Humira has been one of the world's top selling drugs for more than two decades. But thanks to some new copycats — including one that is being sold at entrepreneur Mark Cuban's online pharmacy — its reign could be coming to an end.

Humira is an injectable drug approved in 2002 that treats a range of illnesses, including Crohn's disease and rheumatoid arthritis. The drug is popular with patients but has a list price of nearly $7,000 a month, according to GoodRx, a website that helps patients find discounts on pharmaceuticals.

Even with insurance, the drug, made by AbbVie, can be quite expensive.

There was no direct competition for years, mostly because the company protected the drug with a thicket of patents. Humira generated $21 billion in sales in 2022 alone, according to AbbVie's annual financial filing.

"I think it's fair to say that Humira is the poster child for what plagues the system, and that is an enormous amount of patents protecting various aspects of the molecule, some of which are undeserved," says Ameet Sarpatwari, assistant director of the Program on Regulation, Therapeutics and Law at Harvard Medical School.

In 2016, the Food and Drug Administration approved Amjevita, the first drug that was a close copy of Humira. Humira is an antibody-based drug, and the copies aren't identical. The alternative medicines are called biosimilars.

Patents and PBMs hinder competition for Humira

But the first Humira biosimilar and the handful that followed couldn't come to market until this year because of disputes over all those patents.

As of this month, there are nine Humira biosimilars for sale, but so far, not a whole lot of people are buying them. Many of them cost almost as much as Humira, and lower-priced options aren't necessarily always covered by insurance.

"The reason prices haven't changed overnight is because we have a Byzantine, opaque and in some respects perverse pharmaceutical system from the manufacturer through what's called the pharmacy benefit manager all the way to the pharmacy," says Sarpatwari.

That pharmacy benefit manager he's talking about decides which drugs you can get with your insurance card and how much you pay for them. These middle men purchase drugs and then get a chunk of that money back from drugmakers through rebates. The size of the rebate is usually secret but often influences which drug products get better market share.

So even if a competing drug's price is lower, it might not wind up on the menu of drugs, or formulary, that your insurance will pay for, says Karen Van Nuys, a senior fellow at the Schaeffer Center for Health Policy and Economics at the University of Southern California.

"Who is the pharmacy benefit manager going to put on the formulary?" she says. "And in many cases, it's believed that they prefer the higher rebate drug."

A Humira rival's low price could help it break through

That could change for Humira because of a biosimilar called Yusimry.

The drug, made by Coherus BioSciences, just launched and is being sold for about $1,000 a month. It will be even cheaper through Mark Cuban's online pharmacy CostPlus, where there will be no rebate to a pharmacy benefit manager, and the price tag is about $570 a month plus shipping and fees.

Its list price is cheaper than any other Humira biosimilar on the market, nearly all of which are above $6,000, according to data from GoodRx.

Coherus BioSciences Chief Business and Legal Officer Chris Slavinsky says a rock bottom price is needed to help patients. Yusimry is the company's first foray into drugs administered outside of a hospital setting.

"How can we take this, but stay true to our core values of driving access?" Slavinsky says. "And that became the seed that ultimately became the low list price."

Coherus priced its biosimilar so low that pharmacy benefit managers may opt to forgo the big Humira rebates.

That's because Humira is so popular. Humira and drugs like it account for such a big chunk of drug spending that switching patients to Yusimry could allow plans to lower premiums by saving as much as 11% on total drug spending, says Richard Evans, a pharmaceutical industry veteran who runs the drug-price data firm SSR Health.

And employers making their annual choice of health insurance plans for employees care about saving money on Humira.

"You know, it really does pay you to be aggressive to try to take that 11% of your spending and reduce it as much as possible, because all the savings that you can create and be put back into lower premiums," Evans says.

So if insurance plans are competing for customers by offering lower premiums, they may have to make changes and include Yusimry on formularies.

Time will tell if the cheaper challengers to Humira catch on.