutaneous MCTs, 35% of splenic MCTs, and 33% of GI MCTs were positive for KIT. Expression of these biogenic amines and KIT was less common than expected. Results of this study suggest heterogeneity in feline MCTs based on anatomic location. Further studies are needed to explain the significance of these differences.

Outcome of 19 dogs with parathyroid carcinoma after surgical excision.

Parathyroid carcinoma (PTC) is rare in dogs and there is little information documenting its treatment and prognosis. The objective of this study was to describe the outcome of dogs with PTC treated with surgical excision. Medical records of 19 dogs undergoing surgical excision of PTC between 1990 and 2010 were reviewed retrospectively. Dogs were presented for clinical hypercalcaemia or incidental hypercalcaemia noted by referring veterinarians on routine serum chemistry profiles. A parathyroid nodule was identified with cervical ultrasound in 17/17 dogs. Hypercalcaemia resolved in 18/19 dogs within 4 days postoperatively. Nine developed hypocalcaemia. None were confirmed to develop recurrent or metastatic PTC. The only death associated with PTC was a dog that was euthanized for intractable hypocalcaemia 9 days after surgery. Estimated 1-, 2- and 3-year survival rates were 72, 37 and 30%, respectively. Excision of PTC results in resolution of hypercalcaemia and excellent tumour control.

Comparison of two questionnaires to assess gastrointestinal toxicity in dogs and cats treated with chemotherapy*.

Questionnaires completed by pet owners are widely used instruments to monitor adverse gastrointestinal (GI) effects in the owners' animals undergoing chemotherapy and for reporting toxicoses in clinical trials; however, no questionnaires have been formally evaluated. This study compares two questionnaire-based evaluations of adverse GI events: a basic, open-ended questionnaire and a detailed questionnaire modelled after the grading in the Veterinary Co-operative Oncology Group-Common Terminology Criteria for Adverse Events (VCOG-CTCAE). Owners completed both questionnaires after their dog or cat received moderately emetogenic chemotherapy. Results were used to derive toxicity grades for anorexia, vomiting and diarrhoea. We evaluated 123 pairs of questionnaires. Disagreement in grade of anorexia, vomiting and diarrhoea was found in 24, 7 and 13% of paired questionnaires, respectively (κ = 0.63, 0.83 and 0.71, respectively). Although 'good' to 'very good' agreement was found, the potential for only 'fair' agreement between questionnaire methods is of concern and suggests a need to adopt a standardized form.

Recommended guidelines for submission, trimming, margin evaluation, and reporting of tumor biopsy specimens in veterinary surgical pathology.

Neoplastic diseases are typically diagnosed by biopsy and histopathological evaluation. The pathology report is key in determining prognosis, therapeutic decisions, and overall case management and therefore requires diagnostic accuracy, completeness, and clarity. Successful management relies on collaboration between clinical veterinarians, oncologists, and pathologists. To date there has been no standardized approach or guideline for the submission, trimming, margin evaluation, or reporting of neoplastic biopsy specimens in veterinary medicine. To address this issue, a committee consisting of veterinary pathologists and oncologists was established under the auspices of the American College of Veterinary Pathologists Oncology Committee. These consensus guidelines were subsequently reviewed and endorsed by a large international group of veterinary pathologists. These recommended guidelines are not mandated but rather exist to help clinicians and veterinary pathologists optimally handle neoplastic biopsy samples. Many of these guidelines represent the collective experience of the committee members and consensus group when assessing neoplastic lesions from veterinary patients but have not met the rigors of definitive scientific study and investigation. These questions of technique, analysis, and evaluation should be put through formal scrutiny in rigorous clinical studies in the near future so that more definitive guidelines can be derived.

Phase II, open-label trial of single-agent CCNU in dogs with previously untreated histiocytic sarcoma.

BACKGROUND: Histiocytic sarcoma (HS) is an aggressive neoplasm in dogs, and in most instances, the disease is localized, but not amenable to surgical removal, or is disseminated. Affected patients usually die within 6 months. There have been no prospective studies to determine efficacy of single-agent chemotherapy in dogs with HS. HYPOTHESIS: Single-agent CCNU [1-(2-chloroethyl)3-cyclohexyl-1-nitrosourea; lomustine] has antitumor activity against HS in dogs. ANIMALS: Twenty-one dogs with histologically confirmed, nonresectable localized or disseminated HS. METHODS: Prospective, open-label phase II clinical trial in which dogs with previously untreated HS were uniformly treated with CCNU as a single oral dosage of 90 mg/m2 every 4 weeks. The primary outcome measure was reduction in tumor size. RESULTS: Fourteen dogs with disseminated HS and 7 with localized HS were enrolled between 1999 and 2008. Overall response rate was 29% (95% confidence interval [CI], 14­50%) for a median of 96 days (95% CI, 55­137 days). Three dogs (1 disseminated, 2 localized) had complete responses lasting for 54­269 days and 3 dogs (2 disseminated, 1 localized) had partial responses lasting for 78­112 days. CONCLUSIONS AND CLINICAL IMPORTANCE: CCNU, when used as a single agent, has activity against HS in dogs. Evaluation of CCNU postoperatively for dogs with resectable localized HS and as part of combination therapy for tumors that are nonresectable or disseminated should be considered.

