scorecardresearch Skip to main content

Alnylam is getting a rare kind of leader

Yvonne Greenstreet, named John Maraganore’s successor, will become one of the few Black women to lead a drug company.

Yvonne Greenstreet will become the CEO of Cambridge's Alnylam Pharmaceuticals in January.Suzanne Kreiter/Globe Staff

Before she accepted a recent offer to become chief executive of Alnylam Pharmaceuticals, one of Massachusetts’ biggest biotechs, Yvonne Greenstreet consulted two women she respects, her mother and her daughter.

Miranda Greenstreet, 88, is from the West African nation of Ghana and often blazed trails, her daughter said. She married a white Englishman whom she met in the 1950s when they were students at the London School of Economics. Later, she set up an institute that promoted adult literacy in Ghana. When Yvonne Greenstreet called to ask if she should take the job, she recalled, her mother didn’t hesitate, saying, “Is there a choice?”


Greenstreet’s daughter, a medical student at the University of California, San Francisco, had a similar reaction.

“Mom, if you think you can, please do it,” she recounted Emma Greenstreet saying, “because you have no idea what it’s going to mean to young women like myself to see you in the position.”

Greenstreet, Alnylam’s chief operating officer since 2016, will succeed John Maraganore on Jan. 1. Maraganore has been CEO since Alnylam was founded in 2002 and is highly regarded in the industry. He has led a firm that began with a promising but unproven drug development approach and won approval of four novel medicines for rare diseases in the past three years.

As a Black woman, Greenstreet, 59, will be a rarity in an industry whose top executives are overwhelmingly white men.

“I’ve been in this business for 30 years, and when I started and I looked around, there weren’t a lot of people that looked like me in leadership positions,” Greenstreet, a physician and former senior executive at the drug giants Pfizer and GlaxoSmithKline, said recently over coffee at Bambara in Cambridge. “Fast-forward 30 years, I’m now in the C-suite, and I look around, and there’s still not a lot of people that look like me.”


Greenstreet will be just the sixth woman to head one of the 68 biopharma companies with a market value of at least $5 billion on the Nasdaq or New York Stock Exchange, according to a recent analysis by BioCentury, an industry publication.

The other five are Samantha Du, of Zai Lab, of Shanghai, China; Reshma Kewalramani, of Vertex Pharmaceuticals, of Boston; Martine Rothblatt, of United Therapeutics, of Silver Spring, Md.; Helen Torley, of Halozyme Therapeutics, of San Diego; and Emma Walmsley, of GlaxoSmithKline, of Brentford, England.

Even fewer Black people have run drug companies. The best-known is probably Kenneth Frazier, who served as chief executive of Merck & Co., the N.J.-based pharmaceutical giant, for a decade before retiring in June.

Greenstreet, whose accent betrays her roots in England, says she hopes her appointment will give other biopharma employees from underrepresented groups “extra energy to say, ‘Yes, it’s within my reach, and I’m going to do what I need to do to get there.’”

When Alnylam announced the succession plan on Oct. 28, it surprised some analysts and rattled investors. The company’s share price fell more than 15 percent that day, closing at $162.19. The stock has since rebounded, but many people who follow biotech agree that Maraganore will be a tough act to follow.

“He’s a rock star,” said Alethia Young, an analyst at Cantor Fitzgerald & Co. He guided Alnylam to the first approval ever of a medicine that relies on RNA interference, a Nobel Prize-winning scientific innovation that “silences” disease-causing genes. He then helped persuade the Food and Drug Administration to clear three more.


RNAi represents one of the most promising frontiers in drug development, and Alnylam wants to harness it soon to treat common diseases such as high blood pressure and diabetes with one or two injections a year. Alnylam has a market value of more than $23 billion and 1,600 employees in over a dozen countries, more than five times the size of its workforce in 2016, Greenstreet said. (Bloomberg News recently reported that Switzerland-based Novartis might want to buy Alnylam after the Danish drug giant Novo Nordisk announced it had signed a $3.3 billion deal to acquire another RNAi firm, Dicerna Pharmaceuticals of Lexington. An Alnylam spokeswoman said her company won’t comment “on market rumors and speculation.”)

