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Parallel Bio is building human-first drug discovery using organoids and AI to replace animal models. The company has achieved 87% concordance with clinical patient data versus 3% translational success for animal models, and is backed by AIX Ventures, Marc Benioff, Jeff Dean, and Y Combinator with ~$30M raised.
As Principal Scientist, you will lead the scientific team at the San Francisco site, managing scientists and research associates while remaining hands-on at the bench on the hardest problems. You will set experimental strategy, own scientific decisions on resource allocation, and establish high standards for experimental rigor, controls, documentation, and reproducibility.
Key responsibilities include:
**Scientific Leadership**: Lead and develop the scientific team, set platform direction and experimental strategy, run regular data reviews to distinguish biological from technical effects, establish standards for experimental design and decision-making, facilitate productive scientific disagreement, serve as scientific lead for external partner programs, and remain engaged in difficult experimental work.
**Assay and Process Development**: Build biological systems from concept to characterized, working assays. Own development and maturation of organoid and cell-based assays intended for platform execution. Translate early R&D assays into robust, repeatable, scalable processes. Develop characterization and optimization strategies. Identify critical parameters and their influence on outputs. Design experiments establishing operating ranges, robustness, and variability sources. Lead structured troubleshooting of complex failures.
**Technology Transfer and Platform Readiness**: Define frameworks for transferring assays from R&D through development to routine operations. Establish entry/exit criteria for maturation stages. Define objective acceptance criteria including controls, expected ranges, reproducibility requirements, and system suitability. Ensure transferred assays have sufficient documentation and reference data. Partner with Technical Operations for reproducible execution by trained operators. Lead comparability studies when assays or inputs change.
**Scale-Up and Robustness**: Develop strategies for scaling workflows from exploratory to high-throughput platform processes. Understand and reduce variability from operators, instruments, automation, reagents, donors, and environmental conditions. Establish appropriate process controls and monitoring. Partner with automation and software teams to translate manual workflows into automated, observable processes. Identify where additional automation or instrumentation will improve performance. Balance scientific rigor with throughput, cost, and complexity.
**Cross-Functional Platform Development**: Partner with R&D to ensure new assays are designed for scale and platform implementation. Work with Technical Operations, Platform Software, automation, hardware, and data teams to translate biological requirements into platform capabilities. Contribute to platform roadmap decisions. Support external pharmaceutical programs.
Success means creating a clear path from scientific concept through working model, demonstrated assay, characterized process, scalable workflow, to routine external execution. Teams will understand technology transfer criteria and required evidence. When experiments fail, you will have controls and reference data to determine why. New assays will move to platform faster through clear interfaces and expectations across teams.
**Requirements**:
- Ph.D. in Immunology, Cell Biology, Biology, Bioengineering, Biomedical Engineering, Molecular Biology, or related discipline
- Typically 10–15+ years of relevant experience developing complex biological assays, models, and platforms
- Demonstrated significant experience in several of: deep immunology expertise with complex human in vitro models, organoids, primary immune cells, or advanced mammalian cell culture; direct management of bench scientists including setting direction and developing scientific judgment; building biological systems 0-to-1 and adapting to automated platforms; building Process Development functions or technology-transfer frameworks in early-stage biotech; assay development, characterization, optimization, and technology transfer; identifying and controlling biological and technical variability; developing assays for automated or high-throughput environments; translating early-stage R&D methods into robust workflows; establishing controls, acceptance criteria, reference standards, or system-suitability approaches; leading technically complex investigations and troubleshooting
- Bonus: organoid development, immune-cell assays, advanced human cell models, or highly variable biological systems; scaling workflows onto automated platforms; Design of Experiments, process characterization, capability analysis, or Quality by Design; regulated, quality-controlled, or highly documented scientific environments; supporting pharma/biotech partners; partnering with robotics, automation, software, data science, or ML teams
