Principal Scientist, Toxicology


Silverback Therapeutics, a Seattle-based biopharmaceutical company, is seeking a highly motivated individual to join our team and contribute to the discovery, preclinical and clinical development of innovative immune-modulating therapeutics.  This position is responsible for devising, implementing, and leading strategies to characterize the toxicologic properties of potential drug candidates, playing a critical role in advancing molecules through all stages of drug discovery and development.  The successful candidate will make key contributions to regulatory filings and in determining clinical dose levels for initial clinical trials, and will be comfortable working in a dynamic, fast-paced, and collaborative environment. This position is preferably based in Seattle, but flexible for the right candidate.


  • Serve as the Development Sciences/Toxicology Lead on multiple discovery and/or development teams, guiding characterization of safety properties of novel biologics to support decision-making and the advancement of preclinical programs and clinical drug candidates
  • Lead the design and conduct of exploratory, non-GLP, and GLP toxicology studies and the interpretation and reporting of results in the context of mechanisms of action or toxicity, dose- and exposure-response relationships, and the impact to predicted safety margins or therapeutic indices for putative drug candidates
  • Contribute to the design and conduct of related in vitro and in vivo studies (eg. pharmacology, pharmacokinetics) in collaboration with other team members, such as chemists, pharmacologists, bioanalytical scientists, and external contributors at contract research organizations
  • Independently formulate program toxicology strategy for and draft relevant sections of key documents supporting regulatory submissions (e.g. INDs)
  • Interpret, summarize and present data to internal project teams, senior management, and external partners/organizations


  • Ph.D. in toxicology or a related field and 10+ years of biotech/pharmaceutical drug discovery and development experience; Diplomate, American Board of Toxicology (or equivalent) preferred; title will be commensurate with experience
  • Regulatory experience supporting IND/CTA filings; experience in oncology drug development highly preferred and leading toxicology strategy for late-stage programs (e.g., pivotal trial design, NDA/MAA filings) a plus
  • Extensive experience and expertise devising toxicology strategy aligned with regulatory guidance and precedence, and in conducting toxicology studies for small molecule and biologics programs
  • Excellent critical thinking and scientific acumen, with a demonstrated ability to analyze, interpret, and clearly communicate (orally and in writing) complex toxicology study results and their impact to program and regulatory strategy

Silverback Therapeutics™ is a privately held biopharmaceutical company advancing a pipeline of therapies that are systemically delivered but locally active and target fundamental disease pathways. Silverback’s ImmunoTAC™ platform enables innovative therapeutic approaches to oncology, virology and fibrotic diseases. Silverback’s lead candidate, SBT6050, is comprised of a potent TLR8 agonist conjugated to a HER2-directed monoclonal antibody, designed for systemic delivery with tumor-localized activation of myeloid cells. Clinical investigation of SBT6050 is expected to begin in 2020. Silverback was founded in 2016. To learn more, visit We offer our employees competitive compensation and benefits, including paid time off, health insurance, life insurance, flexible spending accounts, a 401(k) plan, and stock options. Qualified candidates should forward their resumes to We are an equal opportunity employer.