Breakthrough nonsurgical treatment for canine mast cell tumors is now on the market

Tigilanol tiglate injection (Stelfonta; Virbac) for treating canine mast cell tumors is now available in veterinarian clinics throughout the United States as an alternative to surgery. The therapy was approved by the FDA in November 2020 for the treatment of nonmetastatic, cutaneous mast cell tumors anywhere on a dog's body and nonmetastatic, subcutaneous mast cell tumors located in the lower parts of dogs' legs.

According to the Morris Animal Foundation, cancer is the leading cause of death in dogs over age 2. Mast cell tumors are the most common type of skin cancer in dogs and often appear as a nodule on or just underneath the skin. Although typical treatment options include surgery, chemotherapy and radiation, these treatments may not be appropriate for every dog.

According to Virbac, tigilanol tiglate is a biologically active pharmaceutical ingredient discovered by Australian company Qbiotics in the seed of the blushwood tree native to the rainforest of North Queensland. Injected directly into the tumor, tigilanol tiglate works by activating the local innate immune system with destruction of the tumor cells and tumor blood supply, leading to tumor destruction. Tigilanol tiglate also promotes complete healing of the typical tissue deficit left after tumor removal with minimal scar formation. Although sedation is not usually required, it may be necessary to administer this injection therapy safely and accurately.

According to Virbac, this therapy can induce a substantial but transitory local inflammatory reaction which may result in pain, bruising, and swelling. Therefore, as with surgery, pain control medication is recommended.

Among dogs treated with tigilanol tiglate in the registration clinical trial conducted in the United States, 75% of mast cell tumors achieved a complete response (complete tumor removal) of the injected tumor with just 1 treatment, and nearly all of the tumor sites healed within 6 weeks. According to Virbac, some wounds can be more extensive and may require additional management and healing time. In this same controlled clinical trial, interventions such as a collar or bandages to manage wounds were minimal and only required in 5 of 117 cases.

Since tigilanol tiglate received approval from the FDA, roughly 88% of United States veterinarians polled who have used the therapy to treat canine mast cell tumors reported satisfactory experiences. It has also received approval from regulatory agencies in Australia, Europe and the United Kingdom for the treatment of canine mast cell tumors.

Tigilanol tiglate may cause extensive wound formation at the tumor site, including cellulitis and severe tissue sloughing that may require additional management and healing time. The most common adverse reactions seen in the clinical trial were wound formation, injection site pain, lameness in the treated limb, vomiting, diarrhea, hypoalbuminemia, and injection site bruising. Sedation of the dog may be necessary to administer tiglate tigilanol safely and accurately, and to decrease the chance of accidental self-injection that may cause local inflammation and wound formation. The safe use of tigilanol tiglate has not been evaluated in dogs younger than 3.5 years old.

Reference

Virbac announces FDA approval of new cancer treatment for dogs derived from Australian rainforest plant. News release. August 16, 2021; Virbac. Accessed August 16, 2021. https://www.prnewswire.com/news-releases/virbac-announces-fda-approval-of-new-cancer-treatment-for-dogs-derived-from-australian-rainforest-plant-301355529.html