Evaluation of toceranib for treatment of apocrine gland anal sac adenocarcinoma in dogs

Case report: Adjuvant therapy with toceranib for an incompletely resected renal cell carcinoma with suspected pulmonary metastasis in a dog

Primary renal neoplasia is rare in humans and dogs, with renal cell carcinoma (RCC) being the most common form of this cancer. As RCC is often diagnosed at an advanced stage, pulmonary metastasis is frequently observed. Tyrosine kinase inhibitors (TKIs) are the standard adjuvant treatments for metastatic RCC in humans. Similarly, in veterinary medicine, recent trials have employed TKIs for early-stage RCC patients who underwent complete surgical resection and showed no distant metastasis. However, the use of TKIs has not yet been reported commonly in cases of advanced RCC with metastasis. This case study presents the first clinical outcomes of TKI therapy in a dog with incompletely resected RCC and metastasis. A 5-year-old spayed female Chihuahua was referred to our hospital with a right renal mass and multiple pulmonary nodules suspected to be metastases. A portion of the renal mass was surgically removed, and histopathological examination revealed RCC with a high mitotic index. Adjuvant chemotherapy was administered, owing to incomplete resection with suspected pulmonary metastasis. An anticancer drug response prediction test was conducted using patient tissues. Since toceranib showed the most favorable responsiveness, it was selected as a therapeutic agent. Toceranib was orally administered at a dosage of 2.27 mg/kg every 48 h. Regular medical records for potential adverse effects were obtained, including systemic blood pressure, complete blood count, serum biochemical examination, and urinalysis. After 2 weeks of toceranib therapy, partial remission of pulmonary nodules continued for 2 months. The patient did not experience any adverse effects of the anticancer drug during the 4-month follow-up period. However, the patient died from an unidentified cause 6 months after the initial detection of the renal mass. This report describes the use of toceranib in dogs with RCC. In the present case, the patient showed an initial response to chemotherapy, and despite the presence of several poor prognostic factors, the dog survived beyond the expected 3-month lifespan to 6 months. Notably, no adverse events were observed during treatment.

Palmar-plantar erythrodysesthesia syndrome resulting from toceranib phosphate in a dog with apocrine gland anal sac adenocarcinoma: a case report

An 11-year-old neutered male Miniature Poodle with a stage 3 apocrine gland adenocarcinoma was started on chemotherapy with toceranib phosphate after surgery. Beginning on day 10 of toceranib, the dog's foot pads became erythematous and hyperkeratinized. The dog complained of pain, inability to walk, depression, and loss of appetite. The symptoms resolved when toceranib was discontinued and reappeared when toceranib was resumed. Grade 3 palmar-plantar erythrodysesthesia was identified as an adverse event of toceranib based on the VCOG-CTCAE and Naranjo scale. Although very rare in veterinary medicine, clinicians should consider that palmar-plantar erythrodysesthesia can occur after toceranib administration.

Toceranib phosphate and firocoxib-mediated partial response in a dog with advanced intranasal sarcoma

A nine-year-old, castrated male mixed-breed dog presented with a three-month history of sneezing and stertorous breathing. Computed tomography revealed a soft tissue mass in the left nasal cavity with lysis of the cribriform plate. The mass was diagnosed as intranasal sarcoma based on histopathological analysis. The tumor cells were immunohistochemically positive for KIT and platelet-derived growth factor receptor α/β and negative for vascular endothelial growth factor receptor 2 and cyclooxygenase-2. Treatment with toceranib phosphate (TOC) and firocoxib reduced the tumor size, which was defined as partial response (PR). After PR induction, TOC alone mediated survival for 205 days. This case report suggests that the combination of TOC and possibly firocoxib may be a therapeutic option for canine intranasal sarcoma.

Development of Monoclonal Antibodies Targeting Canine PD-L1 and PD-1 and Their Clinical Relevance in Canine Apocrine Gland Anal Sac Adenocarcinoma

