Gemcitabine as a Radiosensitizer for Nonresectable Feline Oral Squamous Cell Carcinoma

Tracheal Squamous Cell Carcinoma Treated with Tracheal Resection and Anastomosis in a Cat

A 10-year-old male castrated domestic shorthair cat presented for a suspected tracheal mass. Radiographs confirmed an intraluminal tracheal mass. Tracheal resection and anastomosis of 5 tracheal rings was performed with minimal, mild intraoperative complications and no postoperative complications. Histopathology of the tracheal mass revealed a diagnosis of squamous cell carcinoma (SCC) with incomplete margins both cranially and caudally. Further treatment, including surgical revision, radiation therapy, or chemotherapy, was recommended. At the time of publication, no further treatment has been initiated, and a scheduled consultation with the oncologist has been canceled. The cat is doing well at home with no reported signs of recurrence 120 days postoperatively. This is the first report of a cat with a tracheal SCC to be treated with a tracheal resection and anastomosis and only the third feline tracheal SCC to be treated in the veterinary literature.

Outcomes of cats treated with maxillectomy: 60 cases. A Veterinary Society of Surgical Oncology retrospective study

Maxillectomy is poorly described for the management of oral tumours in cats and is occasionally not recommended because of the high complication rate and sub-optimal outcome reported in cats treated with mandibulectomy. The purpose of this study was to retrospectively evaluate the complications and oncologic outcome in cats treated with maxillectomy. Sixty cats were included in the study. Maxillectomy procedures included unilateral rostral (20.0%), bilateral rostral (23.3%), segmental (10.0%), caudal (20.0%) and total unilateral maxillectomy (26.7%). Intra-operative and post-operative complications were reported in 10 (16.7%) and 34 (56.7%) cats, respectively. The most common post-operative complications were hyporexia (20.0%) and incisional dehiscence (20.0%). The median duration of hyporexia was 7 days. Benign tumours were diagnosed in 19 cats (31.7%) and malignant tumours in 41 cats (68.3%). Local recurrence and metastatic rates were 18.3% and 4.9%, respectively; the median progression-free interval (PFI) was not reached. The disease-related median survival time was not reached overall or for either benign or malignant tumours. The 1- and 2-year survival rates were, respectively, 100% and 79% for cats with benign tumours, 89% and 89% for cats with malignant tumours, 94% and 94% for cats with fibrosarcomas, 83% and 83% for cats with squamous cell carcinomas, and 80% and 80% for cats with osteosarcomas. Poor prognostic factors included mitotic index for PFI, adjuvant chemotherapy for both PFI and survival time, and local recurrence for survival time. Maxillectomy is a viable treatment option for cats resulting in good local tumour control and long survival times.

Toxicity and outcome in cats with oral squamous cell carcinoma after accelerated hypofractionated radiotherapy and concurrent systemic treatment

Recently, a multimodal approach to oral squamous cell carcinoma (SCC) in cats, combining medical treatment and accelerated radiation therapy, showed a substantial outcome improvement in a small pilot study. Herein we retrospectively review 51 cats with unresectable, histologically confirmed oral SCC and a complete initial staging work-up: cats in group A (n = 24) received medical anti-angiogenic treatment consisting of bleomycin, piroxicam and thalidomide, cats in group B (n = 27) received the anti-angiogenic treatment and concurrent accelerated hypofractionated radiation therapy with 48Gy delivered in 10 fractions. Overall median progression-free interval (PFI) was poor with 70 days (95% CI: 48;93). In the irradiated cats (group B), however, PFI was significantly longer with 179 days (95% CI: 58;301) days, vs 30 days (95% CI: 23;38) in medically only treated cats (P < .001). Overall median overall survival (OS) was 89 days (95% CI: 55;124), again significantly longer in the irradiated cats (group B) with 136 (95% CI: 40;233) vs 38 days (95% CI: 23;54) (P < .001). In 8 of the 27 (29.6%) cats in group B, however, severe toxicity (grade 3) occurred. Neither onset nor severity of toxicity could be associated with any of the tested variables, including anatomic site, tumour size, clinical stage and duration of neoadjuvant medical treatment. Given the potential severe acute effects and the impact on quality of life after chemo-radiotherapy, owners must be clearly informed about the risks of treatment. With the overall poor outcome and high occurrence of acute toxicity, we cannot recommend the use of this accelerated radiation protocol combined with anti-angiogenic therapy for oral SCC in cats.

