Johnson & Johnson’s Remicade, which remains one of the world’s best-selling drugs, is one step closer to facing competition after a FDA advisory committee voted 21-3 in support of approving a biosimilar version of the commonly prescribed therapy for rheumatoid arthritis, Crohn’s disease and four other diseases.

The committee on Tuesday voted in favor of approving Celltrion’s CT-P13, which will be named Inflectra if approved in the US and commercialized by Pfizer. (The drug is called Remsima in Europe.) The FDA, which is not required to follow the committee’s recommendation but usually does, is expected to make a decision about the drug in April.

The drug, developed by South Korean drugmaker Celltrion, would be the second biosimilar to receive FDA approval and the first biosimilar monoclonal antibody. The regulator last year approved Novartis’ Zarxio—a biosimilar version of Amgen’s Neupogen. The drugmaker’s generics subsidiary, Sandoz, last summer launched Zarxio.

See also: Sandoz: Zarxio marketing to be similar to a branded-drug launch

The FDA initially approved Remicade in 1998 as a treatment for Crohn’s disease. It now has 16 indications for six diseases and has been used to treat more than 2.4 million patients across the globe. Analysts have said that the drug is prescribed off-label for at least 15 additional indications.

J&J spent about $13 million advertising Remicade in 2014, according to Kantar Media.

The drug brought in $6.56 billion in revenue in 2015, down from the nearly $6.87 billion it generated in 2014. In the US alone, Remicade had $4.45 billion in sales in 2015, up 7.2% compared to $4.15 billion in 2014.

Unsurprisingly J&J is urging the FDA to take into account what it views as significant differences in the drugs.

“We believe that the data to date, absent of direct comparisons of CT-P13 and Remicade in patients with inflammatory bowel disease, leave uncertainty about whether differences in safety or efficacy may emerge for patients,” Dr. Jay Siegel, J&J’s chief biotechnology officer and head of scientific strategy and policy, said in a statement.

During an earnings call in July, J&J CEO Alex Gorsky told investors he expects patients and prescribers to treat biosimilars differently than they do generics. “About 70% of the current patients are receiving sustained and effective treatment so we believe their doctors are very unlikely to switch them off with that level of success,” Gorsky said then.

See also: J&J prepares to defend Remicade market share

However, the FDA’s Arthritis Advisory Committee said that CT-P13 is “highly similar” to Remicade and found no meaningful clinical differences between the two products, Celltrion said in a news release. 

Biosimilar drugs are not exact copies of biologic drugs but they do function similarly to the way that generic drugs do, and some experts believe that biosimilar drugs will help lower drug costs.

Express Scripts, the nation’s largest pharmacy benefit manager, has estimated that a biosimilar version of Remicade could bring $17 billion in savings over 10 years.