Establishment of two vaccine-associated feline sarcoma cell lines and determination of in vitro chemosensitivity to doxorubicin and mitoxantrone

In vitro chemosensitivity testing of the feline large granular lymphocyte cell line (S87)

BACKGROUND

Feline large granular lymphocyte (LGL) lymphoma is an aggressive neoplasia characterised by short survival and poor response to chemotherapy.

OBJECTIVES

In this study, the effect of different chemotherapeutic agents on the growth kinetics of the feline cell line S87, a non-MHC-restricted feline LGL cell line, was investigated. Where possible, IC50 (inhibitory concentration 50) values were determined. The IC50 values of the cell line as lymphoma models can provide clues to the situation in vivo and serve as a basis for studying resistance mechanisms.

METHODS

Cells were incubated with various concentrations of vincristine, doxorubicin, 4-hydroperoxycyclophosphamide, prednisolone, methotrexate and L-asparaginase for 24 and 48 h, respectively.

RESULTS

The IC50 values could be determined as 14.57 (7.49-28.32) μg/mL at 24 h incubation and 5.72 (4.05-8.07) μg/mL at 48 h incubation for doxorubicin and 9.12 (7.72-10.76) μg/mL at 24 h incubation and 4.53 (3.74-5.47) μg/mL at 48 h incubation for 4-hydroperpoxycyclophosphamide. Treatment with vincristine and methotrexate resulted in relatively high cell resistance whereas L-asparaginase and prednisolone treatment led to a reduction in cell number compared to control while cell viability was not affected (cytostatic effect).

CONCLUSION

Overall, the feline LGL cell line S87 proves to be relatively sensitive to doxorubicin and 4-hydroperoxycyclophosphamide and relatively resistant to treatment with vincristine, prednisolone, methotrexate and L-asparaginase. The results of this study can be used for further investigations on resistance mechanisms in feline LGL lymphoma. Doxorubicin and cyclophosphamide can be interpreted as promising candidates for the therapy of feline LGL lymphomas.

Pharmacokinetics of platinum and safety evaluation of carboplatin-impregnated calcium sulfate hemihydrate beads after implantation in healthy cats

OBJECTIVE

To evaluate the pharmacokinetics (PK) of platinum (Pt) and safety of carboplatin-impregnated calcium sulfate hemihydrate (C-I CSH) beads after implantation in healthy cats.

STUDY DESIGN

In vivo experimental study.

ANIMALS

Six healthy adult cats.

METHODS

Three C-I CSH beads were implanted in muscle pockets over the right and left hemithoraces of each cat (~3.9 mg/kg of Pt; 60.4 mg/m² of calculated carboplatin). Hematology and blood chemistry were tested at baseline and 3, 7, 14, and 21 days postimplantation. Serum was analyzed for Pt at specific times from 1 hour to 21 days. Tissue was obtained for histopathology and analysis of Pt at 3, 7, 14, and 21 days at standardized distances from implantation sites.

RESULTS

Platinum was detected in tissues at all times and distances (range, 0.1-4.19 μg/g). Serum Pt increased up to 2.6 hours (3.25 μg/mL) then decreased sharply. Samples containing muscle had higher Pt compared with samples without muscle (P = .004). Mild hypercalcemia was noted in four cats, and mild inflammatory reaction was noted on histopathology of all samples.

CONCLUSION

Platinum was released from C-I CSH beads differentially into surrounding tissues over 21 days. Systemic absorption of Pt was minimal, but mild hypercalcemia occurred.

CLINICAL SIGNIFICANCE

Implantation was well tolerated by healthy adult cats. Securing beads within muscle may limit Pt diffusion to targeted tissue. Although Pt concentrations did not achieve levels reported to be cytotoxic for feline sarcoma cells in culture, results provide evidence to support evaluation of efficacy in the tumor microenvironment of cats with locally invasive cancers.

