Short Treatment of 42 Days with Oral GS-441524 Results in Equal Efficacy as the Recommended 84-Day Treatment in Cats Suffering from Feline Infectious Peritonitis with Effusion-A Prospective Randomized Controlled Study.

In the past, feline infectious peritonitis (FIP) caused by feline coronavirus (FCoV) was considered fatal. Today, highly efficient drugs, such as GS-441524, can lead to complete remission. The currently recommended treatment duration in the veterinary literature is 84 days. This prospective randomized controlled treatment study aimed to evaluate whether a shorter treatment duration of 42 days with oral GS-441524 obtained from a licensed pharmacy is equally effective compared to the 84-day regimen. Forty cats with FIP with effusion were prospectively included and randomized to receive 15 mg/kg of GS-441524 orally every 24h (q24h), for either 42 or 84 days. Cats were followed for 168 days after treatment initiation. With the exception of two cats that died during the treatment, 38 cats (19 in short, 19 in long treatment group) recovered with rapid improvement of clinical and laboratory parameters as well as a remarkable reduction in viral loads in blood and effusion. Orally administered GS-441524 given as a short treatment was highly effective in curing FIP without causing serious adverse effects. All cats that completed the short treatment course successfully were still in complete remission on day 168. Therefore, a shorter treatment duration of 42 days GS-441524 15 mg/kg can be considered equally effective.

Clinical Follow-Up and Postmortem Findings in a Cat That Was Cured of Feline Infectious Peritonitis with an Oral Antiviral Drug Containing GS-441524.

This is the first report on a clinical follow-up and postmortem examination of a cat that had been cured of feline infectious peritonitis (FIP) with ocular manifestation by successful treatment with an oral multicomponent drug containing GS-441524. The cat was 6 months old when clinical signs (recurrent fever, lethargy, lack of appetite, and fulminant anterior uveitis) appeared. FIP was diagnosed by ocular tissue immunohistochemistry after enucleation of the affected eye. The cat was a participant in a FIP treatment study, which was published recently. However, 240 days after leaving the clinic healthy, and 164 days after the end of the 84 days of treatment, the cured cat died in a road traffic accident. Upon full postmortem examination, including histopathology and immunohistochemistry, there were no residual FIP lesions observed apart from a generalized lymphadenopathy due to massive lymphoid hyperplasia. Neither feline coronavirus (FCoV) RNA nor FCoV antigen were identified by quantitative reverse transcription polymerase chain reaction (RT-qPCR) and immunohistochemistry, respectively, in any tissues or body fluids, including feces. These results prove that oral treatment with GS-441524 leads to the cure of FIP-associated changes and the elimination of FCoV from all tissues.