Virbac, a French animal health company with North American headquarters in Westlake’s Solana District, has good news for very sick dogs: A newly approved cancer treatment is now available in vets’ offices nationwide.

The drug, Stelfonta (tigilanol tiglate injection), received FDA approval last November to treat dogs with non-metastatic, skin-based mast cell tumors (MCTs). The FDA also approved Stelfonta for use in treating non-metastatic MCTs located under the dog’s skin in particular areas of a dog’s leg.  

Stelfonta was developed by Australian life sciences firm QBiotics. Its research team discovered Stelfonta’s active ingredient, tigilanol tiglate, in the seed of the Australian native blushwood tree from the rainforest of North Queensland. 

Virbac is QBiotics’ marketing and distribution partner. Administrative, commercial, and IT departments work out of Virbac’s North American headquarters in the Westlake suburb of Dallas-Fort Worth. Virbac is the world’s seventh-largest veterinarian biopharma group, with a presence in 100 countries and revenue of $1.05 billion in 2019. (Virbac is an acronym of virology and bacteriology.)

The most common malignant skin tumor in dogs

MCTs are the most common malignant skin tumor in dogs, usually appearing as a lump on or under the skin. Full surgical removal can be difficult, especially when they occur on a dog’s leg. If an MCT isn’t fully removed, malignant cells that remain can grow and spread rapidly. Stelfonta is a novel way to treat the condition as the only FDA-approved intratumoral injection.

How Stelfonta works

Stelfonta is injected directly into the tumor and works by activating a protein that spreads throughout the treated tumor, which disintegrates tumor cells.

“Stelfonta is a medical breakthrough for the treatment of mast cell tumors in dogs and there’s no other treatment like it,” said Dr. Cristiano von Simson, DVM, director of veterinary services at Virbac, in a statement. “It mobilizes the local immune cells to destroy the tumor and then promotes the growth of healthy tissue.”

Dr. von Simson noted that as with any manipulation of a mast cell tumor, potential risk of serious mast cell degranulation exists when using Stelfonta. However, he says this can be managed with pre- and post-treatment medications.

An alternative option for older dogs

Stelfonta hasn’t been evaluated in dogs with signs of systemic disease due to an MCT. But Dr. von Simson says it can be an alternative option to treat local skin tumors in older dogs, who have increased risks from surgery or chemotherapy. It’s also an alternation option “in cases where the dog owner isn’t comfortable with surgery or anesthesia.”

88% vet satisfactory rate

Since Stelfonta’s FDA approval in November, about 88 percent of veterinarians in the U.S. who’ve used the drug to treat dogs’ MCTs have reported “satisfactory” experiences, reports Virbac.

Besides winning FDA approval, Stelfonta has been approved by regulatory agencies in Australia, Europe, and the United Kingdom.

Adverse reactions

Virbac says Stelfonta may cause extensive wound formation at the tumor site—including cellulitis and severe tissue sloughing—that may require additional management and healing.

The most common adverse reactions during the clinical trial were wound formation, injection site pain, lameness in the treated limb, vomiting, diarrhea, hypoalbuminemia, and injection site bruising.

Dogs may need to be sedated to allow for Stelfonta to be safely and accurately administered. The safe use of Stelfonta in dogs younger than 3.5 years old has not been evaluated.

You can find more info about Stelfonta here.

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