New York, Apr 29 (IANS): US-based Gilead Sciences on Wednesday said a closely-watched study of the investigational antiviral remdesivir for the treatment of Covid-19 has "met its primary endpoint".

"Gilead Sciences. Inc. is aware of positive data emerging from the National Institute of Allergy and Infectious Diseases' (NIAID) study of the investigational antiviral remdesivir for the treatment of COVID-19," the company said.

NIAID is part of National Institutes of Health, an agency of the United States Department of Health and Human Services.

"We understand that the trial has met its primary endpoint and that NIAID will provide detailed information at an upcoming briefing," it added.

Gilead also shared additional remdesivir data from the company's open-label Phase 3 SIMPLE trial in patients with severe Covid-19 disease.

The Phase 3 trial evaluated 5-day and 10-day dosing durations of remdesivir in hospitalised patients with severe manifestations of Covid-19.

The study demonstrated that patients receiving a 10-day treatment course of remdesivir achieved similar improvement in clinical status compared with those taking a 5-day treatment course.

No new safety signals were identified with remdesivir across either treatment group.

Gilead said it plans to submit the full data for publication in a peer-reviewed journal in the coming weeks.

"These study results complement data from the placebo-controlled study of remdesivir conducted by the National Institute for Allergy and Infectious Diseases and help to determine the optimal duration of treatment with remdesivir," said Merdad Parsey, Chief Medical Officer, Gilead Sciences.

"The study demonstrates the potential for some patients to be treated with a 5-day regimen, which could significantly expand the number of patients who could be treated with our current supply of remdesivir," Parsey added.

In this study, the time to clinical improvement for 50 percent of patients was 10 days in the 5-day treatment group and 11 days in the 10-day treatment group.

More than half of patients in both treatment groups were discharged from the hospital by day 14, the company said.

At day 14, 64.5 percent -- 129 out of 200 -- of patients in the 5-day treatment group and 53.8 percent -- 106 out of 197 -- of patients in the 10-day treatment group achieved clinical recovery, the results showed.

"These data are encouraging as they indicate that patients who received a shorter, 5-day course of remdesivir experienced similar clinical improvement as patients who received a 10-day treatment course," said Aruna Subramanian, Professor of Medicine, Chief, Immunocompromised Host Infectious Diseases, Stanford University School of Medicine, and one of the lead investigators of the study.

"While additional data are still needed, these results help to bring a clearer understanding of how treatment with remdesivir may be optimised, if proven safe and effective."

Shares of Gilead rose as much as 11 per cent in early trading on Wednesday.