Senior Scientist, Process Development

About the role

The Senior Scientist, Purification Process Development & Technology Transfer will provide scientific and technical leadership for the development, scale-up, characterization, technology transfer, and manufacturing implementation of biologics drug substance purification processes.

This role spans the purification process from harvest through bulk drug substance, including harvest clarification, chromatography, virus inactivation, virus filtration, ultrafiltration/diafiltration, formulation, and drug substance final filtration. The successful candidate will combine strong hands-on purification expertise with demonstrated experience transferring drug substance processes to internal manufacturing sites and external partners or contract development and manufacturing organizations and supporting GMP manufacturing execution.

Key Responsibilities

• Serve as the purification technical lead for assigned pivotal and commercial programs, providing scientific direction, identifying technical risks, and communicating recommendations, trade-offs, and mitigation strategies to project and functional teams.
• Lead drug substance technology-transfer workstreams to internal manufacturing sites and external partners or contract development and manufacturing organizations, including process scale-up, facility fit, manufacturing readiness, and transfer execution.
• Lead the development, optimization, scale-up, and characterization of robust, scalable, and manufacturable biologics purification processes.
• Provide hands-on technical leadership across harvest clarification, chromatography, virus inactivation, virus filtration, other filtration operations, ultrafiltration/diafiltration, formulation, and final filtration.
• Design, execute, and interpret process characterization and scale-down studies using appropriate scientific and statistical approaches, including Design of Experiments.
• Establish scientifically justified operating ranges and contribute to the development of integrated process control strategies.
• Develop project plans, coordinate technical activities, manage risks, and deliver purification work products in alignment with program objectives and timelines.
• Provide technical support during engineering, clinical, process performance qualification, and other GMP manufacturing campaigns, including on-site and person-in-plant support as needed.
• Lead or support troubleshooting, deviation investigations, root-cause assessments, and technical investigations related to process performance and GMP manufacturing.
• Author and review development reports, study protocols, process descriptions, technology-transfer documentation, standard operating procedures, manufacturing batch records, and CMC regulatory content.
• Collaborate across Process Development, Manufacturing and MSAT, Analytical Development, Formulation Development, Quality, Regulatory Affairs, Supply Chain, and other CMC functions.
• Mentor junior scientists and contribute to the advancement of purification technologies, platform processes, and organizational best practices.
• Travel as needed to support technology transfers and provide technical oversight at internal and external manufacturing facilities.

Basic Qualifications

• PhD in Chemical Engineering, Biochemical Engineering, Bioengineering, Biochemistry, or a related scientific discipline with 2 or more years of relevant experience;
• MS in a relevant scientific or engineering discipline with 6 or more years of relevant experience; or
• BS in a relevant scientific or engineering discipline with 8 or more years of relevant experience.

Preferred Qualifications

• Experience in biologics purification process development, characterization, scale-up, and GMP manufacturing implementation.
• Demonstrated experience leading drug substance technology transfers to internal manufacturing sites, external partners, or contract development and manufacturing organizations.
• Broad technical expertise in harvest clarification, chromatography, virus inactivation, virus filtration, ultrafiltration/diafiltration, formulation, and final filtration.
• Experience supporting engineering, clinical, process performance qualification, and commercial manufacturing campaigns, including batch-record review and on-site or person-in-plant support.
• Experience establishing and qualifying scale-down models and applying Design of Experiments and statistical analysis to define operating ranges and characterize process performance.
• Experience developing process control strategies and supporting process validation readiness.
• Experience authoring or contributing to CMC regulatory filings and responses to health authority questions.
• Demonstrated ability to identify and resolve complex technical risks using sound scientific judgment.
• Strong technical writing, communication, cross-functional collaboration, and project leadership skills.

Pay and benefits

The salary range for this position is: $169,320.00 - $219,120.00. Gilead considers a variety of factors when determining base compensation, including experience, qualifications, and geographic location. These considerations mean actual compensation will vary. This position may also be eligible for a discretionary annual bonus, discretionary stock-based long-term incentives (eligibility may vary based on role), paid time off, and a benefits package. Benefits include company-sponsored medical, dental, vision, and life insurance plans*.

For additional benefits information, visit

• Eligible employees may participate in benefit plans, subject to the terms and conditions of the applicable plans.

Your Rights Under the Family and Medical Leave Act

Gilead Sciences will not discharge or in any other manner discriminate against employees or applicants because they have inquired about, discussed, or disclosed their own pay or the pay of another employee or applicant.

However, employees who have access to the compensation information of other employees or applicants as a part of their essential job functions cannot disclose the pay of other employees or applicants to individuals who do not otherwise have access to compensation information, unless the disclosure is (a) in response to a formal complaint or charge, (b) in furtherance of an investigation, proceeding, hearing, or action, including an investigation conducted by the employer, (c) consistent with the legal duty to furnish information; or (d) otherwise protected by law.

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• Gilead provides a work environment free of harassment and prohibited conduct. We promote and support individual differences and diversity of thoughts and opinion.

For Current Gilead Employees and Contractors

Please apply via the Internal Career Opportunities portal in Workday.