RNA Therapeutics: Navigating The "Holy Trinity" Of Structure, Process, & Biology

By Anna Rose Welch, Editorial & Community Director, Advancing RNA

In this industry, we love to group our biggest challenges into threes:

Education, education, education.

Quality, quality, quality.

Delivery, delivery, delivery. 

Such repetition is certainly warranted, given the importance of each of these terms in the RNA space.

But, as luck would have it, my conversation with Bernard Sagaert, CEO of etherna, circled around another equally important (and more diverse) “holy trinity” for the mRNA space: “Structure, Process, and Biology.”

During our hour-long conversation, Sagaert and I covered a lot of ground on the current state of the industry. But given his background in quality, it shouldn’t come as a surprise that our conversation ultimately gravitated back to some of the biggest questions we currently have and need to answer about our product’s structure and function — and how to adequately demonstrate this critical knowledge to regulators. Here, he outlines where some of the most prominent knowledge gaps exist and what we must clarify in the years ahead (with the help of regulatory guidance!) to ensure we come to a clear understanding of the “holy trinity” for each of our mRNA/RNA products.    

mRNA Quality & Variability: Achieving A Reproducible Process in a “Gray Zone”

It's not unusual for me to ask C-Suite executives about their visions of what a mature RNA therapeutics industry will look like in the future. Though it may be incredibly early in the game to be putting the terms “mature” and “mRNA” together in the same sentence, I’ve found that, as the industry pushes along with each year, each executive’s “vision” of what maturity is/means is becoming less lofty/aspirational and increasingly nuanced and actionable.

For Sagaert, who has lived and worked in both the generics and the mRNA space, his visions of the current and future of our industry are balanced on keeping quality and COGS top of mind from the beginning. However, throughout our conversation, we kept returning to the fact that much of our work is being carried out today in a “gray zone,” thanks to our current lack of mRNA-specific regulatory guidance.  

As I’ve written before and Sagaert reinforced, we’re certainly not living in a regulatory desert, particularly when it comes to GMP compliance. However, when it comes to advanced therapies quality and GMP principles, there are a number of “grey areas that are open for interpretation and discussion,” Sagaert said.

Though grey areas can be liberating, they are also — as the name implies — a slightly “murky” place in which to be. As Sagaert explained, in the mRNA/RNA space, we are all striving to establish a reproducible process that produces a consistent product. However, it’s still (very) early days in terms of understanding how our CQAs inform clinical responses in general — let alone how any shifts in those CQAs may ultimately inform the clinical response. In the words of Goldilocks and the Three Bears, we’re still striving to identify what is “just right” in terms of our quality ranges to ensure a safe and consistent clinical response. (It should also go without saying that “just right” will likely look different depending on the type of RNA therapy we’re exploring.)

First and foremost, understanding what “just right” means starts with thorough characterization of our molecules to understand their structure and how that structure changes over time following any planned process changes or deviations. But the lingering question mark for a majority of this pre-clinical field remains how any variability — no matter how small — may influence clinical effect. While we’ve spent the past few years aligning around a suite of quality attributes for our mRNA-LNP products, Sagaert reminds us that we still don’t have enough information on the extent to which our CQAs can shift without inspiring (unwanted) clinically meaningful differences.

These current knowledge gaps also raise questions for our field about how we could demonstrate/justify that a process change or deviation does not have an impact on the product and its safety/efficacy.

“How do you as a Qualified Person, for example, say this deviation does not have an impact on the product and its expression in vivo?” Sagaert asked. “This is a question facing the entire biologics field, but the RNA industry needs to grow its knowledge here in particular.”

What Makes A Cell “Tick?” RNA Optimizations For Improved Clinical Response

Finding and achieving this level of “just right” in terms of characterization and process is complicated by the fact we’re still exploring a lot of innovations on the R&D front — both in terms of payload (e.g., novel RNA modalities and modifications) and LNPs (e.g., novel lipids, optimizing ratios, active delivery). Not only do these innovations challenge us further analytically and in terms of quality, we also can’t overlook the critical role cell biology plays in informing some of these innovations and optimizations. For example, as we continue chiseling away at targeted, cell-specific delivery, we must do our due diligence to understand and demonstrate that a “slight change” in the LNP does not impact the product’s biodistribution, for example. Likewise, Sagaert pointed to advancements we’ve made in modifying/optimizing UTRs and open reading frames to improve translation, expression, and durability. But we’re still unclear about which factors influence a product’s “success” within specific cells.

“Is it the folding structure of the RNA?” Sagaert said. “Does the cell prefer a specific coding sequence that leads to more stable expression?” As he went on to explain, to achieve the ideal RNA structure, we must pinpoint which optimization(s) is/are responsible for the effect. “The only thing we can do today is generate data, data, data, and, based on that data, we can eventually rely more on machine learning to standardize our outputs,” he added.

To Sagaert, our ongoing optimization and understanding of RNA structure is not only one of the foremost challenges facing us in the years ahead, but it remains one of the greatest untapped opportunities for us to ultimately achieve a lower COGS. In fact, he expressed concerns that many early RNA programs today are halted simply because companies didn’t optimize sufficiently upfront to achieve the desired levels of protein expression (in turn influencing dosage and clinical effect). Likewise, it’s not often clear (or thoroughly investigated) whether any observed preclinical toxicities are tied to the structure and biology of the molecule itself or the overall quality of the product.

“We need to work more carefully on the design of our RNA-LNP-based therapies from the beginning,” Sagaert concluded. “That’s how I anticipate we’ll make the biggest advancements in this space. For example, if we can achieve a five-fold increase in protein expression and significantly decrease dose by optimizing UTRs, this would lead to a much-needed reduction in COGS. Not to mention, the lower the dose we can achieve, the fewer side effects our patients will have, which would be another equally important advancement for all of us.”