Preclinical study of sequential tumor necrosis factor and interleukin 2 in the treatment of spontaneous canine neoplasms.

Recombinant human tumor necrosis factor and recombinant human interleukin 2 were administered in a sequential schedule to 30 dogs with a variety of spontaneous neoplasms. Dose escalation of both drugs was performed, and a maximally tolerated dose of recombinant human tumor necrosis factor of 125 mg/m2 i.v. for 3 days, followed by 1.5 x 10(6) units/m2 of recombinant human interleukin 2 s.c. for 9 days, was derived. Dose-limiting toxicities were primarily gastrointestinal; however, weakness and malaise were seen during therapy at doses higher than the maximally tolerated dose. No clinically significant hematological toxicities were seen at any dose level. Objective tumor responses were seen in dogs with oral mucosal melanoma and cutaneous mastocytoma. Because of the histological, behavioral, and epidemiological similarities between human and canine tumor types, the canine cancer patient provides a unique model for the preclinical evaluation of recombinant cytokine therapy.

K-ras activation in non-small cell lung cancer in the dog.

To investigate the role of K-ras mutations in canine non-small cell lung cancer, we first determined the nucleotide sequence of the normal canine K-ras gene and then examined 21 canine lung tumors for activating K-ras mutations. Canine K-ras was analyzed by direct sequencing of polymerase chain reaction products generated with oligonucleotide primers derived from the human K-ras sequence. Four nucleotide differences were found between the canine and human K-ras sequence from position 5 to 211. The deduced amino acid sequence of the canine gene was identical to that of the human. Activated K-ras alleles were detected in 5 of the 21 canine lung tumors examined. The activating lesions were point mutations, predominantly in codon 12. Of the 14 adenocarcinomas examined, 2 (14%) had K-ras mutations. Two of 5 (40%) adenosquamous carcinomas and the only large cell carcinoma also contained activated alleles. The overall frequency of K-ras point mutation in non-small cell lung cancer (25%) is similar to that reported in human non-small cell lung cancer. We conclude that K-ras activation by point mutation is associated with, but not necessary for, non-small cell lung cancer development in the dog.

Liposome-encapsulated muramyl tripeptide phosphatidylethanolamine adjuvant immunotherapy for splenic hemangiosarcoma in the dog: a randomized multi-institutional clinical trial.

Canine splenic hemangiosarcoma (HSA) is a spontaneous tumor with high metastatic potential. Despite surgical excision, most dogs die within 2 months of diagnosis as a result of widespread visceral metastasis. This study was designed to determine the efficacy of liposome-encapsulated muramyl tripeptide phosphatidylethanolamine (L-MTP-PE) when used in combination with splenectomy and systemic chemotherapy for the treatment of HSA in the dog. Thirty-two dogs with HSA and without gross evidence of metastases were treated with splenectomy, stratified by clinical stage, and randomized to receive doxorubicin/cyclophosphamide chemotherapy and either L-MTP-PE immunotherapy or lipid equivalent (placebo liposomes). Dogs were subsequently followed to determine disease-free survival and overall survival times. The effects of L-MTP-PE on serum tumor necrosis factor-alpha and interleukin 6 activity were assessed on a small subset of dogs. Dogs receiving L-MTP-PE had significantly prolonged disease-free survival (P = 0.037) and overall survival (P = 0.029) compared with dogs receiving placebo. Dogs with clinical stage I disease had significantly prolonged disease-free survival (P = 0. 026) and overall survival (P = 0.017) compared with dogs with clinical stage II disease. Dogs receiving L-MTP-PE had significantly greater serum tumor necrosis factor-alpha (P < 0.001) and interleukin 6 (P = 0.007) activities compared with placebo-treated dogs. L-MTP-PE has significant antimetastatic activity in highly malignant, spontaneously occurring, splenic HSA in the dog. Canine HSA may have potential as a large animal model for additional investigation of antimetastatic chemoimmunotherapy.

Adjuvant therapy for osteosarcoma in dogs: results of randomized clinical trials using combined liposome-encapsulated muramyl tripeptide and cisplatin.

