Enbrel's recent US patent win has ensured a further eight years of exclusivity for the rheumatoid arthritis treatment. Amgen's biological had already secured its place in biopharma's hall of fame as the fourth biggest selling drug of all time to date, and currently stands to be the third biggest product looking as far ahead as 2024, according to EvaluatePharma consensus.
This forecast does not take into account any extra sales from the extension in Enbrel's patent life, so it could become even bigger in the coming years – not bad for a product in its twenties (What Enbrel needs to do after its patent win, August 12, 2019).
But Enbrel’s longevity is nothing compared with some of the behemoths of the industry. Until last year Lipitor still claimed the title of the industry’s drug with the biggest lifetime sales, with a heroic $164.4bn and counting.
The lipid-lowering drug’s achievement is impressive because of its small molecule status and its approval in a narrow indication. However, there are five other drugs that have also had cumulative sales topping the $100bn mark, as of 2018.
Unsurprisingly, the majority of the products in the top 10 are biologics, the exceptions being Advair, Zantac, Lipitor and Plavix. The huge sales of biologics are down to their ability to command big ticket reimbursement and, in many cases, the number of indications into which they have successfully expanded.
Perhaps the biggest win for biologics has been their ability to avoid – so far – an onslaught from biosimilars in the key US market, helped by a vigorous patent defence from their manufacturers and barriers to biosimilar reimbursement.
This ability to fend off biosimilar competition is one of the reasons Humira is set to snatch Lipitor’s crown next year as the industry’s most successful drug. Abbvie has gained a reputation for rigorously defending the IP of its cash cow. Given that the rheumatoid arthritis drug still accounts for 61% of the company's sales, and that investors have been less than impressed with Abbvie’s attempts to reduce its reliance on Humira, these efforts have been more than worthwhile.
Even with the expected uplift in sales that Enbrel will have secured with its patent win, it looks unlikely to bypass Lipitor in the future biggest sellers stakes. One drug that has leapfrogged much of the competition to become one of the industry’s biggest future best-sellers is Revlimid. A look at the chart shows that projected sales of the drug over the next six years will actually outstrip its sales to date. However, much of this is dependent on whether generic competition will arrive ahead of the drug's 2022 patent expiry.
*Enbrel forecasts made prior to patent victory; Source: EvaluatePharma