1. Humira

AbbVie’s aggressive patent defense has kept biosimilar competition out of the U.S. market until 2023. (AbbVie)

1. Humira
2018 U.S. sales: $13.7 billion
Used for: rheumatoid arthritis, polyarticular juvenile idiopathic arthritis, psoriatic arthritis, ankylosing spondilitis, Crohn's disease, hidradenitis suppurativa, ulcerative colitis, plaque psoriasis

With more than double the U.S. sales of its closest competitor, AbbVie’s wonder immunology drug Humira has once again secured its spot as pharma’s blockbuster to beat.

Humira cleared $13.68 billion in the U.S. last year, a 10.1% increase over the previous year. With an aggressive strategy of fending off competitors through litigation, outspending other drugmakers in advertising and routinely hiking Humira's U.S. list price, AbbVie has reliably posted impressive growth.

Those sales are soon to reach their peak, though, if they haven't already. AbbVie’s aggressive patent defense has kept biosimilar rivals out of the U.S. market until 2023, but the drug faces stepped-up competition from next-gen immunology drugs stateside as biosims in Europe take their toll.

In October last year, AbbVie and Novartis’ Sandoz unit reached a patent settlement that will delay the challenger’s U.S. biosimilar launch until late 2023. In settling, the Swiss drugmaker joined Amgen, Merck and Mylan in line to challenge Humira’s iron grip.

At the time, one company had chosen to hold out in hopes of jumping ahead of the pack. AbbVie sued in September against Boehringer Ingelheim’s Cyltezo, alleging the Humira copy violated dozens of the company’s patents. In its defense, Boehringer accused AbbVie of forming a “patent thicket” to protect Humira’s sales after the drug’s primary patent expired in 2016. But Boehringer has since settled, too, agreeing to roll out its copy in 2023 just as its peers did.

Maintaining U.S. exclusivity is no laughing matter for Humira. As biosims of the drug launch in Europe, the company has projected it could lose 50% of the ex-U.S. market by 2020, a disastrous result for the bestseller. In the first quarter of 2019, AbbVie posted a 5.6% drop in worldwide sales—its first—to $4.46 billion, while U.S. sales increased 7% to $3.2 billion. And according to a June 2019 EvaluatePharma report, Humira will cede its spot as the world's bestselling drug to Merck's Keytruda by 2024.

Competing with U.S. biosims could well extend Humira's streak as the most marketed drug in the industry, though. In April, AbbVie spent $45 million on TV ads for Humira, with Pfizer's Xeljanz a distant second in the ad-spending ranks at $25.8 million.

That marketing wave has accompanied increased scrutiny from legislators about Humira's pricing, with a Senate committee in February 2019 accusing the company of price-gouging the drug to achieve consistent profits.

1. Humira