134. KRP-A218, an Orally Active and Selective PI4KB Inhibitor with Broad-Spectrum Anti-Rhinovirus Activity, Has Potent Therapeutic Antiviral Activity In vivo
Authors: Matsui Toshiyuki , Fujita Motomichi , Ishibashi Yuji , Nomanbhoy Tyzoon , Rosenblum Jonathan S , Nagasawa Michiaki 
Published: December 2021

Abstract

Background
Rhinovirus (RV) is a major respiratory virus that poses a threat to immunocompromised people and those with underlying disease. However, there are no approved therapies. Moreover, RV infection cannot be prevented by a vaccine because there are over 100 serotypes. Here we report the pharmacological profile of a novel small-molecule host-targeted antiviral (HTA), KRP-A218 (A218). A highly potent and selective inhibitor of phosphatidylinositol 4 kinase beta (PI4KB), a key host factor of RV replication, A218 is undergoing clinical study.

Methods
in vitro antiviral activities of A218 and Vapendavir (Vap), a virus-targeted antiviral, were examined by inhibition of CPE, viral load, or replication. in vivo antiviral activity and pathological analysis of A218 were examined in coxsackievirus B3 (CVB3; belong to the genus enterovirus as with RV)-infected mice as a surrogate model of RV infection as CVB3, unlike RV, replicates very well in both mouse and human tissue. Daily oral dosing of A218 (1-10 mg/kg) was started 2 days post intraperitoneal infection with CVB3. Tissue viral load, pancreas pathological change at 4 days post infection, and survival rate up to 14 days were evaluated. PI4KB heterozygous kinase-dead mice (PI4KB KD) were established by a CRISPR-Cas9 system. Viral load and survival rate following viral infection were evaluated in these mice.

Results
A218 showed broad antiviral activity for RV and enteroviruses (Table) and has a higher barrier to drug resistance than Vap. These results are consistent with expectations for HTAs. Repeated dosing of A218 starting 2 days post infection decreased viral load and improved acute pancreatitis, accompanied by decrease of inflammatory and pancreatitis markers in plasma. Moreover, therapeutic dosing of A218 improved survival rate in a CVB3-infected lethal mouse model (Figure). These results show the first evidence that a PI4KB inhibitor has potent therapeutic efficacy in a severe viral infection model. Similar effects were observed in PI4KB KD, supporting the on-target effect of A218.
Table. Antiviral activity of A218 and Vap against RV/EV infection

Figure. Therapeutic effect of A218 on survival rate in CVB3-infected mice

Conclusion
A218 is a promising therapeutic agent for improving the exacerbation of pathological conditions caused by RV infection. Nonclinical package including GLP-Tox also supports the ongoing first-in-human study of A218.

Disclosures
Toshiyuki Matsui, MPharm, Kyorin pharmaceutical Co., LTD (Employee) Motomichi Fujita, PhD, Kyorin Pharmaceutical Co., Ltd. (Employee) Yuji Ishibashi, PhD, Kyorin Pharmaceutical co., ltd. (Employee) Tyzoon Nomanbhoy, PhD, ActivX Biosciences (Other Financial or Material Support, Full time employee of ActivX, a wholly owned subsidiary of Kyorin Pharmaceuticals) Jonathan S. Rosenblum, PhD, ActivX Biosciences (Employee) Michiaki Nagasawa, PhD, Kyorin Pharmaceutical Co., Ltd (Employee)