Shionogi’s COVID-19 Treatment Rapidly Lowered Virus Counts

Shionogi’s investigative COVID-19 therapy is showing some promise in early laboratory studies, rapidly clearing viral levels and decreasing the period of active shedding, the company reported at the European Congress of Clinical Microbiology and Infectious Diseases.

Clinical effects of the molecule, dubbed S-217622, were less clear. The phase 2b study found no significant difference in total score of 12 COVID-19 symptoms relative to placebo. In a post-hoc analysis, S-217622 conferred an improvement in composite score of five “respiratory and feverish” symptoms compared to placebo, the company said.

S-217622 inhibits the action of 3CL protease, the main protease in all coronaviruses. It’s essential for viral replication. Inhibiting that may suppress the growth of SARS-oV-2.

A phase 2b study enrolled 428 patients with confirmed COVID-19 randomized to five days of oral S-217622 or placebo. The primary outcomes were changes in viral levels. After three doses of the drug, patients showed a “significant and rapid decrease in viral titer and/or viral RNA” with about a 90 percent reduction relative to placebo.

The period of viral shedding decreased by one to two days compared to placebo. Patients who got S-217622 also showed a significant reduction in viral RNA on days two, four, six and nine vs. placebo.

The molecule was well-tolerated with few drug-related discontinuations and no serious adverse events. Treatment-emergent adverse events in these trials were generally mild-to-moderate and resolved without treatment, the company said.

“These results demonstrate that S-217622 rapidly eliminates SARS-CoV-2 in patients vs. placebo, marking its potential,” said Shionog CEO, Isao Teshirogin. He said the company is planning continued study of the antiviral in phase 3 trials.

A separate global phase 3 study of S-217622 is underway aiming to recruit participants globally to support regulatory filings this year, the company said. — Michele G. Sullivan