Sr Scientist/Principal Scientist, Discovery Oncology (in vivo Biology)

Job ID: R-109631Company: LillyLocation: San Francisco, California, United States of AmericaJob Type: Full TimeCategory: Research & DevelopmentPosted Date: 2026-08-04At Lilly, the work is demanding because patients are waiting. We unite caring with discovery to help make life better for people around the world, knowing that every decision, every detail, and every day matters. Headquartered in Indianapolis, Indiana, our over 50,000 employees around the globe take on complex challenges to discover and deliver life-changing medicines, strengthen how health is understood and managed, and support the communities we serve. This is hard, urgent, selfless work—but it’s work worth doing. If you’re driven by purpose and ready to bring your best to work that truly matters for patients, we invite you to join us. JOB DESCRIPTIONPosition: Senior/Principal Scientist, Discovery Oncology (in vivo Biology)Location: South San Francisco, CaliforniaOverview:At Lilly, we serve an extraordinary purpose. We make a difference for people around the globe by discovering, developing and delivering medicines that help them live longer, healthier, and more active lives. Not only do we deliver breakthrough medications, but you also can count on us to develop creative solutions to support communities through philanthropy and volunteerism. We give our best effort to our work, and we put people first. We're looking for people who are determined to make life better for people around the world.Position Summary:We are seeking a highly motivated and experienced scientist to join our in vivo team within Discovery Oncology. Working with a high degree of independence under the guidance of a senior scientific lead and/or director, the successful candidate will design, execute, and interpret in vivo (mouse and rat) studies — alongside supporting ex vivo and in vitro assays — to identify and validate novel druggable oncology targets, de-risk on-target toxicity liabilities, and advance targets from the pre-portfolio pipeline into the formal discovery portfolio.The ideal candidate is an experienced, hands-on in vivo scientist with a strong foundation in mouse study design and execution, well-organized and detail-oriented, able to work independently and troubleshoot with minimal oversight, and comfortable mentoring more junior colleagues while partnering cross-functionally to move programs forward with rigor and pace.Responsibilities:In this role, you willDesign, execute, and interpret in vivo studies (e.g., xenograft, syngeneic, and/or PDX models) in mice to evaluate tumor progression, target engagement, and efficacy in support of target identification and validation.Design, execute and interpret in vivo genetic or pharmacological perturbation studies, to decipher mechanism of action of novel oncology targets.Design and conduct in vivo studies to help de-risk on-target toxicity in early discovery programs.Harvest, process, and analyze tumor and tissue samples, including basic necropsy technique and coordination of histopathology as needed.Perform routine in vitro cell cultures (e.g., cancer cell lines, primary tissue culture).Perform routine biochemical and cellular assays (e.g., PCR, immunoblotting, ELISA…) to support and complement in vivo findings.Identify pitfalls and independently troubleshoot and resolve technical roadblocks.Oversee day-to-day mouse and rat colony management, including breeding strategy, genotyping, and compliance with IACUC protocols.Analyze data and present results to cross-functional project teams.Partner cross-functionally with in vitro biology, translational medicine, toxicology, and computational biology colleagues to advance shared project goals.Mentor junior scientists and research associates in in vivo techniques, study design, and best practices.Contribute to a safe, efficient, and compliant vivarium and laboratory environment.Basic Requirements:BS in biology, cancer biology, molecular biology, cell biology, biochemistry, or a related discipline with 3-5 years of academic, research, or industry lab-based experience; OR MS in a related discipline with 5-8 years of relevant lab-based experience. A Ph.D. is not considered for this role.Qualified applicants must be authorized to work in the United States on a full-time basis. Lilly will not provide support for or sponsor work authorization or visas for this role, including but not limited to F-1 CPT, F-1 OPT, F-1 STEM OPT, J-1, H-1B, TN, O-1, E-3, H-1B1, or L-1."Additional Preferences:Extensive, hands-on experience with in vivo mouse work; experience with rat models is a plus.Demonstrated experience with oncology tumor models (e.g., xenograft, syngeneic, GEMM, and/or