Short- and Long-Term Outcomes of Unlicensed Gs-441524-Like Antiviral Therapy at-Home Treatment of Feline Infectious Peritonitis

ABSTRACT

Introduction: Prognosis of cats with feline infectious peritonitis (FIP), hitherto an invariably fatal disease, has purportedly improved with the introduction of the unlicensed nucleoside analog GS-441524 (GS). Method(s) A prospective observational study. Inclusion criteria comprised a complete medical record, characteristic clinical signs and laboratory changes, and a confirmatory RT-PCR test for the presence of feline coronavirus and FIP pathogenic strains in pleural/peritoneal/cerebrospinal fluid samples. Clinical signs, laboratory parameters, and adverse effects were recorded at diagnosis, during treatment, and at the end of a 12-week observation period. Remission was defined as completion of 12 weeks or more of treatment and resolution of clinical signs. Result(s) Overall, 175 medical files were reviewed but only 38 cases met the inclusion criteria. Samples of used vials were analyzed by high-performance liquid chromatography and identified GS-441524 as the active component. Twenty-one cats (55%) were considered in full remission, 7 (18 %) cats are currently treated, and 4 cats are in the 12-week observation period. Two cats experienced a relapse, 1 and 6 weeks after completion of treatment. Six (15%) cats died. Anemia (65%), jaundice (50%), thrombocytopenia (50%), and an albumin globulin ratio under 0.6 (81%) were common findings. Clinical manifestation included effusive (n = 30), noneffusive (n = 3), and neurological (n = 6) forms. Adverse effects included injection site reactions (52% of cats) and pain (95% of cats), and temporary creatinine increase (64%). Conclusion(s) Short-term efficacy against FIP disease, using an unlicensed nucleotide analog, was observed herein. The unknown purity or biological activity of these unlicensed compounds is a major limitation of this treatment.