Principal Scientist/Associate Director, Molecular and Cellular Biology

Location: South San Francisco, CA / Flexible

TRexBio is a discovery stage biotechnology company leveraging cutting edge computational biology tools, a focus on human tissue, and expertise in immunobiology to develop revolutionary therapeutics for inflammatory diseases. Our powerful ‘deep biology’ discovery engine maps human tissue Treg behavior to disease processes, allowing us to identify and characterize novel targets for therapeutic intervention. Leveraging this platform, we are building a broad portfolio of novel therapies that modulate the immune system to restore human tissue immune homeostasis.

Our Culture:

At TRexBio, you will have the opportunity to work with amazingly smart humans who strive to make the world a better place. In addition to our team-centric culture, we believe that your individual creativity will help us to be our best. Our staff happy hours, organized by our Culture Club, bring us all together in creative and social activities. Our colleagues admire and respect one another.  We celebrate our wins, update company news and acknowledge each other’s achievement weekly and monthly at all company meetings that celebrate our work and our people.

Position Summary:

We are seeking a talented and highly-motivated scientist to join our Molecular and Cellular Biology group at TRexBio. This position offers an opportunity to work as part of a small, dynamic team to elucidate the biology of novel targets, design target specific screening and characterization assays in primary immune cells and cell lines to screen and rank novel immunomodulatory drugs. Leadership, teamwork, a can-do attitude, scientific integrity and transparency are key attributes for this position. The incumbent will take a lead on therapeutic programs, strategize on target specific in vitro assays, perform day-to-day laboratory benchwork, analyze and interpret data, and present project updates to multiple audiences. Responsibilities include validation of target biology, development of robust screening and characterization assays combined with the ability to collate data into summary figures to enable the project team to select lead candidates. Relevant techniques include primary immune cell-based assays, flow cytometry, proliferation, immunoassays, cytokine release on Luminex, as well as emerging technologies.


  • PhD in Cell Biology, Immunology or a related field
  • 8+ years of relevant biopharmaceutical industry experience, including experience developing cell based functional assays; at least 2 years in the area of large molecules/biologics in autoimmune, inflammation, and/or immuno-oncology disease areas. Job title will be commensurate with experience.
  • Extensive experience with in vitro cell-based techniques including isolation and culture of primary immune cell subsets, functional assays including co-culture, advanced flow cytometry (10+ colors), proliferation, cytotoxicity, cytokine release and ELISA techniques
  • May manage junior members of the team and lead project teams
  • Experience with FACSDiva, FlowJo, Prism, and Microsoft Office programs
  • Detail-oriented and analytical with excellent problem-solving skills
  • Proven ability to collaborate in a team-oriented environment
  • Diligent, strong growth mindset with a positive “can-do” attitude to advance programs
  • Good planning and organizational skills to meet deadlines
  • Excellent written and interpersonal communication skills

TRexBio offers a very competitive benefits including medical, dental, vision, short/long term disability, life insurance as well as 401(k) match, bonus and paid time leave.

TRexBio is proud to be an AA/EEO employer and all qualified candidates will receive consideration without regard to characteristics protected by applicable local, state, or federal law, such as race, color, sex, age, religion, national origin, physical or mental disability, pregnancy, marital status, veteran or military status, genetic information, or sexual orientation.

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