JAVMA News logo

January 15, 2020

FIP drugs continue to show promise, while being sold on black market

Published on
information-circle This article is more than 3 years old
Bubba was a participant in the field trial of the antiviral drug GS-441524 for treatment of feline infectious peritonitis and is still doing very well two years later. (Courtesy of Dr. Niels C. Pedersen)

Two antiviral drugs have shown promise in the past few years for the treatment of cats with feline infectious peritonitis, which has been almost always fatal. Some desperate cat owners have turned to the black market to buy the unapproved drugs.

In April, the Journal of Feline Medicine and Surgery published the latest study on the antiviral drugs, evaluating the efficacy and safety of the nucleoside analog GS-441524 for cats with naturally occurring FIP. Treatment was successful in 25 of 31 cats, and the researchers described the safety profile of the drug as impressive.

Efficacy against naturally occurring FIP appeared greater with GS-441524 than with the viral protease inhibitor GC376, the first antiviral drug evaluated for treatment of cats with FIP. When given to younger kittens, GC376 interfered with the development of permanent teeth. Nevertheless, the researchers wrote in the April paper, “GC376 should be further studied using a minimum of 12 weeks with a higher dosage and a larger number of cats before making any final comparisons.”

In 2018, Kansas State University licensed GC376 to Anivive Lifesciences Inc. of California for commercial development.

A number of entities, largely in China, are manufacturing unapproved versions of GS-441524 and GC376 for sale to owners of cats with FIP, according to a June update from Dr. Niels C. Pedersen, FIP researcher and professor emeritus at the University of California-Davis School of Veterinary Medicine.

“Veterinarians, who are under more legal and ethical constraints, may view the black market quite differently from owners of cats suffering from FIP,” Dr. Pedersen wrote. “Some may refuse to participate beyond making the initial diagnosis of FIP, some may help with drug administration and monitoring as long as the owners provide the drug, and some may require signed waivers freeing them of any legal or ethical obligations.”

UC-Davis has compiled a list of general FIP resources. The resources include updates from Dr. Petersen, studies, literature reviews, and information about treatment.

As for prevention of FIP, researchers at Colorado State University, funded by Morris Animal Foundation, are working on a vaccine for the feline enteric coronavirus, which can mutate into the FIP virus. If successful, the vaccine will control pervasive FECV infection in animal shelters and other multicat environments while also protecting individual cats against FIP. Vaccination against FIP itself has so far been unsuccessful.

In a second study funded by the foundation, Colorado State researchers are working to develop a new diagnostic test for FIP. They have identified 18 proteins in the blood of cats, among thousands, that appear to be common in cats with the disease. The team aims to prove that the proteins are indeed markers for FIP and determine which ones can be detected easily and developed into a diagnostic test.