By Ben Hirschler
LONDON (Reuters) - AstraZeneca's (L:AZN) chief medical officer and head of global late-stage drug development Briggs Morrison is to leave the company, creating a gap at the top of the group's research operations.
A spokeswoman said on Wednesday Morrison was departing to become chief executive of an unlisted venture capital-backed drugmaker in the United States, adding there had been no disagreement with other top managers at AstraZeneca.
"It is not appropriate for us to confirm the name of the company but it is an exciting new opportunity for him," she said.
Morrison, who joined AstraZeneca from Pfizer (N:PFE) in 2012, has played a central role in the British drugmaker's bid to turn around its portfolio. He also helped defend the firm's independence in the face of a $118 billion takeover attempt by Pfizer last year.
Morrison will cease his current roles at the end of the week and leave AstraZeneca shortly after.
While the drugmaker seeks a successor, Chief Executive Pascal Soriot will take over responsibility for medicines development and Elisabeth Bjork will act as chief medical officer.
Soriot, who took over as CEO in October 2012, chose Morrison as one of his key drug research lieutenants, alongside Mene Pangalos, who heads early development work, and Bahija Jallal, leader of the group's MedImmune biotech unit.
AstraZeneca has won plaudits for recent progress with its pipeline of experimental drugs, especially in cancer, where it is investing heavily in the hot new field of immunotherapy.
Still, many industry analysts remain sceptical about its ability to lift sales to $45 billion by 2023 from $26 billion last year, a target set by Soriot when the company was fighting off Pfizer's attempted takeover last year.
It has suffered some setbacks, too, most recently when its partner Amgen (O:AMGN) pulled out of a psoriasis drug collaboration last month after suicidal thoughts were observed in patients taking the medicine.
AstraZeneca said it had not issued a formal statement about Morrison's exit because he was not a board member.