Canine apocrine gland anal sac adenocarcinoma (AGASACA) is an aggressive canine tumor originating from the anal sac glands. Surgical resection, with or without adjuvant chemotherapy, represents the standard of care for this tumor, but the outcome is generally poor, particularly for tumors diagnosed at an advanced stage. For this reason, novel treatment options are warranted, and a few recent reports have suggested the activation of the immune checkpoint axis in canine AGASACA. In our study, we developed canine-specific monoclonal antibodies targeting PD-1 and PD-L1. A total of 41 AGASACAs with complete clinical and follow-up information were then analyzed by immunohistochemistry for the expression of the two checkpoint molecules (PD-L1 and PD-1) and the presence of tumor-infiltrating lymphocytes (CD3 and CD20), which were evaluated within the tumor bulk (intratumor) and in the surrounding stroma (peritumor). Seventeen AGASACAs (42%) expressed PD-L1 in a range between 5% and 95%. The intratumor lymphocytes were predominantly CD3+ T-cells and were positively correlated with the number of PD-1+ intratumor lymphocytes (ρ = 0.36; p = 0.02). The peritumor lymphocytes were a mixture of CD3+ and CD20+ cells with variable PD-1 expression (range 0-50%). PD-L1 expression negatively affected survival only in the subgroup of dogs treated with surgery alone (n = 14; 576 vs. 235 days). The presence of a heterogeneous lymphocytic infiltrate and the expression of PD-1 and PD-L1 molecules support the relevance of the immune microenvironment in canine AGASACAs and the potential value of immune checkpoints as promising therapeutic targets.

Toceranib phosphate in the management of canine insulinoma: A retrospective multicentre study of 30 cases (2009-2019)

BACKGROUND

Insulinomas are the most common tumour of the endocrine pancreas in dogs. These malignant tumours have a high metastatic rate and limited chemotherapeutic options. The multi-receptor tyrosine kinase inhibitor sunitinib malate has benefit in the treatment of metastatic insulinoma in people. Toceranib phosphate, an analogous veterinary agent, may provide benefit for dogs.

METHODS

A retrospective study describing the extent and duration of clinical outcomes and adverse events (AEs) in dogs diagnosed with insulinoma and receiving toceranib.

RESULTS

Records for 30 dogs diagnosed with insulinoma and having received toceranib were identified from a medical record search of five university and eight referral hospitals. The median progression-free interval and overall survival time were 561 days (95% confidence interval (CI): [246, 727 days]) and 656 days (95% CI: [310, 1045 days]), respectively. Of the dogs for which the canine Response evaluation criteria for solid tumours tool could be applied, the majority (66.7%) showed either a complete response, partial response or stable disease. Time to clinical progression was associated with prior intervention and type of veterinary practice. Larger dogs were at increased risk for disease progression and death. No novel AEs were reported.

CONCLUSIONS

Most dogs diagnosed with insulinoma and receiving toceranib appeared to have a clinical benefit. Randomised, prospective studies are needed to better elucidate and objectively quantify the potential effect and survival benefit of toceranib therapy for management of insulinoma in dogs.

Immunohistochemical Expression of Platelet-Derived Growth Factor Receptor β (PDGFR-β) in Canine Cutaneous Peripheral Nerve Sheath Tumors: A Preliminary Study

Simple Summary

The peripheral nerve sheath tumors are relatively common neoplasms, belong to the soft tissue sarcomas group, and are poorly investigated in veterinary medicine; the diagnosis is complex, and therapeutic options are limited. The platelet-derived growth factor receptors, namely the β subunit, are an important class of tyrosine kinase receptors that can be activated by genetic alterations and contribute to the process of carcinogenesis, so the inhibition of this receptor is an important therapeutic target. Using the immunohistochemical technique, this study aims to evaluate the expression of this receptor in 19 samples, 10 malignant and 9 benign tumors. The results showed that the majority of benign tumors, about 67% of cases, expressed the receptor in less than 25% of neoplastic cells and, in 80% cases of malignant tumors, the receptor was expressed in more than 25% of neoplastic cells. It was also found that, in the larger tumors, the expression of this receptor was significantly higher. With these findings it seems reasonable to speculate that the drugs able to inhibit this receptor, such as toceranib, may be considered in the therapeutic approach of these tumors.

Abstract

As in humans, the prevalence of tumors in companion animals is increasing dramatically and there is a strong need for research on new pharmacological agents particularly for the treatment of those tumors that are resistant to conventional chemotherapy agents such as soft tissue sarcomas (STS). Because malignant (MPNST) and benign peripheral nerve sheath tumors (BPNST) are relatively common STS in dogs, the aim of this retrospective study was to evaluate the immunohistochemical (IHC) expression of PDGFR-β, contributing to its characterization as a potential target for their treatment. A total of 19 samples were included, 9 histologically classified as benign and the other 10 as malignant. The results showed diffuse immunoexpression in the cytoplasm of neoplastic cells. Six (66.7%) BPNST expressed the receptor in less than 25% of neoplastic cells and only three (33.3%) exhibited labelling in more than 25% of neoplastic cells. In contrast, all MPNST expressed PDGFR-β, and in 8 (80%) of these samples, the receptor was expressed in more than 25% of neoplastic cells, and only 2 (20%) cases expressed the receptor in less than 25% of neoplastic cells. PDGFR-β expression was significantly higher in MPNST and larger tumors, suggesting that drugs able to inhibit the activity of this tyrosine kinase receptor, such as toceranib, may be considered in the approach of unresectable tumors and/or in the context of adjuvant or neoadjuvant therapies.

