Gregg Semenza

Gregg Semenza is the scientist who answered one of biology’s most fundamental questions: how do cells know when they are running out of oxygen, and what do they do about it? His discovery of hypoxia-inducible factor 1 — HIF-1 — cracked open a molecular mechanism so central to life that it governs everything from embryonic development to tumor growth, from red blood cell production to the progression of heart disease. For this work, Semenza shared the 2019 Nobel Prize in Physiology or Medicine with William Kaelin Jr. and Peter Ratcliffe, in recognition of discoveries the Nobel Committee called “one of the most important adaptive processes in life.”

Nobel Prize speaker Gregg Semenza is the C. Michael Armstrong Professor of Genetic Medicine at the Johns Hopkins University School of Medicine, where he has spent his career as the founding director of the Vascular Program at the Institute for Cell Engineering. Educated at Harvard, the University of Pennsylvania (MD-PhD), and Duke, he joined Johns Hopkins as a postdoctoral fellow and never left — building one of the most cited laboratories in the history of biomedical research. His work on HIF-1 has been cited more than 130,000 times and has shaped the research programs of laboratories on every continent.

The discovery itself began with a deceptively simple biological puzzle: why does the kidney produce more red blood cells when oxygen levels fall? Semenza traced the answer to a protein — HIF-1 — that acts as a master switch, binding to DNA and activating entire programs of gene expression whenever a cell detects hypoxia. Under normal oxygen conditions, HIF-1α is rapidly degraded. Under low oxygen, it stabilizes, accumulates, and orchestrates the cellular response: stimulating new blood vessel formation, switching metabolic pathways, and — critically — allowing cancer cells to survive and proliferate in the oxygen-poor cores of tumors. The implications of this single discovery span the entirety of modern medicine.

From Molecular Switch to the Medicine Cabinet

The translational impact of HIF biology is now reaching patients directly. HIF stabilizers and inhibitors are currently in clinical trials for the treatment of anemia and cancer, respectively. The drug roxadustat — a HIF stabilizer — has already been approved in multiple countries for the treatment of anemia in chronic kidney disease, offering patients an oral alternative to injectable erythropoietin. In oncology, researchers are studying how HIF inhibitors may be used to block cancer cells from surviving in low oxygen environments, and the Johns Hopkins Sidney Kimmel Comprehensive Cancer Center continues to advance this research. Semenza’s lab remains active, with ongoing investigations into HIF inhibition in combination with immunotherapy — work presented at the American Association for Cancer Research annual meeting as recently as 2025.

As a speaker, Gregg Semenza gives audiences something rare: the chance to hear a Nobel Prize winner explain, in vivid and accessible terms, how a lifetime of following a scientific question leads to a discovery that changes medicine. He speaks on the process of scientific inquiry as much as the discovery itself — on patience, on failure, on what it means to pursue understanding for its own sake and then watch it save lives. His talks resonate with audiences in healthcare, biotech, pharma, and beyond, and with any organization that values the connection between deep curiosity and transformative innovation.