Evaluation of adjuvant chemotherapy in feline injection site-associated sarcoma

ABSTRACT Feline Injection Site-Associated Sarcoma (FISS) is a neoplasm that implies in reduction of quality of life and overall survival in feline patients. A retrospective study of 13 cases of FISS was conducted to evaluate the efficacy of surgical treatment associated to chemotherapy with doxorubicin or carboplatin. Local recurrence occurred in all patients. Patients treated with surgery and chemotherapy presented a longer overall survival and disease-free interval when compared to those that solely received surgical treatment, although no statistical significance was observed (p= 0.3360 and 0.7506, respectively). Surgery remains as the main option for FISS treatment. Further prospective studies with larger samples are warranted to investigate the benefit of chemotherapy for this neoplasm.

Current knowledge on feline injection-site sarcoma treatment

Feline injection-site sarcomas (FISS) are malignant skin tumours of mesenchymal origin, the treatment of which is a challenge for veterinary surgeons. The role of surgery, radiotherapy and chemotherapy in FISS treatment has been studied, and a correlation between “clean” surgical margins and disease-free survival has been shown. In addition, clean surgical margins are one of the most important factors for achieving a low recurrence rate. The most effective method of FISS treatment includes combining radical surgery with pre- or postoperative radiotherapy. Chemotherapy may be used as a palliative method of treatment or may be considered an adjunctive therapy for surgery and radiotherapy. In cats with FISS without metastasis, the use of immunostimulant treatment with Oncept IL-2, intended as a complementary immunotherapy in association with surgery and brachytherapy, may also be considered to reduce the risk of relapse and increase the time to relapse. Additionally, this review focuses on recent advances in FISS treatment, including the use of novel compounds, such as doxorubicin conjugated to glutathione-stabilized gold nanoparticles, liposomal doxorubicin or tyrosine kinase inhibitors.

Cats, Cancer and Comparative Oncology

Naturally occurring tumors in dogs are well-established models for several human cancers. Domestic cats share many of the benefits of dogs as a model (spontaneous cancers developing in an immunocompetent animal sharing the same environment as humans, shorter lifespan allowing more rapid trial completion and data collection, lack of standard of care for many cancers allowing evaluation of therapies in treatment-naïve populations), but have not been utilized to the same degree in the One Medicine approach to cancer. There are both challenges and opportunities in feline compared to canine models. This review will discuss three specific tumor types where cats may offer insights into human cancers. Feline oral squamous cell carcinoma is common, shares both clinical and molecular features with human head and neck cancer and is an attractive model for evaluating new therapies. Feline mammary tumors are usually malignant and aggressive, with the ‘triple-negative’ phenotype being more common than in humans, offering an enriched population in which to examine potential targets and treatments. Finally, although there is not an exact corollary in humans, feline injection site sarcoma may be a model for inflammation-driven tumorigenesis, offering opportunities for studying variations in individual susceptibility as well as preventative and therapeutic strategies.

Enhancing anti-tumor efficacy of Doxorubicin by non-covalent conjugation to gold nanoparticles - in vitro studies on feline fibrosarcoma cell lines

Background

Feline injection-site sarcomas are malignant skin tumors of mesenchymal origin, the treatment of which is a challenge for veterinary practitioners. Methods of treatment include radical surgery, radiotherapy and chemotherapy. The most commonly used cytostatic drugs are cyclophosphamide, doxorubicin and vincristine. However, the use of cytostatics as adjunctive treatment is limited due to their adverse side-effects, low biodistribution after intravenous administration and multidrug resistance. Colloid gold nanoparticles are promising drug delivery systems to overcome multidrug resistance, which is a main cause of ineffective chemotherapy treatment. The use of colloid gold nanoparticles as building blocks for drug delivery systems is preferred due to ease of surface functionalization with various molecules, chemical stability and their low toxicity.

Methods

Stability and structure of the glutathione-stabilized gold nanoparticles non-covalently modified with doxorubicin (Au-GSH-Dox) was confirmed using XPS, TEM, FT-IR, SAXRD and SAXS analyses. MTT assay, Annexin V and Propidium Iodide Apoptosis assay and Rhodamine 123 and Verapamil assay were performed on 4 feline fibrosarcoma cell lines (FFS1WAW, FFS1, FFS3, FFS5). Statistical analyses were performed using Graph Pad Prism 5.0 (USA).

