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

A Scoping Review on Tyrosine Kinase Inhibitors in Cats: Current Evidence and Future Directions

Tyrosine kinase inhibitors (TKIs) have become invaluable in the treatment of human and canine malignancies, but their role in feline oncology is less defined. While toceranib phosphate and masitinib mesylate are licensed for use in dogs, no TKI is yet approved for cats. This review systematically maps the research conducted on the expression of tyrosine kinases in neoplastic and non-neoplastic domestic feline tissues, as well as the in vitro/in vivo use of TKIs in domestic cats. We identify and discuss knowledge gaps and speculate on the further research and potential indications for TKI use in cats. A comprehensive search of three electronic databases and relevant paper reference lists identified 139 studies meeting the inclusion criteria. The most commonly identified tumors were mast cell tumors (MCTs), mammary and squamous cell carcinomas and injection-site sarcomas. Based on the current literature, toceranib phosphate appears to be the most efficacious TKI in cats, especially against MCTs. Exploring the clinical use of TKIs in mammary carcinomas holds promise. Despite the progress, currently, the evidence falls short, underscoring the need for further research to discover new indications in feline oncology and to bridge the knowledge gaps between human and feline medicine.

Feline restrictive orbital myofibroblastic sarcoma treated with toceranib phosphate (Palladia) as adjuvant chemotherapy: A case study of one cat

Key Clinical Message

This is the first case report of treatment with toceranib phosphate as postsurgical adjuvant chemotherapy for advanced FROMS. This reported case highlights the need for further studies on the efficacy of toceranib phosphate as adjuvant chemotherapy for FROMS.

Abstract

Feline restrictive orbital myofibroblastic sarcoma (FROMS) is a rare aggressive tumor in cats. We explored the effectiveness of using toceranib phosphate as postsurgical adjuvant chemotherapy for advanced FROMS in a 7-year-old cat. Despite treatment, the cat died 4 months after surgery. This report highlights the need for further studies on the efficacy of toceranib phosphate as adjuvant chemotherapy for FROMS.

Low dose meloxicam is safe and tolerable when combined with toceranib phosphate in cancer-bearing cats

OBJECTIVES

Non-steroidal anti-inflammatory drugs (NSAIDs) are infrequently utilized in cats due to concern for renal compromise; however, recent studies demonstrate tolerability of low dose meloxicam. Toceranib phosphate is used to treat several feline cancers and is well tolerated. This study aimed to determine the tolerability and adverse event profile of combined toceranib and low dose meloxicam in cancer-bearing cats. Secondary goals involved assessing anticancer tumor efficacy and impact upon quality of life and analgesia.

METHODS

Cats with any cancer not involving the kidneys were eligible. The study adopted a conventional 3 + 3 dose escalation design. Toceranib was administered every other day at a standard dose with meloxicam administered in an escalating fashion in subsequent cohorts, at a starting dose of 0.01 mg/kg on opposite days to toceranib, up to a maximum of 0.02 mg/kg daily, based upon previous safety studies. Laboratory work, blood pressure, tumor measurements, pain score and client-completed quality-of-life surveys were recorded every 2-4 weeks during the 12-week study period.

RESULTS

Twenty-one cats were enrolled. When combined with toceranib, a meloxicam dose of 0.02 mg/kg q24h was safe and well tolerated, with no cats being withdrawn due to adverse events from the drug combination. The majority of cats demonstrated clinical benefit with stable to mildly improved tumor measurements, quality of life and pain scores.

CONCLUSIONS AND RELEVANCE

Low dose meloxicam combined with toceranib is safe and well tolerated in cancer-bearing cats. Continued patient recruitment and data collection are needed to determine the maximum tolerated dose of meloxicam. The results of our study will guide further phase II/III trials.

Feline Oral Squamous Cell Carcinoma: A Critical Review of Etiologic Factors

Simple Summary

Feline oral squamous cell carcinoma (FOSCC) is the most common oral neoplasia in cats. This malignant tumor is locally invasive, has a high mortality rate, and its etiology is not yet known. A critical review about the potential etiologic factors of FOSCC was performed, considering publications between 2000 and 2022. The initial search resulted in 553 publications, with only 26 of these being included in the review. Sixteen studies were related to viral etiology and nine related to environmental factors such as exposure to tobacco smoke, ectoparasitic products, and the presence of oral comorbidities. When evaluated, feline papillomavirus was detected in 16.2% of samples of FOSCC. In the three studies focused on exposure to tobacco smoke, 35.2% (30/85) of cats with FOSCC had a history of this exposure. Among 485 cats with FOSCC, 6.4% had dental and oral pathology. The present study demonstrates that the available evidence on the etiology of FOSCC is still limited, however, there has been increasing interest in this topic.

