Walgreens Boots Alliance Inc sued Theranos Inc on Tuesday, seeking $140 million in damages while accusing its onetime lab-testing partner of breaching a contract, according to court records.
The company's Walgreen Co unit filed the lawsuit in federal court in Wilmington, Delaware, five months after the drugstore chain announced it was ending its relationship with Theranos.
Details of the lawsuit were unclear, as Walgreens filed it under seal, citing a confidentiality agreement between the two companies. A Walgreens spokesman declined to comment.
In a statement, Theranos said it was "disappointed" Walgreens filed the lawsuit. Theranos claimed Walgreens has "consistently failed to meet its commitments to Theranos" and mishandled the companies' partnership.
"We will respond vigorously to Walgreens' unfounded allegations, and will seek to hold Walgreens responsible for the damage it has caused to Theranos and its investors," Theranos said.
Theranos was founded by CEO Elizabeth Holmes in 2003 to develop a blood-testing device that would deliver quicker results using only a drop of blood.
The Palo Alto, California-based company ran into trouble after the Wall Street Journal published a series of articles beginning in October 2015 suggesting its blood-testing devices were flawed and inaccurate.
In June, Walgreens announced that it was terminating its relationship with Theranos and closing operations at 40 blood-draw sites that the Silicon Valley company ran in Arizona at Walgreens' stores.
The decision came after Walgreens in January decided to halt Theranos laboratory testing services at its Palo Alto location.
The case is Walgreen Co v. Theranos Inc, U.S. District Court, District of Delaware, No. 16-01040.