Immunohistochemical Features of Epithelial-Mesenchymal Transition in Feline Oral Squamous Cell Carcinoma

Feline oral squamous cell carcinoma (FOSCC) is an aggressive malignancy with invasive and metastatic behavior. It is poorly responsive to chemotherapy and radiation. Neoplastic epithelial-mesenchymal transition (EMT) portends highly malignant behavior and enhances resistance to therapy. In transitioning to a more malignant phenotype, carcinoma stem cells undergo transformation mediated by expression of proteins, endowing them with mesenchymal properties advantageous to cell survival. The goal of the current study was to identify proteins associated with EMT in FOSCC. This study documents protein expression patterns in 10 FOSCC biopsies and 3 FOSCC cell lines (SCCF1, SCCF2, SCCF3), compatible with an EMT phenotype. As markers of EMT, P-cadherin, N-cadherin, vimentin, nuclear transcription factors Twist and Snail, hypoxia inducible factor 1α (HIF-1α), programmed death ligand 1, and vascular endothelial growth factor D, as well as E-cadherin, were examined using immunohistochemistry, Western blot, and enzyme-linked immunosorbent assay. P-cadherin, Twist, HIF-1α, and programmed death ligand 1 were commonly expressed in biopsies and cell lines. N-cadherin, classically associated with EMT, was not highly expressed, and E-cadherin was coexpressed along with proteins characteristic of EMT in all specimens. Production of vascular endothelial growth factor A by cell lines, a process regulated by HIF-1α expression, was suppressed by the small-molecule inhibitor dasatinib. These data are consistent with EMT in FOSCC and shed light on cellular changes that could contribute to the aggressive behavior of FOSCC.

Vicenin-2: a potential radiosensitizer of non-small cell lung cancer cells

Non-small cell lung cancer (NSCLC) is a major form of cancer and is resistant to chemo- and radio-therapy. Vicenin-2 (VCN-2) is a flavonoid obtained from Ocimum sanctum L. and it has been reported to have radioprotective and anti-cancer properties. This study was conducted to check for the radiosensitizing potential of VCN-2 in the NSCLC cell line, NCI-H23. NCI-H23 cells were exposed to VCN-2 singularly, and to X-rays with and without prior VCN-2 treatment. Cytotoxicity assay, cell proliferation assay, caspase-3 activity assay, DNA fragmentation assay and Western blotting for Rad50, MMP-2 and p21 were performed to investigate the radiosensitizing properties of VCN-2. Fibroblast survival assay was performed using HEK293T cells to check for any adverse effects of VCN-2 on normal fibroblast cell line. VCN-2 singularly and in combination with radiation reduced the surviving cancer cells, increased caspase-3 activity, increased DNA fragmentation, increased the levels of Rad50 and lowered levels of MMP-2 and p21 proteins while being non-toxic and radioprotective to the fibroblast cells. VCN-2 showed a potent radiosensitizing property while also showing a chemotherapeutic property against NSCLC cell line NCI-H23.

Tolerability of toceranib phosphate (Palladia) when used in conjunction with other therapies in 35 cats with feline oral squamous cell carcinoma: 2009-2013

Objectives Squamous cell carcinoma (SCC) is the most common oral tumor in cats and typically carries a poor prognosis with current treatment options. The objective of this study was to evaluate the toxicity of toceranib phosphate (Palladia; Pfizer) in cats with oral SCC in combination with other treatment modalities. Methods In this study, 35 cats were retrospectively evaluated to determine toxicity when treated with toceranib in combination with other treatment modalities. Cats received toceranib at a median dose of 2.75 mg/kg (range 1.9-4.17 mg/kg) 3 days a week. Cats also underwent additional therapies, including surgical excision, radiation therapy, chemotherapy and/or use of non-steroidal anti-inflammatory drugs. Results Toxicity was seen in six cats, with five cases of grade 1 or 2 gastrointestinal (GI) toxicity and one grade 4 metabolic toxicity. Toceranib was discontinued in one cat and two cats received dose reductions. None of the cats required treatment delays or hospitalization due to toxicity. Median toceranib treatment duration was 77 days (range 7-741 days). Conclusions and relevance This study revealed that toceranib was well tolerated by the majority of cats, with five cases of low-grade GI toxicity and one case of metabolic toxicity. Given the favorable toxicity profile, future studies further evaluating the safety and efficacy of toceranib for cats with oral SCC should be considered.