Two randomized, double-blind clinical trials in dogs with spontaneous appendicular osteosarcoma treated with combination chemoimmunotherapy are reported. In both trials, dogs without overt metastasis underwent complete amputation of the affected limb. In trial 1, 40 dogs were treated with cisplatin chemotherapy [(CDDP), 70 mg/m2 i.v. every 28 days x 4]. Following CDDP, dogs without evidence of overt metastasis (n = 25) were randomized to receive liposome-encapsulated muramyl tripeptide phosphatidylethanolamine ](L-MTP-PE), 2 mg/m2 i.v.) or placebo liposomes (lipid equivalent) twice weekly for 8 weeks. Of 14 dogs in the placebo group, 13 (93%) died of metastasis; the median survival time was 9.8 months. Of 11 dogs in the L-MTP-PE group, 8 (73%) developed metastasis; the median survival time was 14.4 months, which was significantly longer than that of the placebo group (P < 0.01). In trial 2, 64 dogs received CDDP (70 mg/m2 i.v. every 21 days x 4) and were randomized to concurrently receive L-MTP-PE (2 mg/m2 i.v.) twice or once weekly, or placebo liposomes once weekly for 8 weeks. Median survival times were 10.3, 10.5, and 7.6 months, respectively. There were no significant differences among the three treatment groups in trial 2. Survival times for dogs receiving L-MTP-PE in trial 1 were significantly longer than those for dogs in trial 2 that received four doses of CDDP concurrently with twice weekly L-MTP-PE (P < 0. 04). The results of the first trial confirm our previous observation that L-MTP-PE has antimetastatic activity in dogs with osteosarcoma when given following amputation. The results of the second trial demonstrate that there is no survival advantage of administering L-MTP-PE concurrently with CDDP.

Adjuvant therapy for melanoma in dogs: results of randomized clinical trials using surgery, liposome-encapsulated muramyl tripeptide, and granulocyte macrophage colony-stimulating factor.

Spontaneous canine oral melanoma (COM) is a highly metastatic cancer, resistant to chemotherapy, and can serve as a model for cancer immunotherapy. Liposome-encapsulated muramyl tripeptide-phosphatidylethanolamine (L-MTP-PE) can activate the tumoricidal activity of the monocyte-macrophage system following i.v. injection. The objective of these studies was to evaluate the therapeutic effectiveness of L-MTP-PE administered alone and combined with recombinant canine granulocyte macrophage colony-stimulating factor (rcGM-CSF) in dogs undergoing surgery for oral melanoma. Ninety-eight dogs with histologically confirmed, clinically staged, oral melanoma were entered into two randomized, double-blind, surgical adjuvant trials. In trial 1, 50 dogs were stratified based on clinical stage and randomized to once a week L-MTP-PE or lipid equivalent (control). When all of the clinical stages were combined, no difference in disease-free survival or in survival time (ST) were detected. However, within stage I, dogs receiving L-MTP-PE had a significant increase in ST compared with control, with 80% of the dogs treated with L-MTP-PE still alive at >2 years. Within each stage II and stage III, there was no difference detected between the treatment groups. In trial 2, 48 dogs were stratified on the basis of clinical stage and extent of surgery (simple resection or radical excision), treated with L-MTP-PE two times a week, and randomized to rcGM-CSF or saline (placebo) given s.c. daily for 9 weeks. Within each stage and when all of the stages were combined, there was no difference between the treatment groups. In both studies, stage I COM is associated with a better prognosis. No effect on survival was observed with regard to tumor location in the oral cavity, sex, type/extent of surgery, or age. In a subset of dogs tested, pulmonary alveolar macrophage cytotoxicity was enhanced with combined rcGM-CSF and L-MTP-PE but not in dogs treated with L-MTP-PE alone. The present study indicates that after surgery, L-MTP-PE administered alone or combined with rcGM-CSF showed no significant antitumor activity in treating advanced stage COM. In early stage COM, L-MTP-PE was shown to result in a prolongation of ST. Furthermore, this study provides additional rationale for the use of the dog model for human malignant melanoma.

Cyclin D3 expression in normal fetal, normal adult and neoplastic feline tissue.

Cyclin D3 is a tightly regulated cell cycle protein and member of the cyclin D family-a group of proteins that facilitates the progression of a cell through G(1) and into the S phase of the cell cycle. All cells use at least one of the cyclin D proteins for cell cycle regulation. In this study, feline tissues (normal fetal and adult, and neoplastic) were examined immunohistochemically for expression and topographical distribution of cyclin D3. Its distribution was similar to that in human tissues in health and neoplasia, and suggested a dual role of cyclin D3 in cell proliferation and differentiation. Immature lymphoid tissue and proliferating epithelial cells in health and neoplasia were immunoreactive for cyclin D3, whereas expression of the protein in other immunoreactive tissues reflected differentiated cell types. Immunoreactivity for cyclin D3 was particularly striking in germinal centre cells of normal lymph nodes and B-cell lymphomas, and in normal suprabasal epithelial cells of the skin and mucous membranes of the oropharynx and in squamous cell carcinomas at these sites.

Concurrent irradiation and intratumoral chemotherapy with cisplatin: a pilot study in dogs with spontaneous tumors.

