Adjuvant doxorubicin vs metronomic cyclophosphamide and meloxicam vs surgery alone for cats with mammary carcinomas: A retrospective study of 137 cases

Distribution of Inflammatory Infiltrate in Feline Mammary Lesions: Relationship With Clinicopathological Features

Inflammation is a frequent finding in feline mammary neoplasms. Recent research suggests that the presence and location of tumour-associated immune cells might play a significant role in the clinical outcome of feline mammary carcinomas. The present study aimed to characterise the overall inflammatory infiltrates in healthy, hyperplastic/dysplastic, benign and malignant lesions of the feline mammary gland, and to evaluate its association with clinicopathological features. Perilesional and intralesional inflammatory foci were evaluated in 307 lesions from 185 queens, and categorised according to its distribution and intensity. The presence, location and density of tertiary lymphoid structures were also assessed. A control group included 24 queens without mammary changes. The presence of intralesional and perilesional inflammatory infiltrate was observed in a majority of the lesions (80.8% and 90.2%, respectively), but differed according to the type of mammary lesion, being more remarkable in malignant neoplasms. Only scarce individual cells were observed in 28.1% of the normal mammary glands. Data analysis revealed statistically significant associations (p < 0.05) between the presence of a more prominent intralesional and perilesional inflammatory reaction and several clinicopathological features associated with worse prognosis, including clinical stage, tumour size, mitotic count, lymphovascular invasion and lymph node metastasis. Furthermore, tertiary lymphoid structures were significantly more frequent in tumours with an infiltrative growth and lymph node metastasis. According to our results, the inflammatory reaction present in different types of feline mammary lesions is associated with the development of more aggressive tumours.

Metronomic chemotherapy: bridging theory to clinical application in canine and feline oncology

Veterinary oncology has experienced significant evolution over the last few decades, with chemotherapy being currently applied to several neoplasms with therapeutic success. Traditionally, chemotherapy protocols are based on classic cytostatic drugs under the concept of maximum tolerated dose (MTD), which has been associated with a greater risk of toxicity and resistance. Thus, new therapeutic alternatives have emerged, such as metronomic chemotherapy (MC), introducing a new paradigm in cancer treatment. MC consists of administering low doses of chemotherapy drugs continuously over a long period of time, modulating the tumour microenvironment (TME) due to the combination of cytotoxic, antiangiogenic and immunomodulatory effects. This multi-targeted therapy has been described as a treatment option in several canine and feline cancers since 2007, with positive results already published in the literature, particularly in mammary carcinomas and soft tissue sarcomas in dogs. The aim of this review article is to describe the current knowledge about the use of MC in small animal oncology, with emphasis on its mechanisms of action, the most commonly used drugs and clinical outcome.

Platelet count and MCHC as independent prognostic markers for feline mammary carcinomas

Mammary neoplasms are common in felines species and represent a significant disease for its unfavorable prognosis. Changes in the blood count and serum biochemical profile of these patients have potential as non-invasive prognostic markers prior to mastectomy, however, they are poorly described in literature. In this study univariate and multivariate analyses were performed using these factors to determine the effect of each parameter on the one-year survival time after the surgical procedure in these animals. The median overall survival (OS) and the disease-free survival (DFS) were 365 and 242 days, respectively. In univariate analysis, values within the reference range of monocyte, platelet and creatinine counts were identified as significant prognostic factors for OS and only creatinine was significant for DFS (P < 0.05). In the multivariate analysis, platelets and mean corpuscular hemoglobin concentration (MCHC) remained independent prognostic factors for OS. The results presented suggest that monocytes, platelets and creatinine may be important non-invasive pre-surgical prognostic markers, and that platelet count and MCHC are independent prognostic markers for feline mammary carcinomas (FMC). The correlation between such alterations is of important relevance for veterinary oncology, and prospective studies are needed to validate their clinical use and that platelet count and MCHC are independent prognostic markers for FMC. The results found in this study can also be studied in human medicine, regarding blood markers in human breast cancer (HBC).