Canine Apocrine Gland Anal Sac Adenocarcinoma: A Review

Apocrine gland anal sac adenocarcinoma (AGASAC) is a relatively uncommon tumor in the dog and comprises approximately 17% of perianal malignancies; however, it is one of the most common causes of paraneoplastic hypercalcemia. Clinical signs in affected dogs most commonly are associated with mechanical obstruction caused by the primary tumor or enlarged regional metastatic lymph nodes and the effects of paraneoplastic hypercalcemia when present. Surgical excision of the primary tumor and metastasectomy of affected locoregional lymph nodes is the preferred initial treatment option for most dogs, although radiation therapy and adjuvant chemotherapy are commonly incorporated into multi-modality treatment plans. A significant role for the use of adjuvant chemotherapy has not been clearly demonstrated. Prolonged survival times are possible, especially for dogs with smaller primary tumors and for dogs that undergo further treatments for recurrent disease. In this article, we review the clinical signs, diagnosis, staging, treatment, and prognosis of AGASAC in the dog.

Multimodal Treatment of a Canine Lingual Melanoma Using a Combination of Immunotherapy and a Tyrosine Kinase Inhibitors

A 9-year-old female neutered Miniature Schnauzer was diagnosed with a lingual malignant melanoma on the basis of incisional biopsy and histopathology. The patient was initially given a guarded prognosis of a few months’ survival as surgical treatment options were declined by the owner. In order to control the disease a combination treatment of immunotherapy and tyrosine kinase inhibitors was initiated. The mass showed a marked and sustained reduction in size, whilst preserving quality of life for the patient, with a survival at the time of writing of 15 months since diagnosis. This experience suggests that combination therapy for oral malignant melanoma using immunotherapy and tyrosine kinase inhibitors may be successful in some patients and warrants further investigation.

The role of toceranib phosphate in dogs with non-mast cell neoplasia: A systematic review

The use of tyrosine kinase inhibitors (TKI) has gained significant importance in veterinary cancer patients over the last decade. Toceranib phosphate has been licensed for the treatment of dogs with mast cell tumours. Its molecular similarity to sunitinib, a TKI used in human medicine, has led many veterinary oncologists to use this agent for multiple neoplastic diseases. The aim of the current study was to perform a systematic review of the evidence for the use of toceranib in dogs with non-mast cell neoplasia. Two electronic databases were searched. Publications were included if toceranib was used as a treatment option in canine patients. Studies and case reports were excluded if toceranib was used as part of a multi-modal treatment plan and response or outcome data related to toceranib therapy were not described. A total of 28 studies were included from 122 references. The most common types of neoplasias identified were neuroendocrine tumours, anal gland sac adenocarcinoma, and osteosarcoma. Multiple other neoplasias had one or two studies identified to describe the use of toceranib. Results of the study support that toceranib phosphate may have efficacy against certain types of neoplasia under certain conditions, such as neuroendocrine tumours, gastrointestinal stromal tumours and anal sac adenocarcinomas, while it is probably not effective for the management of metastatic osteosarcoma based on the findings of the review.

A Retrospective Study of Clinical and Histopathological Features of 81 Cases of Canine Apocrine Gland Adenocarcinoma of the Anal Sac: Independent Clinical and Histopathological Risk Factors Associated with Outcome

Canine apocrine gland anal sac adenocarcinoma (AGASAC) is a malignant tumour with variable clinical progression. The objective of this study was to use robust multivariate models, based on models employed in human medical oncology, to establish clinical and histopathological risk factors of poor survival. Clinical data and imaging of 81 cases with AGASAC were reviewed. Tissue was available for histological review and immunohistochemistry in 49 cases. Tumour and lymph node size were determined using the response evaluation criteria in the solid tumours system (RECIST). Modelling revealed tumour size over 2 cm, lymph node size grouped in three tiers by the two thresholds 1.6 cm and 5 cm, surgical management, and radiotherapy were independent clinical variables associated with survival, irrespective of tumour stage. Tumour size over 1.3 cm and presence of distant metastasis were independent clinical variables associated with the first progression-free interval. The presence of the histopathological variables of tumour necrosis, a solid histological pattern, and vascular invasion in the primary tumour were independent risk factors of poor survival. Based upon these independent risk factors, scoring algorithms to predict survival in AGASAC patients are presented.

