Covid-19 Pill Competing With Pfizer’s Looks for Quick Approval in Japan

Still, Shionogi said it believed its trials to date, covering about 400 mostly Japanese patients, would offer sufficient evidence to seek approval in Japan, where the Pfizer drug is expected to be approved shortly, but is likely to be in limited supply. Shionogi said its trial found the pill, code-named S-217622, neutralized the virus quickly and didn’t cause serious or lasting side effects.

“I think this is excellent data,” said Shionogi’s chief executive, Isao Teshirogi.

Covid-19 vaccine shots have proven largely effective in keeping people who contract the virus out of the hospital, but doctors have said that treatment pills could add to the protection when people are infected. Only two such pills have been approved in the U.S. so far, Paxlovid and Merck & Co.’s molnupiravir, which appeared less effective than Paxlovid in trials.

Shionogi said it would file its application to Tokyo drug regulators in the next week or two and, if approved, Japanese patients could be getting the drug as soon as early March. It said it planned to manufacture enough doses for one million patients by the end of March.

Shionogi says its pill offers advantages over Paxlovid because it is taken once a day without any additional medication. Paxlovid is taken twice a day together with another pill called ritonavir.

Shionogi said it was in talks with global partners to do a large trial that could open the way for approval from the Food and Drug Administration in the U.S., but the first results from the trial aren’t expected until summer. That means the drug, if proven safe and effective, likely wouldn’t be available to American patients until late this year at the earliest.

On Monday, Shionogi released detailed information from an early trial of 47 Japanese patients. Of these, 30 took the pill for five days and 17 took a placebo. The median patient on the pill tested negative for the Covid virus, SARS-CoV-2, after about 2 ½ days, which was two days faster than the median patient on placebo. Two patients on placebo developed more serious cases, while all the patients on the pill recovered without serious illness.

However, the trial was too small to give statistically significant results. The data haven’t been published in a scientific journal.

On another measure, Shionogi said patients who received the placebo had more than 10 times as much viral RNA after five days as those who took the drug. Pfizer’s data, released in December, showed that Paxlovid also had a powerful antiviral effect but viral load in the placebo group was slightly less than 10 times the amount in the pill group. It isn’t known how those kinds of changes in viral level would translate into real-life effects.

Both the Pfizer and Shionogi pills work by blocking a key enzyme that SARS-CoV-2 needs to copy itself. After the virus invades human cells and hijacks their genetic machinery, it needs a protein cutter known as main protease to chop up long virus protein chains and turn them into functional proteins. The pills block this protease.

Because the main protease is shared by the known variants of SARS-CoV-2 including Omicron, test-tube studies have suggested that the Pfizer and Shionogi pills would work equally well against Omicron, although that has yet to be proven in human patients.

Write to Peter Landers at [email protected]