U.S. Pharmacopeia (USP), the independent organization that helps develop quality standards for pharmaceuticals, has launched new standards for viral vectors that they hope will help the rapidly developing field of cell and gene therapy.
The newest standards, which are due to be discussed during a session at Bioprocessing Summit Europe in March, aim to support manufacturers and regulators in maintaining the quality and consistency of advanced therapies.
“The field is moving very fast with lots of innovation, more therapies, and new companies jumping into the space,” explains Diane McCarthy, PhD, vice president of biologics at USP.
“There’s a need for standards to aid with consensus building and the development of best practice,” McCarthy adds.
According to McCarthy, among the biggest challenges in cell and gene therapy is the complexity of the entire biomanufacturing process. Even raw materials, such as plasmid DNA, can be complex with huge variability in quality.
For this reason, USP assembled a panel of industry experts to come up with a consensus for best practices for plasmid DNA as a starting material. This information has been published and will become official in February 2026.
Within adeno-associated virus (AAV) manufacturing, meanwhile, one of the most challenging aspects, McCarthy explains, is how to analyze the number of viral vectors containing the gene of interest compared to those that are an empty shell—or empty-full ratio.
To tackle this, USP collaborated with the U.S. Institute of Standards and Technology (NIST) and the National Institute for Innovation in Manufacturing Biopharmaceuticals (NIIMBL) to study how measurements of empty-full ratios varied from lab to lab.
USP has subsequently developed a set of empty-full standards, McCarthy explains, which can be used to support consistency across labs and methods, and to benchmark new analytical technologies, as they come onstream, against previous methods. A final version of a chapter on best practices for AAV manufacturing will be published in 2026, once experts address public comments, she says.
Going forward, USP now plans to address other common viral vectors, such as best practices for lentivirus, and will also aim to work with stakeholders to develop standards for chimeric antigen receptor therapy (CAR T) manufacturing, she says.
“What we’re trying to do is ensure the quality and consistency of these innovative medicines, and so anything we can do to support that will be beneficial to both manufacturers, who hope to innovate, and regulators trying to review their development,” she adds.