Gene therapies represent a very different paradigm than conventional therapeutics. Not only are most curative treatments single-dose, but many candidates in the clinic that are nearing commercialization target rare diseases with limited patient populations and no existing treatment options. Downstream separation issues, a lack of appropriate analytical tools, and capacity and sourcing issues are all challenges manufacturers are facing. There is no one-size-fits-all manufacturing solution for these complex products. Purity requirements, vector quantity, and other needs vary depending on the indication, size of the patient population, route of administration, and dosage required.
Solutions for the Immediate Term—Scalable Transfection
In the immediate term, it is important to focus on existing production processes that are more appropriate for GMP manufacturing, scale-up, and commercial launch. Transient transfection is the fastest, most widely used, and regulatory-validated approach. Scalability limitations can be successfully overcome with scaling out and pooling strategies. Fixed-bed bioreactor options for scalable adherent transient transfection are also available.
The iCELLis Bioreactor platform from Pall Biotech has been used for the commercial production of approved products, and the introduction of the scale-X fixed-bed bioreactor portfolio from Univercells Technologies enhances the viability of this approach. For further scalability, co-infection methods using the insect-based baculovirus expression vector system (BEVS) and human-derived herpes simplex virus (HSV) type 1 systems typically perform better than transient transfection. Active infection methods, in fact, have proven to be efficient even at the 2,000-liter scale. Additionally, these methods often result in higher yields by at least 10-fold and higher percentages of full capsids out of the bioreactor, increasing the feasibility of ion exchange methods to achieve an acceptable purity profile. However, developers will need to balance timeline and manufacturing complexity with these methods.
Solutions for the Longer Term
The most robust and scalable solutions for AAV vector manufacturing leverage packaging and producer cell lines. Packaging cell lines contain the rep and cap components, and only the gene of interest (GOI) must be transfected into the cell. Producer cell lines have both the rep and cap components and the GOI integrated into the host cell genome. Over the last few years, the use of packaging and producer cell lines has begun to increase, which in turn has led to advances in supporting technologies.
Early investment into potency assays prior to Phase I studies is critical for developers to put good methods into place. This enables a smooth transition to late-stage development and manufacturing by demonstrating correct expression and activity. This is a very complex challenge that can compound if left until late in the development cycle. A robust potency assay also facilitates comparability and leaves the door open for process changes should the need ever arise.
About the Center for Breakthrough Medicines
With in-house capabilities for plasmid manufacturing, process development, high-throughput vector manufacturing, and integrated analytical and testing capabilities at a single source, CBM’s vector solutions drastically simplify the value chain and accelerate timelines at every stage of development and commercialization. Since its inception, CBM has actively aligned with partners across academia and industry to bring in novel technologies and platforms to ensure quality while accelerating the manufacturing of vector-based therapies.
Consult with a CBM expert today to advance your drug development.