Intratumoral injection of radioactive holmium ( 166 Ho) microspheres for treatment of oral squamous cell carcinoma in cats

BACKGROUND & AIMS

A "microbrachytherapy" was developed as treatment option for inoperable tumours by direct intratumoral injection of radioactive holmium-166 ( ¹⁶⁶ Ho) microspheres (MS). ¹⁶⁶ Ho emits β-radiation which potentially enables a high, ablative, radioactive-absorbed dose on the tumour tissue while sparing surrounding tissues.

MATERIALS & METHODS

Safety and efficacy of ¹⁶⁶ Ho microbrachytherapy were evaluated in a prospective cohort study of 13 cats with inoperable oral squamous cell carcinoma without evidence of distant metastasis.

RESULTS

Local response rate was 55%, including complete response or partial response (downstaging) enabling subsequent marginal resection. Median survival time was 113 days overall, and 296 days for patients with local response. Side effects were minimal. Tumour volume was a significant predictor of response.

DISCUSSION

Response rate may be further improved by optimizing the intratumoral spatial distribution of ¹⁶⁶ Ho MS.

CONCLUSION

¹⁶⁶ Ho microbrachytherapy has potential as a minimally invasive, single procedure radio-ablation treatment of unresectable tumours with minimal morbidity.

Retrospective evaluation of toceranib phosphate (Palladia) in cats with oral squamous cell carcinoma

Objectives The aim of the study was to determine the clinical benefit and adverse event profile of toceranib phosphate in the treatment of feline oral squamous cell carcinoma (FOSCC). Methods Data obtained from the medical records of cats with oral squamous cell carcinoma diagnosed between 2010 and 2014 treated with toceranib phosphate were compared with medical record data from cats that did not receive toceranib, cytotoxic chemotherapy or radiation, to determine the response to toceranib treatment and adverse event profile of toceranib in cats. Concurrent use of non-steroidal anti-inflammatory drugs (NSAIDs) was allowed. Results Forty-six cats with FOSCC were included; 23 received treatment with toceranib (group 1) and 23 did not (group 2). The overall biological response rate in group 1 was 56.5%. Median survival time of toceranib-treated cats was significantly longer at 123 days compared with 45 days in cats not treated with toceranib ( P = 0.01). Cats achieving stable disease or better on toceranib therapy had significantly longer progression-free survival ( P <0.0001) and median survival ( P = 0.0042) times than those with progressive disease on toceranib. Administration of NSAIDs was also associated with significantly improved survival time ( P = 0.0038) among all cats. Anorexia was common but may reflect the underlying disease in these patients. Toceranib was well tolerated in cats, with the most common side effect being mild gastrointestinal toxicity. Conclusions and relevance Toceranib was well tolerated in cats with oral squamous cell carcinoma and may lead to improved survival times, especially when combined with NSAIDs. NSAID administration was also associated with improved survival times, and the relative benefit of toceranib and NSAIDs is difficult to determine from this retrospective study. Despite improvement in survival times, long-term survival in this patient population remained poor. As toceranib was well tolerated and may improve survival time, prospective evaluation of toceranib alone is warranted to assess response as a single agent and as part of multimodal therapy in an effort to achieve a more durable response in FOSCC.