Topoisomerase IIα immunoexpression in feline mammary carcinomas: A correlation with Ki67 immunoexpression and the mitotic count

The aim of the study was to compare the immunohistochemical expression of topoisomerase IIα protein (Topo IIα) with Ki67 expression and mitotic count in feline mammary carcinomas (FMCs). Topo IIα is considered as a proliferation indicator as well as a molecular target of anthracycline chemotherapy. The studied material included 70 FMCs from female cats treated with mastectomy. Primary mouse monoclonal antibodies directed against Topo IIα and Ki67 were used in immunohistochemical reactions. The number of mitotic figures was counted at 400× magnification in a field of 2.37 mm2. Immunohistochemical reaction for Topo IIα occurred in cell nuclei. The Topo IIα index ranged from 6.12% to 54.60% and was positively correlated with the values of the Ki67 index (r = 0.7193) and the mitotic count (r = 0. 2858). This indicates the potential possibility of use of the immunohistochemical expression of Topo IIα to assess the rate of proliferation in FMCs. The wide range of expression of Topo IIα in individual tumorus found in the conducted studies allows us to hypothesize that its assessment could be used as a predictive marker in chemotherapy of FMCs with the use of anthracyclines. However, this requires confirmation in clinical trials.

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.

Mammary carcinoma: Comparative oncology between small animals and humans-New therapeutic tools

The poor outcomes associated with mammary carcinomas (MCs) in dogs and cats in terms of locoregional recurrence, distant metastasis and survival, highlight the need for better management of mammary cancers in small animals. By contrast, the outcomes of women with breast cancer (BC) have dramatically improved during the last 10 years, notably thanks to new therapeutic strategies. The aim of this article was to imagine what could be the future of therapy for dogs and cats with MCs if it became inspired from current practices in human BC. This article focuses on the importance of taking into account cancer stage and cancer subtypes in therapeutic plans, on locoregional treatments (surgery, radiation therapy), new developments in endocrine therapy, chemotherapy, PARP inhibitors and immunotherapy. Ideally, multimodal treatment regimens would be chosen according to cancer stage and cancer subtypes, and according to predictive factors that are still to be defined.

Urinary bladder hemangiosarcoma in a cat treated with partial cystectomy and adjuvant metronomic cyclophosphamide and thalidomide

Visceral hemangiosarcomas (HSA) are rare in cats and typically associated with aggressive biologic behavior and poor prognosis. A 4-year-old male neutered domestic shorthair cat was presented with a 3-month history of hematuria and stranguria; ultrasonography identified a large bladder mass. Complete excision was achieved by partial cystectomy. Histopathology and immunohistochemistry for von Willebrand factor confirmed HSA. The cat was treated using adjuvant cyclophosphamide, thalidomide, and meloxicam for 8 months. Abdominal ultrasonography repeated at 2 months and computed tomography repeated at 5 and 19 months after diagnosis showed no evidence of local recurrence or metastasis. The cat was alive at last follow-up (896 days). Although the cat described in this report experienced a more favorable prognosis compared to other visceral HSA locations, additional cases are needed to further understand the biological behavior of bladder HSAs and guide treatment decisions.

Feline Oncogenomics: What Do We Know about the Genetics of Cancer in Domestic Cats?

Simple Summary

Cancer is a significant cause of suffering and death in domestic cats. In humans, an understanding of the genetics of different types of cancers has become clinically important for all aspects of patient care and forms the basis for most emerging diagnostics and therapies. The field of ‘oncogenomics’ characterises the alterations of cancer-associated genes that are found in tumours. Such a thorough understanding of the oncogenome of human tumours has only been possible due to a high-quality reference genome and an understanding of the genetic variation that can exist between people. Although a high-quality reference genome for cats has only recently been generated, investigations into understanding the genetics of feline cancers have been underway for many years, using a range of different technologies. This review summarises what is currently known of the genetics of both common and rare types of cancer in domestic cats. Drawing attention to our current understanding of the feline oncogenome will hopefully bring this topic into focus and serve as a springboard for more much-needed research into the genetics of cancer in domestic cats.

