Great news! There’s a new fibrosarcoma treatment for cats. This immunotherapy provides hope for kitties fighting fibrosarcoma and vaccine-associated sarcomas.

The USDA granted a conditional license toMerial Animal Health for Feline Interleukin-2 Immunomodulator, an immunotherapy that delays return of fibrosarcoma in adult cats with stage 1 disease.

Fibrosarcoma is an aggressive cancer of the cat’s fibrous connective tissue. Some of these cancers have been associated with the injection of feline leukemia vaccine containing adjuvants. While these fast-growing tumors rarely spread to other parts of the body, they usually return after being surgically removed.

Feline Interleukin-2 Immunomodulator uses a weakened canarypox virus to insert IL-2 genes into cells around the tumor site. This stimulates an antitumor immune response, fighting the tumor using several approaches including natural killer cells that target the cancer. This is not a stand-alone treatment, but is provided in addition to aggressive surgical removal of the tumor and possibly radiation therapy.

The treatment is given via subcutaneous (under the skin) injections at multiple locations around the surgical site. The first of six injections is given the week before the cat’s cancer removal surgery. Following injections occur one to two weeks apart. A European field trial indicated that IL-2 used in additional to surgery and radiotherapy significantly reduced tumor recurrence and increased the period before relapse.

In the U.S., Feline Interleukin-2 Immunomodulator can be used by veterinary oncologists or internal medicine vets. Other trials are being conducted which would expand use by general vets.