Evaluation of a bladder tumor antigen test as a screening test for transitional cell carcinoma of the lower urinary tract in dogs

OBJECTIVE: To evaluate the veterinary version of the bladder tumor antigen (V-BTA) test as a screening test for transitional cell carcinoma (TCC) of the lower urinary tract of dogs. ANIMALS: 229 client-owned dogs. PROCEDURE: Urine samples from dogs were shipped overnight to a single laboratory to facilitate testing within 48 hours of collection by use of the V-BTA rapid latex agglutination urine dipstick test. Groups of dogs included the following: 1) dogs with TCC of the lower urinary tract, 2) healthy control dogs, 3) unhealthy control dogs with non-TCC urinary tract disease, and 4) unhealthy control dogs without urinary tract disease. Test sensitivity and specificity were calculated by use of standard methods. Logistic models were developed to assess the effect of disease status, test conditions, urine composition, and signalment on the performance of the V-BTA test. RESULTS: A total of 229 urine samples were analyzed, including 48 from dogs with suspected (n = 3) or confirmed (45) TCC. Test sensitivities were 88, 87, and 85% for all dogs with (suspected and confirmed) TCC, dogs with confirmed TCC at any site, and dogs with confirmed TCC of the urinary bladder, respectively. Test specificities were 84, 41, and 86% for healthy control dogs, unhealthy control dogs with non-TCC urinary tract disease, and unhealthy control dogs without urinary tract disease, respectively. The test performed slightly better on centrifuged urine samples than on uncentrifuged urine samples. CONCLUSIONS AND CLINICAL RELEVANCE: Our results indicate that the V-BTA test is useful in screening for urinary tract TCC in dogs.     

Phase I Clinical Trial and Pharmacokinetics of Intravesical Mitomycin C in Dogs with Localized Transitional Cell Carcinoma of the Urinary Bladder

Background: Transitional cell carcinoma (TCC) is the most common cancer of the urinary tract in dogs. The most frequent cause of death is urinary obstruction from the primary tumor. Standard medical therapy for TCC is only partially effective. Hypothesis/Objectives: Intravesical administration of mitomycin C (MMC) in dogs with invasive TCC will result in antitumor activity against the primary tumor and minimal systemic drug absorption. Animals: Thirteen privately owned dogs with naturally occurring, histopathologically diagnosed TCC of the urinary bladder. Methods: A prospective phase I trial was performed. MMC was given intravesically (600 μg/mL initial concentration) for 1 h/d for 2 consecutive days each month. The MMC concentration was escalated to a maximum of 800 μg/mL in groups of 3 dogs until the maximum tolerated dose (MTD) was determined. Serum assays for MMC were performed to determine the extent of systemic absorption of the MMC. Results: The MTD of MMC based on local toxicoses was 700 μg/mL (1‐h dwell time, 2 consecutive days). In addition, 2 dogs had severe myelosuppression and appeared to have systemic absorption of MMC. Five dogs had partial remission, and 7 dogs had stable disease. Conclusions: Intravesical MMC has antitumor activity in dogs with invasive TCC. Further study is needed to determine the cause of the myelosuppression associated with MMC administration, and to develop strategies to minimize this risk.     

Detection of canine transitional cell carcinoma using a bladder tumor antigen urine dipstick test

Canine transitional cell carcinoma (TCC) carries a poor prognosis in part due to late disease detection. The measurement of specific tumor markers shed in the urine may aid in sensitive, early disease detection and therefore improved prognosis. A 1-year prospective clinical trial was designed to assess the efficacy, sensitivity and specificity of the first generation Bard BTA test to diagnose TCC in dogs. This test is a qualitative, rapid, latex agglutination, dipstick test run on voided urine, which measures a glycoprotein antigen complex associated with bladder cancer in human patients. Sixty-five dogs were entered in the study: 20 TCC confirmed patients, 19 healthy controls and 26 urologic controls with a variety of conditions including urinary tract infection, crystalluria and proteinuria. Overall test sensitivity was 90% and specificity was 78%. False positive test results were noted in the presence of significant glucosuria (4+), proteinuria (4+), and pyuria or hematuria (> 30-40 WBC or RBC per hpf). Urine parameters that had no effect on efficacy included collection method (cystocentesis or free catch), pH, specific gravity, crystalluria, bilirubinuria, bacteriuria and casts. These data indicated that the Bard BTA test was sensitive for the detection of the bladder tumor-associated antigen complex in canine TCC. As evaluated, this test may serve as a useful adjunct to diagnosis, especially when cytology or biopsy is questionable or impractical. Furthermore, because of the high sensitivity of the test, it may be a practical screening test to rule out TCC in geriatric patients or patients with clinical signs related to the lower urinary tract, particularly before pyuria and hematuria develop which may interfere with test results.     