Long-term survival in a dog with primary hepatic neuroendocrine tumor treated with toceranib phosphate

Primary hepatic neuroendocrine tumors (PHNETs) are rare in dogs, and limited information exists about the treatment of these tumors. A 12-year-old castrated male French bulldog was presented to our clinic with gastrointestinal signs. Diagnostic tests revealed increased hepatic enzyme levels, a mass in the hepatic quadrate lobe, multiple intrahepatic nodules, and enlarged hepatic hilar lymph nodes. The liver mass was diagnosed cytologically as a malignant epithelial tumor suspected to be of neuroendocrine origin. The dog was treated with single-agent toceranib phosphate (TOC) and survived 25.1 months after the initial presentation. On necropsy, a liver mass was found and was subsequently diagnosed as a PHNET on histopathology. To the best of our knowledge, this is the first report of long-term survival in a dog with PHNET treated with TOC.

Canine anal sac gland carcinoma with regional lymph node metastases treated with sacculectomy and lymphadenectomy: Outcome and possible prognostic factors

The staging system commonly used in canine anal sac gland carcinoma (ASGC) is a revised Tumour-Node-Metastasis (TNM) system published in 2007. This staging system consists in four stages and, for dogs with nodal metastases, the size of the metastatic lymph node (mLN) defines the N stage. However, we hypothesise that (1) the mLN size has no prognostic significance when the mLN can be excised, (2) a high number of mLNs is associated with poorer prognosis and (3) the measurement of the mLN on imaging is not reproducible. To investigate these hypotheses, medical records and diagnostic images of dogs with ASGC and mLN, treated with sacculectomy and lymphadenectomy, with or without chemotherapy, were reviewed. Interobserver variability for mLN measurement was assessed. Prognostic factors including mLN size and number were investigated. Time to documented progression (TDP) and disease-specific survival (DSS) were evaluated. Progression-free interval (PFI) was analysed with interval-censored data analysis. Fifty-seven dogs were included. The median PFI, TDP and DSS were 110 (95%CI 61.5-185.5), 196 (95%CI 162-283) and 340 days (95%CI 321-471), respectively. For measurement of the largest mLN, interobserver agreement was excellent but limits of agreement reached 39.7%. Neither the size of the largest mLN nor the use of adjuvant chemotherapy were associated with outcome. The number of mLNs was associated with outcome and having more than four mLNs was associated with shorter PFI (p < .001), TDP (p = .004) and DSS (p < .001). While mLN size measurement was not consistently reproducible and did not influence outcome in our cohort, number of mLNs did. Further studies are required for development of a revised staging system.

Prognostic Value of Ki67 and Other Clinical and Histopathological Factors in Canine Apocrine Gland Anal Sac Adenocarcinoma

Simple Summary

Apocrine gland anal sac adenocarcinoma (AGASACA) is a locally aggressive tumor with a high metastatic rate to the regional ileo-sacral lymph nodes and later to distant sites. Clinical signs depend on the tumor and regional lymph nodes size or on the paraneoplastic hypercalcemia. Therefore, dogs are often referred for perineal swelling, tenesmus, constipation and/or polyuria, polydipsia. Surgical excision of both the neoplastic anal sac and the metastatic regional lymph nodes represents the standard of care. Adjuvant chemotherapy and/or radiotherapy are also indicated. Prognostic factors include tumor size, hypercalcemia, regional lymph nodes metastasis and tumor histologic features. The aim of the study was to retrospectively evaluate the prognostic significance of tumor Ki67 expression. The authors’ hypothesis was that higher Ki67 index correlated with decreased disease-free interval and overall survival time. Clinical data such as tumor size, regional lymph nodes metastasis and hypercalcemia at presentation and histological features such as tumor pattern, mitotic count, necrosis, inflammatory infiltration, vascular invasion, anisokaryosis, and anisocytosis were also investigated and correlated to the oncologic outcome in the dogs included in the study.

