In less than two months after Coherus BioSciences succeeded in winning a key intellectual property lawsuit on AbbVie’s Humira, another biological company seeking to launch a biosimilar rival to Humira, a rheumatoid arthritis drug, has scored the same victory.

Last Thursday, the U.S. Patent and Trademark Office’s Patent Trial and Appeal Board (PTAB) ruled in favor of Boehringer Ingelheim in a case that challenged five claims for the ‘135 methods patent on AbbVie. PTAB condemned such patent protection method of AbbVie in the court. This ‘135 patent is one of the basic terms for the patent protection of Humira.

In the opinion of the author: ‘135 patent restricts the injection frequency of 40mg once every 13-15 days for rheumatic arthritis and psoriasis indications, but according to PTAB, there is no patentability in it.

AbbVie extended ‘135 patent to 2022, which resulted in the Humira biosimilar of Samsung Pharm to be not approved in the Europe, however, AbbVie also lost the patent lawsuit of both parties in the UK.

Losing in those two patent challenges makes it more difficult for AbbVie to overturn the PTAB’s rulings, while the ‘619 patent formulated for Humira will also be challenged by other biosimilar companies this summer.

Humira is the world’s top-selling drug, and accounts for more than 60% of AbbVie’s revenue. The 15% increase of Humira sales in the first quarter this year helped drive the company’s total revenue to USD 6.5 billion and net earnings to USD 1.7 billion.

AbbVie continues its efforts to diversify beyond Humira, but with decidedly mixed results.

 "One of our biggest successes is our blood cancer drug Imbruvica, which is now prescribed as a first-line treatment to 21% of patients with chronic lymphocytic leukemia (CLL). The sales of the drug in the first quarter jumped 45% to USD 551 million," mentioned by the CEO Richard Gonzalez during the first-quarter report.

 "But AbbVie’s hepatitis C combo, Viekira Pak, has struggled to compete against Gilead’s Harvoni. What’s more, the hep C market is rapidly shrinking, since the drugs in the newest generation are essentially cures. Sales of Viekira Pak dropped 36% in the first quarter to USD 263 million."

The biosimilar threat to Humira, however, is real—and already an issue in the European market. Last month, EMA approved a Humira biosimilar named Imraldi co-developed by Samsung BioLogics and Biogen, which would be the second Humira biosimilar to market in Europe after Amgen’s Amjevita.

Meanwhile, the parent company of AbbVie is already ready for Humira’s decline. In May, UBS Analyst Marc Goodman reported in a note to investors that AbbVie executives are predicting Humira will peak overseas in 2018 before biosimilars take a significant bite out of sales. Then it expects to see international sales decline 15% a year through 2020.