Epidermal growth factor receptor expression in canine transitional cell carcinoma

Transitional cell carcinoma (TCC), a urinary bladder tumor with high mortality, is encountered commonly in dogs. Whereas overexpression of epidermal growth factor receptor (EGFR) is associated with development of human urinary bladder cancer, information on EGFR expression in canine TCC is lacking. In this study, EGFR protein and mRNA expression in canine normal bladder (n=5), polypoid cystitis (n=5) and TCC (n=25) were examined by immunohistochemistry and real-time polymerase chain reaction. EGFR protein expression was significantly higher in TCC than that in normal healthy bladder (P<0.001) and polypoid cystitis (P<0.005). High EGFR protein expression was significantly (P<0.01) associated with TCC with a sensitivity of 72% and specificity of 100%. Comparative analysis of protein and mRNA expression levels in TCC showed significant positive correlation (r=0.88, P<0.05) between mRNA and protein expression. These findings suggest that intense expression of EGFR protein could be used as a marker to help canine TCC diagnosis.     

High Urine Concentrations of Basic Fibroblast Growth Factor in Dogs With Bladder Cancer

Because dogs with bladder cancer often have advanced disease at the time of diagnosis, the identification and use of a tumor marker that could facilitate earlier diagnosis is a valid approach to improve prognosis. The objective of this study was to determine if urine concentrations of the proan-giogenic peptide, basic fibroblast growth factor (bFGF), are high in dogs with bladder cancer compared with normal dogs and dogs with urinary tract infection. We used a commercially available enzyme-linked immunosorbent assay test kit to quantitate bFGF in the urine of 17 normal dogs, 10 dogs with urinary tract infection, and 7 dogs with locally active transitional cell carcinoma of the urinary bladder. In normal dogs, the median urine bFGF concentration was 2.23 ng/g creatinine (quartile range, 1.53 to 5.12 ng/g creatinine). The median urine bFGF concentration in dogs with urinary tract infection did not differ significantly from normal dogs. Dogs with bladder cancer had significantly higher urine bFGF concentrations than normal dogs ( P < .002) and dogs with infection ( P < .02). The median urine bFGF concentration in dogs with transitional cell carcinoma was 9.86 ng/g creatinine (quartile range, 7.40 to 21.63 ng/g creatinine). Six of 7 dogs with bladder cancer had urine bFGF concentrations that were up to 7.4 times the 90th percentile value for normal dogs. Only 1 of 10 dogs with infection had a urine bFGF concentration that exceeded the 90th percentile of normal. These data suggest that canine bladder cancers export bFGF, and that urine bFGF may be useful as a diagnostic tumor marker or noninvasive indicator of treatment response. J Vet Intern Med 1996;10:231–234. Copyright © 1996 by the American College of Veterinary Internal Medicine .     

Expression of receptor tyrosine kinase targets PDGFR‐β, VEGFR2 and KIT in canine transitional cell carcinoma

Transitional cell carcinoma (TCC) is the most common neoplasia of the canine urinary tract. It tends to be locally invasive and has a moderate metastatic rate. Receptor tyrosine kinases (RTKs) play an important role in promoting cell growth, differentiation and regulation of cell function. RTK inhibitor toceranib phosphate has been used anecdotally to treat TCC. The goal of this study was to evaluate archived normal urinary bladder, TCC and cystitis bladder samples for expression of toceranib phosphate targets: VEGFR2, PDGFR‐β and stem cell factor receptor (KIT). A significant number of TCC samples expressed PDGFR‐β compared with cystitis and normal bladder samples (P<.0001). While all the tumour samples stained positively for VEGFR2, there was no significant difference between tumour, cystitis and normal bladder samples in intensity scores or staining distribution. Minimal positive staining for KIT was noted in the tumour samples. Based on this proof of target study, further investigation is warranted to determine clinical response of TCC to toceranib phosphate.     

