25 April 2022 - - Japan-based pharmaceutical company Shionogi and Co., Ltd. has posted new results from two late-breaking presentations of S-217622 at the 32nd European Congress of Clinical Microbiology and Infectious Diseases (ECCMID) in Lisbon, 23 26 April.

S-217622 is an investigational 3CL protease inhibitor that was studied for once-daily oral administration in mainly vaccinated patients, with no risk factors for severe complications, within five days of COVID-19 symptom onset.

At the meeting, Shionogi presented new late-breaking Phase 2b results from the Phase 2/3 clinical trial of S-217622, completed in Asia (presenter: Norio Ohmagari, Disease Control and Prevention Center, National Center for Global Health), which followed previously reported topline results from the Phase 2b study. These new data showed:

According to the company, S-217622 demonstrated rapid clearance of the infectious SARS-CoV-2 virus. On day four of treatment (following the third dose), the proportion of patients with positive viral titer decreased by approximately 90% versus placebo.

S-217622 shortened infectious virus shedding by 1-2 days versus placebo. S-217622 showed a significant reduction in viral RNA on days 2, 4, 6 and 9 versus placebo (difference versus placebo in the Least Squares mean change from baseline in viral RNA; under -1.0 logx copies/mL on day four at each dose).

There was no significant difference in total score of 12 COVID-19 symptoms between treatment arms, however, S-217622 showed improvement in composite score of five "respiratory and feverish" symptoms (post-hoc analysis).

Both the Phase 1 and 2a/b parts of the Phase 2/3 clinical trials showed that S-217622 was well-tolerated, with few discontinuations due to drug, and no reports of serious adverse events or death. Treatment-emergent adverse events in these trials were generally mild to moderate, and resolved without treatment.

The Phase 2b study was conducted with 428 patients in Japan and South Korea. Its main purpose was to confirm the antiviral effect and clinical symptom improvement of S-217622 when orally administered once daily for five days, versus placebo.

S-217622, an investigational therapeutic drug for COVID-19, is an 3CL protease inhibitor created through joint research between Hokkaido University and Shionogi.

SARS-CoV-2 utilizes an enzyme called 3CL protease that is essential for the replication of the virus. S-217622 suppresses the replication of SARS-CoV-2 by selectively inhibiting 3CL protease.

In the Phase 2 trial (Phase 2a and 2b parts), completed in Japan and Korea, patients treated with S-217622 showed a significant and rapid decrease in viral titer and/or viral RNA on day 4 (after the 3rd dose) compared to the placebo, and no serious safety concerns were reported.

The Phase 3 part of the Phase 2/3 clinical trial is in progress. Additionally, in the preliminary in vitro study, S-217622 exhibited similar antiviral activity against the Omicron subvariant BA.2 and other existing variants.

Recognizing the urgent global need for more therapies to address COVID-19, Shionogi has already begun working with worldwide health authorities including those located in Japan, where it filed for manufacture and sales approval on February 25, 2022, as well as in the United States.