Prospective evaluation of toceranib phosphate in metastatic canine osteosarcoma

Sarcomas represent a group of genomically chaotic, highly heterogenous tumours of mesenchymal origin with variable mutational load. Conventional therapy with surgery and radiation therapy is effective for managing small, low‐grade sarcomas and remains the standard therapeutic approach. For advanced, high‐grade, recurrent, or metastatic sarcomas, systemic chemotherapy provides minimal benefit, therefore, there is a drive to develop novel approaches. The discovery of “Coley's toxins” in the 19th century, and their use to stimulate the immune system supported the application of unconventional therapies for the treatment of sarcomas. While promising, this initial work was abandoned and treatment paradigm and disease course of sarcomas was largely unchanged for several decades. Exciting new therapies are currently changing treatment algorithms for advanced carcinomas and melanomas, and similar approaches are being applied to advance the field of sarcoma research. Recent discoveries in subtype‐specific cancer biology and the identification of distinct molecular targets have led to the development of promising targeted strategies with remarkable potential to change the landscape of sarcoma therapy in dogs. The purpose of this review article is to describe the current standard of care and limitations as well as emerging approaches for sarcoma therapy that span many of the most active paradigms in oncologic research, including immunotherapies, checkpoint inhibitors, and drugs capable of cellular metabolic reprogramming.

Section: Receptor Tyrosine Kinase Inhibitorsmentioning

confidence: 99%

Emerging therapeutic approaches for canine sarcomas: Pushing the boundaries beyond the conventional

Borgatti

Dickerson

Lawrence

2019

“…Despite aggressive adjuvant cytotoxic chemotherapy regimens, little advancement in the systemic treatment of OSA has led to stagnant survival rates in humans and dogs, of 70% at 5 years and 15% at 2 years, respectively, in cases that present without gross metastasis . Furthermore, the prognosis is particularly dire for humans and dogs with gross metastatic disease . Therefore, novel therapeutics designed to target a variety of host immune cells and enhance the anti‐tumour immune response are being investigated in both species for their activity in OSA …”

Section: Introductionmentioning

confidence: 99%

Metastatic immune infiltrates correlate with those of the primary tumour in canine osteosarcoma

Withers

York

Choi

et al. 2019

Our lack of understanding of the immune microenvironment in canine osteosarcoma (cOSA) has limited the identification of potential immunotherapeutic targets. In particular, our ability to utilize readily available tissue from a dog's primary tumour to predict the type and extent of immune response in their pulmonary metastatic lesions is unknown. We, therefore, collected 21 matched pairs of primary tumours and pulmonary metastatic lesions from dogs with OSA and performed immunohistochemistry to quantify T‐lymphocyte (CD3), FOXP3+ cell, B‐lymphocyte (Pax‐5), and CD204+ macrophage infiltration. We found that T‐lymphocytes and FOXP3+ infiltrates in primary tumours positively correlated with that of metastatic lesions (ρ = 0.512, P = 0.038 and ρ = 0.698, P = 0.007, respectively), while a strong trend existed for CD204+ infiltrates (ρ = 0.404, P = 0.087). We also observed T‐ and B‐lymphocytes, and CD204+ macrophages to be significantly higher in a dog's pulmonary metastasis compared to their primary tumour (P = 0.018, P = 0.018, P = 0.016, respectively), while FOXP3+ cells were only significantly higher in metastases when all primary tumour and metastasis lesions were compared without pairing (P = 0.036). Together, these findings suggest that the metastatic immune microenvironment may be influenced by that of the primary cOSA, and that primary tumour immune biomarkers could potentially be applied to predict immunotherapeutic responses in gross metastatic disease. We, therefore, provide a rationale for the treatment of cOSA pulmonary metastases with immunotherapeutics that enhance the anti‐tumour activity of these immune cells, particularly in dogs with moderate to high immune cell infiltration in their primary tumours.

“…However, there is increasing evidence that other solid tumours, such as anal sac, head‐neck and thyroid carcinomas, and OSA can be successfully treated with TOC . Clinical trials performed on canine OSA patients showed controversial results when using Palladia as a single agent in canine metastatic OSA or in combination with other drugs, suggesting that more data are needed to clarify its benefit . Xenograft mouse models represent important tools for investigating the in vivo response to cancer therapeutic interventions.…”

Section: Introductionmentioning

confidence: 99%

In vitro and in vivo effects of toceranib phosphate on canine osteosarcoma cell lines and xenograft orthotopic models

Sánchez-Céspedes

Accornero

Miretti

et al. 2019

Canine osteosarcoma (OSA) is the most common primary malignant bone tumour in dogs, and it has a high metastatic rate and poor prognosis. Toceranib phosphate (TOC; Palladia, Zoetis) is a veterinary tyrosine kinase inhibitor that selectively inhibits VEGFR‐2, PDGFRs and c‐Kit, but its efficacy is not yet fully understood in the treatment of canine OSA. Here, we evaluated the functional effects of TOC on six OSA cell lines by transwell, wound healing and colony formation assays. Subsequently, two cell lines (Wall and Penny) were selected and were inoculated in mice by intrafemoral injection to develop an orthotopic xenograft model of canine OSA. For each cell line, 30 mice were xenografted; half of them were used as controls, and the other half were treated with TOC at 40 mg/kg body weight for 20 days. TOC inhibited cell growth of all cell lines, but reduced invasion and migration was only observed in Penny and Wall cell lines. In mice engrafted with Penny cells and subjected to TOC treatment, decreased tumour growth was observed, and PDGFRs and c‐Kit mRNA were downregulated. Immunohistochemical analyses demonstrated a significant reduction of Ki67 staining in treated mice when compared to controls. The results obtained here demonstrate that TOC is able to slightly inhibit cell growth in vitro, while its effect is evident only in a Penny cell xenograft model, in which TOC significantly reduced tumour size and the Ki67 index without modifying apoptosis markers.