Principal Scientist

Job title : Principal Scientist

• Location: Waltham, MA

About the Job

The Genomic Medicine Unit (GMU) CMC group at Sanofi is dedicated to the establishment of best-in-class manufacturing platforms to support development of life-changing advanced cell and gene therapy products, including recombinant AAV vectors, lentiviral vectors and cell therapy products. Sanofi is looking for an experienced cell culture development professional with experience in cell therapy process development to join the Genomic Medicine Cell Therapy Process Development Group located in Waltham, MA in the role of Senior Scientist. The Genomic Medicine Cell Therapy Development group within Sanofi operates with the mission to develop robust, scalable, and innovative cell culture processes for Sanofi’s genomic medicine pipeline.

This position is a senior individual contributor embedded within the Upstream Scale-Up Laboratory, responsible for execution of cell culture bioprocesses at pilot and manufacturing scales (200L–2000L). This role serves as a technical cornerstone of the scale-up team, driving process understanding, operational excellence, and cross-functional alignment with downstream Scale-Up Laboratory team and manufacturing organizations. While this position carries no direct people management responsibilities, the incumbent is expected to demonstrate strong technical leadership — guiding peers, influencing process strategy, and serving as a subject matter expert (SME) in upstream bioprocessing. The role operates at the intersection of process science, engineering rigor, and operational execution, requiring both hands-on laboratory proficiency and the strategic mindset to translate bench-scale learnings into robust, scalable processes.

Join the engine of Sanofi’s mission — where deep immunoscience meets bold, AI-powered research. In R&D, you’ll drive breakthroughs that could turn the impossible into possible for millions.

About Sanofi:

We’re an R&D-driven, AI-powered biopharma company committed to improving people’s lives and delivering compelling growth. Our deep understanding of the immune system – and innovative pipeline – enables us to invent medicines and vaccines that treat and protect millions of people around the world. Together, we chase the miracles of science to improve people’s lives.

Main responsibilities:

• Lead scale-up activities from bench scale to pilot scale (200L–2000L), applying engineering principles (mixing, mass transfer, shear stress, dissolved oxygen control) to ensure process comparability at large scale.

• Collaborate with process development scientists to translate laboratory findings into scalable, robust manufacturing processes.

• Review and approve JSAs written by equipment owners and provide feedback.

• Train employees to adopt best practice for safety, efficiency and operational success.

• Build robust internal interfaces with the CMC community and promote the adoption of best practices.

• Demonstrate expertise in upstream process operations at all scales.

• Lead root cause analysis (RCA) investigations for process deviations, equipment failures at pilot scale.

• Present findings and/or results to senior management, external stakeholders, and industry leaders at national/international conferences.

About You

• Master’s degree in Chemical Engineering, or related discipline with a minimum of 6 years of relevant experience to large-scale bioreactors, or a Ph.D degree with a minimum of 4 years of industry experience related to large-scale bioreactors.

• Strong background in cell culture bioreactor operations and scale-up technologies.

• Experience in the biotech/pharmaceutical industry within a cell culture role and an excellent understanding of the operational excellence.

• Experience with perfusion process operations at various scales.

• Understanding of engineering principles related to cell culture process is required.

• Ability to lead matrix teams for operations and lab management.

Preferred Qualifications:

• Experience managing cross-functional team and initiatives.

• Experience in cell culture process development for AAV manufacturing.

• Expertise in mammalian cell culture and related aspects such as cell metabolism/media optimization, engineering fundamentals on cell culture scale-up/down, cell biology/physiology.

• Process automation experience.

Why Choose Us

• Bring the miracles of science to life alongside a supportive, future-focused team.

• Discover endless opportunities to grow your talent and drive your career, whether it’s through a promotion or lateral move, at home or internationally.

• Enjoy a thoughtful, well-crafted rewards package that recognizes your contribution and amplifies your impact.

• Take good care of yourself and your family, with a wide range of health and wellbeing benefits including high-quality healthcare, prevention and wellness programs and at least 14 weeks’ gender-neutral parental leave.

• Be part of a pioneering biopharma company that engages patients early in drug development and uses their insights to design studies that reflect real-world needs.

• Help improve the lives of millions of people globally by making drug development quicker and more effective.

• Work at the forefront of drug discovery, harnessing cutting-edge AI, data, and digital platforms to push the boundaries of science.

Sanofi Inc. and its U.S. affiliates are Equal Opportunity and Affirmative Action employers committed to a culturally diverse workforce. All qualified applicants will receive consideration for employment without regard to race; color; creed; religion; national origin; age; ancestry; nationality; marital, domestic partnership or civil union status; sex, gender, gender identity or expression; affectional or sexual orientation; disability; veteran or military status or liability for military status; domestic violence victim status; atypical cellular or blood trait; genetic information (including the refusal to submit to genetic testing) or any other characteristic protected by law.

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Pursue progress , discover extraordinary

Better is out there. Better medications, better outcomes, better science. But progress doesn’t happen without people – people from different backgrounds, in different locations, doing different roles, all united by one thing: a desire to make miracles happen. So, let’s be those people.

At Sanofi, we provide equal opportunities to all regardless of race, colour, ancestry, religion, sex, national origin, sexual orientation, age, citizenship, marital status, ability or gender identity.

Watch our ALL IN video ( and check out our Diversity Equity and Inclusion actions at sanofi.com ( !

US and Puerto Rico Residents Only

Sanofi Inc. and its U.S. affiliates are Equal Opportunity and Affirmative Action employers committed to a culturally inclusive and diverse workforce. All qualified applicants will receive consideration for employment without regard to race; color; creed; religion; national origin; age; ancestry; nationality; natural or protective hairstyles; marital, domestic partnership or civil union status; sex, gender, gender identity or expression; affectional or sexual orientation; disability; veteran or military status or liability for military status; domestic violence victim status; atypical cellular or blood trait; genetic information (including the refusal to submit to genetic testing) or any other characteristic protected by law.

North America Applicants Only

The salary range for this position is:

$122.250,00 - $176.583,33

All compensation will be determined commensurate with demonstrated experience. Employees may be eligible to participate in Company employee benefit programs. Additional benefits information can be found through the LINK ( .

We are an R&D driven, AI-powered biopharma company committed to improving people’s lives and creating compelling growth. Our team is guided by one purpose: we chase the miracles of science to improve people’s lives.

We want to build a healthier, more resilient world, and turn the impossible into the possible by discovering, developing, and delivering medicines and vaccines for millions of people around the world.

Discover more about us visiting or via our movie We are Sanofi (

Start a career that makes a difference.

Reinvention is in our DNA. It’s what drove our evolution from a small French enterprise to one of the world’s leading biopharma companies. Whether it’s using AI to shorten drug-discovery times or building trust in healthcare, you could be helping our teams make life better for patients, partners, and communities.

This is where you grow your career. We open the door for you to explore new opportunities, push your limits, and connect with people who are driven by a shared purpose: we chase the miracles of science to improve people’s lives.