K777是口服活性不可逆半胱氨酸蛋白酶抑制剂，兼具CYP3A4抑制（IC50=60nM）、CCR4拮抗及广谱抗病毒活性，可不可逆抑制克鲁斯锥虫半胱氨酸蛋白酶、组织蛋白酶B/L，还能抑制SARS-CoV（IC50=0.68nM）和EBOV（IC50=0.87nM）的组织蛋白酶介导的细胞进入。

[1] Zhou Y, Vedantham P, Lu K, Agudelo J, Carrion R Jr, Nunneley JW, Barnard D, Pöhlmann S, McKerrow JH, Renslo AR, Simmons G. Protease inhibitors targeting coronavirus and filovirus entry. Antiviral Res. 2015 Apr;116:76-84. doi: 10.1016/j.antiviral.2015.01.011. Epub 2015 Feb 7. PMID: 25666761; PMCID: PMC4774534.[2]Sato T, Iwase M, Miyama M, Komai M, Ohshima E, Asai A, Yano H, Miki I. Internalization of CCR4 and inhibition of chemotaxis by K777, a potent and selective CCR4 antagonist. Pharmacology. 2013;91(5-6):305-13. doi: 10.1159/000350390. Epub 2013 Jun 5. PMID: 23751403.[3]Ndao M, Nath-Chowdhury M, Sajid M, Marcus V, Mashiyama ST, Sakanari J, Chow E, Mackey Z, Land KM, Jacobson MP, Kalyanaraman C, McKerrow JH, Arrowood MJ, Caffrey CR. A cysteine protease inhibitor rescues mice from a lethal Cryptosporidium parvum infection. Antimicrob Agents Chemother. 2013 Dec;57(12):6063-73. doi: 10.1128/AAC.00734-13. Epub 2013 Sep 23. PMID: 24060869; PMCID: PMC3837922.