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

SIMPLE SUMMARY: Oncology is a rapidly advancing field in small-animal medicine, underscoring the importance of innovative therapeutic approaches. Tyrosine kinase inhibitors (TKIs) are drugs that block various important cellular functions and play an important role in treating cancer in people and dogs. However, their role in feline oncology is less established. This comprehensive review surveys the existing literature on tyrosine kinases (TKs) and the use of TKIs in cats, aiming to identify knowledge gaps, speculate on potential indications and lay the groundwork for future investigations. Diverse feline tissues have been examined for various TK expressions. However, although limited evidence exists on the use of TKIs in specific feline tumors, it trails behind progress in human and canine oncology. We believe additional research could identify new uses for these drugs and improve therapeutic options for cats with cancer in the future. ABSTRACT: 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.