Overexpression of HER‐2 via immunohistochemistry in canine urinary bladder transitional cell carcinoma ‐ A marker of malignancy and possible therapeutic target

Transitional cell carcinoma (TCC) is the most commonly diagnosed neoplasm in the urinary bladder. Distant metastases to the regional lymph nodes, lungs, abdominal organs or bones are noted in up to 50% of dogs at time of death. Surgical excision is often not practical as TCC typically involve the trigone of the bladder and/or occurs multifocally throughout the bladder with field cancerization. Therapeutic approaches are very challenging and the requirement to evaluate alternative therapeutic protocols that may prolong survival times in dogs bearing these tumours is compelling. We assessed the immunohistochemical expression of HER‐2 in 23 cases of canine TCCs of the urinary bladder and compare it with non‐neoplastic urothelium in order to evaluate a rationale for targeted therapies and gene‐based vaccines. HER‐2 positivity was recorded in 13/23 (56%) neoplastic lesions. The receptor was significantly overexpressed in neoplastic than in non‐neoplastic samples (P = .015). According to our preliminary results, it would be of interest to further evaluate the role of HER‐2 in canine TCCs as a marker of malignancy and a therapeutic target for cancer vaccine and antibodies. Moreover, the significantly different overexpression of HER‐2 in TCCs than in non‐neoplastic urothelium further supports to investigate its role in the progression toward malignancy of non‐neoplastic lesions.     

Evaluation of microsatellite instability in urine for the diagnosis of transitional cell carcinoma of the lower urinary tract in dogs

Background: The accumulation of frame‐shift mutations in microsatellites (MS), termed microsatellite instability (MSI), is associated with certain tumors. MSI and its detection in urine samples has been used to aid in the detection of human bladder cancer. Hypothesis: Evaluation of MSI in urine is a useful assay test for diagnosis of transitional cell carcinoma (TCC) in dogs and is more specific than the commercially available, veterinary bladder tumor analyte (V‐BTA) test. Animals: Seventy‐three dogs: healthy controls (n= 21), proteinuric (n= 12), lower urinary tract disease excluding TCC (n= 17), and TCC (n= 23). Methods: Prospective observational study. Urine samples collected from each animal were evaluated for MSI and using the V‐BTA. For MSI detection, 22 MS sequences were polymerase chain reaction amplified from urine and blood, subjected to capillary electrophoresis, and the MS genotypes were compared. Aberration in ≥15% of MS was considered indicative of MSI. Results: MSI was detected in 11 of 23 (48%) urine samples from dogs with TCC. MSI was also detected in 12 of 50 (24%) of the control animals, including 29, 16, and 24% of healthy, proteinuric, and lower urinary disease dogs, respectively. In this population, sensitivity and specificity of MSI analysis was 48 and 76%, respectively, compared with 83 and 64%, respectively, for the V‐BTA test. Conclusions: MS analysis as performed in this study is not useful in the diagnosis of TCC.     

Clinical outcome of partial cystectomy for transitional cell carcinoma of the canine bladder

Canine transitional cell carcinoma (TCC) of the bladder has historically been treated with a combination of chemotherapy, cyclooxygenase inhibitors and radiation therapy. While surgery has been used to treat TCC of the bladder, its efficacy has yet to be established. Thirty‐seven client owned dogs that underwent partial cystectomy +/? various nonsurgical treatments for TCC were retrospectively evaluated. The overall median progression‐free interval (PFI) was 235 days and the median survival time (ST) was 348 days. Prognostic factors identified on univariate analysis significant for ST were age, tumor location, full thickness excision and frequency of piroxicam administration. Prognostic factors significant for PFI were full thickness excision and frequency of piroxicam administration. The median ST with partial cystectomy and daily piroxicam therapy, with or without chemotherapy, was 772 days. Dogs with non‐trigonal bladder TCC treated with full thickness partial cystectomy and daily piroxicam (+/? chemotherapy) may have improved outcome compared to dogs treated with medical therapy.     