Evaluation of an Accelerated Chemoradiotherapy Protocol for Oropharyngeal Squamous Cell Carcinoma in 5 Cats and 3 Dogs

Accelerated radiation therapy protocols address the specific biology of aggressive oropharyngeal squamous cell carcinoma and this approach was applied in 5 feline and 3 canine oropharyngeal squamous cell carcinoma patients where surgery was not possible (4/5 feline and 2/3 canine cases) or was declined (1/5 feline and 1/3 canine cases). A protocol using 14 fractions of 3.5 Gy over 9-days, combined with carboplatin chemotherapy as a radiosensitiser (total dose 180 mg/m2 in feline and 300 mg/m2 in canine cases) resulted in a complete tumor response in most cases (4/5 feline and 3/3 canine cases) with acceptable acute and long-term side effects. Results achieved in feline cases correspond with published data where these specific radiotherapy protocols were employed. A complete response and long-term survival (> 2-years) was achieved in all canine patients. Although no standardized chemoradiotherapy protocols currently exist, this therapeutic approach can be a useful addition for the management of oropharyngeal squamous cell carcinoma of cats and dogs when the goals of treatment include maximizing tumor control while maintaining function and quality of life.

Feline Oral Squamous Cell Carcinoma: Clinical Manifestations and Literature Review

Squamous cell carcinoma (SCC) is the most commonly encountered malignant oral tumor in cats. The etiology of this locally invasive tumor is likely multifactorial. Several risk factors have been identified, including the use of flea collars, and a history of feeding canned food and canned tuna. Clinical signs vary depending on tumor location. The tumor commonly arises from the gingiva and mucosa of the maxilla, mandible, tongue, sublingual area, or tonsillar region. Maxillary SCC commonly presents clinically as an ulcerative lesion, whereas mandibular SCC is commonly proliferative, expansile, and firm. Lingual/sublingual SCC may be ulcerative, necrotic, infiltrative, or proliferative. In general, feline oral SCC is an invasive and malignant neoplasm regardless of its location. Surgery, radiation therapy, chemotherapy and combinations thereof have been attempted with rarely a satisfactory response. Currently, cures are obtained only in a small subset of cats whose tumors are amenable to complete resection, or where resection with microscopic residual disease is followed by definitive radiation therapy. A multimodal treatment approach likely offers the best chance of success. For cats with advanced disease, palliative care may improve patients' quality of life, albeit transiently. Sequelae associated with tumor progression and local tissue destruction often result in euthanasia of feline patients with oral SCC.

Palliative radiation therapy outcomes for cats with oral squamous cell carcinoma (1999-2005)

Squamous cell carcinoma (SCC) accounts for approximately 10% of all feline tumors. The purpose of this retrospective study was to describe outcomes for a group of cats with oral SCC that were treated with palliative radiation therapy. Fifty-four cats met the inclusion criteria of nonresectable, oral SCC treated with coarse fractionated megavoltage (MeV) radiation therapy. Radiation therapy for all cats was delivered with a 6 MeV linear accelerator. Total radiation doses of 24 Gray to 40 Gray were administered in three to four fractions, once-per-week over 4 to 5 weeks. Concurrent chemotherapy protocols varied and were administered at the discretion of the clinician and client. Forty-nine patients completed the planned treatment protocols. Overall mean and median survival times for cats completing the planned treatment protocols were 127 and 92 days (n = 49). Mean and median survival times of cats receiving palliative radiation therapy alone were 157 and 113 days (n = 12). Mean and median survival times of patients receiving both radiation therapy and chemotherapy were 116 and 80 days (n = 37). Patients with sublingual tumors had a median survival time of 135 days (n = 15), compared to mandibular tumors that had a median survival time of 80 days (n = 26). For the majority of patients that completed the planned treatment protocol (65%), owners reported a subjectively improved quality of life. Findings from this uncontrolled study supported the use of palliative radiation therapy for cats with nonresectable oral squamous cell carcinoma.

Using canine osteosarcoma as a model to assess efficacy of novel therapies: can old dogs teach us new tricks?

