# Efficacy of GS-441524 for Feline Infectious Peritonitistis: A Systematic Review (2018-2024)
## 3 Results
### Summary of Treated Cases and Outcomes  
Across the 11 studies, data for 650 FIP cases treated with GS-441524 were compiled. Among these, 524 cases (80.6%) achieved remission with their initial GS-441524 treatment course, and an additional 26 cases (4.0%) achieved remission after experiencing a relapse and undergoing a second GS-441524 treatment. Therefore, the combined treatment success rate was 84.6% (550/650 survived in remission). Conversely, 72 cats (11.1%) died without ever reaching remission, and 2 cats (0.3%) died after initially improving and then relapsing. An additional 26 cats (4.0%) experienced a relapse and were switched to an alternative antiviral (Molnupiravir)--these cases are considered treatment failures of GS-441524 for the purpose of GS-441524 efficacy evaluation, though many of them were ultimately saved by the rescue therapy (as reported in those studies). Among the 650 cases, 169 cats (26.0%) had what we term \"complicated FIP\", defined as FIP with aggravating clinical signs such as neurological or ocular involvement. A breakdown of these cases is shown in Table 2. \begin{table}
\begin{tabular}{c c c c c c} \hline  & **Number of** & **Remission** & **Remission** & **Death After** & **Relapse Requiring** \\  & **Cases** & **After Relapse** & **Relapse** & **Treatment Change** \\ \hline Total & 169 & 116 & 10 & 2 & 13 \\ \hline Neurological signs & 106 & 66 & 7 & 2 & 9 \\ \hline Ocular signs & 48 & 42 & 1 & 0 & 1 \\ \hline Neurological and ocular & 7 & 2 & 1 & 0 & 3 \\ \hline Renal & 8 & 6 & 1 & 0 & 0 \\ \hline \end{tabular}
\end{table} 
Table 2: Number of cases of complicated FIP divided into subgroups of reported clinical signs and treatment outcomes. Figure 1: Clinical decision-making diagram for cats diagnosed with feline infectious peritonitis (FIP). Cats presenting with FIP typically exhibit either the effusive or non-effusive form of the disease. The effusive form may manifest as ascites, bicavitary effusions, or pleural effusion. Cats with either form may additionally present aggravating clinical signs, including neurological symptoms, ocular involvement, or nephropathy. Treatment options include GS-441524, alone or in combination with supportive therapies, resulting in several possible clinical outcomes: remission, remission after relapse, relapse requiring a treatment change, death after relapse, or death without remission. Thus, in cats with any neurological and/or ocular signs, the success rate was noticeably lower (around 74.5% combined success versus \(\sim\)84% in the overall population; \(p=0.0076\)). Specifically, cats with only ocular complications responded as well as uncomplicated cases (around 90% success), whereas those with neurological FIP had a success rate of \(\sim\)68%, and those with both neuro and ocular signs had an even lower success (\(\sim\)43%). These findings reflect the challenge of treating neurologic FIP. Cases by FIP form were also categorized:  
* Effusive FIP: 202 cases (31.1%). Among these, 148 (73.3%) achieved remission, 9 (4.5%) went into remission after relapse, 1 (0.5%) died after relapse, 35 (17.3%) died without remission, and 9 (4.5%) were switched to another treatment after relapse. Success rate for wet FIP was \(\sim\)77.7%. * Non-effusive FIP: 187 cases (28.8%). Outcomes: 154 (82.4%) went into remission, 10 (5.3%) went into remission after relapse, 1 (0.5%) died after relapse, 10 (5.3%) died without remission, and 12 (6.4%) switched after relapse. Success rate \(\sim\)87.7%. * Mixed FIP (both effusive and non-effusive components): 162 cases (24.9%). Outcomes: 134 (82.7%) went into remission, 3 (1.9%) went into remission after relapse, 0 died after relapse, 24 (14.8%) died without remission, and 1 (0.6%) switched after relapse. Success rate \(\sim\)84.6%. Comparing forms, non-effusive FIP cases had the highest success rate (\(\sim\)-88%) (\(p=0.039\)), significantly higher than effusive FIP (\(\sim\)78%). Mixed FIP was intermediate (\(\sim\)85%) and not significantly different from non-effusive FIP (\(p=0.56\)).