Open-label clinical trial of orally administered molnupiravir as first-line treatment for naturally occurring feline effusive infectious peritonitis

Krystle L. Reagan, Terza Brostoff, Jully Pires, Amy Rose, Diego Castillo, Brian G. Murphy

26.9.2024

Original full article:
Open label clinical trial of orally administered molnupiravir as a first-line treatment for naturally occurring effusive feline infectious peritonitis

Basic information
Before the discovery of effective antiviral drugs, feline infectious peritonitis (FIP) was a fatal disease of cats. Multiple antiviral treatments have been identified, but optimization of treatment protocols is needed.

The goal
To evaluate the efficacy of PO molnupiravir (MPV; EIDD-2801) in the treatment of effusive FIP.

The animals
Ten cats with naturally occurring effusive FIP and 10 cats from the control group were treated PO with GS-441524.

Methods
Prospective, open-label, longitudinal, comparative study with a reference control group. Ten cats with FIP were enrolled and treated with PO MPV (10–15 mg/kg PO q12h) for 84 days. Cats were evaluated at weeks 0, 6, and 16, and the proportion of cats in clinical remission at week 16 was determined. Survival and clinicopathological characteristics were compared with control cats with effusive FIP treated with PO GS-441524.

The results
Eight of the 10 cats treated with MPV survived and were in remission after 16 weeks. Two cats that did not survive died within the first 24 hours of treatment. No adverse events requiring discontinuation of treatment were observed. Survival of cats treated with PO MPV was not inferior to the historical control group of cats treated with PO GS-441524 (5/9 survived [55 %]), with a survival difference of 25 % (90 % confidence interval, −9.3 % to 59.3 %). Clinicopathological features associated with FIP normalized over the course of the study, and no differences in clinicopathological data were observed at any time point in the study when comparing cats treated with MPV and GS-441524.

Conclusions and clinical significance
Molnupiravir is an effective antiviral treatment for effusive FIP.

The entire study is available in English at https://pmc.ncbi.nlm.nih.gov/articles/PMC11586577/