FDA approves intratumoral injection for dogs

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The US Food and Drug Administration (FDA) announced last month the approval of Stelfonta (tigilanol tiglate injection), the first intratumoral injection to treat nonmetastatic cutaneous mast cell tumors (MCTs) in dogs.

Stelfonta, which is injected directly into the MCT, activates a protein that spreads throughout the treated tumor and disintegrates tumor cells, according to the FDA website.

“This approval provides an additional treatment option to help treat local mast cell tumors on or under the skin in dogs,” says Steven M. Solomon, DVM, MPH, director of the FDA’s Center for Veterinary Medicine.

MCTs are the most common malignant skin tumors in dogs. Full surgical removal of mast tumor cells can be challenging when tumors are located in certain areas, like the leg. If not fully removed, the remaining malignant cells can start to grow and spread rapidly. “Stelfonta offers a novel way to treat nonmetastatic MCTs as the only approved intratumoral injection,” according to the FDA.

Stelfonta’s safety was demonstrated in a laboratory study of 118 dogs with a measurable cutaneous or a subcutaneous MCT on the lower leg. A total of 80 dogs were treated with Stelfonta, and 38 were in an untreated control group. After monitoring the dogs for a month, the complete remission rate of the treated group was 75%.

Eighteen dogs in the treatment group, whose tumors didn’t completely disappear, were retreated with Stelfonta a second time about a month after their first treatment. Approximately a month after receiving their second treatment, 44% of these dogs’ tumors had disappeared completely. Dogs in the untreated control group were treated with Stelfonta for the first time a month after the study began; 62% of those dogs’ tumors disappeared.

The most common adverse reactions associated with Stelfonta administration include wound formation at the tumor site and injection site reactions, such as pain, swelling, reddening of the skin, bruising, thickening, scarring, and death of some cells in the tissues.

Stelfonta is available by prescription only, as it should be administered only by veterinary personnel with the expertise to ensure safe use of the drug, assess the patient for contraindications, and monitor for adverse reactions.

Additionally, this drug should always be administered with a corticosteroid, an H1-receptor blocking agent and an H2-receptor blocking agent, thus decreasing the risk of severe systemic adverse reactions, including death, from mast cell degranulation.

The FDA also advises veterinarians to provide clients with handouts detailing important information about Stelfonta, including how to care for their pets after drug administration.

Stelfonta will be marketed in the United States by Virbac. To learn more, go here.