PDX).Solid working knowledge of routine molecular and cellular biology techniques.Excellent organizational, documentation, and cross-functional collaboration skills.Excellent communication skills and a collaborative mindset.Candidates who possess the following skills could be well-suited for this role:Previous experience using gene editing (e.g. CRISPR RNPs) in cell lines.Familiarity with in vivo imaging modalities (e.g., bioluminescence, MRI).Experience with histology, IHC, and basic pathology interpretation.Physical Demands/Travel:The physical demands of this job are consistent with working in a vivarium and laboratory/bench environment, including some light lifting and maneuvering.The physical demands here are representative of those that must be met by an employee to successfully perform the essential functions of this job.Work Environment:This position's work environment is in a vivarium and laboratory/bench setting.The work environment characteristics described here are representative of those an employee encounters while performing the essential functions of this job.To perform this job successfully, an individual must be able to perform the role and responsibilities satisfactorily. The requirements listed above are representative of the knowledge, skill, and/or ability required. Reasonable accommodations may be made to enable individuals with disabilities to perform the essential functions.Additional Information:The appointed candidate will work on site in South San Francisco, California. Lilly is dedicated to helping individuals with disabilities to actively engage in the workforce, ensuring equal opportunities when vying for positions. If you require accommodation to submit a resume for a position at Lilly, please complete the accommodation request form ( for further assistance. Please note this is for individuals to request an accommodation as part of the application process and any other correspondence will not receive a response.Lilly is dedicated to helping individuals with disabilities to actively engage in the workforce, ensuring equal opportunities when vying for positions. If you require accommodation to submit a resume for a position at Lilly, please complete the accommodation request form () for further assistance. Please note this is for individuals to request an accommodation as part of the application process and any other correspondence will not receive a response.Lilly is proud to be an EEO Employer and does not discriminate on the basis of age, race, color, religion, gender identity, sex, gender expression, sexual orientation, genetic information, ancestry, national origin, protected veteran status, disability, or any other legally protected status.Our employee resource groups (ERGs) offer strong support networks for their members and are open to all employees. Our current groups include: Africa, Middle East, Central Asia (AMECA), Black Employees at Lilly (View email address on click.appcast.io), Chinese Culture Network (CCN), EnAble, Evolve, Lilly Indian Network (LIN), Organization of Latinx at Lilly (OLA), Pride (LGBTQ+ Allies), Veterans Leadership Network (VLN) and Women’s Initiative for Leading at Lilly (WILL).Actual compensation will depend on a candidate’s education, experience, skills, and geographic location. The anticipated wage for this position is$71,250 - $187,000Full-time equivalent employees also will be eligible for a company bonus (depending, in part, on company and individual performance). In addition, Lilly offers a comprehensive benefit program to eligible employees, including eligibility to participate in a company-sponsored 401(k); pension; vacation benefits; eligibility for medical, dental, vision and prescription drug benefits; flexible benefits (e.g., healthcare and/or dependent day care flexible spending accounts); life insurance and death benefits; certain time off and leave of absence benefits; and well-being benefits (e.g., employee assistance program, fitness benefits, and employee clubs and activities).Lilly reserves the right to amend, modify, or terminate its compensation and benefit programs in its sole discretion and Lilly’s compensation practices and guidelines will apply regarding the details of any promotion or transfer of Lilly employees.#WeAreLillySkillsin vivo mouse study designin vivo study executionin vivo genetic perturbationin vivo pharmacological perturbationtumor sample processinghistopathologyin vitro cell culturebiochemical assayscellular assayspcrimmunoblottingelisaxenograft modelssyngeneic modelspdx modelsgenotypingiacuc compliancedata analysismentoringcross-functional collaborationgene editingcrisprin vivo imagingbioluminescencemrihistologyimmunohistochemistrypathology interpretation