Also interesting link within the article: https://www.bloomberg.com/news/articles/2017-09-07/this-shield-of-patents-protects-the-world-s-best-selling-drug http

Also interesting link within the article: https://www.bloomberg.com/news/articles/2017-09-07/this-shield-of-patents-protects-the-world-s-best-selling-drug https://www.bloomberg.com/news/articles/2017-09-07/this-shie... TL;DR Humira is protected by over 100 patents, covering how it's produced etc. That's partially what's preventing other companies from coming up with a replacement, despite the main patent having already expired.