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The Ellisen Lab

Professor of Medicine, Harvard Medical School

Program Director, Breast Medical Oncology

Investigator, Ludwig Center at Harvard

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 DNA repair. Through a detailed molecular understanding of these factors we seek to improve diagnosis, therapeutic prediction, and treatment efficacy. Our published work within the last five years has revealed fundamental new genetic mechanisms in HR+ breast cancer (Reinbay et al, Nature 2017; Matissek et al, Cancer Discovery 2018) and discovered a new and therapeutically relevant signature of homologous recombination deficiency (Polak et al, Nat Genet 2017). Our work on a DNA damage response pathway led directly to a national clinical trial for triple-negative breast cancer (TNBC) at 10 major cancer centers (Isakoff et al, J Clin Oncol 2015), and to the discovery of a new oncogene controlling the tumor epigenome (Saladi et al, Cancer Cell 2017). We were among the first to define the intra-tumoral heterogeneity of TNBC (Karaayvaz et al, Nature Comm, 2018), and recently discovered that DNA damage and altered signaling precede histologic abnormalities in noncancerous breast tissues of BRCA2 mutation carriers (Karaayvaz et al, Science Advances, 2020).


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.

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Sarah Mueller

Postdoctoral Fellow

I am originally from St. Louis, Missouri and received my undergraduate degree in Chemistry from Washington University in St. Louis. I completed my MD and PhD in Pharmacology and Cancer Biology at Duke University. I came to Massachusetts General Hospital for my residency in Clinical Pathology and fellowship in Molecular Genetic Pathology. My current research involves characterizing early changes in precancerous breast tissue from patients with defects in homologous repair pathways (e.g., BRCA1 mutations) with the goal of developing biomarkers that predict progression to cancer and identifying targets for cancer prevention in this population.

Siang Boon Koh

Postdoctoral Fellow
I am originally from Malaysia. I received my undergraduate degree from the Department of Pharmacy in National University of Singapore, and my graduate degree from the Cancer Research UK Cambridge Institute in Cambridge University. My major research interest is in studying tumor heterogeneity to identify therapeutically actionable cellular vulnerabilities.

Sheng Sun


I am originally from China. I received my undergraduate degree from Anhui Normal University in China, master’s degree from Beijing Normal University in China, and PhD degree from The University of Texas MD Anderson Cancer Center. My major research interests are exosome cargo loading and function, analysis of novel gene fusions identified in breast cancer, and the mechanisms of a novel antibody drug conjugate (IMMU132) in TNBC.

Shufeng Zhou

Postdoctoral Fellow
I am originally from China. I received my undergraduate degree from Sun Yat-Sen University of Medical Science in Guangzhou, China and my graduate degree from the McGill university department of surgery. My major research interest is to define the transcriptional factors that contribute to the pathogenesis of head and neck squamous cell carcinoma.

James Coates​

Research Fellow

I am originally from Vancouver, Canada and received my undergraduate in Chemical & Biomedical Engineering from McGill University. I completed both an MSc in Cancer Biology and a PhD in Cancer Drug Discovery at Oxford, focusing on identifying small molecules that can reverse tumour hypoxia. My current major research interests include the characterization of next-generation antibody-drug conjugates for precision oncology and exploiting artificial intelligence for drug discovery.

Nayana Thimmiah

Research Assistant
I am originally from Worcester, Massachusetts. I received my Bachelor of Science degrees in Biochemistry and Molecular Biology and Applied Mathematics from the University of Massachusetts Amherst. My current research interests involve genome wide CRISPR screening and mechanistic studies behind irregularly expressed proteins in TNBC cells. My future plans include furthering my education within the healthcare field to continue to help those in need.

Natalie Moffit

TNBC program coordinator
I am originally from Essex, Vermont. I received my undergraduate degree in Health Science from Boston University, and my Master of Public Health from the Boston University School of Public Health, focusing in biostatistics and epidemiology. I am interested in cancer prevention, improving cancer outcomes, and disparities in cancer care. I am particularly interested in triple negative breast cancer, and am the program coordinator for the MGH Triple Negative Breast Cancer Program.

Nsan Melkonjan

Research Assistant 

I am originally from Lithuania and Russian. I attended the University of Massachusetts Amherst where I received my undergraduate degrees in Microbiology and Public Health Sciences. My current research involves investigating novel therapeutic strategies for triple negative breast cancers. In the near future, I will be applying to medical schools to further my education.

Mark Gonzalez

Research Assistant

I am originally from San Juan, Puerto Rico. I received my bachelor’s degree in Pre-Med and Biology from the University of Puerto Rico- Mayaguez Campus. My major research interests involve the identification of transcriptional factors and regulation of immune evasion by chromatin remodeling in Head and Neck Squamous Cell Carcinoma (HNSCC). My future plans include applying for an MD/PhD where I can work and develop my skill set to innovate, bring solutions to diseases affecting our human population but more importantly, to find more efficient ways to improve the quality of life for patients all over the world and science itself.


Chanyce Kane

Laboratory administrator

I am originally from Revere Massachusetts. I graduated from Merrimack College where I received my bachelor’s degree in Biology with a concentration in cellular and molecular biotechnology and a minor in Business. In the future I hope to become a doctor or nurse to pursue my goal of helping people.

Nicole Smith

Laboratory Manager

Coming Soon…

Taisha Joseph

Bioinformatics Analyst

I am originally from Haiti. I received my Bachelor of Science degrees from Brandeis University in Neuroscience, Biology, and French & Francophone Studies with a minor in Chemistry. I am currently interested in investigating genetic patterns involved in intratumoral heterogeneity and treatment resistance in different types of breast cancers. I have been accepted into the University of Illinois College of Medicine in Chicago, and hope to become a physician-scientist in the future.


Assistant Professor, Harvard Medical School

Assistant Professor, Harvard Medical School

Associate Professor w/ Tenure, University of Nantes, France

Assistant Professor, Cleveland Clinic Genomic Medicine Institute

Associate Professor w/ Tenure, International Medical University, Malaysia
Associate Vice-President, Merck
Senior Scientist, Pfizer
Senior Scientist, Abbvie