Proven Intelligence Accelerating Next-Generation Therapies.

Executive Summary

The development and validation of reporter-gene assays are used to quantify the functional titer and transduction efficiency of lentiviral (LV) vectors. A robust, phase-appropriate potency assay is a required component of the analytics package for Investigational Medicinal Product Dossier (IMPD) submissions and overall product characterization. The approach detailed here is science-driven, covering cell line selection, assay optimization, and GxP-compliant validation to ensure data integrity for regulatory review in the EU and beyond.

Quantifying Lentiviral Vector Potency

Determining the biological activity of a lentiviral vector is more complex than simple physical particle counting. A functional assay is needed to confirm that the vector can successfully enter a target cell, integrate its genetic payload, and drive expression. A well-designed reporter-gene assay provides this quantitative measure of functional vector particles, which is a direct indicator of product potency.

Establishing a reproducible method to assess vector performance in relevant biological systems is a prerequisite for program advancement. Work with pseudotyped lentiviral vectors has shown that vector design directly impacts transduction efficiency and cellular toxicity in target human cells, such as insulin-secreting beta cells (PMID: 14975193). Selecting the correct analytical method directly de-risks a therapeutic program.

A Phase-Appropriate Reporter-Gene Assay Strategy

A standard, one-size-fits-all template for potency assays does not exist. Our approach is tailored to the specific LV vector, its intended clinical application, and the program’s developmental stage.

• Vector & Cell Line Selection: The process begins by matching the vector’s characteristics (e.g., pseudotyping envelope) with an appropriate, biologically relevant target cell line.

• Assay Optimization: Key parameters are systematically optimized, including cell density, multiplicity of infection (MOI), and incubation times to establish a reliable assay window with a robust signal-to-noise ratio.

• Qualification & Validation: Assays are qualified for research-grade use and can be formally validated under GxP conditions for later-stage clinical programs. This ensures the method is suitable for its intended purpose, whether for internal characterization or for regulatory submissions.

“We started collaborating with UPenn Vector core in 2023 and the AAV vector which they manufactured laid a foundation for development of a gene therapy candidate which will enter soon preclinical studies. The key people from UPenn Vector Core joined Franklin Biolabs and our partnership transitioned without interruption from UPenn Vecor Core to Franklin Biolabs Research Vector Division. Franklin Biolabs is an essential collaborator in our AAV-vector based gene therapy candidate development and we hope to continue the partnership for years to come.”
— Biotech Partner

Broader Implications for Viral Vector Characterization

The principles of functional characterization extend across different viral vector platforms. Experience in developing molecular clones and characterizing novel adenoviral vectors, for instance, informs a broader understanding of vector biology and production (PMID: 15144581). This deep technical background allows for accelerated characterization for rapid product validation.

Our teams operate within a >100,000 sq ft facility, providing the laboratory infrastructure to develop these complex analytical methods in parallel with other CMC activities. This integrated approach supports an 18-24 month timeline to get candidates to IND. While the Franklin Biolabs brand launched in 2024, our scientific leadership has maintained a 100% successful IND-enabling program rate since 2019.