Efficacy of a 3C-like protease inhibitor in treating various forms of acquired feline infectious peritonitis

Pedersen, Niels C; Kim, Yunjeong; Liu, Hongwei; Galasiti Kankanamalage, Anushka C; Eckstrand, Chrissy; Groutas, William C; Bannasch, Michael; Meadows, Juliana M; Chang, Kyeong-Ok

The first five cats in the trial were treated initially for 2 weeks (CT01, CT02, CT03, CT04 and CT05). A rapid improvement in health was observed in all cats and treatment was stopped. Despite the favorable initial response, disease signs recurred 1 (CT01, CT05), 2 (CT03, CT04) or 7 (CT02) weeks after the 2 week treatments ended ( Figure 2 ). The cats were then retreated, the rationale being to progressively extend primary and secondary treatment periods for as long as their FIP remained responsive to GC376 (see CT04, CT22, Figure 2 ). New cats that entered the trial were next treated for 3 (CT07) or 4 weeks (CT08, CT16). Cats CT08 and CT16 responded initially, but their disease signs reappeared while on treatment. Cat CT08 developed neurologic disease, whereas cat CT16 had a recurrence of abdominal lesions ( Table 1 ). The primary and secondary treatment periods were then extended to 9 weeks (CT07, CT09, CT10, CT14) ( Figure 2 ). Cat CT09 developed neurologic signs during the 9 week primary treatment and was eventually euthanized when disease signs became severe. Cat CT07 developed neurologic disease 6 weeks after starting the second treatment. At that point, all new cats admitted to the trial, and earlier cats such as CT10, were treated or retreated for at least 12 weeks. The benefit of 12 weeks of treatment was most apparent in cat CT04 that had been treated three other times for shorter periods and then eventually relapsed ( Figure 2 ). Treatment was stopped in cats that had no clinical or laboratory disease signs after 12 weeks of either primary or secondary treatments. It was determined that a minimum treatment period should be around 12 weeks. Cat CT21 was treated for 17 weeks because of delayed improvement in total protein and white blood cell counts ( Figure 2 ). This cat suffered a relapse of pleural FIP 13 weeks later and is at the time of writing receiving more treatment.