The U.S. pharmacy group Walgreens Boots Alliance has appointed Rosalind (Roz) Brewer as its new CEO, effective March 15. Brewer will also join the group’s board of directors. She succeeds Stefano Pessina, who moves to the role of executive chairman.

Pessina has served as the CEO of the group for six years following the merger between Walgreens and Alliance Boots in Dec. 2014. Pessina will replace James Skinner as executive chairman in March. Skinner will remain on the board as a non-executive director.

Brewer most recently served as chief operating officer, president and member of the board of the American coffeehouse chain Starbucks. Prior to Starbucks, she was president and CEO of Sam’s Club, the members-only warehouse channel of the U.S. retailer Walmart.

Walgreens jointly owns with De Rigo the British chain Boots Opticians.