Preclinical evaluation of 5-aminolevulinic acid-based photodynamic therapy for canine transitional cell carcinoma

As a prelude to photodynamic therapy, 5‐aminolevulinic acid (ALA) was given orally to healthy dogs. ALA‐induced protoporphyrin IX (PpIX) fluorescence significantly increased in the mucosa of the urinary bladder in an ALA dose‐dependent fashion. Vomiting occurred after ALA administration in 70% of the dogs but did not affect PpIX fluorescence. ALA‐based photodynamic therapy (PDT) of the urinary bladder in healthy dogs caused only submucosal oedema within the bladder wall. No haematologic or serum biochemistry abnormalities were observed after ALA administration. Microscopic haematuria was observed in all the dogs after PDT but was mild and self limiting. ALA‐based PDT was administered to six dogs with transitional cell carcinoma (TCC) of the lower urinary tract. ALA‐based PDT resulted in tumour progression‐free intervals from 4 to 34 weeks in five dogs; one dog with pre‐existing hydronephrosis died shortly after PDT. Dogs with TCC represent an outbred, spontaneous, tumour model for developing PDT protocols for humans with bladder cancer.     

Hedgehog signaling is activated in canine transitional cell carcinoma and contributes to cell proliferation and survival

Transitional cell carcinoma (TCC) is the most commonly diagnosed tumor of the canine urinary system. Hedgehog (HH) signaling represents one possible novel therapeutic target, based on its recently identified central role in human urothelial carcinoma. The purpose of this study was to determine if HH mediators are expressed in canine TCC and the effect of inhibition of this pathway on cell growth and survival. HH pathway mediators were found to be expressed in five canine TCC cell lines. Indian HH was expressed in tumor cells in five canine bladder tumor tissues, but not in normal canine bladder tissue. Inhibition of HH signaling with cyclopamine and GANT61 led to significantly decreased cell proliferation but had a smaller effect on apoptosis. These results support future investigation of inhibitors of HH signaling in the treatment of canine TCC.     

Antitumor effects of deracoxib treatment in 26 dogs with transitional cell carcinoma of the urinary bladder

OBJECTIVE-To evaluate the antitumor activity and toxic effects of deracoxib, a selective cyclooxygenase-2 inhibitor, in dogs with transitional cell carcinoma (TCC) of the urinary bladder. DESIGN-Clinical trial. Animals-26 client-owned dogs with naturally occurring, histologically confirmed, measurableTCC of the urinary bladder. PROCEDURES-Dogs were treated PO with deracoxib at a dosage of 3 mg/kg/d (1.36 mg/lb/d) as a single-agent treatment for TCC. Tumor response was assessed via radiography, abdominal ultrasonography, and ultrasonographic mapping of urinary bladder masses. Toxic effects of deracoxib administration in dogs were assessed through clinical observations and hematologic and biochemical analyses. RESULTS-Of 24 dogs for which tumor response was assessed, 4 (17%) had partial remission, 17 (71%) had stable disease, and 3 (13%) had progressive disease; initial response could not be assessed in 2 of 26 dogs. The median survival time was 323 days. Median time to progressive disease was 133 days. Renal, hepatic, and gastrointestinal abnormalities attributed to deracoxib administration were noted in 4% (1/26), 4% (1/26), and 19% (5/26) of dogs, respectively. CONCLUSIONS AND CLINICAL RELEVANCE-Results indicated that deracoxib was generally well tolerated by dogs and had antitumor activity against TCC.     

Carboplatin and piroxicam therapy in 31 dogs with transitional cell carcinoma of the urinary bladder

Invasive transitional cell carcinoma (TCC) of the urinary bladder responds poorly to medical therapy. Combining platinum chemotherapy with a cyclooxygenase (cox) inhibitor has shown promise against canine TCC, where the disease closely mimics the human condition. A phase II clinical trial of carboplatin combined with the cox inhibitor, piroxicam, was performed in 31 dogs with naturally occurring, histopathologically confirmed, measurable TCC. Complete tumour staging was performed before and at 6‐week intervals during therapy. Tumour responses in 29 dogs included 11 partial remissions, 13 stable disease and five progressive disease. Two of the 31 dogs were withdrawn prior to the re‐staging of the tumour. Gastrointestinal toxicity was observed in 23 dogs. Hematologic toxicity was noted in 11 dogs. The median survival was 161 days from first carboplatin treatment to death. In conclusion, carboplatin/piroxicam induced remission in 40% of dogs providing evidence that a cox inhibitor enhances the antitumour activity of carboplatin. The frequent toxicity and limited survival, however, do not support the use of this specific protocol against TCC.     

