Vertex Pharmaceuticals on Tuesday said its experimental painkiller, which is being tested as an alternative to addictive opioids, significantly decreased post-surgery pain in late-stage trials

The drug, known as VX-548, did not work better than a popular opioid, however.

Still, the trial results bring the biotech company one step closer to developing a drug that can provide strong pain relief without the addictive potential of opioids, which have caused a horrific epidemic in the U.S. Plenty of other similar painkillers never reached the market.

Vertex said it would file for Food and Drug Administration approval of the painkiller for the treatment of moderate-to-severe acute pain by the middle of this year.

Acute pain is usually caused by injury, surgery, illness, trauma or painful medical procedures and is likely to ease with time. Around 80 million patients are prescribed a medicine for their moderate-to-severe acute pain every year in the U.S., Vertex said in a release.

Wall Street analysts have said that the drug, which works by blocking pain signals at its origin before they reach the brain, could become a blockbuster drug if it wins approval from regulators, estimating its annual sales could exceed $1 billion.

“We are very pleased with the results from the VX-548 pivotal program, which demonstrate a compelling and consistent combination of efficacy and safety across multiple acute pain conditions and settings,” Vertex CEO Dr. Reshma Kewalramani said in a release.

Shares of Vertex rose more than 2% on Tuesday following the data release. The company, best known for developing drugs to treat the serious genetic disorder cystic fibrosis, has a market value of about $115 billion.

Last year, the company’s painkiller produced positive results in a mid-stage trial in diabetes patients suffering from a chronic nerve condition. The stock also saw a boost from U.S. approval of the first-ever gene-editing therapy for sickle cell disease from Vertex and its partner CRISPR Therapeutics.

Vertex said Tuesday its painkiller was more effective in reducing the intensity of pain after 48 hours in two late-stage studies on more than 1,000 patients who had abdominoplasties, also known as “tummy tucks,” and roughly another thousand in people who had bunion surgery. Those two procedures are commonly used in studies of people with acute pain.

The company’s painkiller, however, failed to meet the secondary goal in both trials of reducing pain when compared to a combination of the opioid drug hydrocodone, which is frequently abused, and acetaminophen, the basis for popular pain medications like Tylenol.

Jefferies analyst Michael Yee said the drug’s failure to meet that goal is in line with expectations and that overall, the late-stage trial results released Tuesday are positive.

VX-548 was also safe and well-tolerated in the two trials and an additional study examining the safety and tolerability of the drug in people experiencing pain from a variety of conditions. Common side effects included nausea and constipation.