On Friday, November 17, Genentech, a Roche company, sued Pfizer in a federal court in Wilmington, Delaware, over Pfizer’s biosimilar for Genentech’s Herceptin. Genentech is claiming that Pfizer’s proposed biosimilar infringes 40 of its patents. Genentech also is demanding compensation for lost sales if Pfizer launches its copycat version before the Herceptin patents expire.

In 2016, Herceptin brought in $2.5 billion in U.S. sales. The drug was approved by the U.S. Food and Drug Administration (FDA) in 1998 and is used to treat breast cancer. Pfizer’s biosimilar is PF-05280014. A biosimilar is essentially a generic version of a biologics drug.

BloombergTechnology writes, “Roche is leaning on new drugs such as the multiple sclerosis therapy Ocrevus to drive growth as its three most lucrative drugs—the cancer-fighting trio of Herceptin, Rituxan and Avastin—face competition from biosimilars or newer treatments. The company could lose almost $4 billion in sales to the cheaper versions of the three drugs in 2020, Sanford C. Bernstein & Co. said in April. Roche has said that competition for its two best-selling medicines, Rituxan and Herceptin, will probably start to have an impact on revenue in 2018.”

Genentech’s concerns are legitimate. On Sunday, Nov. 20, the European Commission approved Samsung Bioepis Co. Ld's Ontruzant, a biosimilar of Herceptin. Europe is ahead of the U.S. in the biosimilar market. It’s been seven years since Congress passed laws allowing biosimilars, but so far the FDA has only approved five, while 25 have been approved in Europe. The rationale, much like that for generics, is that the competition will push down drug prices.

BloombergTechnology notes, “Regulatory approval isn’t the only hurdle for copies of biotechnology drugs like Herceptin. The drugs are complex, and it’s not unheard of for one to be tied to more than 100 patents, which can generate extensive litigation. And drugmakers may use contracts with drug plans and insurers to thwart competitors.”

This isn’t the first time Pfizer has gotten tangled in lawsuits over biosimilars. Its first biosimilar, Inflectra, launched in the U.S. in October 2016. Inflectra is a biosimilar to Johnson & Johnson’s Remicade. Pfizer proactively sued J&J, arguing that it was engaged in anti-competitive practices intended to block Inflectra.

The Center for Biosimilars notes, “While Pfizer has not yet announced its submission of a Biologics License Application for its proposed trastuzumab biosimilar, it has released positive data from a comparative clinical trial comparing PF-05280014 to reference trastuzumab in patients with operable HER2-positive early breast cancer. The study demonstrated that PF-05280014 had similar safety, efficacy, and immunogenicity to its reference, and that it was non-inferior, in terms of pharmacokinetics, to the reference drug.”

And it’s not Pfizer’s only biosimilar in the pipeline. It also has biosimilar in Phase III development for Humira (adalimumab), Avastin (bevacizumab), Epogen and Procrit (epoetin alfa), Rituxan and MabThera (rituximab). The Center for Biosimilars says, “Forbes reports that the total sales of the reference products targeted by Pfizer totaled over $35 billion in 2014, and that ‘Theoretically speaking, replacing [these drugs’] entire sales with biosimilars even with a 50 percent pricing discount will open up a market worth nearly $18 million for Pfizer.’”