Principal Scientist / Associate Director, Developability & Protein Sciences

Job description

About the Role We are looking for a Principal Scientist or Associate Director to lead developability and protein sciences for our bispecific and multispecific antibody programs, including T-cell engagers. You will own the biophysical and developability screening that informs lead selection, along with the expression and purification that supplies it, working in house and with external partners. You will manage and grow a small team of scientists and play a leading role on cross-functional therapeutic program teams. This is a hands-on, hybrid role based onsite in South San Francisco, with roughly half of your time at the bench alongside the team. You will turn developability data into program decisions and work with Antibody Engineering, Pharmacology, and program leadership to act on them. We expect the scope of the role to grow with the team and the pipeline. Key Responsibilities Developability & Biophysical Characterization Deliver developability and biophysical data for therapeutic programs as candidates advance from hit screening through lead optimization to development candidate nomination. Own the developability screening cascade, including thermal stability (e.g. DSF, DSC), aggregation (e.g. analytical SEC), self-association (e.g. AC-SINS, DLS), charge variants (e.g. IEX, cIEF), hydrophobicity (e.g. HIC), polyspecificity (e.g. BVP ELISA, PSR), and molecular integrity (e.g. intact mass, CE-SDS). Integrate in silico biophysical property assessment (e.g. sequence liabilities, surface patch analysis, aggregation propensity) with experimental data to prioritize and engineer candidates. Characterize advanced leads and development candidates in depth through stress and forced degradation studies, PTM mapping (e.g. peptide mapping LC-MS), and early formulation development. Help define and own the developability criteria at each program decision gate, and apply them consistently across programs. Expand the throughput, robustness, and technical scope of our protein analytics capabilities to support AI/ML-driven antibody engineering. Protein Expression & Purification Oversee research-stage protein production from 1 mL to 10 L scale, in house and through external partners, run as a service with clear intake, prioritization, turnaround, and quality acceptance of incoming material. Optimize transient production of multi-chain bispecific and multispecific assemblies (knob-into-hole heterodimers, VHH-containing trispecifics), including plasmid chain-ratio tuning to maximize correctly assembled product. Direct purification strategies that resolve bispecific product-related species from the correctly paired heterodimer, using Protein A capture with ion exchange, hydrophobic interaction, mixed-mode, and preparative size-exclusion polishing. Scale plate-based expression and purification, both in house and through external partners, to keep pace with screening throughput to support our AI/ML-driven antibody engineering platform. Deliver low-endotoxin, high-monomer material meeting in vivo dosing specifications for mouse pharmacology and non-GLP nonhuman primate (NHP) studies. Program Leadership & Cross-Functional Work Lead Protein Sciences work on cross-functional therapeutic program teams, bringing developability and manufacturability risk into design and advancement decisions and driving those decisions to closure. As the portfolio grows, have the opportunity to lead cross-functional program teams, aligning Antibody Engineering, Pharmacology, and Computational Biology around program goals, timelines, and gate decisions. Communicate data, risks, and recommendations clearly to program teams and leadership, and build alignment across functions on the decisions that follow. Team Leadership Manage, mentor, and develop scientists in protein purification and analytics, and set the day-to-day practices and priorities for the function. Build data capture, analysis, and automation into the team's workflows, working closely with team members who develop internal software and AI tools. Required Qualifications PhD in protein science, biochemistry, biophysics, chemical or biological engineering, or a related discipline with 5+ years (Principal Scientist) or 8+ years (Associate Director) of biopharmaceutical industry experience; or an MS with commensurate additional directly relevant experience. Hands-on experience with bispecific or multispecific antibodies (e.g. knob-into-hole, common light chain, VHH / single-domain fusions), including analysis of product-related species. Hands-on expertise with biophysical and developability methods, such as DSF or DSC, analytical SEC, IEX, HIC, CE-SDS, intact mass, self-association assays (e.g. AC-SINS), and polyspecificity assays (e.g. BVP ELISA, PSR). Developability triage experience in a research or discovery setting, translating biophysical data into candidate selection decisions. Experience with mammalian transient expression and multi-step antibody purification on FPLC systems (AKTA or equivalent), including Protein A capture and polishing by IEX, HIC, or mixed-mode chromatography. Experience serving as the protein sciences or developability expert on cross-functional therapeutic project teams, including developability data you presented that shaped a candidate selection or advancement decision. Demonstrated ability to lead cross-functional teams without direct authority, including setting priorities, running team meetings, and driving decisions to closure. Experience managing or mentoring scientists. Hands-on experience writing code to analyze data or automate lab workflows (e.g. Python or R), including with AI coding assistants such as Claude Code. Preferred Qualifications Experience leading or co-leading a cross-functional therapeutic program team, or serving as deputy to a program lead. Experience using in silico tools to predict antibody developability and biophysical properties. Experience with PTM characterization by peptide mapping LC-MS and with stress and forced degradation studies. Formulation development experience, particularly high-concentration (greater than 100 mg/mL) formulations for subcutaneous dosing. Experience with liquid-handling automation and high-throughput purification and characterization. Experience managing outsourced protein production or characterization. Knowledge of T-cell engaging antibody platforms and a background in oncology or immuno-oncology. Experience building data pipelines, analysis tools, or agentic workflows with AI coding tools. About Cartography Biosciences Cartography Biosciences is advancing a differentiated oncology pipeline of antibody-based therapies designed to target tumors with unprecedented precision. The company’s ATLAS and SUMMIT discovery platforms are powered by an industry-leading, fully integrated dataset spanning hundreds of thousands of cell states across healthy tissues alongside large-scale single-cell profiling of patient tumors. By combining petabyte-scale proprietary data, machine learning, and AI-driven biological insights, Cartography is identifying highly specific tumor targets and logic-gated target combinations to generate therapies engineered for maximal tumor selectivity and meaningful patient impact. The company’s lead program, CBI-1214, is a T-cell engager in development for colorectal cancer. CBI-1214 entered the clinic in early 2026 and is currently enrolling and treating patients in a phase 1 trial.