Antiviral MedChem Director & Discovery Leader (Hybrid)

Assembly-Biosciences,-Inc.; South San Francisco (CA); Hybrid; USD 220,000 - 234,000; Full time

Job summary

Assembly Biosciences, Inc. in South San Francisco, CA, seeks a Director of Medicinal Chemistry to co-lead a full-phase antiviral discovery program from lead optimization through candidate nomination. The role requires steering design, synthesis, testing, and analysis while collaborating across virology, DMPK, and computational teams.

You will contribute to multiple discovery projects, mentor CRO partners, and help shape strategy and data-driven decisions in a small, impactful team environment.

Qualifications

• PhD in synthetic organic or medicinal chemistry.
• Minimum of 8 years of drug discovery experience in the pharmaceutical or biotechnology industry.
• Demonstrated experience leading or co-leading a discovery program from hit-to-lead, lead optimization, to development candidate nomination.
• Demonstrated creativity in drug design and problem solving, including the ability to generate novel chemical matter and new approaches.
• Working knowledge of PK and PK/PD concepts and their application to compound design and candidate selection.
• Demonstrated ability to diagnose and solve DMPK issues in a lead optimization setting.
• Experience with structure-based drug design and the practical use of protein structures and computational tools in compound design.
• Demonstrated sound decision making, particularly with respect to advancing project goals under real-world data and resource constraints.
• Resourcefulness in acquiring the appropriate tools, data and expertise required for problem solving.
• Demonstrated success designing and directing synthetic chemistry executed by either domestic or / and international CRO partners.
• Excellent written and oral communication skills, including the ability to present and defend a scientific position to cross-functional colleagues and senior leadership.
• Strong interpersonal skills and a genuine orientation toward teamwork; able to contribute constructively to programs he/she does not lead and to operate with minimal supervision in a fast-paced, small-company environment.
• Knowledge and experience in antiviral drug discovery is desirable but not required

Responsibilities

• Co-leading a full-phase small molecule discovery program: own the MedChem strategy with a program co-lead, drive the design–synthesis–test–analysis cycle, and advance the program through lead optimization to development candidate nomination
• Designing new target molecules and chemical series to build structure-activity relationships, applying property-based and structure-based design in close partnership with computational chemistry and structural biology scientists
• Directing and rigorously managing external synthetic chemistry resources at CROs — setting chemistry priorities, reviewing and troubleshooting synthetic routes, safeguarding data quality and compound integrity, and delivering on timelines across multiple time zones
• Integrating virology, biochemistry, DMPK, and safety data into compound design; diagnose and resolve DMPK liabilities (metabolic stability, permeability, efflux and transporters, protein binding, CYP inhibition/induction and DDI risk) and apply PK/PD reasoning to define target exposures and dosing hypotheses
• Providing scientific input, design ideas, and constructive feedback to other discovery programs in various team settings
• Contributing to early-phase discovery, including target and hit triage, hit-to-lead progression, and evaluation of new chemical starting points and modalities
• Exercising sound, data-driven decision making on series progression, resource allocation and go/no-go calls, with a consistent bias toward advancing project goals
• Being resourceful in acquiring the right tools to solve problems — identifying and securing the computational, biophysical, structural, analytical or synthetic capabilities a program needs, internally or externally
• Actively participating in multidisciplinary teams, collaborating closely with virology, DMPK, computational chemistry, informatics, pharmacology, toxicology and CMC colleagues
• Presenting research updates and recommendations clearly to project teams, R&D leadership and external partners
• Reviewing patent literature and work with company patent attorney on invention disclosures, patent generation, and filings to build and defend a strong proprietary estate
• Mentoring and developing colleagues and CRO partner scientists, and contributing to a collegial, rigorous scientific culture
• Other duties as assigned

Education

PhD in synthetic organic or medicinal chemistry

Tools

Structure-based drug design

Job description

Assembly Biosciences, Inc. in South San Francisco, CA, seeks a Director of Medicinal Chemistry to co-lead a full-phase antiviral discovery program from lead optimization through candidate nomination. The role requires steering design, synthesis, testing, and analysis while collaborating across virology, DMPK, and computational teams.

You will contribute to multiple discovery projects, mentor CRO partners, and help shape strategy and data-driven decisions in a small, impactful team environment.