Results

A novel approach, glutathione-stabilized gold nanoparticles (4.3 +/- 1.1 nm in diameter) non-covalently modified with doxorubicin (Au-GSH-Dox) was designed and synthesized. A higher cytotoxic effect (p<0.01) of Au-GSH-Dox than that of free doxorubicin has been observed in 3 (FFS1, FFS3, FFS1WAW) out of 4 feline fibrosarcoma cell lines. The effect has been correlated to the activity of glycoprotein P (main efflux pump responsible for multidrug resistance).

Conclusions

The results indicate that Au-GSH-Dox may be a potent new therapeutic agent to increase the efficacy of the drug by overcoming the resistance to doxorubicin in feline fibrosarcoma cell lines. Moreover, as doxorubicin is non-covalently attached to glutathione coated nanoparticles the synthesized system is potentially suitable to a wealth of different drug molecules.

In vitro efficacy of doxorubicin and etoposide against a feline injection site sarcoma cell line

Feline injection site sarcoma (ISS) is a locally invasive tumor, in which surgical treatment is frequently combined with radiation or chemotherapy to improve tumor control. The focus of this study was to evaluate the cytotoxic effects of doxorubicin or etoposide on a feline injection site sarcoma cell line (JB) and to assess the impact of combining these drugs on cell death and cell cycle. Both single agent and combination drug administration increased cell death and significantly reduced the number of viable cells. Cells in G0/G1 were significantly reduced while the G2/M fraction was significantly increased following treatment. Collectively, combining doxorubicin and etoposide at the lower EC yielded comparable results to the EC50 of either drug alone in degree of cytotoxicity, level of apoptosis, and % of cells in G2/M. The results of this study indicate that doxorubicin and etoposide alone and in combination differentially alter ISS cell viability and cycle.

Feline injection site-associated sarcoma: Is it a reason to critically evaluate our vaccination policies?

Feline injection site-associated sarcoma (FISAS) or vaccination-associated sarcoma is a serious problem in cats because of the ethical and therapeutic consequences associated with the disease. The exact aetiology of FISAS is unclear; therefore, instituting preventative measures such as delaying or discontinuing vaccination schedules is questionable. This paper will give insights into the disease process, will attempt to answer the question, "what causes FISAS?", and will discuss preventative measures to decrease the chance of occurrence. Tumours are in general uncommon in the cat, however, malignant tumours, such as sarcomas, occur relatively frequently. FISAS have stimulated interest because of their reported linkage to certain types of vaccine. FISASs are reported to have an incidence of 1-10 per 10,000 cats and often appear in conjunction with a traumatic incident (such as a vaccination). The tumour displays an extreme malignant biological behaviour, both being locally aggressive and metastasising in 25-70% of the cases. Although the pathology still remains unclear, an exaggerated inflammatory/granulomatous response seems to be the predisposing factor in the transformation to FISAS. A multi-step carcinogenesis model, including genetic, iatrogenic and local factors seems to be the most plausible explanation for the occurrence of the tumour. Multi-modal therapy, based on aggressive surgical removal of the tumour in combination with radiation and/or chemotherapy, is usually recommended but randomised clinical studies have not yet been performed to prove the efficacy of any of the modalities. The question of whether FISAS can be prevented by not injecting irritant products remains unanswered. No specific brands of vaccine, manufacturers or factors associated with vaccine administration have been significantly associated with FISAS in a multi-institutional and epidemiological study. Control and evaluation measures as recommended by the US-based taskforce include determination of risk groups, extending re-vaccination intervals, the use of single component products and the use of consistent, predetermined sites for vaccination.

Somatic alterations of thep53tumor suppressor gene in vaccine-associated feline sarcoma

OBJECTIVE

To determine somatic alterations in p53 in vaccine-associated feline sarcoma (VAFS). Animals-27 domestic shorthair cats undergoing first surgical treatment for primary VAFS with no history of chemotherapy or gamma radiation.