Since its domestication more than 10,000 years ago, the dog has been the animal that most intimately shares our work and homelife. Interestingly, the dog also shares many of our diseases including cancer such as osteosarcoma. Like the human, osteosarcoma is the most common bone malignancy of the dog and death from pulmonary metastasis is the most common outcome. The incidence of this spontaneous bone neoplasm occurs ten times more frequently that it does so in children with about 8,000-10,000 cases estimated to occur in dogs in the USA. Because there is no "standard of care" in veterinary medicine, the dog can also serve us by being a model for this disease in children. Although the most common therapy for the dog with osteosarcoma is amputation followed by chemotherapy, not all owners choose this route. Consequently, novel therapeutic interventions can be attempted in the dog with or without chemotherapy that could not be done in humans with osteosarcoma due to ethical concerns. This chapter will focus on the novel therapies in the dog that have been reported or are in veterinary clinical trials at the author's institution. It is hoped that collaboration between veterinary oncologists and pediatric oncologists will lead to the development of novel therapies for (micro- or macro-) metastatic osteosarcoma that improve survival and might ultimately lead to a cure in both species.

Assessment of predictive molecular variables in feline oral squamous cell carcinoma treated with stereotactic radiation therapy

This study evaluated molecular characteristics that are potentially prognostic in cats with oral squamous cell carcinoma (SCC) that underwent stereotactic radiation therapy (SRT). Survival time (ST) and progression-free interval (PFI) were correlated with mitotic index, histopathological grades, Ki67 and epidermal growth factor receptor expressions, tumour microvascular density (MVD), and tumour oxygen tension (pO(2)). Median ST and PFI were 106 and 87 days, respectively (n = 20). Overall response rate was 38.5% with rapid improvement of clinical symptoms in many cases. Patients with higher MVD or more keratinized SCC had significantly shorter ST or PFI than patients with lower MVD or less keratinized SCC (P = 0.041 and 0.049, respectively). Females had significantly longer PFI and ST than males (P ≤ 0.016). Acute toxicities were minimal. However, treatment-related complications such as fractured mandible impacted quality of life. In conclusion, SRT alone should be considered as a palliative treatment. MVD and degree of keratinization may be useful prognostic markers.

Aerosol gemcitabine: preclinical safety and in vivo antitumor activity in osteosarcoma-bearing dogs

BACKGROUND

Osteosarcoma is the most common skeletal malignancy in the dog and in young humans. Although chemotherapy improves survival time, death continues to be attributed to metastases. Aerosol delivery can provide a strategy with which to improve the lung drug delivery while reducing systemic toxicity. The purpose of this study is to assess the safety of a regional aerosol approach to chemotherapy delivery in osteosarcoma-bearing dogs, and second, to evaluate the effect of gemcitabine on Fas expression in the pulmonary metastasis.

METHODS

We examined the systemic and local effects of aerosol gemcitabine on lung and pulmonary metastasis in this relevant large-animal tumor model using serial laboratory and arterial blood gas analysis and histopathology and immunohistochemistry, respectively.

RESULTS AND CONCLUSIONS

Six hundred seventy-two 1-h doses of aerosol gemcitabine were delivered. The treatment was well tolerated by these subjects with osteosarcoma (n = 20). Aerosol-treated subjects had metastatic foci that demonstrated extensive, predominately central, intratumoral necrosis. Fas expression was decreased in pulmonary metastases compared to the primary tumor (p = 0.008). After aerosol gemcitabine Fas expression in the metastatic foci was increased compared to lung metastases before treatment (p = 0.0075), and even was higher than the primary tumor (p = 0.025). Increased apoptosis (TUNEL) staining was also detected in aerosol gemcitabine treated metastasis compared to untreated controls (p = 0.028). The results from this pivotal translational study support the concept that aerosol gemcitabine may be useful against pulmonary metastases of osteosarcoma. Additional studies that evaluate the aerosol route of administration of gemcitabine in humans should be safe and are warranted.

Epidermal growth factor receptor expression in feline oral squamous cell carcinomas

Feline oral squamous cell carcinomas (SCC) have a poor prognosis despite aggressive treatment with surgery, radiation and anticancer drugs. Overexpression of the epidermal growth factor receptor (EGFR), a membrane-bound tyrosine kinase receptor, has been found in many human epithelial neoplasms, including oral SCC. EGFR overexpression has been associated with advanced disease and a poor prognosis. The purpose of this study was to determine whether feline oral SCC express EGFR. Thirteen formalin-fixed paraffin wax-embedded biopsy samples from feline oral SCC were analysed for EGFR expression using immunohistochemistry. Nine of 13 tumours (69%) were positive for EGFR expression, suggesting that altered EGFR expression plays a role in feline oral SCC and provides a rationale for a potential clinical benefit using EGFR inhibitors in combination with conventional treatments.

