Scientist II - HSV1 Viral Vector Process Development

About Replay, now part of LEO Pharma

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.

Your Role

We are seeking a talented Scientist II to join our Process Development Replay team to develop and optimize downstream manufacturing processes for HSV‑1 gene therapy vectors.

You will take hands‑on responsibility for clarification, filtration, chromatography and tangential flow filtration (TFF), design and run experiments, analyse results quantitatively and make clear, actionable recommendations across CMC and cross‑functional teams. You will also support upstream process work as needed.

You will work within a focused Process Development team and collaborate cross functionally to support CMC activities, regulatory submissions and manufacturing readiness.

Reporting into the Principal Scientist, you’ll be an effective and confident technical contributor with visibility across development and manufacturing functions.

Key responsibilities will include:

• Developing and optimizing downstream purification for HSV‑1 vectors, including depth filtration, TFF and chromatography.


• Planning and executing TFF development studies: membrane screening, diafiltration optimization, fouling characterization and defining operating ranges.


• Evaluating and improving harvest clarification strategies with a focus on scalability and robustness.


• Operating, programming and troubleshooting ÄKTA chromatography systems and leading chromatography screening campaigns.


• Designing experiments, analysing data quantitatively (statistical and process evaluation) and presenting results and next steps.


• Supporting upstream process development activities as required.


• Drafting and reviewing technical reports, protocols, batch records and technology transfer documents.


• Executing process characterisation studies to support regulatory filings (IND/IMPD).


• Maintaining detailed laboratory notebooks, confidently presenting data in group meetings and contributing to technical strategy discussions.


• Maintaining laboratory equipment and consumables inventory and observing safety and housekeeping standards.

What success looks like:

• Robust, scalable downstream processes and characterization packages that support clinical manufacturing and regulatory submissions.


• Clear, reproducible experimental data and recommendations that move projects to next stage milestones.


• Effective collaboration with upstream, analytics, QA/Regulatory and Manufacturing partners to enable technology transfer and manufacturing readiness.

Your Qualifications

• BSc, MS or PhD in Chemical/Biochemical Engineering, Bioprocessing, Virology, Molecular Biology or a related discipline.


• 4+ years hands‑on experience in downstream process development for viral vectors or biologics, ideally including HSV‑1 or similar large DNA viral vectors.


• Demonstrated experience with TFF (membrane selection, diafiltration, fouling), depth/clarification filtration and column chromatography.


• Hands‑on experience operating and programming ÄKTA systems.


• Competent experimental design, data analysis and scientific communication skills.


• Experience supporting process characterisation and regulatory submissions preferred.


• Experience with scale‑up and tech‑transfer to GMP manufacturing (Desirable)


• Prior exposure to IND/IMPD filing support (Desirable)


• Familiarity with aseptic techniques and GMP expectations (Desirable)

If you’re ready to bring structure to complexity and make a measurable difference, we’d love to hear from you!

Compensation

The base salary range for this position is $115,000 - $150,000. The base salary range represents the anticipated low and high of the range for this position. Salary will vary based on several factors such as the candidates qualifications, skills, competencies and proficiency for the role. In addition, some positions may include eligibility to earn commissions/bonus based on company and/or individual performance.

Your Application

You do not need to upload a cover letter, but feel free to add a few sentences in your resume on why this position sparked your interest. Please refrain from including a photograph.

Beyond the skin

Become part of Replay and the LEO Pharma partnership, as we go beyond the skin to make a lasting impact. We are the legacy-builders of the future – enabling people to have a better today and tomorrow. Through collaboration and partnerships, we can do much more. 

For certain positions, you may be required to complete a background check conducted by a third party.

Join us and make an impact - Together, we reach far beyond the skin