Abstract

Feline oral squamous cell carcinoma (FOSCC) is the most common oral neoplasia in cats. This malignant tumor is locally invasive, has a high mortality rate, and its etiology is not yet known. In humans, head and neck squamous cell carcinoma is associated with tobacco smoke, alcohol consumption, and human papillomavirus infection. Herein, a critical review about the potential etiologic factors of FOSCC was performed, considering publications between 2000 and 2022, aiming to synthesize all available scientific evidence regarding this issue. Recommendations of the PRISMA statement and the Cochrane Collaboration were followed and the PubMed database searched by using the MeSH terms MeSH terms “oral”, “mouth”, “lingual”, “labial”, “gingiva”, “carcinoma”, “squamous”, and “feline”. The selection process for eligible studies was based on specific inclusion and exclusion criteria and the quality of the studies assessed. The initial search resulted in 553 publications, with only 26 of these being included in the review. Sixteen studies were related to viral etiology and nine related to environmental factors such as exposure to tobacco smoke, ectoparasitic products, and the presence of oral comorbidities. When evaluated, feline papillomavirus was detected in 16.2% of samples of FOSCC. In the three studies focused on exposure to tobacco smoke, 35.2% (30/85) of cats with FOSCC had a history of this exposure. The consumption of canned food and the use of deworming collars were associated, in only one publication, with a risk of neoplasia increased by 4.7 and 5.3 times, respectively. Among 485 cats with FOSCC, 6.4% had dental and oral pathology (i.e., periodontal disease or feline chronic gingivostomatitis). The present study demonstrates that the available evidence on the etiology of FOSCC is still limited, however, there has been an increasing interest on this topic. To better understand the role of the possible etiological factors of this aggressive disease, and model for its human counterpart, large, prospective multi-institutional studies are needed.

Intersecting Mechanisms of Hypoxia and Prostaglandin E2-Mediated Inflammation in the Comparative Biology of Oral Squamous Cell Carcinoma

The importance of inflammation in the pathogenesis of cancer was first proposed by Rudolph Virchow over 150 years ago, and our understanding of its significance has grown over decades of biomedical research. The arachidonic acid pathway of inflammation, including cyclooxygenase (COX) enzymes, PGE2 synthase enzymes, prostaglandin E2 (PGE2) and PGE2 receptors has been extensively studied and has been associated with different diseases and different types of cancers, including oral squamous cell carcinoma (OSCC). In addition to inflammation in the tumour microenvironment, low oxygen levels (hypoxia) within tumours have also been shown to contribute to tumour progression. Understandably, most of our OSCC knowledge comes from study of this aggressive cancer in human patients and in experimental rodent models. However, domestic animals develop OSCC spontaneously and this is an important, and difficult to treat, form of cancer in veterinary medicine. The primary goal of this review article is to explore the available evidence regarding interaction between hypoxia and the arachidonic acid pathway of inflammation during malignant behaviour of OSCC. Overlapping mechanisms in hypoxia and inflammation can contribute to tumour growth, angiogenesis, and, importantly, resistance to therapy. The benefits and controversies of anti-inflammatory and anti-angiogenic therapies for human and animal OSCC patients will be discussed, including conventional pharmaceutical agents as well as natural products.

Management of a feline gastric stromal cell tumour with toceranib phosphate: a case study

BACKGROUND

A fifteen-year old, female spayed domestic longhaired cat was presented for a routine vaccination during which an incidental abdominal mass was palpated. After further inquiry, occasional vomiting was reported to occur once every few weeks to months, associated with no other gastrointestinal signs.

CASE REPORT

Ultrasonography revealed a gastric mass. Histopathology and immunohistochemistry confirmed a CD117 positive, smooth muscle actin and desmin negative neoplasm, consistent with a gastrointestinal stromal cell tumour (GIST). Treatment was initiated with toceranib phosphate resulting in stable disease for over eighteen months, and the patient was still alive at the time of writing.

CONCLUSION

GISTs are rare in cats and this is the first report of medical management of feline GIST using toceranib.

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.

Targeted Therapies in Veterinary Oncology

Advances in molecular biology have permitted a much more detailed understanding of cellular dysfunction at the molecular and genetic levels in cancer cells. This has resulted in the identification of novel targets for therapeutic intervention, including proteins that regulate signal transduction, gene expression, and protein turnover. In many instances, small molecules are used to disrupt the function of these targets, often through competitive inhibition of ATP binding or the prevention of necessary protein-protein interactions. More than 40 small molecule inhibitors are now approved to treat a variety of human cancers, substantially impacting patient outcomes.

