New results from a placebo-controlled study of the Gilead Sciences Inc. antiviral remdesivir for the treatment of COVID-19 run by the U.S. National Institute of Allergy and Infectious Disease (NIAID) have yielded "positive data," meeting the adaptive study's primary endpoint of time to recovery, the company said. NIAID expects to provide detailed information in a briefing held later today, a representative told BioWorld.

Meanwhile, Gilead shared results of its own from an open-label study of the drug as company's shares (NASDAQ:GILD) tilted higher Wednesday, gaining about 5.5% by mid-morning.

Though results of Gilead's own phase III SIMPLE trial, evaluating five-day and 10-day dosing of remdesivir in patients with severe cases of COVID-19 are hard to interpret since the trial didn't include a comparator, Evercore ISI analyst Umer Raffat said during a Tuesday morning webinar that he does expect it to win FDA approval. "But it's not going to be a silver bullet," he added.

Gilead said that, among 200 COVID-19 patients who received a five-day course of remdesivir in SIMPLE, 65% achieved a clinical recovery, with most discharged from the hospital after treatment. Results for a 10-day course of treatment yielded similar results. Though no new safety signals were identified with remdesivir across either treatment group, 8% of patients receiving the five-day regimen and 11% of those in the 10-day treatment arm died.

Furthermore, an exploratory analysis revealed that patients who received remdesivir within 10 days of symptom onset had improved outcomes compared with those treated after more than 10 days of symptoms, the Foster City, Calif.-based company said. Pooling data across treatment arms, by day 14, 62% of patients treated early were able to be discharged from the hospital, compared with 49% of patients who were treated late.

The study is the first of two randomized, open-label, multicenter SIMPLE studies Gilead is running to test remdesivir in countries with high prevalence of COVID-19 infection. The second is evaluating the safety and efficacy of five-day and 10-day dosing durations of remdesivir administered intravenously in patients with moderate manifestations of COVID-19, compared with standard of care.

"While additional data are still needed, these results help to bring a clearer understanding of how treatment with remdesivir may be optimized, if proven safe and effective," said Aruna Subramanian, a clinical professor of medicine, and chief of Immunocompromised Host Infectious Diseases at Stanford University School of Medicine. Subramanian is one of the lead investigators of the study.

A contrasting picture

Despite the positive picture of remdesivir emerging from Gilead and its report of the NIAID trial's outcome, a top-line view of results from the first randomized trial of the drug conducted at 10 hospitals in Wuhan, China, and published in The Lancet presented an alternative perspective on remdesivir effects.

The study was stopped early due to the difficultly of recruiting patients after the outbreak was brought under control, causing investigators to caution that interpretation of the findings could be limited. Still, "unfortunately, our trial found that while safe and adequately tolerated, remdesivir did not provide significant benefits over placebo," said Bin Cao, professor at China-Japan Friendship Hospital and Capital Medical University in China, who led the research.

"Future studies need to determine whether earlier treatment with remdesivir, higher doses, or combination with other antivirals or SARS-CoV-2 neutralizing antibodies, might be more effective in those with severe illness," he added.

Fortuitously, those studies are underway, though interpretation could be made difficult by the vast number of variables impacting the emergent course of the pandemic. Varying degrees of disease severity, source of infection, and differing regional approaches to care have all been identified as confounding factors in the interpretation of COVID-19 trial data.

"In the end, the details will be critical to put the true potential of this antiviral into context," said J.P. Morgan analyst Cory Kasimov, "but we suspect regulators could move fast to make the product available given the low bar/unmet medical need. The ultimate implications for GILD remain unclear."