The Food and Drug Administration announced in June it had approved the first cancer therapy for dogs in the United States.
The drug, Palladia, was created by Pfizer Animal Health Inc. as an oral product to treat Patnaik grade II or III recurrent cutaneous mast cell tumors with or without regional lymph node involvement.
Mast cell tumors are responsible for approximately one out of five cases of skin cancer in dogs, the FDA explained in its announcement. Until now, all cancer drugs used in veterinary medicine were developed for use in humans and had to be used in an extralabel manner to treat cancer in animals.
"This cancer drug approval for dogs is an important step forward for veterinary medicine," said Dr. Bernadette M. Dunham, director of the FDA Center for Veterinary Medicine.
"Prior to this approval, veterinarians had to rely on human oncology drugs, without knowledge of how safe or effective they would be for dogs," Dr. Dunham continued. "(This) approval offers dog owners, in consultation with their veterinarian, an option for treatment of their dog's cancer."
Palladia is a tyrosine kinase inhibitor that kills tumor cells and cuts off the blood supply to the tumor. In a clinical trial, the drug caused a statistically significant difference in tumor shrinkage when compared with a placebo, according to the FDA.
The most common adverse effects associated with Palladia, the agency said, are diarrhea, decrease in or loss of appetite, lameness, weight loss, and blood in the feces.
Pfizer announced the FDA approval during the American College of Veterinary Internal Medicine Forum and Canadian VMA convention, held in early June. George Fennell, vice president of Pfizer's Companion Animal Division, said the company will be introducing Palladia in the months ahead to board-certified veterinarians.
"The experience gained during this time will enable us to support veterinarians more effectively when we make the product available for purchase in early 2010," Fennell said.
Dr. Cheryl A. London, a board-certified veterinary oncologist and associate professor at The Ohio State University College of Veterinary Medicine, described Palladia as an exciting new treatment option for dogs with mast cell tumors.
"At the completion of a Palladia clinical study, approximately 60 percent of dogs had their tumors disappear, shrink, or stop growing. Also, we determined that dogs whose tumors responded to Palladia experienced an improved quality of life," said Dr. London, who has worked with Pfizer since 2000 on the drug's development.