Harmonizing Gene Delivery: Global Standardization of Terminology and Quantification

Published

February 23, 2026

Author(s)

Edward Kwee, Jamie Almeida, Sheng Lin-Gibson

Abstract

Introduction Gene delivery systems, consisting of viral and non-viral vectors, are heterogeneous preparations with a variety of assays to describe identity, quantity, and potency. However, a significant lack of standardization in terminology and reporting units has led to industry-wide inconsistencies, such as the interchangeable and potentially inaccurate use of functional titers and physical capsid measurements. The Gene Delivery Systems standards series was established in ISO Technical Committee 276/Subcommittee 1/Working Group 1. This series aims to harmonize gene delivery system terminology and assay requirements, facilitating common terms for developers, manufacturers, and regulators. Methods The International Organization for Standardization (ISO) utilizes a voluntary, international consensus-building process. 17 countries with subject matter experts contributed to the drafting of 16921-1, 16921-2, and 16921-3. The development cycle for the projects included rigorous drafting phases, multi-national expert consultations, and iterative comment resolution periods to ensure broad industry alignment. Results ISO IS 16921-1:2026 Biotechnology - Gene Delivery Systems: Part 1 Vocabulary was initiated in March 2023 and released in January 2026. It defines terms related to gene transfer for mammalian systems, including the use of viral and non-viral gene delivery systems and via mechanical mechanisms. Definitions for analytical methods were also developed to harmonize the international vocabulary of metrology (VIM) and ICH Q2(R2). ISO 16921-2 Biotechnology - Gene Delivery Systems: Part 2 Quantification methods for viral vectors was initiated in March 2023 and passed international voting for Final Draft International Standard (FDIS) in January 2026. It provides minimum requirements for quantifying viral vectors in term of physical titer and functional titer. This included reporting and unit requirements for genome titer, capsid titer, and functional assays for viral vectors. ISO 16921-3 Biotechnology - Gene Delivery Systems: Part 3 Guide for Methods for the Quantification and Characterization of Lipid Nanoparticles was initiated in March 2025 and is under development in the ISO lifecycle. It provides requirements for quantifying and characterizing lipid nanoparticle (LNP) delivery systems containing nucleic acid. Conclusions Parts 1 and 2 of the series have been established to facilitate standardization of gene therapy characterization. The working group is actively seeking industry feedback to inform future revisions and ensure the standards are further developed alongside technological advancements. Part 3 is under active development and is seeking input from technical experts. The continued development and adoption of harmonized terminology and units will enable accelerated development, clinical translation, and regulatory approval of transformative gene therapies.

Proceedings Title

NIIMBL National Meeting 2026

Conference Dates

June 23-25, 2026

Conference Location

Washington DC, DC, US

Conference Title

NIIMBL National Meeting

Pub Type

Conferences

Citation

Kwee, E. , Almeida, J. and Lin-Gibson, S. (2026), Harmonizing Gene Delivery: Global Standardization of Terminology and Quantification, NIIMBL National Meeting 2026, Washington DC, DC, US (Accessed February 24, 2026)