Principal Scientist, Toxicology & Pharmacology
Califesciences, Irvine, CA, United States
Position Overview
We are seeking a strategic and hands-on Principal Scientist in Toxicology & Pharmacology to contribute to strategy and execution of nonclinical safety and pharmacology for our next-generation targeted therapy technology based on pre-targeting enabled by click chemistry.
You will work together with chemistry, biology, and ADME/PK teams to design, lead, and interpret toxicology and pharmacology studies that contribute to therapeutic design, candidate selection, IND-enablement, and clinical strategy in a fast-paced startup environment.
Key Responsibilities
Nonclinical Safety Strategy
Contribute to and execute toxicology strategy for pre-targeted therapeutics, including IND-enabling studies
Design GLP and non-GLP toxicology studies
Identify, characterize, and mitigate safety risks
Establish safety margins and therapeutic index for candidate molecules
Pharmacology & Translational Science
Contribute to pharmacology strategy to demonstrate proof of mechanism and proof of concept
Design and interpret in vivo efficacy studies including model selection/characterization, study design, working with CROs to execute the study, and data analysis/presentation
Define exposure-response relationships
Collaborate on dose and schedule optimization
Cross-Functional Integration
Partner with ADME/PK to integrate pharmacokinetics, biodistribution, and exposure-response modeling
Work closely with chemistry and protein engineering teams to guide design toward safer and more effective molecules
Collaborate with CMC and analytical teams to ensure appropriate characterization of each therapeutic component
Support regulatory strategy, including authoring and reviewing IND sections (e.g., nonclinical overview, tox summaries)
Risk Assessment & Decision Making
Develop safety assessment frameworks tailored to our pre-targeting approach
Drive candidate selection by balancing efficacy, exposure, and safety
Present findings and recommendations to leadership, board members, and external partners
Required Qualifications
PhD, DVM, or equivalent in Toxicology, Pharmacology, or related discipline
4+ years of industry experience in nonclinical safety and/or pharmacology
Demonstrated experience leading IND-enabling toxicology programs
Strong background in small molecules, biologics, or targeted delivery systems (e.g., ADCs, radioconjugates, bispecifics)
Experience designing and interpreting in vivo toxicology and pharmacology studies
Familiarity with regulatory expectations (FDA/ICH) for nonclinical development
Preferred Qualifications
Experience with pre-targeting strategies
Familiarity with bioorthogonal click chemistry (e.g., tetrazine–TCO systems)
Background in oncology or other areas involving targeted therapies
Experience evaluating on-target vs. off-target toxicities in complex systems
Knowledge of safety considerations for reactive intermediates or payload-driven toxicity
Experience integrating PK/PD and tox data for translational modeling
Strong publication record and presentation skills
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We are seeking a strategic and hands-on Principal Scientist in Toxicology & Pharmacology to contribute to strategy and execution of nonclinical safety and pharmacology for our next-generation targeted therapy technology based on pre-targeting enabled by click chemistry.
You will work together with chemistry, biology, and ADME/PK teams to design, lead, and interpret toxicology and pharmacology studies that contribute to therapeutic design, candidate selection, IND-enablement, and clinical strategy in a fast-paced startup environment.
Key Responsibilities
Nonclinical Safety Strategy
Contribute to and execute toxicology strategy for pre-targeted therapeutics, including IND-enabling studies
Design GLP and non-GLP toxicology studies
Identify, characterize, and mitigate safety risks
Establish safety margins and therapeutic index for candidate molecules
Pharmacology & Translational Science
Contribute to pharmacology strategy to demonstrate proof of mechanism and proof of concept
Design and interpret in vivo efficacy studies including model selection/characterization, study design, working with CROs to execute the study, and data analysis/presentation
Define exposure-response relationships
Collaborate on dose and schedule optimization
Cross-Functional Integration
Partner with ADME/PK to integrate pharmacokinetics, biodistribution, and exposure-response modeling
Work closely with chemistry and protein engineering teams to guide design toward safer and more effective molecules
Collaborate with CMC and analytical teams to ensure appropriate characterization of each therapeutic component
Support regulatory strategy, including authoring and reviewing IND sections (e.g., nonclinical overview, tox summaries)
Risk Assessment & Decision Making
Develop safety assessment frameworks tailored to our pre-targeting approach
Drive candidate selection by balancing efficacy, exposure, and safety
Present findings and recommendations to leadership, board members, and external partners
Required Qualifications
PhD, DVM, or equivalent in Toxicology, Pharmacology, or related discipline
4+ years of industry experience in nonclinical safety and/or pharmacology
Demonstrated experience leading IND-enabling toxicology programs
Strong background in small molecules, biologics, or targeted delivery systems (e.g., ADCs, radioconjugates, bispecifics)
Experience designing and interpreting in vivo toxicology and pharmacology studies
Familiarity with regulatory expectations (FDA/ICH) for nonclinical development
Preferred Qualifications
Experience with pre-targeting strategies
Familiarity with bioorthogonal click chemistry (e.g., tetrazine–TCO systems)
Background in oncology or other areas involving targeted therapies
Experience evaluating on-target vs. off-target toxicities in complex systems
Knowledge of safety considerations for reactive intermediates or payload-driven toxicity
Experience integrating PK/PD and tox data for translational modeling
Strong publication record and presentation skills
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