PROCEDURES

Sequence analysis was performed on the genomic sequence of p53 (between exons 5 through 9) from tumor and blood samples obtained from the cats. Cats were monitored for 3 years and disease-free intervals and survival times calculated.

RESULTS

Eight single nucleotide polymorphisms were detected within the genomic sequence of p53, with 20 of 27 cats (74%) having heterozygosity at > or = 1 polymorphic site. Somatic loss of heterozygosity at p53 was detected in the primary tumors of 12 of these 20 (60%) cats. Such allelic deletion was significantly associated with rapid tumor recurrence and reduced overall survival. Point mutations were rare, occurring in 3 of 27 primary tumors. The finding of malignant cells in the surgical margins was significantly associated with disease recurrence, but clear margins (with no detectable malignant cells) were not predictive of positive outcome.

CONCLUSIONS AND CLINICAL RELEVANCE

p53 status is an indicator of postsurgical recurrence and overall survival in cats with VAFS. Careful follow-up is important in treating vaccine-site tumors containing allelic deletion of p53, whereas aggressive surgical treatment may be sufficient to control primary vaccination site tumors without the allelic loss.

Results of a phase II clinical trial on the use of ifosfamide for treatment of cats with vaccine-associated sarcomas

OBJECTIVE

To determine clinical activity and toxic effects of ifosfamide when used to treat cats with vaccine-associated sarcoma (VAS).

ANIMALS

27 cats with a nonresectable, recurrent, or metastatic VAS.

PROCEDURE

Each cat received ifosfamide (900 mg/m(2) of body surface area) as an IV infusion during a 30-minute period. Diuresis by infusion of saline (0.9% NaCl) solution and administration of mesna were used to prevent urothelial toxicosis. Treatments were administered every 3 weeks, and tumor response was assessed after the second treatment. All ifosfamide-associated toxic effects were graded in accordance with predetermined criteria.

RESULTS

61 treatments were administered to 27 cats (median, 2 treatments/cat; range, 1 to 4 treatments/cat). After ifosfamide treatment, 1 cat had a complete response and 10 had partial responses for an overall response rate of 11 of 27 (41%; 95% confidence interval [CI], 25% to 59%). Responses lasted from 21 to 133 days (median, 70 days; 95% CI, 60 to 113 days). The acute dose-limiting toxicosis was neutropenia, which was detected 5 to 28 days (median, 7 days) after treatment. Median nadir neutrophil count was 1,600 cells/muL (range, 200 to 5,382 cells/microL). Nine (33%) cats had adverse gastrointestinal effects (primarily salivation during the ifosfamide infusion and inappetence after treatment). Two cats were euthanatized because of severe nephrotoxicosis, and 1 cat developed pulmonary edema during diuresis.

CONCLUSIONS AND CLINICAL RELEVANCE

Ifosfamide has antitumor activity against VAS in cats and is tolerated well by most cats. Ifosfamide should be evaluated as an adjuvant treatment for cats with VAS.

Surgery alone versus surgery and doxorubicin for the treatment of feline injection-site sarcomas: a report on 69 cases

Sixty-nine cats were treated for injection-site sarcomas at the Veterinary Teaching Hospital of Grugliasco, Turin (Italy). The animals were divided into two subgroups: those subjected to four doxorubicin cycles combined with radical surgical excision 10 days after the second chemotherapy cycle (group A, 49 cats) or those treated with surgery alone (group B, 20 cats). Each cat was monitored for lung metastasis and local recurrence. In group A, 28 cats were alive at the end of the follow-up period. In this group, the recurrence rate was 40.8% while lung metastasis occurred in 12% of cats. In group B, eight animals were alive at the end of the follow-up period, while the rates of recurrence and metastasis were 35% and 10%. Neither the median disease-free interval nor the median overall survival was reached in either group. Moreover, there were no statistically significant differences between the two groups.

