Future-Proofing mRNA Drug Manufacturing: IVT And Supply Chain

mRNA-based therapeutics have seen a surge in interest in recent years, spurred by the vaccines developed to combat COVID-19. Since 2020 the space has seen a proliferation of companies interested in developing linear mRNA vaccines, as well as mRNA cancer vaccines and RNA therapeutics geared toward a wide array of indications.

The result is a nascent, predominantly preclinical industry, which is operating largely in a “regulatory black box” as it relates to chemistry, manufacturing, and controls (CMC) strategies for these applications. In a recent panel discussion, experts from pioneering mRNA therapeutics companies explored the go-to best practices for prioritizing and streamlining the technical operations to carry an mRNA product to – and through – clinical development. Speakers for the event included:

• Hari Pujar, chief operating officer, Tessera Therapeutics
• John Stubenrauch, chief operating officer, Nutcracker Therapeutics

One of the greatest challenges facing mRNA therapeutics companies today is establishing a well-defined and high-quality drug product manufacturing process. Doing so in the face of regulatory and technical uncertainty necessitates approaches aimed at predictive and proactive innovation, enabling better manufacturability assessments, more robust in vitro transcription (IVT) techniques, and improved downstream processing.

Determining Manufacturability Through Discovery

Despite the nascency of mRNA therapies in the larger advanced therapeutic space, there exists a “traditional” approach in linear mRNA, which formed the basis of the first COVID vaccines and which is still being broadly leveraged for its prophylactic vaccine potential. When it comes to the ultimate manufacturability of linear mRNA, the key questions are those that accompany any therapeutic modality: What are the product’s critical quality attributes (CQAs)? Are there any impediments to its manufacturability?

“At Nutcracker we have our lead candidate nomination process, where we look not only at potential protein expression, but we perform a manufacturability assessment as part of our core criteria,” Stubenrauch explained. “There are some codon optimization programs that need to be established, and you need to really find the sweet spot of where operability is – you can have a highly expressing process, but if you don’t have appropriate yield or you’re not hitting the CQAs, it becomes a challenge.”

While some manufacturability considerations can be offset by good protein expression, it is important to pursue optimization that enables forecasting for both manufacturability and expression, Stubenrauch added. “When it comes to manufacturing anything, you have to understand the structure of the molecule,” Pujar said. “What is the cap structure that is part of this particular molecule? What does the poly-A tail look like? Most important, what is the overall length of the messenger RNA? Because the length is a key feature of this molecule.”

For Pujar, one of the key advantages of pursuing mRNA modalities is that manufacturability and discovery go hand in hand, to an extent. Because researchers must effectively manufacture mRNA for themselves before they can experiment with it, they often have an idea of what it would take to manufacture a development candidate early on: “You already have a preview of what’s to come,” Pujar added.

Ensuring manufacturability for an mRNA molecule requires early collaboration and integration across an organization. This is particularly true for CMC and R&D, as these teams must work closely together to achieve a product that is optimized for manufacturing at scale alongside more foundational technical considerations.

“In the case of any large molecule therapeutic, the process ends up determining the product. We’re trying to get away from that by fully chemically characterizing the molecule, particularly in the case of mRNA,” Pujar said. This means establishing a close connection between discovery and manufacturing, he explained, adding that in the case of mRNA, the two are highly intertwined. “How you manufacture the molecule in discovery determines the outcome of the discovery, which leads to whether a candidate is nominated or not.”

Given the need to incorporate manufacturing as part of the discovery phase for mRNA, biopharmas should prioritize integrating business units early in development. “You have to think about things from an end-to-end perspective, and that drives a high level of internal collaboration,” Stubenrauch said.  “If you think about the regulatory environment as well, and the stages as you're progressing through your clinical programs, [you should] drive a level of process understanding and change early in that paradigm,” he explained. “As you get later into clinical development, there's always mounting pressure to ensure that your process is well characterized and that you have sustained supply.”

Supply Chain Constraints And Raw Material Variability: Standardizing mRNA Production

Establishing the raw materials necessary for manufacturing RNA starts with having the right DNA as a template. Additionally, the individual nucleotides and enzymes, as well as the appropriate reagents, form the baseline critical raw materials for these products. “I think that at this point, the supply chain for all of these is being invested in quite heavily in a way that is much different than it was several years ago,” Pujar said. Plasmid manufacturing continues to be another major cause of supply chain pressures for mRNA, as the demand for plasmids across the cell and gene therapy space continues to grow to meet burgeoning development and manufacturing needs.

While the supply chain challenges remain for mRNA therapies, many companies are working to address gaps by building out internal capabilities and capacity to support their efforts. This can help to ameliorate one of the biggest challenges related to raw material supply chain for a range of biopharmaceuticals: variability. Building out the necessary analytical capabilities to characterize raw materials can help organizations achieve greater process consistency. “The good news is that we’ve spent 40 years now characterizing proteins, so we can apply that knowledge to enzymes, which typically have not been characterized to that level because they’re raw materials,” Pujar explained. “We have all the tools, and the rest of the characterization is even simpler because they’re small molecules.”

Upstream Optimization: Perfecting The IVT Process

From a facility footprint and capex standpoint, mRNA applications can possess somewhat more efficiency than cell-based processes. Despite this, there exists plenty of opportunity to optimize the IVT process, which can be well characterized analytically from a chemistry and pharmacokinetic perspective. “The opportunity for us is, how do you grow your understanding of the kinetics, and then how do you optimize your reaction? I’m a big believer, coming from the world of biologics, in looking to focus on the optimization of an upstream process to lower the burden of subsequent verification steps,” Stubenrauch said.

This simplicity relative to biologics can allow developers to establish a “deterministic system,” according to Pujar, wherein teams can leverage classic differential equations to perform modeling. “I think there’s a lot more sophistication to be had across the industry, and in 10 years we will have applied all of the engineering principles that are very standard in other industries in IVT to make it a very efficient and low-cost process,” he said. By focusing on the foundational science around reactions, kinetic modeling, stoichiometry, and additives, mRNA researchers will be able to further optimize across the sequence-independent variables that most impact manufacturability.

Conclusion

For companies in the mRNA space, navigating the complexities of the raw material supply chain, coupled with the pace of innovation in the greater pipeline, requires accelerating timelines and creating process-level efficiencies. The unique nature of these therapies creates the potential for more capital-efficient models when compared to other advanced therapies; moreover, the potential range of applications possible for mRNA, coupled with interest from researchers and developers, is set to spark a new wave of promising treatments for some of the most intractable diseases.