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Scientist profiles M-R

SRI Profiles

Rossanna Pezo, MD, PhD, FRCPC

Affiliate scientist

Sunnybrook Health Sciences Centre
2075 Bayview Ave., T2 126
Toronto, ON
M4N 3M5

Phone: 416-480-4757
Fax: 416-480-6002

Administrative Assistant: Lorenda Williams
Phone: 416-480-4757


  • BA, 2000, molecular biophysics and biochemistry, Yale University, Connecticut, U.S.
  • MD/PhD, 2009, anatomy/structural biology and cell biology, Albert Einstein College of Medicine, New York, U.S.
  • FRCPC, 2013, internal medicine
  • Board certification, 2013, American Board of Internal Medicine, U.S.
  • FRCPC, 2015, medical oncology, Canada

Appointments and Affiliations:

  • Affiliate scientist, Biological Sciences, Odette Cancer Research Program, Sunnybrook Research Institute
  • Staff medical oncologist, Odette Cancer Centre, Sunnybrook Health Sciences Centre
  • Assistant professor, department of medicine, University of Toronto

Research Foci:

  • Immunotherapy
  • Microbiome
  • Targeted therapies

Research Summary:

A key focus of Dr. Pezo’s research is investigating the role of the gut microbiome in resistance to immunotherapy and targeted therapies. The intestinal microbiome plays a key role in modulating the host immune system and in the response to anti-cancer therapies. A better understanding of the interactions between gut bacteria and the immune system will lead to the development of novel strategies to combat therapeutic resistance.

Selected Publications:

See current publications list at PubMed:

  1. Pezo RC, Chen TW, Berman HK, Mulligan AM, Razak AA, Siu LL, Cescon DW, Amir E, Elser C, Warr DG, Sridhar SS, Yu C, Wang L, Stockley TL, Kamel-Reid S, Bedard PL. Impact factor of multi-gene mutational profiling on clinical trial outcomes in metastatic breast cancer. Breast Cancer Res Treat. 2018 Feb 1;168(1):159­–168.
  2. Bailey SD, Desai K, Kron KJ, Mazrooei P, Sinnott-Armstrong NA, Treloar AE, Dowar M, Thu KL, Cescon DW, Silvester J, Yang SY, Wu X, Pezo RC, Haibe-Kains B, Mak TW, Bedard PL, Pugh TJ, Sallari RC, Lupien M. Noncoding somatic and inherited risk-variants converge to promote ESR1 expression in breast cancer. Nature Genetics. 2016;48(10):1260–66.
  3. Belcheva A, Irrazabal T, Robertson SJ, Streutker C, Maughan H, Rubino S, Moriyama EH, Copeland JK, Surendra A, Kumar S, Green B, Geddes K, Pezo RC, Navarre WW, Milosevic M, Wilson BC, Girardin SE, Wolever TMS, Edelmann W, Guttman DS, Philpott DJ, Martin A. Gut microbial metabolism fuels colorectal cancer in Msh2-deficient hosts. Cell. 2014;158(2):288–99.