By Manas Mishra and Michael Erman

(Reuters) – Gilead Sciences Inc on Wednesday took the unusual step of asking the U.S. Food and Drug Administration to rescind a controversial orphan drug designation the agency had granted for the biotech company’s potential coronavirus treatment remdesivir just 48 hours earlier.

The FDA agreed to the withdrawal, and said it is actively working to speed development of medical products desperately needed to prevent or treat the highly contagious COVID-19 illness caused by the virus.

Shares of the California-based company closed down nearly 6% at $69.66.

The company was criticized by lawmakers and patient advocates after receiving the orphan designation on Monday for the experimental antiviral drug, saying it was taking advantage of the rapidly accelerating health crisis.

The drug, which previously failed as an Ebola treatment, is being tried on COVID-19 patients. It has been described by U.S. President Donald Trump and health officials as one of the more promising candidates to fight the virus.

Orphan status is granted by the FDA to encourage development of drugs for rare conditions. The designation comes with a seven-year marketing exclusivity period if the drug is approved, and other benefits such as potentially faster approvals.

Rare disease treatments typically cost more than other drugs, allowing drugmakers to recoup development costs and make a profit while serving relatively small patient populations.

The FDA said there have previously been four approved orphan drugs that had the designation withdrawn by their sponsor.

Patients groups and activists criticized Gilead for applying for the status and the FDA for granting it.

Senator Bernie Sanders said on Tuesday the company was profiteering and asked the FDA to rescind the designation.

Gilead said it originally sought orphan status to expedite remdesivir’s approval timeline.

It said on Wednesday that regulatory agencies have been moving quickly and it was now confident of maintaining a faster timeline for review of remdesivir without orphan status.

Advocacy group Public Citizen said on Wednesday it was outrageous that Gilead had sought the designation given that the patient population in the United States could reach into the millions. There are currently more than 60,000 known U.S. cases.

Drugmakers and medical researchers are stepping up their efforts to battle the coronavirus pandemic, which has infected some 460,000 people worldwide and killed over 20,0000.

Other treatments being tested include the generic malaria drug hydroxychloroquine and AbbVie Inc’s HIV drug, Kaletra.

(Reporting by Manas Mishra in Bengaluru and Michael Erman in Maplewood, N.J.; Editing by Bill Berkrot)