The canine tumour micro-environment and advances in antitumour therapy in canine melanoma

Cancer poses a substantial health burden in both humans and dogs. Despite significant advances, durable tumour control is often not achieved, highlighting the need for novel targeted therapies and immunotherapies. However, translation of these approaches into human and veterinary oncology has been slow. Comparative oncology offers a valuable translational strategy, as naturally occurring cancers in dogs share significant clinical, molecular, and genetic similarities with human malignancies. This review provides an overview of the canine tumour microenvironment (TME), with a primary focus on melanoma as an aggressive and immunogenic tumour model. Key immune components, including T cells, B cells, natural killer cells, tumour-associated macrophages, and myeloid-derived suppressor cells, are discussed in the context of tumour progression and immune evasion. Furthermore, current advances in immunotherapeutic strategies, such as immune checkpoint inhibitors and therapeutic cancer vaccines, as well as receptor tyrosine kinase-targeted therapies, are evaluated in canine cancers. While these approaches have shown promise, challenges such as tumour heterogeneity, immunosuppressive TMEs, and therapeutic resistance are difficult to overcome, resulting in limited clinical efficacy. Integrating insights from human and veterinary oncology underscores the potential of comparative approaches to improve translational success and develop more effective combination therapies for both species.