Sean Bohen

In the small Olema office on Brannan Street, the calendar is organized around something most CEOs never see this close - the readout of a Phase 3 trial. Sean Bohen runs the place. He is a physician, a biochemist, and the kind of executive who can describe the conformational geometry of an estrogen receptor without losing the room. His company has 96 people, one drug deep in pivotal trials, and a problem worth solving - metastatic breast cancer, which is still, in 2026, the disease that kills more American women than almost any other cancer.

The drug is palazestrant. Bohen calls it a complete estrogen receptor antagonist. Translated - it doesn't just dim the signal that fuels ER+ breast cancer cells. It shuts the receptor off and degrades it, even when the receptor has mutated in ways that let it function without estrogen at all. "Lock the receptor in an inactive conformation," he told the Biotech Nation podcast, "regardless of whether it has changes to make it estrogen independent or not." In a category of drugs called oral SERDs - selective estrogen receptor degraders - palazestrant is the one Bohen and his team think is built right.

There is a reason Olema has a CEO who can argue mechanism instead of market. Bohen's whole career has been a setup for this job. Bacteriology at Wisconsin. An M.D. and a Ph.D. at UCSF in biochemistry and biophysics. A postdoctoral fellowship at the National Cancer Institute. Another at Stanford, under Howard Hughes Medical Institute, while teaching as an adjunct clinical instructor in the oncology division. He saw patients. He ran experiments. He learned how a molecule becomes a medicine.

Then Genentech. Thirteen years. He arrived as an assistant medical director on the Rituxan program - the antibody that rewrote how oncologists treat B-cell cancers - and left as Senior Vice President of Early Development at gRED, the side of Genentech where new clinical candidates are born. In between, he ran exploratory oncology, immunology, and the kinds of programs nobody puts in slide decks because the molecules either work or quietly disappear. Bohen learned the discipline of disappearing molecules. He learned which kinds were worth saving.

In 2015, AstraZeneca asked him to be the worldwide Chief Medical Officer. He took it. For four years, Bohen sat in the seat where every clinical decision the company made eventually landed - oncology, cardiovascular, respiratory, every therapeutic area, every late-stage trial, every regulatory negotiation. Drugs that arrived during his tenure went on to treat HER2+ metastatic breast cancer, basal cell carcinoma, bladder cancer, chronic lymphocytic leukemia, mantle cell lymphoma, melanoma, non-small cell lung cancer, ovarian cancer, and prostate cancer. Nine cancer types. One CMO.

Then he left. In September 2020, Olema - a then-private South San Francisco startup with a single lead compound and a thesis about complete estrogen receptor antagonism - named him President and CEO. Two months later, Olema went public on the Nasdaq. The deal made the company an overnight clinical-stage public biotech, and it made Bohen something he had never been before - the person who has to defend a clinical hypothesis to public-market investors quarter after quarter.

Bohen's pitch for Olema is unfashionable and clear. ER+/HER2- breast cancer is the largest subtype of the disease. The standard endocrine therapies - aromatase inhibitors, fulvestrant - work, until they don't. Resistance comes, often from mutations in the estrogen receptor itself. The next generation of medicines has to cover both kinds of disease, the resistant and the not-yet-resistant, in a pill a patient can swallow at home. Palazestrant, Bohen argues, does that. At a March 2026 conference, he told investors the compound has "superior exposure" against rival oral SERDs - meaning the body sees enough of it, at high enough levels, for long enough, to combine cleanly with other therapies without dropping the dose.

He is not a salesman by nature. Listen to him on a podcast and the cadence is a clinician's - careful, qualified, declarative only where the data lets him be. He is happiest in the mechanism. He talks about pharmacokinetics, about the conformational lock, about how a molecule degrades the protein it was built to silence. The investor questions about commercial positioning - those he answers in the same voice, but with less obvious pleasure.

The bench behind the suit

Bohen's earliest published science was in molecular chaperones and steroid receptors at UCSF - work on the protein machinery that lets receptors like the estrogen receptor fold and function. Three decades later, his company is degrading the receptor he once helped understand. There is a tidiness to it that doesn't usually exist in biotech careers. Most CEOs run companies whose science they admire from a distance. Bohen runs a company whose science he can argue with his own postdoc advisor.

Beyond palazestrant, Olema is advancing a KAT6 inhibitor - a second program in the same therapeutic neighborhood. Bohen has talked about it at the Citi conference and others, but the narrative gravity at Olema today is palazestrant. The KAT6 program is the "what's next" answer. Palazestrant is the "what now" answer.

There is also a board seat at AltruBio, where he serves as a non-executive director, and prior service on the board of Gyroscope Therapeutics. They round him out - the operator who still wants a view into the small companies that don't yet have a market cap to defend.

What he is betting on

Bohen's wager is not really about a single drug approval. He is betting that the right oral endocrine therapy can change what metastatic breast cancer looks like as a life. Today it is a series of lines of treatment - this drug, then that one, then a chemo. He has said, in interviews, that he wants the disease to be chronic, manageable, the kind of thing patients live with for years on a pill, with later lines held in reserve. The technical word is "stable disease." The human word is "more time."

If palazestrant lands, that is the chapter he gets to write. If it doesn't, he will have done one of the harder things a physician can do - put the credibility he built across nine approved oncology drugs behind a single molecule and let the readout decide. Either way, his name is in the footnotes. Read the leadership page at Olema and the bio is small and clinical, written in the third person, scrubbed of dramatics. The CEO of a single-drug biotech does not, it turns out, need to be loud about himself. The drug is loud enough.