PURPOSE: A preliminary study was undertaken to determine whether the addition of a collagen gel in the formulation of cisplatin for intratumoral administration of cisplatin affected platinum plasma concentrations. A second study was undertaken to determine the local effects of intratumoral administration of cisplatin mixed with collagen given concurrently with irradiation. METHODS AND MATERIALS: Twelve dogs with advanced stage tumors were administered a dose of 0.25 mg of cisplatin per kg of body weight intratumorally with or without collagen using a two-period crossover design. Twelve additional dogs received concurrent irradiation (48 Gy) delivered in 12 fractions over 4 weeks and intratumoral cisplatin chemotherapy given the first day of each week at a dose of 0.5 mg of cisplatin per cm3 of tissue. RESULTS: The cumulative cisplatin plasma concentrations varied over time from dog to dog, but the use of collagen in the formulation significantly reduced the systemic exposure of cisplatin. For the dogs given intratumoral cisplatin and irradiation, complete responses were observed in 10 dogs. Seven dogs had local recurrence. One dog had tumor recurrence in the radiochemotherapy field and six dogs had recurrence at the margin of the radiochemotherapy field, but within the irradiation field. Normal tissue reactions were similar in the radiochemotherapy field and in the margin treated with radiation only. Cumulative effect of repeated intratumoral administration on plasma concentration of cisplatin was not observed. CONCLUSIONS: These findings provide support for an extended investigation of this combined regimen. The lack of systemic toxicity associated with intratumoral administration of cisplatin mixed with collagen may allow a safe clinical evaluation of the interaction between cisplatin and radiation.

Sequence analysis of canine p53 in the region of exons 3-8.

An 828 base pair region of canine wild-type p53, corresponding to codons 25 through 312 in the human p53 gene, was directly sequenced from asymmetric polymerase chain reaction (PCR) products. The deduced amino acid sequence of the dog was 86%, 73% and 83% homologous to that of the cat, mouse and human proteins, respectively. In the evolutionarily conserved domains II through V, the canine sequence approached 100% homology with the human sequence. The region sequenced encompasses exons 3-8 where the majority of mutations have been identified in neoplastic specimens from human patients.

Analysis of the equine tumor suppressor gene p53 in the normal horse and in eight cutaneous squamous cell carcinomas.

Wild type equine p53 was amplified between exons 2 and 9 by the polymerase chain reaction using primers designed from conserved regions in other species. An 828 base pair region, corresponding to codons 25-313 of human p53, was sequenced in both directions. Human and equine amino acid sequences were 87% homologous in this region and 96% homologous in conserved domains II-V. Of eight equine cutaneous or mucocutaneous squamous cell carcinomas directly sequenced from exons 5-8, two had p53 point mutations resulting in single amino acid substitutions.

K-ras mutations in 239PuO2 canine lung neoplasms.

Single-strand conformational polymorphism (SSCP) analysis and direct sequencing methods were used to examine lung tumors derived from a cohort of beagle dogs with inhalational exposures to 239PuO2. These exposures were done at Pacific Northwest Laboratories where 18-month-old beagle dogs were given 239PuO2 by single-dose inhalation and allowed to live out their life-spans. Formalin-fixed paraffin-embedded blocks of tissues from 25 dogs exposed to 239PuO2 by aerosol inhalation which later developed lung tumors were available for this study. Two of 25 tumors had mutations within exon 1 of K-ras detected by SSCP analysis. Both mutations were GGT to GAT transitions at codon 12 confirmed by direct sequencing experiments. One was an adenocarcinoma from the medium-high exposure group and the other was a broncheolo-alveolar carcinoma from the medium-low exposure group. The rate of K-ras mutations in plutonium-induced lung tumors described herein (8%) was greater than previously described in canine plutonium-induced lung tumors (0%), but was less than that which we have described in spontaneous canine lung cancer (16%), less than that reported for human spontaneous non-small cell lung cancer (13-36%) and less than that described in rats with spontaneous lung cancer (40%) or lung tumors following 239Pu inhalation exposure (46%).

False DNA aneuploidy in canine and human neoplasms.

In most cases, the appearance of aneuploid peaks in DNA histograms may be an artefact of tissue preparation or it may reflect non-stoichiometric dye binding of a cellular subpopulation rather than true DNA aneuploidy. This report reviews how false DNA aneuploidy can be recognized and eliminated from sample submitted for DNA flow cytometric analysis.

Canine and bovine ras family expression detected and discriminated by use of polymerase chain reaction.

