Principal Scientist - HSV‑1 Viral Vector Process Development

LEO Pharma • San Diego, CA

1d • $160,000 - $210,000

About The Position

Replay Holdings, Inc. ("Replay"), now part of LEO Pharma, is advancing the future of gene therapy for patients with rare disease. Originally built as a preclinical gene therapy company focused on HSV-based vectors for topical dermatology applications, Replay combines the agility of a small, high-impact team with the global reach and patient commitment of LEO Pharma. Together, we are building the CMC capabilities needed to advance our lead program from pre-clinical development through IND submission and GMP clinical manufacturing. Our platform leverages the large payload capacity of HSV vectors (up to 150 kb) to deliver complex therapeutic genes, with the goal of bringing meaningful new treatment options to patients with high unmet needs. As a Principal Scientist you will be empowered to build an entire Analytical Development and QC function, laying the foundations for robust GMP analytics, and playing a critical role in regulatory submissions, all within a fast-paced and highly collaborative environment. You will directly influence product quality, regulatory readiness, and operational success as we transition from early-stage development to clinical manufacturing. Reporting into the Vice President of CMC, you’ll be an effective and confident technical contributor with visibility across development and manufacturing functions.

Requirements

• Ph.D. in Biochemistry, Molecular Biology, Virology, Analytical Chemistry, or related field; or M.S. with 10+ years of directly relevant industry experience
• Progressive experience in analytical development for viral vector or gene therapy biologics programs
• Proven track record of qualifying and validating analytical methods for IND-enabling programs
• Demonstrated ability to build QC systems and release-testing frameworks - ideally in a small biotech where you established them from the ground up
• Experience authoring analytical sections of IND or CTA submissions for FDA or EMA
• Hands-on expertise with PCR-based (qPCR, ddPCR, RT-qPCR), cell-based (plaque assay, potency assays), and protein-based (ELISA, SDS-PAGE, western blot, SEC, DLS) analytical methods
• People management experience, with the ability to coach, mentor and develop others.
• PCR assay design and validation (qPCR, ddPCR, RT-qPCR)
• Cell-based potency and reporter assay development and standardization
• Protein analytics using ELISA, SDS-PAGE, western blot, SEC-HPLC, DLS
• Impurity and residuals testing, including host-cell DNA quantitation, endotoxin (LAL/rFC), and protein (micro-BCA)
• Management of release testing, stability programs, method lifecycle, and OOS/OOT investigations
• Regulatory writing: method validation to ICH Q2(R2)/Q14, IND/CTA authorship, and generating certificates of analysis
• Excellent communication skills to clearly convey complex technical information to diverse audiences.
• Advanced analytical thinking with data-driven decision making is a must, as is a proactive, collaborative approach to problem-solving.

Nice To Haves

• Direct experience with HSV vector analytical characterization and release testing is a major differentiator
• Familiarity with HSV-specific assay challenges (e.g., plaque assay variability, qPCR/ddPCR quantification for large genomes, HCP ELISA for novel producer lines, residual host-cell DNA sizing)
• Experience supporting analytical development for topical gene therapy products, including excipient compatibility testing and formulation-specific stability methods
• Experience supporting CDMO QC method transfer and providing on-site analytical oversight for viral vector programs
• Successful track record in small biotech/start-up environments, establishing new systems and frameworks

Responsibilities

• Leading development, qualification and validation of analytical methods for GMP release and characterization assays.
• Defining method suitability, system suitability, and acceptance criteria.
• Developing comparability protocols to support process changes, scale-up, and site transfers.
• Establishing analytical control strategies, including CQAs and specifications.
• Designing QC systems from scratch, including release panels for drug substance/product, process testing, and raw/excipient testing.
• Implementing stability programs across multiple storage conditions.
• Establishing reference standard programs, environmental monitoring, and equipment qualification plans.
• Authoring analytical sections for FDA & EMA IND/CTA submissions.
• Preparing method validation reports, analytical development reports, and method transfer protocols.
• Developing specifications and justification documents for regulatory filings.
• Leading analytical method transfers to CDMO laboratories, ensuring equivalence and integrity.
• Reviewing and approving CDMO QC data packages for lot release.
• Providing on-site analytical support during GMP campaigns.
• Mentoring junior scientists, fostering career development within AD/QC.
• Prioritising concurrent analytical workstreams across multiple CDMOs.
• Collaborating effectively with process development, formulation, and R&D teams.

Benefits

• The base salary range for this position is $160,000 - $210,000.
• In addition, some positions may include eligibility to earn commissions/bonus based on company and/or individual performance.

What This Job Offers

• Job Type: Full-time
• Career Level: Principal
• Education Level: Ph.D. or professional degree