Shares in Gilead were up in premarket trading after the company announced it had increased the size of its trials for its COVID-19 drug remdesivir.
The big US pharma made no announcement but changes to summary information on clinicaltrials.gov show the company has also tinkered with the endpoints of the studies.
Remdesivir is one of the most closely watched drugs in the fight against COVID-19 and is a broad-spectrum antiviral originally developed to tackle Ebola and other diseases.
But it has shown early promise against the COVID-19 coronavirus and trials have quickly begun to test its safety and efficacy against the epidemic.
As it is an antiviral it won’t confer immunity against the virus but it’s hoped that remdesivir will help those who are infected to recover, potentially reducing death rates and relieving the pressure on healthcare systems.
Data from independent studies of remdesivir in China are due to be published any day soon, which should give a clearer indication about whether the drug could provide some relief against the virus in the short term until a safe and effective vaccine is found.
While Gilead has not made clear why it has increased the trial size and effectively changed the goalposts midway through, investors interpreted this as a positive development.
The size of a trial in severe patients has now been increased from 400 to 2,400 patients.
In a trial involving patients with moderate COVID-19, the size of the patient sample has been increased from 600 to 1,600.
Both trials have new primary endpoints, which will assess the likelihood of improvement on a seven-point scale starting at death to not hospitalised.
There are also new arms to the studies, including one with mechanically ventilated patients in the severe disease trial.
Analysts are split over the significance of the development, with the bearish ones suggesting this means the drug is not working as planned, and others suggesting this could mean Gilead has increased confidence in its efficacy.
It could also reflect the need to get a more accurate picture of how the drug is working and the increased availability of patients in the US where the epidemic is still in its growth phase.
Independent trials of remdesivir, which works by blocking the replication of the virus, have stopped early in China where the disease has been brought under control with severe lockdown measures.