Abstract

Cancer is a significant cause of morbidity and mortality in domestic cats. In humans, an understanding of the oncogenome of different cancer types has proven critical and is deeply interwoven into all aspects of patient care, including diagnostics, prognostics and treatments through the application of targeted therapies. Investigations into understanding the genetics of feline cancers started with cytogenetics and was then expanded to studies at a gene-specific level, looking for mutations and expression level changes of genes that are commonly mutated in human cancers. Methylation studies have also been performed and together with a recently generated high-quality reference genome for cats, next-generation sequencing studies are starting to deliver results. This review summarises what is currently known of the genetics of both common and rare cancer types in cats, including lymphomas, mammary tumours, squamous cell carcinomas, soft tissue tumours, mast cell tumours, haemangiosarcomas, pulmonary carcinomas, pancreatic carcinomas and osteosarcomas. Shining a spotlight on our current understanding of the feline oncogenome will hopefully serve as a springboard for more much-needed research into the genetics of cancer in domestic cats.

The Landscape of Tumor-Infiltrating Immune Cells in Feline Mammary Carcinoma: Pathological and Clinical Implications

Feline mammary carcinoma (FMC) shares key molecular and clinicopathological features with human breast cancer. We have herein studied the inflammatory infiltrate of FMC in order to uncover potential therapeutic targets and prognostic markers. To this end, the expression of different markers (CD3, CD4, CD8, CD20, CD56, FoxP3, CD68 and CD163) was analyzed in total, stromal (s) and intratumoral (i) tumor-infiltrating lymphocytes (TILs) and tumor-associated macrophages (TAMs), in 73 feline mammary carcinomas. The results revealed that higher percentages of sCD8⁺ TILs were associated with longer disease-free survival (p = 0.05) and overall survival (p = 0.021). Additionally, higher percentages of iCD4⁺ TILs correlated with positive lymph node status (p = 0.003), whereas CD163⁺ TAMs were associated with undifferentiated tumors (p = 0.013). In addition, sCD3⁺ (p = 0.033), sCD8⁺ (p = 0.044) and sCD68⁺ (p = 0.023) immune cells were enriched in triple negative normal-like carcinomas compared to other subtypes. Altogether, our results suggest that specific subsets of immune cells may play a major role in clinical outcome of cats with mammary carcinoma, resembling what has been reported in human breast cancer. These data further support the relevance of the feline model in breast cancer studies.

Multimodal Blockade of the Renin-Angiotensin System Is Safe and Is a Potential Cancer Treatment for Cats

Simple Summary

As activation of the renin-angiotensin system (RAS) promotes cancer cell growth, medications that inhibit RAS activation could reduce cancer progression. However, studies in people in which RAS has been inhibited by a single treatment have not been consistently beneficial, possibly as RAS can be activated by many different cellular pathways. Multiple treatments have been used to more consistently block RAS in people, but such multimodal treatments have never previously been evaluated in veterinary species. In the present study, the safety of multimodal RAS inhibition using a combination of five treatments was assessed in six cats with cancer. Cats were treated for 8 weeks and none of the cats developed low blood pressure, evidence of kidney or liver disease, or significant adverse effects. Of the six cats enrolled in the study, one cat was withdrawn from the study due to difficulties administering the medications and another cat died of an unrelated cause. Two cats were euthanatized due to cancer progression during the study period while two cats completed the 8-week treatment period. The study showed that a multimodal blockade of RAS has the potential to be a safe and cost-effective treatment for cancer in cats.

