Efficacy and safety of the nucleoside analog GS-441524 for treatment of cats with naturally occurring feline infectious peritonitis
Niels C Pedersen1 , Michel Perron2, Michael Bannasch1,
Elizabeth Montgomery1, Eisuke Murakami2,
Molly Liepnieks3 and Hongwei Liu3
Objectives The aim of this study was to determine the safety and efficacy of the nucleoside analog GS-441524 for
cats suffering from various forms of naturally acquired feline infectious peritonitis (FIP).
Methods Cats ranged from 3.4–73 months of age (mean 13.6 months); 26 had effusive or dry-to-effusive FIP and five
had non-effusive disease. Cats with severe neurological and ocular FIP were not recruited. The group was started
on GS-441524 at a dosage of 2.0 mg/kg SC q24h for at least 12 weeks and increased when indicated to 4.0 mg/kg
Results Four of the 31 cats that presented with severe disease died or were euthanized within 2–5 days and a
fifth cat after 26 days. The 26 remaining cats completed the planned 12 weeks or more of treatment. Eighteen of
these 26 cats remain healthy at the time of publication (OnlineFirst, February 2019) after one round of treatment,
while eight others suffered disease relapses within 3–84 days. Six of the relapses were non-neurological and two
neurological. Three of the eight relapsing cats were treated again at the same dosage, while five cats had the
dosage increased from 2.0 to 4.0 mg/kg q24h. The five cats treated a second time at the higher dosage, including
one with neurological disease, responded well and also remain healthy at the time of publication. However, one of
the three cats re-treated at the original lower dosage relapsed with neurological disease and was euthanized, while
the two remaining cats responded favorably but relapsed a second time. These two cats were successfully treated
a third time at the higher dosage, producing 25 long-time survivors. One of the 25 successfully treated cats was
subsequently euthanized due to presumably unrelated heart disease, while 24 remain healthy.
Conclusions and relevance GS-441524 was shown to be a safe and effective treatment for FIP. The optimum
dosage was found to be 4.0 mg/kg SC q24h for at least 12 weeks.
Keywords: Nucleoside analog; GS-441524; feline infectious peritonitis; FIP; field trial
Análogo de nucleosídeo, peritonite infecciosa felina, PIF,