Cellular proto-oncogenes are highly conserved genes thought to be critical in cell growth and differentiation. In this study, we used human sequence designed oligonucleotide primers to detect and discriminate c-Ha-ras-1, c-Ki-ras-2 and c-N-ras genes of dogs and cows by polymerase chain reaction (PCR) amplification of genomic DNA (DNA/PCR). Further, we have applied PCR for analysis of expressed mRNA transcribed from the RAS genes (RNA/PCR).

Detection of mammalian and avian hepadnaviruses by the polymerase chain reaction.

The hepadnavirus family contains a number of related viruses able to infect a variety of animal species. In the present study, we have used the polymerase chain reaction and oligonucleotide primers to a conserved region of the viral replicase gene of hepadnaviruses to identify viral sequences in de novo tissues in three well-characterized hepadnavirus systems: the woodchuck, ground squirrel and Pekin duck. We did not detect related hepadnavirus sequences in liver specimens from tree squirrels putatively infected with the tree squirrel hepatitis virus, or in liver specimens from horses with hepatitis (serum sickness), or from dogs with chronic active hepatitis or hepatocellular carcinoma.

Flow cytometric analysis of lectin-binding to canine blood lymphocytes.

The cell surface glycoconjugates of blood lymphocytes from 19 dogs with and without neoplastic disease were quantitated using flow cytofluorometric analysis of the binding characteristics of 3 lectins, namely, wheat germ agglutinin, concanavalin-A, and Lens culinaris agglutinin. The specificity of lectin binding was determined using competitive monosaccharide inhibitors. The results show enhanced binding of concanavalin-A to blood lymphocytes from dogs with lymphosarcoma relative to healthy dogs, or those with a variety of neoplastic and nonneoplastic diseases.

Chronic oral infections of cats and their relationship to persistent oral carriage of feline calici-, immunodeficiency, or leukemia viruses.

Two hundred and twenty-six cats from the Veterinary Medical Teaching Hospital (VMTH), a cat shelter, and a purebred cattery were tested for chronic feline calicivirus (FCV), feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) infections. Chronic oral carriage of FCV was present in about one-fifth of the cats in each of the groups. FIV infection was not present in the purebred cattery, was moderately prevalent (8%) in the pet population of cats examined at the VMTH for various complaints and was rampant in the cat shelter (21%). Unexpectedly high FeLV infection rates were found in the hospital cat population (28%) and in the purebred cattery (36%), but not in the cat shelter (1.4%). FCV and FeLV infections tended to occur early in life, whereas FIV infections tended to occur in older animals. From 43 to 100% of the cats in these environments had oral cavity disease ranging from mild gingivitis (23-46%), proliferative gingivitis (18-20%), periodontitis (3-32%) and periodontitis with involvement of extra-gingival tissues (7-27%). Cats infected solely with FCV did not have a greater likelihood of oral lesions, or more severe oral disease, than cats that were totally virus free. This was also true for cats infected solely with FeLV, or for cats dually infected with FeLV and FCV. Cats infected solely with FIV appeared to have a greater prevalence of oral cavity infections and their oral cavity disease tended to be more severe than cats without FIV infection. FIV-infected cats that were coinfected with either FCV, or with FCV and FeLV, had the highest prevalence of oral cavity infections and the most severe oral lesions.

ras p21 expression in ovine pulmonary carcinoma.

We have adapted an enzyme-linked immunoblot assay (ELIBA) for the detection of a c-ras proto-oncogene and oncogene protein products in human cell lines and tumors of 21,000 daltons molecular weight (p21ras) to studies of tissues derived from sheep. In the ELIBA, a double antibody system is used in which p21ras proteins are initially immunoprecipitated from protein extracts with monoclonal antibodies, and subsequently identified using additional anti-ras antibodies. Binding is identified with a non-radioactive enzyme-linked colorimetric detection system. In the present study, the ELIBA system was used to study twenty-seven ovine lung specimens, representing normal lung, inflammatory, and neoplastic lesions. We detected p21ras protein expression in every tissue examined, but the nature and amount of the protein product varied significantly among the tissues examined. Some tissues expressed multiple ras species. Broncho-alveolar carcinoma specimens were most likely to express c-Ki-ras proteins. Mutant proteins of c-N-ras and c-Ki-ras were detected in several bronchoalveolar carcinoma specimens, based on migrational differences between mutant and normal proteins in 15% polyacrylamide gels. The results of this study demonstrate the utility of the ELIBA system for detection of c-ras expression in ovine lung tissues, and demonstrate the ability of the system to discriminate specific ras protein species. The prognostic significance of ras expression in sheep pulmonary carcinoma has yet to be determined.

A comparison of six monoclonal antibodies for detection of cytokeratins in normal and neoplastic canine tissues.

