BIO
Michelle Pietzak, M.D.
Therapeutic Area Lead, Gastroenterology
Explore end-to-end solutions throughout development — from portfolio optimization and regulatory strategy, to Phase I-IV clinical trials, market access planning, and more.
Our team optimizes your portfolio utilizing integrated expert clinical, regulatory, and market access strategies, enabling earlier and more informed risk-reward decisions.
Our multi-disciplinary early phase approach accelerates the path to proof of concept by integrating diverse expertise to optimize study design, generate robust clinical evidence, and reduce gaps between development phases.
We deliver whole-study solutions with integrated strategies that ensure safety, data integrity, and regulatory compliance. We design patient-informed protocols that remove participation barriers, accelerate enrollment, and increase the likelihood of successful drug launches.
Our team of former regulators and HTA professionals provide tailored regulatory, compliance, and market access strategies across specialized therapeutic areas, creating customized pathways to maximize global market reach throughout your product's lifecycle.
We enhance your product's value story through post-approval studies and holistic lifecycle management services that satisfy regulators and payers while building stakeholder trust and maximizing your drug's market impact throughout its entire lifecycle.
We bring together experienced cross-functional experts to implement best practices, process simplifications, and technology standardization that accelerate timelines and improve quality.
Get the personal, responsive, and committed approach of a small CRO, with all the benefits of a large CRO, to help you develop life-changing treatments for patients.

Clinical Trialblazers
Step into the world of biotech leaders and hear the untold stories behind their journeys to bring breakthrough innovations to life.
Utilize our expertise across therapeutic areas, combining innovative trial designs, leading clinical and regulatory expertise, global reach, and a passion for changing patient lives.
Our team delivers high-quality clinical trials through forward-thinking medical expertise across multiple indications by combining strategic insight with operational excellence to support programs of all sizes.
Our infectious disease and vaccines cro services help treat and prevent life-threatening illnesses. Learn how our team of experts can aid in any complex trial.
Discover our inflammation and immunology CRO services. We bring agile support and a unique MOA-driven model to inflammation and immunology.
Parexel is a leading Oncology CRO with more than 80 ex-agency regulators and nearly 2,500 sites globally. Learn more about our oncology indications.
As a leading neuroscience CRO, we leverage global site relationships, specialized resources, and indication-specific expertise to accelerate breakthroughs in neurological and psychiatric treatments for patients worldwide.
Our experts help you stay at the forefront of the industry — and ahead of change.

Optimizing the clinical research workforce: An industry analysis by Parexel
At the heart of Parexel sits the world’s most unique insight-generation engine: our people.
Thinking about joining a clinical trial? Learn the drug development process, what it’s like to participate, how to find a trial, and answers to frequently asked questions.
Clinical trials provide patients with access to innovative investigational treatments that advance medical research. Participation requires careful consideration that weighs both the benefits and risks.

Patient Stories
Clinical study participation represents a deeply personal decision with potentially far-reaching impact, as evidenced by these inspiring individual stories that highlight both the life-changing potential for participants and the broader advancement of healthcare for all.
Want to collaborate with us to offer clinical trials at your site? We would welcome the opportunity to discuss.

Enabling successful sites
Our Enabling Successful Sites thought leadership series pairs site representatives with clinical operations experts to identify root causes of investigative site challenges and develop collaborative solutions.
We are one of the largest CROs in the world, speeding life-changing medicine to market by engaging patients With Heart™. Learn about who we are, what we do, and what we believe.
With decades of biopharmaceutical leadership experience and a deep dedication to patients, our executive team drives us forward in delivering better trials, faster.
Find key information on our policies, strategies, pay data, and more.
Explore end-to-end solutions throughout development — from portfolio optimization and regulatory strategy, to Phase I-IV clinical trials, market access planning, and more.
Our team optimizes your portfolio utilizing integrated expert clinical, regulatory, and market access strategies, enabling earlier and more informed risk-reward decisions.
Our multi-disciplinary early phase approach accelerates the path to proof of concept by integrating diverse expertise to optimize study design, generate robust clinical evidence, and reduce gaps between development phases.
We deliver whole-study solutions with integrated strategies that ensure safety, data integrity, and regulatory compliance. We design patient-informed protocols that remove participation barriers, accelerate enrollment, and increase the likelihood of successful drug launches.
Our team of former regulators and HTA professionals provide tailored regulatory, compliance, and market access strategies across specialized therapeutic areas, creating customized pathways to maximize global market reach throughout your product's lifecycle.
We enhance your product's value story through post-approval studies and holistic lifecycle management services that satisfy regulators and payers while building stakeholder trust and maximizing your drug's market impact throughout its entire lifecycle.
We bring together experienced cross-functional experts to implement best practices, process simplifications, and technology standardization that accelerate timelines and improve quality.
Get the personal, responsive, and committed approach of a small CRO, with all the benefits of a large CRO, to help you develop life-changing treatments for patients.

