Attenuated Semliki Forest virus for cancer treatment in dogs: safety assessment in two laboratory Beagles.

BACKGROUND: Dogs suffer from spontaneous tumors which may be amenable to therapies developed for human cancer patients, and dogs may serve as large-animal cancer models. A non-pathogenic Semliki Forest virus vector VA7-EGFP previously showed promise in targeting human tumor xenografts in mice, but the oncolytic capacity of the virus in canine cancer cells and the safety of the virus in higher mammals such as dogs, are not known. We therefore assessed the oncolytic potency of VA7-EGFP against canine cancer cells by infectivity and viability assays in two dog solid tumor cell lines. Furthermore we performed a 3-week safety study in two adult Beagles which received a single intravenous injection of ~2 × 10(5) plaque forming units of parental A7(74) strain. RESULTS: VA7-EGFP was able to replicate in and kill both canine cancer cell lines tested. No adverse events were observed in either of the two virus-injected adult Beagles and no infective virus could be recovered from any of the biological samples collected over the course of the study. Neutralizing antibodies to Semliki Forest virus became detectable in the dogs at 5 days post infection and remained elevated until study termination. CONCLUSIONS: Based on these results, testing of the oncolytic potential of attenuated Semliki Forest virus in canine cancer patients appears feasible.

Incomplete but infectious vaccinia virions are produced in the absence of oncolysis in feline SCCF1 cells.

Vaccinia virus is a large, enveloped virus of the poxvirus family. It has broad tropism and typically virus replication culminates in accumulation and lytic release of intracellular mature virus (IMV), the most abundant form of infectious virus, as well as release by budding of extracellular enveloped virus (EEV). Vaccinia viruses have been modified to replicate selectively in cancer cells and clinically tested as oncolytic agents. During preclinical screening of relevant cancer targets for a recombinant Western Reserve strain deleted for both copies of the thymidine kinase and vaccinia growth factor genes, we noticed that confluent monolayers of SCCF1 cat squamous carcinoma cells were not destroyed even after prolonged infection. Interestingly, although SCCF1 cells were not killed, they continuously secreted virus into the cell culture supernatant. To investigate this finding further, we performed detailed studies by electron microscopy. Both intracellular and secreted virions showed morphological abnormalities on ultrastructural inspection, suggesting compromised maturation and morphogenesis of vaccinia virus in SCCF1 cells. Our data suggest that SCCF1 cells produce a morphologically abnormal virus which is nevertheless infective, providing new information on the virus-host cell interactions and intracellular biology of vaccinia virus.

Safety and biodistribution of a double-deleted oncolytic vaccinia virus encoding CD40 ligand in laboratory Beagles.

We evaluated adverse events, biodistribution and shedding of oncolytic vaccinia virus encoding CD40 ligand in two Beagles, in preparation for a phase 1 trial in canine cancer patients. Dog 1 received one dose of vaccinia virus and was euthanized 24 hours afterwards, while dog 2 received virus four times once weekly and was euthanized 7 days after that. Dogs were monitored for adverse events and underwent a detailed postmortem examination. Blood, saliva, urine, feces, and organs were collected for virus detection. Dog 1 had mild fever and lethargy while dog 2 experienced a possible seizure 5.5 hours after first virus administration. Viral DNA declined quickly in the blood after virus administration in both dogs but was still detectable 1 week later by quantitative polymerase chain reaction. Only samples taken directly after virus infusion contained infectious virus. Small amounts of viral DNA, but no infectious virus, were detected in a few saliva and urine samples. Necropsies did not reveal any relevant pathological changes and virus DNA was detected mainly in the spleen. The dogs in the study did not have cancer, and thus adverse events could be more common and viral load higher in dogs with tumors which allow viral amplification.

A nonhealing ulcerative skin lesion associated with Trichinella nativa infection in a cat.

Trichinella spp. can infect various domestic and wild species, including companion animals. Infection occurs because of the ingestion of raw meat (e.g., infected prey). In experimental studies, cats have been found to be a very susceptible host to infection by Trichinella spp.; naturally occurring feline infections have also been reported. However, clinically apparent disease seems to be a rare manifestation of this infection in cats. The skin biopsy of an 8-year-old, neutered, male, domestic cat revealed an inflammatory granulation tissue that surrounded a well-preserved cyst that contained a Trichinella sp. larva. Distinct seropositive reaction against Trichinella spp. antigens was demonstrated by enzyme-linked immunosorbent assay and Western blot. Immunohistochemistry, by using serum from the infected cat as the source of antibody, showed strong immunostaining of Trichinella spp. larvae. During a 1-year follow-up, a postexcisional local tissue reaction was observed. This manifested as a firm, poorly circumscribed subcutaneous mass adjacent to the eye, which demonstrated clinical features and histopathologic findings indicative of chronic inflammation associated with granulation tissue and fibrodysplasia. Digestion of the muscle biopsy revealed one Trichinella sp. larva, which was identified by multiplex polymerase chain reaction as Trichinella nativa. To the authors' knowledge, this is the first documented case of trichinellosis in a cat with a nonhealing ulcerative skin lesion as the main clinical manifestation of the infection.

