Gilead Sciences has announced that Daniel O'Day, the current chief executive (CEO) of Roche's pharmaceutical unit, will become its chief executive effective from March 1 next year.

He will replace current CEO John Milligan, who will step down at the end of 2018.

Daniel has been head of Roche's pharmaceutical division since 2012, while previously leading the firm's diagnostics unit, having joined the drugmaker in 1987.

Commenting on the appointment, Gilead chairman John Martin said O'Day "is uniquely qualified to take on this role given his track record of success in highly scientific and competitive therapeutic areas, deep understanding of the evolving healthcare environment around the world, and unwavering commitment to driving innovation across all aspects of a business.”

Gilead indicated that Gregg Alton, who currently serves as chief patient officer, will assume the role of interim CEO at the start of 2019 until O'Day takes over the position.

Commenting on O'Day's departure, Roche CEO Severin Schwan said "[he] has had an outstanding 31-year career at Roche and has played a key role in bringing a large number of new, innovative medicines to patients.”