Principal Scientist (Cell Line Development
Listed on 2026-08-05
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Research/Development
Biotech Research, Research Scientist
About Exelixis
Every Exelixis employee is united in an ambitious cause: to launch innovative medicines that give patients and their families hope for the future. Our 25 years in the biotech sector have established a proven track record of resilience, guided by our commercial success and commitment to research in drug discovery, clinical development, and commercialization. We are expanding our global partnerships and investing in R&D to discover breakthroughs for difficult‑to‑treat cancers.
Cancer is our cause. Make it yours, too.
As a member of the Biotherapeutics group, the incumbent will support discovery and preclinical development by leveraging skills in recombinant antibody and bispecific antibody production and purification/characterization. The role focuses on delivering high‑performing, high‑quality mammalian cell lines that enable early‑phase biologics manufacturing for potential therapeutic candidates or ADCs. Duties include designing and testing vector constructs, engineering host cells, and conducting transfection, selection, and clone generation campaigns in CHO cells, with a deep theoretical understanding of recombinant protein expression to guide improvement of titer in stable cell lines.
Key Responsibilities- Design and execute experiments to develop CHO‑based cell lines for biologic therapeutics progressing into clinical development.
- Design complex experimental approaches to improve expression systems and workflows through innovation and new technology.
- Perform therapeutic CHO cell line development processes, including transfection, single‑cell cloning, imaging analysis to document monoclonality, clone screening and progression, characterization, and cell banking and stability assessment of cell banks using state‑of‑the‑art equipment.
- Develop improved expression vectors and genetic components, host cell line engineering, and/or cell line development process optimization.
- Identify emerging practices for biologics therapeutic cell line development and manufacturing to shape scientific strategies and continue innovation.
- Represent the cell line development team on cross‑functional projects, making decisions for cell line activities and effectively communicating results, progress, and plans.
- Comply with company health and safety policies and general laboratory practices.
No supervisory responsibilities. Individual contributor role.
Education, Experience and Knowledge- PhD in molecular biology, biochemistry, biology, or microbiology AND a minimum of five (5) years of experience in the biotechnology/pharmaceutical industry – OR
- Master’s degree in the same disciplines AND a minimum of nine (9) years of experience – OR
- Bachelor’s degree in the same disciplines AND a minimum of eleven (11) years of experience.
Candidate must be a highly skilled, hands‑on, detail‑oriented professional able to contribute with minimal onboarding.
Required Technical Skills- Proficient in molecular biology, vector construction, and genetic elements influencing recombinant antibody/bispecific expression.
- Experience with stable CHO expression platforms, able to articulate pros and cons and recommend suitable platforms for manufacturing cell lines.
- Well versed in transfection methodologies, screening, and selection workflows.
- Deep understanding of regulatory requirements for demonstrating monoclonality.
- Experience culturing CHO cells in shake flasks, spin tubes, deep‑well plate fed‑batch processes, and optionally AM fed‑batch processes.
- Experience in single‑cell cloning and imaging technologies to prove monoclonality.
- Experience running titer determination and standard downstream product quality assessments.
- Authoring and reviewing cell line development reports, summaries and presentations.
- Experience in analytical techniques such as HPLC, LC/MS, and/or CE is a plus.
- Familiarity with automation platforms and data analysis tools is a plus.
- Excellent communication, organization, and documentation skills.
- Ability to design and execute activities aimed at producing and characterizing recombinant antibodies and bispecifics, interpret experimental data, and formulate conclusions and next‑steps.
- Prior experience…
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