Allergan Plc and partner Medytox Inc. are seeking to block U.S. imports of a new rival to the wrinkle-treatment Botox, claiming it was developed using stolen manufacturing secrets and turncoat former employees.

Daewoong Pharmaceuticals Co. and Evolus Inc., which denied the allegations, expect to begin North American sales in the coming months of their competing drug called DWP-450. Medytox contends a former employee handed over to Daewoong the results of its “meticulous, time-consuming, and expensive research” into a new process to make a treatment based on the deadly botulinum toxin, according to the complaint filed Wednesday at the U.S. International Trade Commission in Washington.

Allergan controls some 70 percent of the $3.5 billion U.S. market for treatments using the toxin, and the rival treatment by Daewoong and Evolus — to be priced 25 percent lower — could be its biggest threat. Madison, New Jersey-based Allergan and Medytox are testing a next-generation drug using the new secret manufacturing process but it’s not expected to get U.S. regulatory approval until 2022.

“Daewoong and Evolus are able to introduce DWP-450 into the U.S. market at a price that they have touted will be substantially lower than the price of Botox, and to thereby undercut the market for Botox, because they were not required to make the massive research and development investments that Allergan and Medytox have incurred and continue to incur to develop their products,” Allergan and Medytox said in the complaint.

Daewoong markets its product in its native South Korea under the name Nabota and plans to sell it elsewhere as Jeuveau. Evolus, run by former Allergan employees, has an exclusive license to sell it in the U.S.

The trade complaint in Washington marks the latest entry in a nearly two-year saga between the two Korean companies.

Medytox in 2017 filed complaints in Korea claiming a former employee stole the company’s “most secret, most protected manufacturing processes” as well as a sample of Medytox’s strain and took it to Daewoong. There’s also a criminal investigation in Korea against Daewoong and the former employee, according to the ITC complaint.

Those cases are continuing, while similar suits in the U.S. were either dismissed or put on hold while the Korean actions proceed.

Evolus said the allegations are “completely without merit” and said the complaint won’t change its plans to begin selling its Jeuveau in the North American spring.

“This complaint and the associated timing reflect the level of concern surrounding Evolus’ entry and the competitive threat it presents to the Botox franchise,” Evolus said in a statement. “This represents another legal maneuver in a long-litany of attempts by Allergan and Medytox to stifle competition and limit physician and consumer choice.”

The process to turn a deadly toxin into Botox, which also is used to treat chronic migraines and urinary incontinence, has been a closely kept secret by Allergan, allowing it to maintain its dominance since it was first approved for sale in 1989.

Medytox’s first botulinum toxin treatment, Meditoxin, began selling in Korea in 2006 and the company has worked since then to develop its newer product, Innotox, in 2014. It plans to sell a derivative of Innotox in the U.S. with Allergan. Medytox uses a liquid-type version that’s seen as easier to use than Botox, which must be mixed with saline for injection.

Medytox uses a liquid-type version that’s seen as easier to use than Botox, which must be mixed with saline for injection.

The commission will consider the complaint and, if it decides to investigate the allegations, could make a final decision in about 15 to 18 months.

This isn’t Allergan’s only legal battle over rivals to its cosmetic treatments. Last week it filed a patent-infringement lawsuit against Prollenium Medical Technologies Inc. over the smaller company’s Revanesse Versa+ wrinkle-filler.

The case is In the Matter of Certain Botulinum Toxin Products, Complaint No. 337-3359, U.S. International Trade Commission (Washington).