Many of the early gene and gene-modified cell therapies are delivered using viral vectors based on adeno-associated virus (AAV) or lentivirus (LV) target orphan diseases that affect a very small percentage of the population. For these often-curative products, being first to market is essential for success. Because reducing time to market was so important to start, process optimization saw less focus initially. However, rising pressure to reduce the cost of these novel, life-changing medicines, combined with advances in fit-for-purpose manufacturing technologies, is leading to more emphasis on both process optimization and time to market.

Early Engagement for Optimization

Engaging early is the key to success in any process. When orphan drug (OD) developers can align with industrial partners at the beginning of the preclinical manufacturing stage, processes are created using longer term thinking. This includes critical decisions about the viral-vector production process, such as whether it will be performed under adherent or suspension cell-culture conditions, and which cell-culture media and transfection agent will be used—all these decisions should be made with the transition to commercialization in mind. Working with experienced partners can help to streamline the process development stage, ultimately resulting in optimized productivity, scalability, time to market and the cost of goods (CoGs) for the final product.

Leveraging Fit-for-Purpose Reagents

OD developers are looking for solutions that fit the evolving profile of drug processes today. Until 2021, there was no reagent designed specifically for AAV transfection. And though there is transferability in processes using PEIpro®, there are still limitations with respect to yields and simplifying upscale process notably by reducing complexation volumes and increasing stability of complexes

Looking to develop a solution for plasmid transfection process optimization, Polyplus-transfection designed an animal-free, fit-for-purpose, chemical transfection agent to produce recombinant AAV vectors in suspension cell culture. FectoVIR®-AAV affords titers up to two-fold greater than with PEIpro, and up to 10-fold greater than those obtained with other commercial PEI-based transfection agents.

The transfection complexes formed with the new reagent are more stable, making it easier to scale to bioreactor volumes up to 2000L. Complexation volume can also be reduced from 10% to 1%, facilitating transfection complex preparation for large-scale manufacturing.

Assuming the same bioreactor size, downstream process steps and efficiency, number of batches per year, etc., an increase in the yield for the plasmid transfection process of 2 to 10-fold would translate to a 2 to 10-fold increase in the number of doses produced each year at the same CoGs level. This means that manufacturers can reach more patients at a much lower cost per dose.

With greater yields and scalability of plasmid transfection processes, it is easier to achieve process intensification at the earliest development stages. Processes are then easier to scale up during later clinical phases because there is no need to change process conditions resulting in less risk for OD developers.

Quality is a Requirement

In addition to demands for higher quality, better/faster access and more affordability from the market, regulators have been raising their expectations for advanced orphan drug developers. There are many existing strict quality requirements for the raw materials and reagents used in viral-vector manufacturing for gene and gene-modified cell therapies. Still, at the time of this paper, none of the pharmacopoeias have established regulations on transfection reagents.  

Access to graded qualities of reagents suited for research phases through to the most stringent current Good Manufacturing Practice (cGMP) requirements presents a potential solution. As such, FectoVIR-AAV GMP is produced under the conditions outlined for Bulk Active Ingredients according to Pharma GMP, ICH Q7, GMP Part II, with fill/finish manufacturing performed according to Pharma GMP, ICH Q7, GMP Part II, Annex I. Both the active substance and the final product meet the requirements for injectable-grade pharmaceutical products.

Residual Transfection reagent tests can also offer an added layer of security. One is currently available for PEIpro, and a similar test is in late-stage for FectoVIR-AAV. With these tests, users can demonstrate that the transfection reagent has been removed during downstream processing, providing further assurance to regulators.

Supply Chains and Partnerships

In a COVID-driven world, supply chain security has become more important than ever. Suppliers must have the resources and network to ensure security of supply from early-stage development through commercialization to avoid significant delays for customers.

Finding the right partners early on delivers multiple advantages in productivity and quality. As the advanced therapies sector rapidly evolves, a new type of partnership is being formed between suppliers of key raw materials and reagents and manufacturers. Finding the right partner can facilitate the development of high-productivity processes in record time with reduced risk and cost.