Oral bioavailability of etoposide after administration of a single dose to tumor-bearing dogs.

OBJECTIVE: To characterize oral bioavailability and pharmacokinetic disposition of etoposide when the IV formulation was administered orally to dogs. ANIMALS: 8 tumor-bearing dogs. PROCEDURES: An open-label, single-dose, 2-way crossover study was conducted. Dogs were randomly assigned to initially receive a single dose of etoposide (50 mg/m2) IV or PO. A second dose was administered via the alternate route 3 to 7 days later. Medications were administered before IV administration of etoposide to prevent hypersensitivity reactions. Oral administration of etoposide was prepared by reconstituting the parenteral formulation with 0.9% NaCl solution and further diluting the reconstituted mixture 1:1 with a sweetening agent. Plasma samples were obtained after both treatments. Etoposide concentrations were measured with a high-performance liquid chromatography assay, and plasma etoposide concentration-time profiles were analyzed by use of noncompartmental methods. RESULTS: 4 dogs had hypersensitivity reactions during IV administration of etoposide. No adverse effects were detected after oral administration. Plasma etoposide concentrations were undetectable in 2 dogs after oral administration. Oral administration of etoposide resulted in significantly lower values for the maximum plasma concentration and the area under the plasma etoposide concentration-versus-time curve, compared with results for IV administration. Oral bioavailability of etoposide was low (median, 13.4%) and highly variable among dogs (range, 5.7% to 57.3%). CONCLUSIONS AND CLINICAL RELEVANCE-Vehicle-related toxicosis can limit the IV administration of etoposide in dogs. The parenteral formulation of etoposide can be safely administered orally to dogs, but routine use was not supported because of low and variable oral bioavailability in this study.

Microalbuminuria is not associated with cisplatin-induced azotemia in dogs.

BACKGROUND: Cisplatin is an effective antineoplastic agent but its use is limited by renal toxicity. Microalbuminuria is a marker of renal damage and might be an indicator of cisplatin-induced azotemia. NULL HYPOTHESIS: Microalbuminuria is not associated with azotemia in dogs treated with cisplatin. ANIMALS: This study used 32 client-owned dogs. METHODS: This was a prospective observational study in which cancer-bearing dogs were treated with cisplatin chemotherapy. Cisplatin-induced azotemia was defined as an increase of serum creatinine concentration above the reference range. Serum creatinine concentration, other routine tests of renal function, and microalbuminuria were measured after each cisplatin treatment. Variables potentially associated with azotemia were compared by use of Fisher's exact test and Wilcoxon's rank-sum test. RESULTS: Cisplatin-induced azotemia occurred in 10 (31%) dogs after 1-5 treatments. At each of the first 3 treatments, the proportions of dogs with microalbuminuria were similar between dogs with and without azotemia. CONCLUSIONS AND CLINICAL IMPORTANCE: Microalbuminuria measured after each treatment was not associated with azotemia through the first 3 treatments. Testing for microalbuminuria as a marker for cisplatin-induced renal damage is insensitive and not recommended.

Comparison of 3 protocols for treatment after induction of remission in dogs with lymphoma.

BACKGROUND: The optimal treatment after inducing complete remission (CR) in dogs with lymphoma has not been established. HYPOTHESIS: After inducing CR with L-asparaginase, vincristine, cyclophosphamide, doxorubicin, prednisone (L-CHOP); consolidation with either half-body radiation therapy (HBRT); or lomustine (CCNU) and mechlorethamine, vincristine, procarbazine, prednisone (MOPP) would improve first remission duration compared with continuing a CHOP-based protocol for an additional 4 months. ANIMALS: Dogs with stage III-V lymphoma. METHODS: Prospective clinical trial in which dogs initially were treated with an 8-week induction protocol that consisted of L-CHOP. Dogs in CR after induction were then allocated to 1 of 2 consolidation arms. A chemotherapy consolidation arm consisted of 2 treatments with CCNU and 1 cycle of MOPP. A HBRT arm consisted of 2 sequential 8.0-Gy fractions to the cranial and caudal half-body separated by 30 days. Vincristine was given between fractions. Results of the consolidation arms also were compared with a historical group treated with the same 8-week induction protocol followed by CHOP therapy until week 24. RESULTS: Overall, 67% of the dogs were in CR after 8 weeks of induction chemotherapy and were compared. Fifty-two dogs were in the historical arm, 23 in the CCNU/MOPP arm, and 27 in the HBRT arm. No difference in first remission duration was found among groups. Median first remission duration for the historical, CCNU/MOPP, and HBRT arms were 307, 274, and 209 days, respectively (P = .28). Overall second CR rate was 82% and was not different among groups (all P > or = .58). Overall remission duration (P = .28) and survival time (P = .48) were not different among groups. CONCLUSIONS AND CLINICAL IMPORTANCE: Consolidation with either CCNU/MOPP or HBRT showed no advantage over a standard CHOP-based protocol.