Senior Principal Machine Learning Scientist

Build AI That Could Help Transform the Future of Medicine Frontier AI is changing what’s possible in science, and few places let you apply it to a problem as consequential as human health. Pfizer is one of them. We have decades of world-class biology and chemistry, rich biomedical data and the global reach to get medicines to patients. We are pairing them with the newest advances in AI and we are doing it along with the world’s leaders in building medicine. At Pfizer, we believe the next generation of scientific breakthroughs will be powered by advances in artificial intelligence. From foundation models and multimodal learning to biological reasoning and agentic systems, AI has the potential to fundamentally change how we discover, develop, and deliver medicines to patients. As a Senior Principal Machine Learning Scientist, you will help create the scientific foundations behind that future at Pfizer. We are not looking for one clever model for one clever problem or applying existing models to a single problem. You will develop, extend, and rigorously evaluate advanced AI methods that generate new scientific insights, accelerate experimentation, and enable better decision-making across the drug discovery and development lifecycle. We are building AI that compounds. A method, benchmark or model that works in one disease area should become a foundation that can impact across oncology, immunology/inflammation, internal medicine, vaccines and beyond. You’ll design for that! Working alongside world-class AI researchers, computational biologists, engineers, and domain experts, you'll tackle some of the most challenging and meaningful problems in healthcare while building technology that has the potential to impact millions of patients worldwide.

Why This Role Is Different

Own Meaningful Scientific Challenges: You will own defined model components, benchmarks, evaluation frameworks, and research workflows that directly influence how AI is applied across Pfizer's R&D organization. You'll build the models, and you'll also decide whether they create real scientific value and whether that value holds up in new contexts. Where you will push the frontier: You'll contribute to cutting-edge research across areas such as:

• Foundation models and representation learning.
• Multimodal learning across molecular, imaging, clinical and omics data
• Agentic AI and scientific reasoning systems
• Biological Sequence & Structure Modeling
• Graph learning and knowledge graphs
• Clinical & Real-World Data Modeling
• Uncertainty-Aware AI, causal ML and Interpretability

Create Impact Beyond Research Papers Publishing matters, but the goal is bigger. Your work will help scientists understand disease biology, prioritize experiments, and evaluate therapeutic opportunities across the portfolio. It will speed up medicines for the people waiting on them. Work at the frontier, with the people who can ship it to patients. You'll collaborate with AI researchers, computational biologists, engineers, and clinical and domain experts. Together you'll push state-of-the-art methods into real discovery programs, where the data is proprietary and the stakes are real. Help invent how science gets done We're building an AI-native operating model. Small, highly capable teams combine deep human expertise with AI agents and intelligent systems to move at a pace that once took far larger organizations. You'll help define it, prove it, and show others across R&D how to work this way. Every problem you solve should make the next one faster. You'll ask what generalizes, what's reusable, and what can run across programs. You'll build for transfer across diseases, modalities, data types, and teams.

The Opportunity

As a Senior Principal Machine Learning Scientist, you will develop and advance machine learning methods that learn from and reason across complex biomedical, clinical, molecular, and scientific data. What You'll Do Develop Frontier AI Methods for Biomedical Research. Create, adapt, and improve foundation models, multimodal and graph-based approaches, generative methods, and agentic reasoning systems. Go where conventional approaches fall short, and test whether what works in one therapeutic area works in the next. Design and Execute Rigorous Experiments. Form clear hypotheses and design controlled, reproducible experiments. Compare competing approaches and find where they succeed, fail, or need rework. Let evidence drive decisions. Set the Evaluation Standard At Scale. Design the datasets, benchmarks, and validation strategies that show whether a model can be trusted. Measure robustness, calibration, temporal and cohort generalization, cross-therapeutic transfer, reasoning ability, interpretability, and failure modes. Look past accuracy to real scientific utility.

• Translate models into scientific evidence. Work with AI engineers, computational biologists, and domain experts to test hypotheses and interpret results, uncertainty, and limitations with transparency. Help promising research become trusted capabilities deployed across many programs.
• Build the shared foundation. Develop reusable methods, benchmarks, model components, and workflows, and work with engineering to run them on common infrastructure. Document, validate, and package them so any team can apply the framework to a new disease area without starting over.
• Raise the scientific bar. Contribute to scientific reviews and research planning. Mentor and learn from colleagues, and help raise AI fluency across R&D.

What You Bring Education & research excellence

• A PhD and 2+ years of experience in Machine Learning, Artificial Intelligence, Computer Science, Statistics, Applied Mathematics, Computational Biology, or a related quantitative field preferred
• A Master's degree with 5+ years of relevant industry or research experience

Proven Scientific Impact You have demonstrated experience:

• Developing, extending, or evaluating machine learning methodologies on hard, ambiguous, high value problems
• Designing rigorous experiments and hypothesis-driven investigations
• Building and comparing models using reproducible scientific approaches
• Identifying limitations, biases, uncertainty, and failure modes
• Translating research insights into meaningful outcomes and recommendations
• Owning a research area, benchmark, model component, or scientific capability from concept through delivery

We are looking for scientists who have moved beyond experimentation alone and can demonstrate measurable contributions to scientific progress, product capabilities, or business impact. Technical & Research Proficiency