Clinical Trialblazers
Step into the world of biotech leaders and hear the untold stories behind their journeys to bring breakthrough innovations to life.
Utilize our expertise across therapeutic areas, combining innovative trial designs, leading clinical and regulatory expertise, global reach, and a passion for changing patient lives.
Our team delivers high-quality clinical trials through forward-thinking medical expertise across multiple indications by combining strategic insight with operational excellence to support programs of all sizes.
Our infectious disease and vaccines cro services help treat and prevent life-threatening illnesses. Learn how our team of experts can aid in any complex trial.
Discover our inflammation and immunology CRO services. We bring agile support and a unique MOA-driven model to inflammation and immunology.
Parexel is a leading Oncology CRO with more than 80 ex-agency regulators and nearly 2,500 sites globally. Learn more about our oncology indications.
As a leading neuroscience CRO, we leverage global site relationships, specialized resources, and indication-specific expertise to accelerate breakthroughs in neurological and psychiatric treatments for patients worldwide.
Our experts help you stay at the forefront of the industry — and ahead of change.

Optimizing the clinical research workforce: An industry analysis by Parexel
At the heart of Parexel sits the world’s most unique insight-generation engine: our people.
Thinking about joining a clinical trial? Learn the drug development process, what it’s like to participate, how to find a trial, and answers to frequently asked questions.
Clinical trials provide patients with access to innovative investigational treatments that advance medical research. Participation requires careful consideration that weighs both the benefits and risks.

Patient Stories
Clinical study participation represents a deeply personal decision with potentially far-reaching impact, as evidenced by these inspiring individual stories that highlight both the life-changing potential for participants and the broader advancement of healthcare for all.
Want to collaborate with us to offer clinical trials at your site? We would welcome the opportunity to discuss.

Enabling successful sites
Our Enabling Successful Sites thought leadership series pairs site representatives with clinical operations experts to identify root causes of investigative site challenges and develop collaborative solutions.
We are one of the largest CROs in the world, speeding life-changing medicine to market by engaging patients With Heart™. Learn about who we are, what we do, and what we believe.
With decades of biopharmaceutical leadership experience and a deep dedication to patients, our executive team drives us forward in delivering better trials, faster.
Find key information on our policies, strategies, pay data, and more.
Michelle is a board-certified gastroenterologist and pediatrician, with over 27 years of experience in treating complex intestinal, nutritional, liver and pancreatic diseases in both children and adults. She has almost 20 years of involvement with both global and local pharmaceutical companies and laboratories, contributing to drug design, clinical study development, data monitoring safety, FDA submissions and clinical/research laboratory regulation.
Work experience
Michelle joined Parexel in 2020 and brings medical leadership and expertise in gastroenterological, nutritional, hepatic and pancreatic diseases to clinical studies. Her main areas of expertise include pediatric nutrition, celiac disease, inflammatory bowel disease, non-alcoholic fatty liver disease, the intestinal microbiome and malabsorption.
Michelle served as an attending at the renowned Children’s Hospital Los Angeles (CHLA), At CHLA and USC, she successfully led many clinical areas, including as Chief of Pediatric Gastroenterology and Nutrition at USC, Co-Chair of the USC Keck School of Medicine GI-Liver System Core, Director of CHLA Nutrition Support Team and Chair of the CHLA Nutrition Advisory Committee. As GI representative for the CHLA Pharmacology and Therapeutics Committee and The Pharmacy Functional Project Team, she was successful in obtaining institutional approval for new drugs and devised and initiated pediatric patient databases for use in clinical research projects in the Division of Gastroenterology and Nutrition and CHLA.
Her past experiences in pancreatic diseases include collaborations with the Cystic Fibrosis Center at Children’s Hospital Los Angeles. Michelle also has experience in treating other conditions with exocrine pancreatic insufficiency, such as congenital malformations of the pancreas, Shwachman-Diamond syndrome, Johanson-Blizzard syndrome, chronic pancreatitis, acute necrotizing pancreatitis, hereditary pancreatitis (PRSS1, SPINK), celiac disease, Crohn disease, and Zollinger-Ellison syndrome.
Education
Michelle received her M.D. at the State University of New York at Buffalo School of Medicine and Biomedical Sciences. She completed her residency in pediatrics and fellowship in gastroenterology and nutrition at Children’s Hospital Los Angeles and the University of Southern California Keck School of Medicine (USC).