Feline injection site sarcomas

Injection site sarcomas in cats have been the topic of more than 40 articles and over 20 scientific abstracts as well as multiple letters to veterinary journals, articles in the popular press, and Internet-based web sites. With the level of discussion that has surrounded this tumor entity, one might expect that great strides have been made in determining the etiology, epidemiology, and preferred treatment options for this disease. Nearly half of the publications on this subject are review articles, however, and that alone indicates both the high level of interest and the lack of information in this situation. This article summarizes the development of our current understanding of this tumor with regard to areas of research into the cause of injection site sarcomas, epidemiology, and the current standard of care for treatment of this iatrogenic disease.

Principles of treatment for vaccine-associated sarcomas

In the last decade, there has been a great deal of information surrounding the etiology, diagnosis, and treatment of feline vaccine-associated sarcomas. The presence of a mass in areas used for subcutaneous or intramuscular injections should alert the clinician to the possibility of a vaccine-associated sarcoma. Early detection and subsequent treatment is paramount to limit local invasion and distant metastasis. The current data are suggesting that a team approach with multi-modality therapy is the appropriate way to address this disease. In the following article, we will discuss the history/incidence, pathology, diagnosis, and current treatment options, which include a combination of surgery, radiation, and chemotherapy for vaccine-associated sarcomas.

Medical management of soft tissue sarcomas

Local therapies for STS, including aggressive surgical resection and radiation therapy, have improved dramatically over the last 10 years. This has resulted in improvement of important clinical outcomes such as enhanced rates of local control and higher quality of life for patients. Systemic therapy for STS, although efficacious to a certain degree, remains investigational. A major task for oncologists will be to measure accurately the single-agent activity of drugs and to integrate promising agents into multiagent regimens. This approach may allow significant progress in the management of STS in canine and feline patients.

Injection site sarcomas in cats

Feline injection-site sarcomas have mostly been associated with the administration of vaccines. Although the pathogenesis remains largely unknown, it is believed that the inflammatory reaction caused from the injection of the compound leads to uncontrolled proliferation of fibroblasts and myofibroblasts that in a subset of cats undergo malignant transformation. Pretreatment evaluation and proper planning of the therapy are essential. Because of the aggressive nature of these tumors, a multimodality treatment approach is being recommended. A combination of surgery and radiation therapy with or without chemotherapy appears to be providing the best prognosis.

Evaluation of in vitro chemosensitivity of vaccine-associated feline sarcoma cell lines to vincristine and paclitaxel

OBJECTIVE

To determine the in vitro sensitivity of 4 vaccine-associated feline sarcoma (VAFS) cell lines to the chemotherapeutic agents vincristine and paclitaxel.

SAMPLE POPULATION

Cell lines derived from 4 VAFS specimens.

PROCEDURES

Cell lines were cultured in vitro and individually exposed to various concentrations of vincristine and paclitaxel. Survival was estimated after 24 and 72 hours of exposure to each drug, and the drug concentrations that resulted in 50 and 90% reduction in number of viable cells (IC50 and IC90, respectively) were calculated.

RESULTS

Both vincristine and paclitaxel had significant dose-dependent effects on the viability of the VAFS cell lines. After 72 hours of drug exposure, the IC50 and IC90 of vincristine for the 4 cell lines were between 0.005 to 0.039 microg/ml and 0.045 to 1.027 microg/ml, respectively. The IC50 and IC90 values for paclitaxel were between 0.037 to 0.092 microg/ml and 2.450 to 15.413 microg/ml, respectively.

CONCLUSIONS

Results of pharmacokinetic studies on vincristine and paclitaxel in other species suggest that concentrations greater than the IC50 values may be possible for both drugs in feline patients as well. The drug concentrations at which viable cell numbers were reduced by 90% may also be attained in vivo for some cases, but detailed information is needed regarding the distribution, concentration, duration of availability, and toxicity of various drugs in cats. Carefully chosen combinations of antineoplastic agents need to be screened to identify treatment protocols that may be further evaluated clinically for the treatment of VAFS.