Greenstreet’s ascension to the corner office shouldn’t surprise anyone who has followed her career, Young said. She held leadership positions at GSK and Pfizer, served as chief operating officer when Alnylam won its four drug approvals, and succeeded Barry Greene as president last year, becoming Maraganore’s heir apparent.

“She’s very, very capable,” Young said. “Her resume speaks for itself.”

Indeed, Maraganore said that when he offered Greenstreet the job of chief operating officer in 2016 over a meal at the Italian restaurant Sorellina in Copley Square ― at table 13, his usual perch ― he already considered her a potential successor. He had met Greenstreet years earlier at GSK, where she worked from 1992 to 2010. In her first project at GSK, she helped bring Zofran, an anti-nausea drug for cancer patients, to market.


“She’s a physician-scientist, so she understands the importance of patients in what we do as an industry,” said Maraganore, 59, who is a biochemist and molecular biologist but not a doctor. “She’s also a very clear and bold thinker who really understands how to push the frontiers of medicine forward.”

Greenstreet was born in London and moved to Ghana with her parents at the age of 4 when they took jobs as professors at the University of Ghana. Five years later, she decided she wanted to be a doctor. Political and economic upheaval in Ghana prompted her father to send her to a girls’ boarding school in England. She earned her medical degree at the University of Leeds and began practicing obstetrics and gynecology in the United Kingdom.

Although she liked being a doctor, Greenstreet wrote in 2009 in The Scientist, a life sciences magazine, she wanted to “impact more than the hundred or so patients I would see in a year.” So she enrolled at the INSEAD Business School in France, where she earned a master’s degree in business administration.

In 1992, she joined what was then called Glaxo, pursuing a career that combined medicine, science, and business. She eventually rose to senior vice president and chief of strategy at GSK, reporting to the chairman of research and development, Moncef Slaoui, who would go on to head the COVID-19 vaccine development effort Operation Warp Speed.


She left GSK in 2010 and spent three years at Pfizer as senior vice president and head of medicines development. She then founded Highgate LLC, which advised life sciences firms, and was running it when Maraganore recruited her to Alnylam.

Amy Schulman, a managing partner at the venture capital firm Polaris Partners, met Greenstreet at Pfizer when Schulman was general counsel for the New York-based pharmaceutical company. Greenstreet, she said, is “a leader who listens but doesn’t have a hard time being decisive,” valuable traits in the drug industry, where most experimental products never win approval.

Greenstreet divides her time between homes in Boston and Philadelphia, where GSK has its US headquarters and her three children grew up. These days, she is an evangelist for RNAi to treat a vast array of diseases.

The first Alnylam medicine to get approved was Onpattro, which treats peripheral nerve damage caused by hereditary transthyretin-mediated amyloidosis. It’s a degenerative, life-threatening disease that affects multiple organs and is estimated to afflict 50,000 people worldwide. Like other drugs for rare diseases, Onpattro came with a breathtaking list price: $450,000 a year.

But Alnylam has a robust pipeline of other potential medicines ― Greenstreet pronounces it “MED-cines,” dropping the second syllable ― including the hypertension drug zilebesiran, which is being studied in a mid-stage clinical trial. If the medication is approved, Greenstreet says, it could benefit hundreds of millions of people around the world who would receive one or two injections a year. Some governments, she said, could buy it from Alnylam in bulk to treat large populations at a relatively modest cost per patient.

Alnylam also has a partnership with Vir Biotechnology of San Francisco to treat hepatitis B ― which afflicts about 300 million people worldwide ― with an RNAi drug that’s also being tested in a mid-stage trial.

“We’re beginning to address the needs of patients with much more prevalent diseases,” Greenstreet said. “I don’t think the world yet appreciates how phenomenal this is going to be. ... It’s just mind-blowing.”

Jonathan Saltzman can be reached at