Abstract

The role of the renin-angiotensin system (RAS) in cancer growth and progression is well recognized in humans. However, studies on RAS inhibition with a single agent have not shown consistent anticancer effects, potentially due to the neoplastic cells utilizing alternative pathways for RAS activation. To achieve more complete RAS inhibition, multimodal therapy with several medications that simultaneously block multiple steps in the RAS has been developed for use in humans. In the present study, the safety of multimodal RAS inhibition using atenolol, benazepril, metformin, curcumin, and meloxicam was assessed in six cats with squamous cell carcinomas. Cats were treated for 8 weeks, with blood pressure measured and blood sampled five times during the treatment period. None of the cats developed hypotension, azotemia, or increased serum liver enzyme concentrations. The packed cell volume of one cat decreased to just below the reference range during treatment. One cat was reported to have increased vomiting, although this occurred infrequently. One cat was withdrawn from the study due to difficulties administering the medications, and another cat died of an unrelated cause. Two cats were euthanatized during the study period due to cancer progression. Two cats completed the 8-week study period. One was subsequently euthanized due to cancer progression while the other cat is still alive 32 weeks after entering the study and is still receiving the multimodal blockade of the RAS. This is the first evaluation of multimodal blockade of the RAS in veterinary species. The study showed that the treatment is safe, with only mild adverse effects observed in two treated cats. Due to the small number of cats, the efficacy of treatment could not be evaluated. However, evidence from human studies suggests that a multimodal blockade of RAS could be a safe and cost-effective treatment option for cancer in cats.

Appetite Stimulant and Anti-Emetic Effect of Mirtazapine Transdermal Ointment in Cats Affected by Lymphoma Following Chemotherapy Administration: A Multi-Centre Retrospective Study

Simple Summary

Feline cancer patients’ owners are increasingly willing to undertake oncologic treatment, such as chemotherapy. Concerns regarding worsening quality of life are common since chemotherapy could cause toxicities, such as vomiting, nausea, anorexia, and consequently weight loss. In humans, mirtazapine effectively prevents chemotherapy-induced nausea and vomiting, improving the quality of life in people receiving chemotherapy. Recently, the use of mirtazapine transdermal ointment has been evaluated in cats with non-cancer diseases. This study describes the use of transdermal mirtazapine administration in cats diagnosed with lymphoma and receiving chemotherapy. Patients included in the study did not receive any prophylactic anti-emetics other than transdermal mirtazapine. Data regarding patients, type of chemotherapy, and incidence of weight loss and gastrointestinal toxicities were retrospectively evaluated. Transdermal mirtazapine was well tolerated, and substantial weight loss was not observed in the 14 days following chemotherapy administration. These results support further studies assessing the impact of mirtazapine in preventing chemotherapy-induced gastrointestinal toxicity in cats.

Abstract

In humans, mirtazapine can prevent chemotherapy-induced nausea and vomiting (CINV) and improve cancer patients’ quality of life (QoL). This drug is being increasingly used as an appetite stimulant in cats. The hypothesis of this retrospective study was that mirtazapine could reduce the incidence of CINV and weight loss in feline patients affected by lymphoma. The objectives were to report the use of mirtazapine transdermal ointment and assess the incidence of gastrointestinal (GI) toxicity and weight loss in cats diagnosed with lymphoma and receiving chemotherapy. Transdermal mirtazapine was topically administered to the inner surface of the pinna (2 mg/cat/daily) for 14 days following chemotherapy administration. Data recorded from 20 patients were collected. Different grades of GI toxicity were shown in 8/20 (40%) patients. Body weight (BW), body condition score (BCS), and muscle condition score (MCS) improved in 12/20 (60%), 6/20 (30%), and 2/20 (10%) cats, respectively. Mirtazapine-induced adverse events (AEs) occurred in 4/20 (20%) cats and did not require mirtazapine discontinuation. Substantial weight loss was not encountered, suggesting that patients had an adequate food intake after chemotherapy administration. Transdermal mirtazapine ointment was considered safe and well tolerated.