Urologic disorders of the geriatric dog

Disorders of the urinary system are common in geriatric dogs. Common urinary disorders that are seen in older dogs include chronic renal failure, urinary incontinence, bladder tumors, and prostate problems. Therapy for chronic renal failure is aimed at both slowing the progression of the disease and ameliorating the signs of uremia. Therapeutic recommendations for the conservative medical management of chronic renal failure include reducing dietary protein, moderately reducing salt intake, maintaining normal serum phosphorus levels, providing free access to water, avoiding stress, supplementing water soluble vitamins, using anabolic steroids to treat the anemia of chronic renal failure, treating acidosis, and controlling hypocalcemia. Urinary incontinence can often be controlled or eliminated. The appropriate approach to management of this disorder is to identify and remove specific causes. Common causes of urinary incontinence are urethral incompetence, urinary tract infection, and polyuria and polydypsia. Bladder tumors are, fortunately, not a common tumor of dogs, but are more common in geriatric dogs than in the young. The most common bladder tumor is the transitional cell carcinoma. Therapy for this tumor is usually palliative because of its malignant nature and because it is usually located in the neck of the bladder. Its location in the bladder often makes it impossible to resect the tumor completely without removing the entire bladder and diverting the ureters. New chemotherapeutic modalities are being evaluated that may increase life expectancy after diagnosis and, therefore, improve prognosis. Prostate disease is also seen in older dogs. Types of prostate abnormalities seen in dogs include prostatic hyperplasia, cysts, abscesses, acute and chronic infection, and neoplasia. The institution of proper therapy requires an accurate diagnosis; neutering is often recommended as a part of therapy regardless of the type of prostatic disease present.     

Phase II Clinical Trial of Carboplatin in Canine Transitional Cell Carcinoma of the Urinary Bladder

Fourteen dogs with histologically-confirmed transitional cell carcinoma (TCC) of the urinary bladder were treated with 300 mg/m² carboplatin every 3 weeks. Response to therapy was assessed with abdominal radiography, double contrast cystography, urinary bladder ultrasonography and thoracic radiography before therapy and at 6–week intervals during therapy. Dogs were monitored for hematologic toxicity with a CBC and platelet count performed immediately before and 10 to 14 days after carboplatin treatment. Tumor responses included progressive disease in 11 dogs and stable disease in 1 dog. Two dogs were euthanized due to carboplatin toxicity before assessment of tumor response. Toxicity included thrombocytopenia with or without neutropenia in 7 dogs and gastrointestinal toxicity in 6 dogs. Carboplatin therapy was not beneficial in the treatment of TCC in the 14 dogs in this study.     

TOLERABILITY AND TUMOR RESPONSE OF A NOVEL LOW‐DOSE PALLIATIVE RADIATION THERAPY PROTOCOL IN DOGS WITH TRANSITIONAL CELL CARCINOMA OF THE BLADDER AND URETHRA

Previously reported radiation protocols for transitional cell carcinoma of the canine lower urinary tract have been ineffective or associated with increased side effects. Objectives of this retrospective, cross‐sectional study were to describe safety of and tumor responses for a novel palliative radiation protocol for transitional cell carcinoma in dogs. Included dogs had cytologically or histologically confirmed transitional cell carcinoma of the bladder or urethra, and were treated with 10 once‐daily fractions (Monday–Friday) of 2.7 Gy. Thirteen dogs were sampled, with six treated using radiation as first‐line (induction) therapy and seven treated using radiation as rescue therapy after failing previous chemotherapy. Within 6 weeks of radiation, 7.6% (1/13) dogs had a complete response, 53.8% (7/13) partial response, 38.5% (5/13) stable disease, and none had progressive disease. Three patients presenting with urethral obstruction had spontaneous micturition restored during the treatment protocol. A single patient with unilateral ureteral obstruction was patent at recheck examination. Median survival time from time of initial diagnosis was 179 days. Median survival time from start of radiation was 150 days. Acute radiation side effects occurred in 31% (4/13) patients and were classified as grade 1 or 2. No significant late side radiation side effects were reported. No variables examined were identified as prognostic factors. Findings indicated that the reported radiation protocol was safe in this sample of dogs with bladder and urethral transitional cell carcinoma. Future prospective studies are needed to determine utility of this treatment as a rescue therapy in patients with complete urinary tract obstruction.     

