Dr. Leif Ellisen is Breast Cancer Program Director and a senior Investigator at the Massachusetts General Hospital (MGH) Cancer Center, and Professor of Medicine at Harvard Medical School. He is also co-Leader of the Breast Cancer Program at the Dana-Farber Harvard Cancer Center. He received his undergraduate degree from Harvard University, MD and PhD degrees from Stanford University, and completed residency training, oncology fellowship training, and postdoctoral research training at Brigham and Women’s Hospital, the Dana-Farber Cancer Institute, and MGH, respectively. The Ellisen laboratory’s research is focused on pathogenesis of breast and other cancers, with a particular focus on triple-negative breast cancer (TNBC), incorporating studies of tissue-specific development, transcription factor networks, and therapeutic response. We were among the first to define the intra-tumoral heterogeneity of TNBC (Karaayvaz et al, Nature Comms 2018); our work has revealed fundamental new genetic mechanisms in HR+ breast cancer (Rheinbay et al, Nature 2017; Matissek et al, Cancer Discovery 2018) and has elucidated a new oncogene controlling the tumor epigenome (Saladi et al, Cancer Cell 2017). We discovered that DNA damage and altered signaling precede histologic abnormalities in noncancerous breast tissues of BRCA2 mutation carriers (Karaayvaz et al, Science Advances 2020), and we applied our findings in a multi-center clinical trial that seeks to change the treatment paradigm for BRCA1/2-associated breast cancers (Spring et al, Nature Cancer 2022). Recent impactful work involves key studies to unravel the therapeutic mechanisms of antibody-drug conjugates that are revolutionizing breast cancer treatment (Coates et al, Cancer Discovery 2021; Bardia et al, Clinical Cancer Research 2024).

The Ellisen lab is uniquely positioned to work at the interface of basic tumor biology and therapeutic application. The lab’s work is strongly supported by a network of collaborators and by the extensive research and clinical infrastructure of the MGH Cancer Center and Harvard Medical School.