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Principal Scientist/Associate Director, Medicinal Chemistry

Cambridge, MA

About Theseus

Theseus Pharmaceuticals is passionately committed to improving the lives of cancer patients by working to outsmart cancer resistance. Led by a team of targeted oncology pioneers with a proven track record developing and commercializing cancer therapeutics, we are developing the next generation of tyrosine kinase inhibitors (TKIs): “pan-variant” targeted therapies that address all known drug resistant mutations. We believe a pan-variant approach is the only way to address cancer resistance. Our lead program, THE-630, is a pan-variant KIT inhibitor for patients with advanced gastrointestinal stromal tumors (GIST), whose cancer has developed resistance to earlier lines of kinase inhibitor therapy. We are also developing a fourth-generation, selective epidermal growth factor receptor (EGFR) inhibitor to address C797S-mediated resistance to first- or later-line osimertinib treatment in patients with non-small cell lung cancer (NSCLC). For more information, visit theseusrx.com or follow the company on LinkedIn.

Role Description

We are seeking a Principal Scientist/Associate Director, Medicinal Chemistry to join our passionate team of scientists. The ideal candidate should be a highly motivated, experienced, and creative medicinal chemist with a proven track record of success in drug discovery from early Lead Generation through late-stage Lead Optimization. Candidates should be motivated to work in an intensely collaborative, multidisciplinary, team-based, and fast paced setting. This role will report to the Vice President of chemistry.


  • Lead an externalized medicinal chemistry team in the discovery of new development candidates to enrich Theseus’ oncology-focused pipelines
  • Manage outsourced chemistry resources, establishing and maintaining excellent working relationships with external providers. Creatively solve problems (synthetic routes, logistics etc.) to ensure delivery of compounds according to timelines.
  • Devise strategies to identify lead molecules and optimize them for potency, selectivity, and ADME properties using structure-based drug design approaches and multi-parameter SAR analysis
  • Work closely with computational chemistry, ADME, biology, pharmacology, and other key disciplines in a highly cross-functional environment
  • Ability to secure intellectual property while driving medicinal chemistry programs
  • Communicate project updates clearly and effectively to the broader team and key stakeholders


  • A Ph.D./Postdoc in organic chemistry with 8 or more years of experience in Pharma/bio-tech drug discovery
  • Experience in leading projects and driving programs through the preclinical development process to candidate selection
  • Experience in managing outsourced resources with evidence of solving complex challenges
  • Expert in modern synthetic organic chemistry approaches and principles demonstrated through publications in peer-reviewed journals and patents
  • Experience working with computational chemists as part of project team in design of drug targets is required
  • Experience with kinase inhibitor design a plus
  • Strong interpersonal, communication, time management, and leadership skills
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