The company sought the review under the conditional approval system following completion of the assessment of primary endpoints in the Phase IIb part of Phase II/III clinical trial of the antiviral.
An inhibitor of 3CL protease, S-217622 was co-created by Shionogi and Hokkaido University .
The placebo-controlled, randomised, double-blind Phase IIb segment enrolled 428 patients with mild/moderate Covid-19 symptoms.
Carried out following the Omicron variant wave, the trial had 419 subjects enrolled in Japan and nine in South Korea.
The key goal of the trial was to validate improvement in clinical symptoms and antiviral effect of a once-a-day dose of S-217622 given for five days.
Findings showed that at both tested doses, the S-217622 arms demonstrated to have a substantial difference on day four following the third dose versus placebo.
The trial met the primary endpoint of a quick decline in viral titer.
There was no substantial difference in the time-weighted average change in the total score of 12 Covid-19 symptoms from the start of dosing to 120 hours even though a trend indicating improvement was observed.
Shionogi noted that the trial failed to meet the second primary endpoint of the trial.
In the Phase IIb part, TEAE and treatment-associated TEAE were in line with those reported in the Phase IIa part without any new adverse events of concern observed.
To date, the company has presented all the non-clinical, manufacturing/CMC data and trial data collected, to the Pharmaceuticals and Medical Devices Agency (PMDA).
Shionogi will also present further assessments of the results from the trial to the PMDA to offer the antiviral soon in the country.
In addition, the company is expediting the ongoing Phase III segment of the trial in mild/moderate Covid-19 patients and Phase IIb/III part of the trial in asymptomatic/only mildly symptomatic subjects.
In April 2020, Shionogi collaborated with public institutions, academia and other firms for developing potential therapies and a vaccine for Covid-19.