Comparison between L-CHOP and an L-CHOP protocol with interposed treatments of CCNU and MOPP (L-CHOP-CCNU-MOPP) for lymphoma in dogs.

An L-CHOP protocol with interposed treatments of CCNU and MOPP (L-CHOP-CCNU-MOPP) was evaluated in 66 dogs with stages III-V lymphoma. Results were compared with a historical group of 71 dogs treated with an L-CHOP protocol. Complete remission (CR) rates (85 and 80%, respectively) did not differ significantly between protocols (P = 0.48). First CR duration for dogs treated with L-CHOP-CCNU-MOPP was significantly longer: median, 317 days; 2-year CR rate, 35% versus median, 298 days; 2-year CR rate, 13%, P = 0.05). For the L-CHOP-CCNU-MOPP protocol, dogs in substage-b had a 4.3 times greater hazard of having a relapse than dogs in substage-a (P = 0.002). Frequency of adverse chemotherapy-associated gastrointestinal effects did not differ between protocols (P = 0.77). Neutropenia (primarily after CCNU) occurred more frequently in dogs treated with L-CHOP-CCNU-MOPP (P < 0.001). In summary, the L-CHOP-CCNU-MOPP protocol showed an improved duration of first CR as compared with an L-CHOP protocol, but the relevance of this finding might be subject to clinical judgement.

Calcitriol (1,25-dihydroxycholecalciferol) enhances mast cell tumour chemotherapy and receptor tyrosine kinase inhibitor activity in vitro and has single-agent activity against spontaneously occurring canine mast cell tumours.

Calcitriol potentiates the effect of multiple chemotherapy agents in a variety of tumour models. In this study, we examine whether calcitriol increases chemotherapy or tyrosine kinase inhibitor in vitro cytotoxicity in canine mastocytoma C2 cells. We also evaluate the in vivo effect of DN101, a highly concentrated oral formulation of calcitriol designed specifically for cancer therapy, as a single-agent therapy in dogs with mast cell tumours (MCTs). Calcitriol exhibits synergistic, antiproliferative activity when used in combination with CCNU, vinblastine, imatinib or toceranib in vitro. The concentrations required for 50% growth inhibition were generally two- to six-fold lower when the drugs were used in combination than when used individually. High-dose oral calcitriol induced remission in 4 of 10 dogs (one complete remission, three partial remissions), although the majority experienced toxicity, necessitating discontinuation of the trial. Further evaluation of calcitriol in combination therapy for dogs with MCTs is warranted.

Phase II open-label study of single-agent hydroxyurea for treatment of mast cell tumours in dogs.

This prospective study evaluated the efficacy and safety of hydroxyurea (HU) in dogs with measurable mast cell tumours (MCTs). Dogs were treated with HU at 60 mg kg(-1)per os q24h for 14 days then 30 mg kg(-1) q24h thereafter or until MCT recurrence. Forty-six dogs were enrolled. The overall response rate was 28%. Two dogs had a complete response (CR) for 256 and 448 days, respectively. Eleven dogs had a partial response for a median duration of 46 days (range, 28-189 days). Grade 2 to 4 neutropenia occurred in eight dogs and grade 4 thrombocytopenia in two. Grade 3-4 anaemia occurred in seven dogs; overall, there was a significant decrease in haematocrit after treatment with HU. The median drop in haematocrit was 10%. This study demonstrated that HU has activity in the treatment of MCTs with mild anaemia being the primary adverse event.

A phase II study to evaluate the toxicity and efficacy of alternating CCNU and high-dose vinblastine and prednisone (CVP) for treatment of dogs with high-grade, metastatic or nonresectable mast cell tumours.

Safety and efficacy of a protocol of alternating 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU; 70 mg m(-2)) and vinblastine (3.5 mg m(-2)), and prednisone (1-2 mg kg(-1); CVP) in dogs with mast cell tumours (MCT) were evaluated. A total of 17 dogs had nonresectable MCTs and 35 received CVP as adjunctive treatment to locoregional control of metastatic MCTs or grade III MCTs. Neutropenia with fever occurred in 8% of dogs after treatment with vinblastine and in 2% after treatment with CCNU. Persistent elevation of serum alanine transaminase, suggestive of hepatotoxicity, occurred in 9% of the dogs. Response rate in dogs with nonresectable MCTs was 65%; five achieved a complete response (median, 141 days) and six achieved a partial response (median, 66 days). Overall median progression-free survival (PFS) time in dogs treated in the adjuvant setting was 489 days. Dogs with grade III MCTs had shorter PFS compared with dogs with metastatic grade II MCTs (190 days versus 954 days; P < 0.001). Phase III studies are needed to provide reliable information about the comparative efficacy of this protocol.