External beam radiotherapy for the treatment of feline salivary gland carcinoma: six new cases and a review of the literature

CASE SERIES SUMMARY

Salivary gland carcinoma is uncommon in cats. We report the outcome of radiation therapy in six cases (four salivary gland adenocarcinomas, one tubulopapillary adenocarcinoma, one carcinoma). Five were treated after surgical excision of the primary tumour, but four had gross disease (primary or metastatic) at the time of starting radiotherapy. Exact progression-free interval from the start of radiotherapy in the two cats where this was known was 120 and 144 days, respectively. One cat was signed off at 766 days with no evidence of recurrence. Another cat was in remission at 202 days (when last seen by the referring practice) but subsequently developed recurrence (date uncertain). Survival time was known for three cats (55 days, 258 days and 570 days from initiation of radiotherapy, respectively). In two cases, locoregional progressive disease (PD) was confirmed, and the other presumed as the cause of death. Two cats, known to have developed PD, were alive at the time of writing (at 206 and 549 days, respectively). No cat died as a result of distant metastatic disease.

RELEVANCE AND NOVEL INFORMATION

There is a paucity of information on the treatment of salivary gland tumours. In humans, as in cats, there is no optimised standard of care for malignant tumours. It is accepted that, for surgical candidates (even with large tumours), surgery and radiotherapy is superior to radiotherapy alone. However, the benefits of postoperative radiotherapy compared with surgery alone are only clear in patients with high-risk tumours (ie, those with large and invasive primary tumours, close or incomplete margins, high histopathological grade, histological evidence of neural or vascular invasion, or positive lymph nodes). This population is analogous to the population reported here, and likely to most cats presented in practice. Thus, radiation therapy may help improve locoregional control and survival in cats.

Investigation of novel chemotherapeutics for feline oral squamous cell carcinoma

Feline oral squamous cell carcinomas (FOSCC) are highly aggressive neoplasms with short survival times despite multimodal treatment. FOSCC are similar to squamous cell carcinomas of the head and neck (SCCHN) in humans, which also present therapeutic challenges. The current study was undertaken to identify novel chemotherapeutics using FOSCC cell lines. A high throughput drug screen using 1,952 drugs was performed to identify chemotherapeutics for further investigation. Two of the drugs identified in the drug screen, actinomycin D and methotrexate, and two drugs with similar molecular targets to drugs found to be efficacious in the screening, dinaciclib and flavopiridol, were selected for further investigation. Drug inhibition profiles were generated for each drug and cell line using an MTS assay. In addition, the effects of the drugs of interest on cell cycle progression were analyzed via a propidium iodide DNA labeling assay. Changes in caspase-3/7 activity after treatment with each drug were also determined. The findings demonstrated effectiveness of the drugs at nanomolar concentrations with sensitivity varying across cell lines. With all of the drugs except for actinomycin D, evidence for G1 arrest was found. Dinaciclib and flavopiridol were demonstrated to induce apoptosis. The results of the study suggest that the selected drugs are potential candidates for developing novel chemotherapeutic approaches to FOSCC. Through these studies, novel therapeutic strategies for the treatment of FOSCC can be developed to provide better care for affected cats which can also serve as proof of concept studies to inform translational studies in SCCHN in humans.

Retrospective evaluation of toceranib phosphate (Palladia) use in cats with mast cell neoplasia

Objectives The purpose of this study was to solicit and compile data from practicing veterinary specialists regarding their use of toceranib in cats with mast cell neoplasia and to provide initial assessment of possible clinical benefit and adverse events. Methods The American College of Veterinary Internal Medicine and Oncology listservs were used to solicit data pertaining to cases in which toceranib was used in the treatment of feline mast cell neoplasia. Cases were included if the following data were received: signalment (age, sex, breed), diagnosis of mast cell neoplasia by either cytology or histopathology, anatomic classification of disease (cutaneous, splenic/hepatic, gastrointestinal, other), previous and concurrent treatment, toceranib dose (mg/kg) and schedule, duration of therapy, best response and documentation of adverse events. Results Case data from 50 cats with cutaneous (n = 22), splenic/hepatic (visceral) (n = 10), gastrointestinal (n = 17) or other (n = 1) mast cell neoplasia were received. Clinical benefit was seen in 80% (40/50), including 86% (19/22) with cutaneous, 80% (8/10) with visceral and 76% (13/17) with gastrointestinal involvement. A majority of cats (n = 35) received glucocorticoids during toceranib treatment. Median duration of treatment in cats experiencing clinical benefit was 36 weeks (range 4-106 weeks), 48 weeks (range 12-199 weeks) and 23 weeks (range 13-81 weeks) for cutaneous, visceral and gastrointestinal cases, respectively. Toceranib was administered at a median dose of 2.5 mg/kg (range 1.6-3.5 mg/kg); in 90% (45/50) the drug was given three times per week. Treatment was generally well tolerated with 60% (30/50) of cats experiencing adverse events. The majority of these events were low-grade (grade 1 or 2) gastrointestinal or hematologic events that resolved with treatment break and/or dose adjustment. Conclusions and relevance Toceranib appears to be well tolerated in feline patients with mast cell neoplasia. Biologic activity of this drug is evident in the studied cats; however, further prospective studies are needed to elucidate fully its role in treatment of this disease.