Pfizer announced that Dr. Mikael Dolsten, chief scientific officer and president of Pfizer research and development (R&D), will be leaving the company. 

In a press release Tuesday morning, the pharma giant announced it has initiated an external search for his successor, which is expected to last several months. 

Dolsten will remain in his current position until a successor is in place and the transition process is complete. 

During his more than 15-year career at Pfizer, Dolsten played a critical role overseeing the company’s 35 drug and vaccine approvals, more than half of which were new molecular entities. 

Most notably, he was Pfizer’s scientific lead during the development, approval and distribution of the company’s COVID-19 vaccine developed alongside BioNTech. He also oversaw the development and approval of its COVID oral therapeutic Paxlovid.

In addition, he played a large role in the creation of products that ranged from therapies for inflammatory diseases, cardiovascular, stroke prevention, hemophilia and cancer to vaccines for RSV, pneumococcal and meningococcal diseases. 

As part of an organizational shakeup last summer, Dolsten was tasked to lead “all discovery, early- and late-stage clinical development, for all non-oncology therapeutic areas” as well as an end-to-end model across all of Pfizer’s other therapeutic areas.

In a post on LinkedIn Tuesday morning, Dolsten wrote that he will always be rooting for science and his colleagues at Pfizer as he pivots to the next chapter of his life.

“I hope that I can contribute to the next wave of breakthroughs in exciting, new ways, working with the next generation of scientific leaders who are pushing the boundaries of science,” he wrote. 

Dolsten joined the company in 2009 following Pfizer’s acquisition of Wyeth Pharmaceuticals, where he served as the president and head of R&D. 

Before that stint, he served as EVP and head of worldwide research at Boehringer Ingelheim and global VP of R&D at AstraZeneca. 

This announcement comes as Pfizer – like many other drugmakers – reevaluates its markets and products in the wake of its success with the COVID-19 vaccine. The company has begun broadening its oncology profile after purchasing Saegan last year for $43 billion. 

Dolsten’s departure comes three weeks before Pfizer will release its annual earnings on July 30.

Pfizer CEO Albert Bourla underscored Dolsten’s profound impact on the industry in a company press release and heralded his commitment to a smooth transition process for his successor.

“I want to thank Mikael for his incredible contributions, not only to Pfizer and the scientific community, but to the millions of patients he has impacted over the years,” he stated. “Mikael is a distinguished scientist, physician, and leader, and his work will undoubtedly leave an important stamp on the legacy of this 175-year-old company.”