Chemotherapy: new uses for old drugs

Using chemotherapy drugs as antiangiogenic agents is a new use for drugs that have been around for a long time. The favorable toxicity profile and reduced cost make low-dose continuous "metronomic" chemotherapy trials appealing, but there is still much to be learned. Challenges ahead include determination of the optimal tumor types, drugs, doses, schedules, and response monitoring (end points). The measurement of angiogenic growth factors and inhibitors and of circulating endothelial progenitor cells or their precursors represents promising strategies in these areas.

Phase II feasibility study of concurrent radiotherapy and gemcitabine in chemonaive patients with squamous cell carcinoma of the head and neck: long-term follow up data

BACKGROUND

Radiotherapy (RT) with concurrent chemotherapy is the current standard of care for patients with unresectable locally advanced squamous cell carcinoma of the head and neck (SCCHN). Gemcitabine (GEM) is a potent radiosensitizer and in addition has activity as an anticancer agent in SCCHN.

PATIENTS AND METHODS

Twenty-six patients with locally far advanced SCCHN were enrolled in a chemoradiation feasibility study between November 1998 and September 2003. Use was made of conventionally fractionated RT and GEM 100 mg/m(2), which was given within 2 h prior to radiotherapy on a weekly basis starting on day 1 of RT. Response was assessed according to WHO criteria, toxicity according to NCI-CTC version 2.

RESULTS

The patients received a median of 7 (2-8) weekly cycles of gemcitabine and a median cumulative RT dose of 70 Gy (66-84.75). Hematologic toxicity was mild, but non-hematologic toxicity was severe: grade 3-4 stomatitis occurred in 85% of patients, dermatitis in 69%, pharyngitis/esophagitis in 81% and 80% of the patients needed a feeding tube during treatment. All 22 evaluable patients responded (50% complete, 50% partial). Median follow up of the surviving patients is 46 months. Median disease-free and overall survival is 13 months and 19 months, respectively; 27% of the patients are alive without evidence of recurrence beyond 3 years.

CONCLUSIONS

Conventionally fractionated RT in combination with GEM 100 mg/m(2) weekly is feasible and highly active in the treatment of locally advanced SCCHN. In particular, long-term local control rate is promising. Acute mucosal toxicities are significant but manageable. Long-term toxicity interferes with normal food intake.

A NINE-DAY ACCELERATED RADIATION PROTOCOL FOR FELINE SQUAMOUS CELL CARCINOMA

Nine cats with oral squamous cell carcinoma were treated with an accelerated radiation protocol (14 fractions of 3.5 Gy in 9 days). Radiation was administered twice daily with a 6hour break between treatments. Median overall survival was 86 +/- 110 days. Median survival for cats with a partial response (n=6) was 60 +/- 7 days, while median survival for cats with a complete response (n=3) was 298 +/- 187 days (P = 0.0639). The accelerated protocol was well tolerated and toxicity in the early and late period was manageable in all cats. Further modification of the protocol is warranted to extend survival.

Veterinary radiation therapy: review and current state of the art

Veterinary radiation oncology became a recognized specialty in 1994. Radiation therapy is an important component of a multimodality approach to treating cancer in companion animals. It is important to understand the many aspects of radiation, including the equipment used in external beam radiation therapy, the basic mechanism of action of ionizing radiation, the results of irradiating various histopathological types of tumors, as well as the associated potential acute and late side effects of radiation. A comprehensive review of radiation therapy is timely and provides information for clients on cancers that may benefit from external beam radiation therapy.

Survival of 54 cats with oral squamous cell carcinoma in United Kingdom general practice

OBJECTIVES

To determine the survival of 54 cats with histologically confirmed feline oral squamous cell carcinoma (FOSCC) treated in UK general practice and to determine factors predictive for survival.