Immunohistochemical expression of p63, Ki67 and β‐catenin in canine transitional cell carcinoma and polypoid cystitis of the urinary bladder

Transitional cell carcinoma (TCC) is a urinary bladder tumour associated with high mortality in dogs. In this study, we investigated the feasibility of using p63, Ki67 or β‐catenin as a clinical marker for predicting biological behaviour and prognosis in canine TCC. Expression levels of these proteins in TCC (n = 25), polypoid cystitis (n = 5) and normal urinary bladder (n = 5) were scored after immunohistochemical staining. The staining scores for p63 (P < 0.01) and β‐catenin (P < 0.05) in TCC were significantly lower than those in normal urinary bladder and polypoid cystitis. In contrast, Ki67 (P < 0.01) staining scores in TCC were significantly higher than those in normal urinary bladder and polypoid cystitis. In TCC, low p63 expression was significantly related to the presence of vessel invasion (P < 0.05) and metastasis (P < 0.01) as well as short survival time (P < 0.05). These findings show that p63 could be a reliable marker for predicting prognosis in canine TCC.     

Evaluation of a bladder tumor antigen test for the diagnosis of lower urinary tract malignancies in dogs

OBJECTIVE: To evaluate the use of a human bladder tumor antigen test for diagnosis of lower urinary tract malignancies in dogs. SAMPLE POPULATION: Urine samples from dogs without urinary tract abnormalities (n = 18) and from dogs with lower urinary tract neoplasia (20) or nonmalignant urinary tract disease (16). PROCEDURE: Test results were compared among groups and among 3 observers. The effects of urine pH and specific gravity, degree of hematuria, and storage temperature and time of urine samples on test results were also assessed. RESULTS: Test sensitivity and specificity were 90 and 94.4%, respectively, for differentiating dogs with lower urinary tract neoplasia from dogs without abnormalities. However, specificity decreased to 35% for differentiating dogs with neoplasia from dogs with nonmalignant urinary tract disease. In dogs with neoplasia, results were significantly affected by degree of hematuria. However, addition of blood to urine from dogs without hematuria had no significant effect on test results. Although intraobserver variation was significant, urine pH, specific gravity, or storage time or temperature had no significant effect on results. CONCLUSIONS AND CLINICAL RELEVANCE: Although this bladder tumor antigen test was sensitive for differentiating dogs with malignancies of the lower urinary tract from dogs without urinary tract disease, it was not specific for differentiating dogs with neoplasia from dogs with other lower urinary tract abnormalities. It cannot, therefore, be recommended as a definitive diagnostic aid for the detection of lower urinary tract malignancies in dogs.     

Antitumor Activity of Mycobacterial Cell Wall‐DNA Complex (MCC) Against Canine Urinary Bladder Transitional Cell Carcinoma Cells

Introduction:  Mycobacterial cell wall‐DNA complex (MCC) is a bifunctional anticancer agent that induces cancer cell apoptosis and stimulates cytokine synthesis by immune cells. Intravesical MCC is currently being evaluated in humans with high‐grade urinary bladder cancer. Evaluation of MCC in dogs with transitional cell carcinoma (TCC) will allow mechanistic studies in a natural animal model of TCC, and a potentially beneficial therapy for dogs with this cancer. In this study, we have determined the anticancer activity of MCC against canine TCC cells in vitro .
Methods:  Canine TCC cells (K9TCC cell line) were incubated with MCC (0.05–100 μg/ml, 0.5–72 hours). Cellular proliferation was measured by MTT reduction. Cell cycle was analyzed by flow cytometry with propidium iodide. Apoptosis was identified by flow cytometry using anti‐active‐caspase‐3/PE and anti‐cleaved‐PARP/FITC antibodies. Apoptosis‐inducing activity of 100 μg/ml MCC in combination with piroxicam (0.1–1.0 uM) was evaluated.
Results:  MCC inhibited K9TCC cell proliferation in a concentration‐dependent manner (maximal activity – 45% at 100 μg/ml MCC) in association with the presence of activated caspase‐3 and cleaved PARP. Inhibition of proliferation and apoptosis‐inducing activities of MCC were independent of cell cycle phase. A thirty‐minute exposure of MCC was sufficient for optimal activity. Piroxicam (0.5 uM) enhanced apoptosis‐inducing activity of MCC.
Conclusions:  MCC induces apoptosis in K9TCC cells. This activity is potentiated by piroxicam. Following positive results in vitro , in vivo studies have been initiated. One dog, treated to date, has had a minor reduction in tumor volume following the first course of treatment with no treatment‐related toxicity.