Antiviral Activity, Safety, and Pharmacokinetics of AL-794, a Novel Oral Influenza Endonuclease Inhibitor: Results of an Influenza Human Challenge Study.

Background: AL-794 is an orally active prodrug of ALS-033719, which selectively inhibits the endonuclease domain of influenza virus A and B polymerase. Methods: In a phase 1, double-blinded, randomized, placebo-controlled study, healthy subjects were inoculated intranasally with influenza virus (A/Perth/16/2009 H3N2) after confirmation of infection or on day 4. Subjects received 50 mg of AL-794, 150 mg of AL-794, or placebo twice daily for 5 days. Viral load, influenza symptoms, pharmacokinetics, and safety were evaluated. Results: A total of 61 subjects were inoculated. In 42 infected subjects, the mean peak viral load for 50-mg AL-794 recipients, 150-mg AL-794 recipients, and placebo recipients was 3.54, 2.77, and 3.72 log10 50% tissue culture infectious doses (TCID50)/mL, respectively. The mean influenza viral load area under the curve in the corresponding treatment groups was 137, 87.5, and 142 log10 TCID50/mL·h, respectively, and the median time to virus nondetection was 117, 75.3, and 108 hours, respectively. AL-794 was well tolerated, and no viral resistance to ALS-033719 was identified. Conclusion: Following oral administration of AL-794, significant dose-dependent antiviral activity was noted, with a greater decrease in viral load, symptoms, and mucus weight at the 150-mg dose, compared with the 50-mg dose, and no safety concerns for either dose or placebo. Clinical Trials Registration: NCT02588521.

Amenamevir: Studies of Potential CYP3A-Mediated Pharmacokinetic Interactions With Midazolam, Cyclosporine, and Ritonavir in Healthy Volunteers.

Amenamevir (formerly ASP2151) is a helicase-primase inhibitor being developed for the treatment of herpesvirus infection. Amenamevir is both a substrate and inducer of cytochrome P450 (CYP) 3A4. Three studies were done in healthy volunteers to investigate potential CYP3A pharmacokinetic interactions with the following drugs: (1) Midazolam (probe substrate for CYP3A): After 10 days' pretreatment with amenamevir 400 mg daily, geometric mean maximum concentration of drug in blood plasma (Cmax ) and area under the plasma drug concentration-time curve from time zero to infinity (AUC0-∞ ) of midazolam 7.5 mg were about 68% and 51%, respectively, of those after midazolam alone. (2) Cyclosporine (substrate and inhibitor of CYP3A): After 5 days' pretreatment with cyclosporine 100 mg twice daily, geometric mean Cmax of amenamevir after 400-mg and 1200-mg single doses was, respectively, about 66% and 69%, and AUC0-∞ about 82% and 79%, of those after amenamevir alone. (3) Ritonavir (inhibitor of CYP3A): When given with single doses of ritonavir 600 mg, geometric mean Cmax of amenamevir after 400-mg and 1200-mg single doses was, respectively, about 1.4 and 1.6 times higher, and geometric mean AUC0-∞ about 2.6 and 3.3 times higher, than after amenamevir alone. Amenamevir has the potential to be involved in CYP3A-mediated pharmacokinetic interactions in clinical practice.