Giovanni Caforio will retire as Bristol Myers Squibb’s CEO on November 1, as part of a broader leadership change, and be replaced by Chief Commercialization Officer (CCO) Chris Boerner. Before the transition, Boerner will serve as chief operating officer.

Caforio has worked at Bristol Myers since 2000 and has served as CEO since May 2015, overseeing the $74 billion acquisition of Celgene. Caforio will serve as executive chairman of the Board of Directors for a transition period that’s yet to be determined.

Boerner, who has been CCO since 2018, joined the company in 2015 and previously served in leadership roles at Seattle Genetics Inc and Roche’s Genentech.

“Chris is an exceptional leader, and the Board and I believe he is the right person to guide Bristol Myers Squibb through its next chapter. Chris’s expertise has been integral to our commercial success during his tenure at BMS,” said Caforio.

BMS has tripled its revenue under Caforio’s leadership, largely from the Celgene deal. Also, Bristol launched 12 new medicines, including five first-in-class drugs in different disease areas, during his tenure.

But the unexpected transition means Boerner will be responsible for guiding the biopharma giant through one of the steepest patent expirations in the industry. Three of BMS’ top-selling drugs – Pfizer-shared blood thinner Eliquis, blood cancer medicine Revlimid and PD-1 inhibitor Opdivo – are all set to lose US patent protections this decade.

Moreover, Bristol Myers is dealing with revenue losses from two of its best-selling cancer medicines, Revlimid and Abraxane. Both are now facing generic competition, and saw their combined sales drop by 33%, or roughly $1.2 billion, in the fourth quarter of 2022. Those losses led Bristol’s revenues to fall 3% last quarter compared with a year ago.