Comparison of first-opinion and second-opinion histopathology from dogs and cats with cancer: 430 cases (2001-2008).

Second-opinion histopathology is intended to detect clinically significant discrepancies that have a direct impact on patient care. We sought to determine if this practice at our institution affected patient management and prognosis. First- and second-opinion histopathology reports from cases were retrospectively reviewed. Reports were considered to be in diagnostic agreement, partial diagnostic disagreement or complete diagnostic disagreement. Four hundred and thirty cases were studied. In 70% of cases there was a diagnostic agreement. In 20% of cases, there was partial diagnostic disagreement, where diagnoses were the same but information such as grade or lymphatic and/or vascular invasion was changed. In 10% of cases, complete diagnostic disagreement resulted from a change in degree of malignancy (malignant to benign, or converse; 7%) or a change in cell type (3%). In 17% of the cases evaluated, the histopathology review prompted a change in treatment or prognosis. These findings support the use of second-opinion histopathology as an important part of patient care.

An immunohistochemical study of vitamin D receptor expression in canine cutaneous mast cell tumours.

The active form of vitamin D (1alpha, 25-dihydroxycholecalciferol; calcitriol) has potent anti-neoplastic activity in the management of a number of human malignancies. Despite promising data to suggest that calcitriol is an effective adjunct to current chemotherapy modalities, the role of calcitriol in animal neoplasia is poorly understood. Vitamin D inhibits growth of canine mast cell tumours (MCTs) in vitro, presumably due to ligand-mediated activation of the vitamin D receptor (VDR). The aim of the present study was to examine immunohistochemically the expression of the VDR by reactive and neoplastic canine cutaneous mast cells. Expression was graded according to frequency, intensity and score (frequency x intensity). VDR expression was found in all samples containing reactive mast cells (n=9), and in 67 of 69 (97%) MCTs selected from each of the three Patnaik grades. The frequency and score of VDR labelling was greater in MCTs compared with reactive mast cells (P=0.0005 and 0.001, respectively). There was no difference in VDR frequency between the MCT grades, but the frequency of labelling in grade 3 MCTs was higher than for reactive mast cells (P=0.001). There was no association between tumour mitotic index and any of the three VDR variables (all P>0.16). VDR is widely expressed by reactive and neoplastic canine mast cells in vivo. VDR expression is unlikely to represent an independent prognostic factor, but its presence within biopsy specimens might be used to identify patients that are suited to high-dose vitamin D therapeutic trials.

Evaluation of dexamethasone as a chemoprotectant for CCNU-induced bone marrow suppression in dogs.

In mice and people, administering corticosteroids before chemotherapy can reduce the severity of myelosuppression without reducing antitumour effects. This study investigated whether pretreatment with dexamethasone would reduce the incidence of grade 4 neutropenia in dogs receiving CCNU. Twenty-five dogs received dexamethasone [0.1 mg kg(-1) per os (PO) every 12 h] for 5 days and on the sixth day received CCNU (90 mg m(-2) PO). Historical dogs (n = 67) received CCNU alone (90 mg m(-2) PO). Forty-five percent of historical dogs had grade 4 neutropenia, while 64% of dogs pretreated with dexamethasone had grade 4 neutropenia (P = 0.16). Dexamethasone plasma levels were quantified by enzyme-linked immunosorbent assay in three healthy dogs. Peak plasma concentrations after a single oral 0.1-mg kg(-1) dose were <80 ng mL(-1), the minimum level associated with chemoprotective effects of dexamethasone in people. Pretreatment with dexamethasone did not reduce the incidence of grade 4 neutropenia in dogs receiving CCNU.

Efficacy of combination chemotherapy for treatment of gastrointestinal lymphoma in dogs.

BACKGROUND: Chemotherapy for multicentric canine lymphoma has favorable results. The gastrointestinal (GI) tract is the most common extranodal site of canine lymphoma, but there have been no prospective studies to determine outcome when dogs with GI lymphoma are treated with chemotherapy. HYPOTHESIS: Treatment with a multiagent chemotherapy protocol is associated with a poor outcome in dogs with GI lymphoma. ANIMALS: Eighteen dogs with histologically confirmed GI lymphoma. METHODS: Prospective clinical trial in which dogs with GI lymphoma were treated with a 20-week combination chemotherapy protocol consisting of induction and consolidation phases. RESULTS: Thirteen dogs had primary GI lymphoma and 5 had multicentric lymphoma with GI involvement. The majority of the lymphomas (63%) were of T-cell origin. Overall remission rate was 56%; 9 dogs achieved a complete remission for a median of 86 days (range, 22-420 days) and 1 dog achieved a partial remission for 26 days. Overall median survival time was 77 days (range, 6-700 days). Dogs that failed to achieve a remission (10 versus 117 days; P= .002) or had diarrhea at initial presentation (70 versus 700 days; P < .001) had shorter survival times. CONCLUSION AND CLINICAL IMPORTANCE: The response and survival of dogs with GI lymphoma treated with multiagent chemotherapy is poor but long-term survival is possible.