• Strong Python and PyTorch, JAX or an equivalent framework
• Model development, optimization, debugging and evaluation methodologies
• Experimental design, statistical analysis and reproducible research practice
• Familiarity with scalable ML workflows, such as distributed training, experiment tracking, and shared evaluation pipelines
• Depth in one or more of: multimodal learning, foundation models, GNNs, generative AI, agentic systems, biological sequence or structure modeling, knowledge graphs, clinical AI, omics and biomedical data, scientific ML

Publications, patents, open-source contributions, deployed research, or other evidence of scientific impact are valued as indicators of expertise and execution. How you work Intellectual curiosity, sharp analytical reasoning, comfort with ambiguity, a habit of challenging assumptions (including your own), and the ability to influence through credibility and execution. Nice to have

• Experience applying AI in life sciences, biotechnology, healthcare, pharmaceuticals, or biomedical research
• Experience with biological, molecular, imaging, clinical, or real-world health data
• Experience building foundation models or multimodal learning systems for scientific applications
• Experience evaluating and implementing responsible AI methodologies
• Experience working across multidisciplinary scientific organizations

What Success Looks Like You take ownership of important scientific questions and design experiments with rigor and purpose. You build things other teams pick up and use. A framework you create in one therapeutic area shows up in the next, and the one after that. You balance innovation with evidence, learn fast from failure, and influence people with data. You make the science around you better, and you stay focused on impact for patients.

Why Pfizer

At Pfizer, AI is becoming a foundational capability that helps power scientific discovery and accelerate the development of medicines and vaccines. You'll have the opportunity to work with exceptional colleagues, unique scientific challenges, and rich biomedical data while helping shape the future of AI-enabled research. Here, you'll find: ✅ Meaningful ownership and scientific autonomy ✅ Challenging, high-impact research problems backed by rich biomedical data ✅ A chance to work with world leaders in medicine and scientific collaborators ✅ Fastest path to growing your technical and scientific influence ✅ The opportunity to build AI that improves patient outcomes worldwide If you want your most ambitious AI work to reach many diseases and many patients, come build it with us. Work Location Assignment Hybrid: Colleagues must live within commuting distance of a Pfizer location and work on-site an average of 2.5 days per week. The annual base salary for this position ranges from $139,100.00 to $231,900.00. In addition, this position is eligible for participation in Pfizer’s Global Performance Plan with a bonus target of 17.5% of the base salary and eligibility to participate in our share based long term incentive program. We offer comprehensive and generous benefits and programs to help our colleagues lead healthy lives and to support each of life’s moments. Benefits offered include a 401(k) plan with Pfizer Matching Contributions and an additional Pfizer Retirement Savings Contribution, paid vacation, holiday and personal days, paid caregiver/parental and medical leave, and health benefits to include medical, prescription drug, dental and vision coverage. Learn more at Pfizer Candidate Site – U.S. Benefits | (uscandidates.mypfizerbenefits.com). Pfizer compensation structures and benefit packages are aligned based on the location of hire. The United States salary range provided does not apply to Tampa, FL or any location outside of the United States. This role is posted in multiple locations. If you are applying for the role in an secondary job posting location where pay transparency regulations apply, your Talent Advisor will share the local pay information with you during the first interview. Relocation assistance may be available based on business needs and/or eligibility. Candidates must be authorized to be employed in the U.S. by any employer. U.S. work visa sponsorship (such as TN, O-1, H-1B, etc.) is not available for this role now or in the future. Sunshine Act Pfizer reports payments and other transfers of value to health care providers as required by federal and state transparency laws and implementing regulations. These laws and regulations require Pfizer to provide government agencies with information such as a health care provider’s name, address and the type of payments or other value received, generally for public disclosure. Subject to further legal review and statutory or regulatory clarification, which Pfizer intends to pursue, reimbursement of recruiting expenses for licensed physicians may constitute a reportable transfer of value under the federal transparency law commonly known as the Sunshine Act. Therefore, if you are a licensed physician who incurs recruiting expenses as a result of interviewing with Pfizer that we pay or reimburse, your name, address and the amount of payments made currently will be reported to the government. If you have questions regarding this matter, please do not hesitate to contact your Talent Acquisition representative. EEO & Employment Eligibility Pfizer is committed to equal opportunity in the terms and conditions of employment for all employees and job applicants without regard to race, color, religion, sex, sexual orientation, age, gender identity or gender expression, national origin, disability or veteran status. Pfizer also complies with all applicable national, state and local laws governing nondiscrimination in employment as well as work authorization and employment eligibility verification requirements of the Immigration and Nationality Act and IRCA. Pfizer is an E-Verify employer. This position requires permanent work authorization in the United States. Pfizer endeavors to make [ accessible to all users. If you would like to contact us regarding the accessibility of our website or need assistance completing the application process and/or interviewing, please email [View email address on joinrs.com](View email address on joinrs.com). This is to be used solely for accommodation requests with respect to the accessibility of our website, online application process and/or interviewing. Requests for any other reason will not be returned. To learn more about acceptable and prohibited uses of AI during the recruitment process, please review our candidate AI-use guidelines available on [Pfizer Careers]( Information & Business Tech