Printer Friendly

Testing New Drug to Fight Feline Injection-Site Sarcoma

By Kelley Weir

Back in the 1990s, veterinarians began to notice an increase in the incidence of sarcoma in cats at the site where injections are routinely given. This type of cancer, which affects approximately 1 in 10,000 cats, was initially associated with vaccines and, thus, named vaccine-associated sarcoma (VAS), but it was subsequently found to be associated with other injections (e.g., antibiotics) and, therefore, is currently called injection-site sarcoma (ISS). ISS is an extremely aggressive cancer: the time from injection to tumor development can be as short as 4 weeks or as long as 10 years. A combination of surgery, radiation therapy and, occasionally, chemotherapy offers cats the best chance for long-term survival. Although treated cats can remain cancer free for 10 to 32 months after treatment, ISS is almost always fatal, so new treatments are needed.

Dr. Jessica Lawrence, along with her colleagues Dr. Corey Saba and Dr. Michelle Turek at the University of Georgia, is researching masitinib, a new drug that was recently approved by the U.S. Food and Drug Administration for use in treating dogs with a particular tumor type. Dr Lawrence hopes to show that the drug could also be beneficial in treating cats with ISS. With funding from Morris Animal Foundation, she is evaluating the drug’s ability to sensitize in vitro feline ISS cells to radiation.

“This study is a rational first step to take before bringing the drug into the clinical setting and testing its effectiveness on cats with ISS,” Dr. Lawrence says.

Masitinib is the active pharmacological ingredient in the first ever European-registered veterinary anticancer drug under its brand name, Masivet (Kinavet in North America). Research trials all over the world have found that the drug shows promise in treating canine atopic dermatitis, inflammatory bowel disease, arthritis and feline asthma. Additionally, promising results have been reported from human clinical trials of masitinib in the treatment of advanced cancers and asthma.

If Dr. Lawrence determines that the drug increases the sensitivity of ISS cells to radiation, her findings will provide the foundation for future studies to identify the best way to incorporate masitinib into the treatment of cats with ISS. The study is unique because it looks at using this drug in combination with existing treatments, Dr. Lawrence says.

Though the rising incidence of ISS is troubling, there is an even greater concern that some cat owners, in an attempt to keep their cats from developing ISS, may choose to stop vaccinating their cats. According to Dr. Lawrence, though this response may be well intentioned, cats have a much higher risk of acquiring a fatal infection than of developing ISS, so it is critical to follow vaccination recommendations.

“It is up to us to determine the best course of action for our pets,” Dr. Lawrence says. “The best suggestions are to learn as much as you can about ISS, discuss the issue with your veterinarian and, as a team, reach a vaccination plan best suited for you and for your cat.”

Learn more about other feline diseases in the Health Info Center at

Posted by MAFon July 11, 2011.

Categories: Cat diseases, Cat health, Feline health


Bookmark and Share

Post a Comment:

(max length 600 characters)
Enter this word:

Submitted by Ishmael at: April 18, 2012
My cat had an injection of antibiotics for a tooth infections; 4 weeks later, the cat had a huge round tumor in his mouth.
Submitted by Lisa at: July 24, 2011
I would also be very interested in seeing this drug in a trial used for feline IBD. I run a website for cats with IBD and it's reaching epidemic levels! prednisone is the first drug of choice but can cause diabetes, lymphoma, etc. Entocort is being used more and with good results. We need more options and also some ways to prevent this disease in the first place!
Submitted by Stephanie M. at: July 17, 2011
Hats off to Dr. Lawrence for her research. I pray that with her continued studies this terrible harm to cats is eliminated. Thank you.
Submitted by Nancy G. Wyse at: July 15, 2011
I had a Maine Coon cat that deveoped a sarcoma when he was six years. He had surgery and did well. The following year he developed the same sarcoma at the same injection and this repeated itself for the following three years. I worked for a vet who did his surgeries and I caught them when they only needed to be surgically removed. I quit vaccinating him and two years later I had his antibodies checked for rabies and they were off the charts. He was a inside cat and I never vaccinated him again and he lived to be seventeen years old without a recurence of the fiber sarcoma.