Abstract

Apocrine gland anal sac adenocarcinoma (AGASACA) is locally aggressive and highly metastatic to regional lymph nodes. The aim of this study was to evaluate the prognostic significance of Ki67 in surgically excised AGASACA. Prognostic impact of size, regional lymph nodes metastasis, hypercalcemia, histologic pattern, mitotic count, necrosis, inflammatory and lympho-vascular invasion, anisokaryosis and anisocytosis was also evaluated. Thirty-five dogs were included, twenty-four of which also had metastatic lymph nodes. When the entire population was evaluated, only metastatic disease spread to regional lymph nodes, and necrosis and inflammatory infiltration were correlated to prognosis. When only dogs with metastatic disease were evaluated, size, solid histologic pattern, presence of lymphatic and vascular invasion showed influence on prognosis. Ki67 index was not associated with survival time and disease free interval in any case. The results of this study showed that lymph nodes metastasis at diagnosis reduced disease free interval. Moreover, tumor size greater than 5.25 cm, presence of lymphatic and vascular invasion and a solid histologic pattern were associated with a shorter survival time in dogs with metastasis to regional lymph nodes. Ki67 expression was not significantly associated with prognosis, therefore it could not be considered as a prognostic factor in this tumor type, while the role of hypercalcemia remained unclear.

Retrospective assessment of radiation toxicity from a definitive-intent, moderately hypofractionated image-guided intensity-modulated protocol for anal sac adenocarcinoma in dogs

A recent calculation study predicted acceptable toxicity in pelvic organs at risk for a new definitive-intent, moderately hypofractionated radiation therapy (RT) protocol (12 x 3.8 Gy), when used with image-guided intensity-modulated radiation therapy (IG-IMRT). We hypothesized this protocol to result in clinically acceptable radiation toxicities. Dogs diagnosed with and irradiated for anal sac adenocarcinoma (ASAC) were retrospectively assessed. Eleven dogs were included, six had prior surgery. Before any therapy, staging according to Polton et al. resulted in the following distribution: stage 1 (n = 1), stage 2 (n = 1), stage 3a (n = 6), stage 3b (n = 3). We scored radiation toxicities at the end of therapy, at weeks 1, 3 and every 3 months after RT according to Veterinary Radiation Therapy Oncology Group radiation toxicity criteria. Clinical follow-up was maintained on regular intervals combined with computed tomography (n = 3). Median follow-up time for dogs still alive was 594 days (range: 224-972 days). Within 1 week post treatment, eight dogs (73%) developed grade 2 and four dogs (36%) grade 1 acute toxicity in the perianal region. All acute toxicities resolved or improved to grade 1 within 3 weeks after treatment. Late toxicity, for example, chronic colitis/diarrhoea, ulcerations, strictures or myelopathies was not observed in any patient. Five dogs were euthanized 105, 196, 401, 508 and 908 days after RT and six dogs were still alive, one in spite of progressive disease. The median progression-free survival was 908 days (95%CI: 215; 1602). The previous theoretically described definitive-intent, moderately hypofractionated protocol using IG-IMRT for the treatment of advanced ASAC showed clinically acceptable acute and late toxicities.

Evaluation of toceranib for treatment of apocrine gland anal sac adenocarcinoma in dogs

BACKGROUND

There is no widely accepted standard medical treatment for apocrine gland anal sac adenocarcinoma (AGASACA) in dogs. Targeted agents such as toceranib may be effective in treatment of AGASACA, but the number of clinical reports investigating its efficacy is limited.

HYPOTHESIS/AIM

To evaluate the efficacy of toceranib treatment of AGASACA in dogs, and to assess prognostic factors in the study population. Our hypothesis was that toceranib would provide a clinical benefit in the treatment of dogs with AGASACA.

ANIMALS

Thirty-six client-owned dogs with either a cytologic or histologic diagnosis of AGASACA that were treated with toceranib alone or in combination with surgery, nonconcurrent chemotherapy or both.

METHODS

Retrospective study.

RESULT

The median progression-free survival (PFS) and overall survival time (OST) for the study population was 313 days and 827 days, respectively. A clinical benefit from toceranib treatment was observed in 69% of dogs, with 20.7% of dogs experiencing partial response and 48.3% of dogs experiencing stable disease. Dogs that responded to toceranib treatment had significantly prolonged PFS and OST. Hypercalcemia was a negative prognostic factor for clinical outcomes.

CONCLUSIONS

Toceranib is effective in the treatment of AGASACA in dogs. Prospective, controlled clinical trials are needed to determine the efficacy of toceranib in comparison to other treatment protocols for dogs with AGASACA.