Twenty normal canine tissue specimens, both fetal and adult; 19 epithelial neoplasms; and 18 nonepithelial neoplasms were examined using 6 commercially available monoclonal antibodies differing in their recognition of various molecular weight cytokeratins in human tissues. Fresh tissue samples were fixed in 100% ethanol and paraffin embedded prior to sectioning. The intermediate filament proteins were identified by an avidin-biotin-immunoperoxidase method. Primary antisera used included AE1/AE3, CAM-5.2, 35BH11, 34BE12, PKK1, MAK-6 cytokeratins, and vimentin. Monoclonal antibodies detected cytokeratins in a wide variety of canine epithelial tissues and neoplasms. Normal mesenchymal tissues and neoplasms, and stromal elements of epithelial tissues, showed no reactivity with anti-cytokeratins, but reacted positively with vimentin. Although PKK1, CAM-5.2, and MAK-6 were the most consistently reactive anti-cytokeratins, the full panel of monoclonals was required to detect cytokeratins in all of the epithelia evaluated.

Clostridium difficile: a survey of fecal carriage in cats in a veterinary medical teaching hospital.

Fecal samples collected from 245 cats over a 6-month period were analyzed for the presence of Clostridium difficile. After culture on selective media, isolates were identified by a latex agglutination test, and the presence of toxin A and toxin B gene sequences was determined by polymerase chain reaction. Clostridium difficile was isolated from 23 (9.4%) of the cats, and 34.8% of that group were colonized with toxigenic strains. All of the cats colonized with toxigenic C. difficile had > or = 1 of the risk factors (antibiotic use, antineoplastic therapy, immunosuppressive virus infection) associated with C. difficile infection in humans. Clostridium difficile was not found in any of the cats from a clinically healthy outpatient group of cats examined from the same hospital nor in cats from a specific-pathogen-free research colony on the same campus tested during the same time period. The data obtained in this study confirm the presence of C. difficile in cats at a veterinary teaching hospital. DNA fingerprinting analysis of these isolates allowed separation of the strains into 5 groups. Type 4 strain found in 7 cats was also recovered from the floor drain in the same hospital, suggesting a possible source of infection. Whether the organism is of clinical significance in diarrheal diseases of cats remains to be determined.

Apparent outbreaks of Clostridium difficile-associated diarrhea in horses in a veterinary medical teaching hospital.

Intestinal colonization with toxigenic strains of Clostridium difficile was documented in 9 of 10 horses with acute onset diarrhea in a veterinary medical teaching hospital, whereas a similar isolate was detected in only 1 of 23 other horses without diarrhea in the hospital. One horse with diarrhea was infected simultaneously with both C. difficile and Salmonella krefeld. Clostridium difficile was detected by fecal culture on selective medium, confirmed with a latex particle agglutination test, and identified as toxigenic by polymerase chain reaction amplification of toxin A and toxin B gene sequences. Using an arbitrarily-primed polymerase chain reaction, 6 distinct C. difficile isolates were detected in the feces of the 9 affected horses at the time of the outbreak of diarrhea.

Apoptotic and proliferation indexes in canine lymphoma.

Proliferative and apoptotic fractions of tumors were evaluated in 41 dogs with lymphoma for prediction of response to chemotherapy. All dogs had advanced clinical stage tumors, were untreated prior to study, and received identical induction-remission chemotherapy. Tumor cell proliferation was determined in all pretreatment biopsy specimens and in 18 specimens collected at the time of clinical relapse from remission. Quantitative measures included mitotic index and immunoreactivities for proliferating cell nuclear antigen (PCNA) and Ki-67. Apoptotic index was evaluated from 40 dogs pretreatment and from 16 dogs at the time of first relapse. Pretreatment tumor values for Ki-67, PCNA, and apoptosis were compared with posttreatment values. The median first relapse-free interval (RFI) and overall survival (OS) time were 174 days and 445 days, respectively. Of the proliferation markers, only the results of the Ki-67 analysis were predictive for duration of the first RFI but not OS. Pretreatment apoptotic index was also predictive of the duration of first RFI but not OS. No significant predictive value for comparison of the pretreatment and postrelapse values was demonstrated. Ki-67 labeling index and apoptotic indexes were combined to form both a proliferation/apoptotic ratio (PAR) and a sum, or turnover index. Only the PAR was predictive for duration of first RFI on multivariate analysis. Other variables that were evaluated for their influence on treatment outcome included patient age, weight, gender, clinical stage, clinical substage, and tumor immunophenotype. Of these variables, only immunophenotype was found to be of value for predicting duration of first RFI and OS.