How mRNA technology is creating affordable, potent vaccine products

BPR: What are the advantages of RNA medicine?​

The pace, efficacy and scalability with which the success of mRNA vaccines against COVID-19 was demonstrated opened endless possibilities for mRNA medicine in broad areas of infectious diseases, cancers and protein-encoding replacement therapies.

In my mind, the advantages of mRNA medicines are obvious, with the ease and speed of design and testing, rapid scale up and manufacture as well as negligible risk of insertional mutagenesis.

The ingenuity lies in mRNA harnessing human cells as its own vaccine-production facility, with several accompanying advantages as it allows human post-translational modification (PTM) of protein products, with the potential for less immunogenicity and full functionality. Moreover, it allows an efficient way to deal with multimeric proteins, including cocktail vaccines and localisation of transmembrane and intracellular proteins, increasing the scope of treatment. This promise is reflected in the number of mRNA-based clinical trials currently under progress.

BPR: In your opinion, what are the benefits of enzymatically produced synthetic DNA over plasmid DNA?​

There are fundamental issues with the use of plasmid DNA, not limited to the presence of bacterial backbone, antibiotic resistance genes and endotoxins, but also long lead times to produce large-scale (several grams) of clinical grade material that is GMP compliant. Plasmid DNA production involves bacterial fermentation in large-scale bioreactors that are often at risk of batch failures.

In addition, plasmid DNA-encoded homopolymeric sequences (poly(A) tails) recombine during bacterial amplification of the plasmid DNA, resulting in sequence instability and heterogeneity. These prevalent issues, combined with large footprint, often accompanied with low yields, can add extreme cost and time to this upstream step.

BPR: How can enzymatically produced synthetic DNA templates overcome these issues with plasmid DNA?​

From a manufacturing standpoint, enzymatic DNA synthesis has a significantly reduced manufacturing footprint; typically DNA is amplified at greater than 1g/L yields. This allows not only for scale up and scale out; a 10g batch of DNA can be manufactured using simple, single use, bench top equipment, but also enables rapid tech transfer. For example, the process could be easily installed in difficult to access areas in remote parts of the world for rapid pandemic response. Use of defined enzymes and components for in vitro DNA synthesis also results in a simplified down-stream purification process; unlike conventional plasmid fermentation.

BPR: What are the benefits of 4basebio's opDNA?​

A key benefit of 4basebio’s opDNA is the fact that the template does not need to be enzymatically linearised prior to in vitro transcription (IVT), a step that is often limited by choice of restriction sites, efficiency and quality of digestion hence reducing the time and cost effectiveness of this critical upstream step. Another benefit is the efficient/reliable inclusion of longer ~120 poly(A) tails that is well established in the industry to enhance stability and translational capacity of the mRNA. Poly(A) tracts are prone to recombination in conventional plasmid fermentation, and often researchers compromise by the inclusion of a linker to break up the poly(A) tract or accept a shorter poly(A) with a degree of heterogeneity within the mRNA transcript. Furthermore, IVT yields per mass of DNA are higher for synthetic DNA templates as, unlike plasmid DNA, they lack non-transcribing DNA backbone, resulting in an overall cost effectiveness.

The turnaround time for GMP-compliant synthetic DNA is significantly reduced as compared to plasmid DNA, where clients may be waiting 6-18 months for release of material.

A final point to mention is the flexibility of batch size of synthetic DNA. 4basebio’s GMP compliant offering starts at 50mg, which is ideally suited for the personalised cancer vaccine (PCV) space. When using a plasmid alternative, clients often have to commit to significantly larger batches of DNA than required, due to inflexibility in bioreactor sizes. 

BPR: Could you tell us more about what 4basebio has been up to?​

In August, 4basebio was delighted to announce that it had received a grant from the Bill and Melinda Gates Foundation to advance our synthetic DNA platform and Hermes nanoparticle platform for the development of thermostable nucleic acid vaccines.

The development program aims to build on preclinical data demonstrating the improved stability offered by the Hermes™ platform, the superior immune responses achieved with 4basebio's synthetic DNA products and high-quality mRNA produced from 4basebio’s opDNA products.

The successful demonstration of the Hermes™ platform and 4basebio’s synthetic nucleic acid payloads in infectious disease vaccines has the potential to enable a faster response to pandemic needs, create highly performant and affordable vaccine products in support of the global fight against infectious diseases and enhance the global availability of such innovative medicines.

We have also received funding from Innovate UK’s Transforming Medicine Manufacturing programme. In collaboration with BIOTOOLMICS and CPI, we are addressing the complexities of current mRNA manufacturing.

Finally, several of our clients expect to be dosing their first patients in 2024, so watch this space for the first clinical applications of 4basebio’s synthetic DNA.