Genentech Inc. has accused Samsung Bioepis Co. in Delaware federal court of infringing 21 patents for its breast cancer drug Herceptin.

In the lawsuit, filed Tuesday in the U.S. District Court for the District of Delaware, Genentech aims to stave off the latest threat of biosimilar competition for the drug, which is used to treat about 20 percent of the 2.8 million women who suffer from a form of breast cancer known as HER2-positive.

Genentech has launched similar lawsuits in recent months against drugmakers Celltrion Inc., Pfizer Inc. and Amgen Inc..

In a 54-page complaint, Genentech, a subsidiary of Roche, said it would suffer “irreparable injury” if Bioepis were allowed to market its planned drug, SB3. The suit requests a declaratory judgment that the sale of SB3 would infringe its patents, as well as an injunction and monetary damages, including lost profits, against Bioepis.

In the filing, Genentech said Bioepis had filed an abbreviated biologics license application in January seeking approval from the U.S. Food and Drug Administration to market SB3.

Under federal law, Bioepis was required to provide Genentech with a copy of its application and other information describing the process for manufacturing SB3; however, Genentech said, Bioepis turned over only redacted portions, which represented a “small fraction” of its entire application.

According to the complaint, Genentech provided a list of patents in April that it believed SB3 would infringe and refused to license the patents to Bioepis. Genentech said that Bioepis continued through August to deny any infringement and challenged the validity of the patents. On Monday, Genentech said, Bioepis agreed to litigate each of the 21 patents.

“Bioepis' failure to provide sufficient information under those circumstances supports Genentech's contention that manufacturing Bioepis' [abbreviated biologics license application] product will infringe such patents,” Genentech said in the complaint, which was signed by Richards, Layton & Finger partner Frederick L. Cottrell III.

Bioepis did not respond Wednesday to an email seeking comment on the lawsuit.

One of Genentech's top-selling cancer treatments, Herceptin was the first treatment to utilize an antibody called trastuzumab to fight HER2-positive breast cancer, and Genentech said that it had worked with the City of Hope cancer center in California to develop some of the key inventions that underpin its drug before gaining FDA approval in 1998. City of Hope is also named as a plaintiff in the suit

The patents, which were issued between 2001 and 2016, include techniques for making antibodies that can be used as drugs and for administering Herceptin in combination with the chemotherapy agent taxoid, the complaint said.

Tuesday's filing comes as Mylan and is looking to break into the market with its own biosimilar version of Herceptin. European regulators in 2016 approved Mylan's drug, which it had developed with Indian pharmaceutical company Biocon. The FDA in December also approved Mylan's drug, Ogivri, as a biosimilar to Herceptin.

In March, Mylan agreed to drop its challenge to two patents for Herceptin, after Genentech  provided Mylan with global licenses for its trastuzumab product.

Both of those patents are asserted in Genentech's current suit against Bioepis. The case, captioned, Genentech v. Samsung Bioepis, has been assigned to U.S. District Judge Gregory M. Sleet of the District of Delaware.

Genentech is represented by William F. Lee, Lisa J. Pirozzolo, Emily R. Whelan, Kevin S. Prussia and Andrew J. Danford of Wilmer Cutler Pickering Hale and Dorr's Boston office; Robert J. Gunther Jr. of the firm's New York office and Robert M. Galvin in Palo Alto, California. The company is also represented by Daralyn J. Durie and Adam R. Brausa of Durie Tangri in San Francisco. Cottrell and Jason J. Rawnsley of Richards Layton are acting as local counsel.

An online docket-tracking service did not list attorneys for Bioepis.