Principal Scientist, LNP Discovery Biology

Merck•Billerica, MA

19h

About The Position

The Principal Scientist, LNP Discovery Biology is a hands-on scientific and cross-functional role developing assays for the in vivo CAR-T program within the Research Unit Neuroscience & Immunology (N&I). The role sits at the interface of LNP delivery and immunology and works closely with formulation/CMC, protein engineering, and analytical teams to advance a differentiated targeted delivery platform. As a core project team member, the scientist represents LNP biology alongside pharmacology, CMC, formulation, analytical, regulatory, program management, and external partners and CROs across sites and time zones. The scientist designs, executes, and leads in vitro and ex vivo studies; helps design in vivo studies in humanized mouse models and non-human primates; runs and interprets multicolor flow cytometry; assesses tolerability; and supports candidate selection through data-driven Go/No-Go recommendations. The role also develops benchmark comparisons, presents findings to internal and external stakeholders, and mentors junior scientists as the LNP Discovery Biology group grows.

Requirements

PhD in immunology, cell biology, molecular biology, or a related field.
At least 6 years of post-PhD experience in biotech or pharma.
Deep T cell immunology background, including CAR biology, pharmacology, and in vitro studies.
Experience with in vivo CAR-T programs using targeted LNP.
Demonstrated ownership of in vivo study design in humanized mouse models and direct experience designing or interpreting NHP studies.
Strong practical command of multicolor flow cytometry, including panel design, compensation, gating strategy, and assay failure modes.
Track record of taking a program through candidate selection or IND-enabling work.
Demonstrated success working cross-functionally on a matrixed or global project team with colleagues and partners across functions, sites, and time zones.
Clear written and verbal communication skills; ability to present regularly to leadership, partners, and advisors and influence without formal authority.

Nice To Haves

Hands-on familiarity with LNP delivery, including mRNA cargo, in vitro pharmacology, biodistribution, and how formulation choices affect in vivo results.
Experience developing and qualifying novel in vivo and ex vivo assays and transferring them to other scientists or CROs.
Prior work on B cell depletion, autoimmune disorders, or CD19/CD20-directed therapies.
Experience designing NHP and in vivo studies in support of drug candidate selection.
Experience in IND-enabling research and GLP study oversight, including regulatory interactions such as pre-IND or IND.
Biotech start-up experience or experience building a platform capability from the ground up.
Demonstrated knowledge of Immunology & Inflammation biology as it relates to targeted delivery therapeutic strategies.
Comfort working in a fast-moving, partner-facing environment where data and slides may be due the same week.

Responsibilities

Design, execute, and lead in vitro and ex vivo studies supporting the targeted LNP delivery platform.
Help design in vivo studies in PBMC- and huCD34+-engrafted NSG humanized mouse models and non-human primates, including group structure, dose levels, dosing schedules, bleed cadence, and endpoint panels.
Run and interpret multicolor flow cytometry readouts for CAR expression, reporter signal, target cell depletion, T cell activation, and engraftment; establish team analysis standards.
Partner with formulation, lipid chemistry, and targeting-ligand teams to translate in vitro conjugation and potency data into in vivo study designs that distinguish candidates.
Interpret tolerability data, including cytokines, liver enzymes, hematology, coagulation, and complement, and drive Go/No-Go recommendations for candidate selection.
Build and defend head-to-head comparisons against commercial benchmarks and published competitor data, accounting for caveats such as pretreatment status, dosing regimen, and assay scaling.
Represent in vivo CAR-T biology on the project team, bring study plans and data to cross-functional reviews, and align timelines with CMC, formulation, analytical, regulatory, and program management teams.
Write and present data to internal leadership, partners, advisors, and, as programs mature, regulators.
Mentor junior scientists and contribute to growing the LNP Discovery Biology group.