Walgreens announced Sunday it would end its partnership with Theranos and would close all 40 of the Theranos blood testing centers in Walgreens' Arizona drugstores -- the only remaining Walgreens locations for the centers.
Walgreens already had halted testing in California after federal regulators raised questions earlier about the accuracy of the tests, which require only very small blood samples.
The closure raises more questions about Theranos' future and the viability of its technology.
This is a major blow for Theranos, which not long ago was a darling in healthcare and tech circles. The company was founded on the premise that its fingerprick blood testing was as accurate as tests requiring larger samples, at a much lower price.
Regulators are still investigating the Thernos technology, but the Walgreens decision makes Theranos' way forward much more difficult. Theranos has its own retail centers but, as The New York Times noted Monday, most of its customers came from the Walgreens testing centers in Arizona.
In April, the Centers for Medicare and Medicaid Services (CMS) proposed banning Theranos founder Elizabeth Holmes from owning or operating a blood-testing lab for two years amid questions about Theranos' lab in Newark, CA. The Justice Department and the Securities and Exchange Commission also are investigating the company.
"Quality and safety are our top priorities and we are working closely with government officials to ensure that we not only comply with all federal regulations but exceed them," Brooke Buchanan, Theranos' vice president of communications, said in a statement released Monday. "We are disappointed that Walgreens has chosen to terminate our relationship and remain fully committed to our mission to provide patients access to affordable health information and look forward to continuing to serve customers in Arizona and California through our independent retail locations.