METHODS

Cases were identified from consecutive samples submitted for histological diagnosis. Observational and survival data were collated retrospectively from submitting practices. Immunohistochemical analysis of cyclooxygenase (COX) expression variables was available using previously published data. Kaplan-Meier product limit estimation for overall survival and Cox proportional hazards regression for potential explanatory variables were performed.

RESULTS

The overall median survival time was 44 days [95 per cent confidence interval (CI): 31-79] and 1 year survival was 9.5 per cent. Variables associated with survival were whether the cat was pedigree [hazard ratio (HR)=8.17, 95 per cent CI: 1.96-34.12], whether the cat received non-steroidal anti-inflammatory drug (NSAID) therapy after diagnosis (HR=0.46, 95 per cent CI: 0.21-0.98) and whether the COX-1 staining distribution was patchy rather than diffuse (HR=0.25, 95 per cent CI: 0.08-0.014).

CLINICAL SIGNIFICANCE

This study suggests that although the prognosis for inoperable FOSCC remains poor, palliative treatments may offer a survival advantage that compares favourably with more aggressive treatment methods. Further work is needed to evaluate NSAID therapy in this disease, in particular to determine whether the potential survival advantage is because of an analgesic or anticancer effect or both. COX-1 distribution patterns may have a role as a prognostic indicator in this disease.

Killing of Feline T-Lymphocytes by Gamma-Rays and Energetic Carbon Ions

High linear energy transfer (LET) heavy charged particles have previously been applied clinically to human cancer radiotherapy because of their excellent physical properties of selective dose distribution and higher relative biological effectiveness (RBE) for human; however, such an approach has yet to be applied to cat patients. The present study investigates the biological effectiveness of low-LET gamma-rays (0.2 keV/micro m) compared to high-LET carbon ions (114 keV/micro m) in feline T- lymphocyte FeT-J cells. Clonogenic survival analysis revealed that the RBE value of carbon ions was 2.98 relative to a 10% survival dose (D(10)) by gamma-rays, and that the inactivation cross-section in cells exposed to gamma-rays and carbon ions was 0.023 and 38.9 micro m(2), respectively. Terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) analysis revealed that TUNEL-positive frequency in carbon-irradiation cells is higher than for gamma-irradiated cells against exposure to the same physical doses, but that very little difference in TUNEL-positive frequency is observed between cells exposed to the respective D(10) dose of gamma-rays. Our data thus indicate that carbon ions are more effective for cell killing than gamma-rays at the same physical doses, but kill cells to an extent that is comparable to gamma-rays at the same biological doses. Carbon ion radiotherapy is therefore a promising modality for cat patients.

N′-(phenyl-pyridin-2-yl-methylene)-hydrazine carbodithioic acid methyl ester enhances radiation-induced cell death by targeting Bcl-2 against human lung carcinoma cells

To develop a new radiosensitizer, we screened a chemical library and selected one chemical reagent, N′-(phenyl-pyridin-2-yl-methylene)-hydrazine carbodithioic acid methyl ester (PHCM), which was already known to have antifungal and antimicrobial properties. PHCM enhanced radiation-induced cell death and its mean calculated dose enhancement ratio was 1.17. PHCM was found to induce the phosphorylation of p38 mitogen-activated protein kinase, and combined treatment with PHCM and radiation down-regulated Bcl-2. In a xenograft assay, the combined PHCM and radiation group showed 39.3 days of growth delay versus the control in terms of tumor growth. The enhancement factor of this combined treatment was determined to be 4.02.

New chemotherapy agents in veterinary medicine

Several anticancer drugs have been added to the therapeutic armamentarium in recent years. Some of these agents are traditional drugs with a long history of use in human oncology. Increased sophistication in clinical trial design in veterinary oncology has allowed the incorporation of agents previously viewed as excessively toxic. Other agents have been developed more recently. This article summarizes the veterinary experience with two older alkylating agents, lomustine and streptozocin, and newer compounds ifosfamide and gemcitabine. The published literature regarding veterinary use of these agents is limited, and the reader is advised to contact a veterinary oncologist for current guidelines when contemplating use of these agents.