Principal Scientist, In Vitro Pharmacology

Sirius Therapeutics, Inc.; San Diego (CA); On-site; USD 120,000 - 180,000; Full time

Job summary

Sirius Therapeutics, Inc. is seeking a Principal Scientist to lead in vitro pharmacology and ex vivo activities for siRNA drug discovery. You will design and execute molecular and cell‑based assays, interpret data, and collaborate across multidisciplinary teams to advance programs.

The role requires extensive hands‑on experience with ELISA, RT‑qPCR, WB, MSD, and flow cytometry, plus mentoring of junior team members in a fast‑paced environment.

Qualifications

• PhD in Pharmacology, Physiology, Biology, or related field with 5+ years in drug discovery.
• Hands‑on experience with ELISA, RT‑qPCR, cell lines, reporter assays, WB, MSD, and flow cytometry.
• Experience training and mentoring junior scientists; strong communication skills.

Responsibilities

• Lead in vitro pharmacology and ex vivo activities in collaboration with In Vivo Pharmacology, Chemistry, and PM teams.
• Develop, optimize, and implement molecular, biochemical, and cell‑based assays (RT‑qPCR, ELISA, WB, MSD, flow cytometry).
• Design and conduct in vitro/ex vivo experiments to assess siRNA activities and generate data for projects.
• Develop translational biomarker strategies and select preclinical models to understand MOA and de‑risk lead molecules.
• Present findings at lab meetings and project reviews; communicate data clearly.

Skills

In vitro pharmacology

RT-qPCR

ELISA

WB

Flow cytometry

Cell line generation

MSD

Mentoring

Education

PhD in Pharmacology or related field

MS with 8+ years experience in drug discovery

Tools

None

Job description

Department: Pharmacology

Reporting to: Senior Director, Pharmacology

About Sirius

Sirius is a clinical stage biotech company developing innovative siRNA therapies for global markets. We are dedicated to discovering and developing new treatment options for cardiovascular and cerebrovascular disease and translating siRNA technology into transformative medicine for the treatment of chronic diseases. Our most advanced products are SRSD107 for the treatment of thromboembolic disorders, SRSD216 for the treatment of hyperlipoproteinemia, and SRSD101 for the treatment of dyslipidemia.

Founded in 2021 by a world‑class leadership team and investors, Sirius is dual headquartered in San Diego, where discovery center is located, and Shanghai, where translational medicine and clinical operation center is based. Sirius has raised nearly US$150 million funding to date from top global VC funds such as OrbiMed and Creacion Ventures.

Summary of Position

We are seeking a highly motivated and experienced Principal Scientist to join the Pharmacology team to lead in vitro pharmacology and ex vivo activities for siRNA drug discovery and development programs. The candidate will lead in vitro and ex vivo efforts in collaboration with Chemistry and Project Management teams to support preclinical research programs. This role involves developing, optimizing and implementing molecular, biochemical and cell‑based assays, designing and executing in vitro and ex vivo experiments to assess the activities of siRNA molecules and generating data to advance pipeline and technology development projects. The ideal candidate is a highly motivated scientist with extensive hands‑on expertise in various in vitro and ex vivo assays, strong critical thinking and communication skills, and the ability to collaborate across multidisciplinary teams.

Responsibilities

• Lead in vitro pharmacology and ex vivo activities in collaboration with In Vivo Pharmacology, Chemistry and Project Management teams to support pipeline and technology development projects.
• Develop, optimize and implement molecular, biochemical, and cell‑based assays including RT-qPCR, ELISA, WB, cell line generation, reporter assays, MSD and flow cytometry.
• Design and conduct in vitro and ex vivo experiments to assess the activities of siRNA molecules. Analyze and interpret data to enable data‑driven decision making.
• Develop translational and biomarker strategies. Select and execute in vitro and ex vivo preclinical models to understand the MOA, de‑risk and optimize lead molecules in support of translational research.
• Present scientific findings and project updates at research and project team meetings
• Provide guidance and training to the junior members of the in vitro team
• Stay current with scientific literature and emerging technologies to enhance in house capability.
• Maintain accurate documentation of experimental protocols and results in lab notebooks to ensure data integrity.

Qualifications

• PhD in Pharmacology, Physiology, Biology, or a related scientific discipline with 5+ years of relevant experience in pharmaceutical or biotechnology drug discovery. Or Masters degree with 8+ years of relevant experience in pharmaceutical or biotechnology drug discovery.
• Extensive hands‑on experience in developing and validating various molecular, biochemical, and cell‑based assays, including but not limited to ELISA, RT-qPCR, cell line generation, reporter assay system, WB, MSD, and flow cytometry, is required. Strong ability in troubleshooting.
• Experience in training and managing junior members.
• Excellent verbal and written communication skills.
• Ability to work independently and in a fast‑paced, collaborative environment.