Inside Alnylam's Playbook For High Volume siRNA Production
By Anna Rose Welch, Editorial & Community Director, Advancing RNA
It’s not everyday that a pharma company announces its intent to open a new manufacturing facility dedicated to a next-gen manufacturing approach. But the RNA space is not just any space, and Alnylam is not just any company.
Back in December, Alnylam broke the news that it would be expanding its Norton, MA facility to include the company’s novel chemoenzymatic ligation platform — the “up and coming” (or “new kid on the block…mer”?) approach for manufacturing large quantities of siRNA. In an interview with me shortly after the announcement, Alnylam’s CTO and Chief Quality Officer Tim Maines and Chief CMC Officer Lubo Nechev joined the ranks of those espousing the merits of and need for enzymatic ligation to the Advancing RNA community here in Part 1 of this two-part article series.
However, our conversation didn’t stop at the “why” behind the company’s $250 million investment in its facility. As one of the first companies to establish such a platform, both Maines and Nechev are also in the perfect position to espouse wisdom on the practical aspects and remaining challenges of implementing enzymatic ligation at a large scale.
Here in this installment, Maines and Nechev outline what they’ve learned thus far about the science of enzymatic ligation, while also paying credence to the unknowns and existing barriers that, as a frontrunner, Alnylam will inevitably (but willingly) be tasked with facing in the future.
The “Elegant Simplicity” of Ligation
For those of you who have read my columns before, you’ll know I’m a sucker for analogies. This was a fact that Maines, a former Erie, Pennsylvania-ite like yours truly, embraced wholeheartedly from the start of our conversation.
As we already know well, enzymatic ligation is only one (albeit important) milestone on the road to a fully enzymatic future for oligo production. As such, Maines likened our industry’s journey to that of the electric car industry. Before there were fully electric vehicles, the industry went through a period of developing hybrid vehicles; however, not every car manufacturer undertook this hybrid step. Likewise, Maines anticipates that, while there are a handful of companies and CDMOs investing in these enzymatic ligation capabilities today, there are other companies watching and waiting for the field to achieve a fully enzymatic synthesis process before investing.
But to both Maines and Nechev, this hybrid ligation path is a critical “step evolution”— one that brings with it several important scientific understandings and efficiencies.
“This process is much simpler than the current solid phase synthesis,” Maines shared. “Enzymatic ligation boasts an elegant simplicity that makes me smile.”
Look no further for such “simplicity” than the learning that ligase has so far proven to be sequence independent — a finding that was particularly reassuring to Nechev.
“I was pleasantly surprised by this process, because in my head, I anticipated that I’d have to modify the enzyme for every sequence. As it turned out, we’re using the same enzyme for multiple different sequences. You can have 10 different duplexes and use the same enzyme for each one of them.”
Another pleasant surprise was the activity of the enzyme itself — a factor informing Nechev’s projections that the established process will be capable of producing between 300-500 kilos.
However, the road to 500 kilos is not yet paved. As Nechev went on to explain, the preliminary goals for the facility are to make 100 kilos per batch. This is, obviously, a pretty big leap from the 1 kilo the process produces today. Having scaled from milligrams to one kilo is proof the process is scalable. Now, the challenge is to build the facility (e.g., order equipment and establish utilities) that can accommodate this process.
Beyond Alnylam: Building a Sustainable Ecosystem for Enzymatic Ligation
Of course, paving this road is not just Alnylam’s responsibility. Successfully and efficiently scaling to metric tons of product will also necessitate tech providers and suppliers to bolster their own capabilities.
“We need to optimize the solid phase synthesis process moving forward to help us make the blockmers more efficiently,” Nechev explained. “In particular, we need to see more companies providing solid support made specifically for shorter oligos/the blockmers.” As he went on to explain, Nitto is one company that has jumped into the ring, providing solid support capable of doubling loading capabilities.
“Such optimizations will be essential to achieve the lowest cost and highest volume of blockmers,” Nechev added.
Likewise, Maines advocated for transformations in the supply chain to happen in parallel to reach a future in which blockmers are commoditized and, hopefully, regulated as starting materials.
As Maine’s point implies, the chemoenzymatic ligation process also raises some big regulatory questions — many of which still do not have concrete answers. In particular, there is the question of whether such a manufacturing paradigm shift can be demonstrated sufficiently using a comparability exercise.
Based on Alnylam’s plans, Nechev anticipates aligning around a comparability strategy will be essential.
“We will need to demonstrate comparability because it’s unlikely our clinical programs will begin with this hybrid manufacturing paradigm,” he said. “The advantage of enzymatic ligation is that we can achieve high volumes. But seeing as we will only need a small amount of drug product to enter the clinic, solid phase synthesis will be the faster approach for early clinical development.” In turn, the company anticipates it will have to make the shift later in clinical development, requiring a protocol to demonstrate that the product produced by the two different processes are the same.
Fortunately, as Nechev explained, products produced by this hybrid process are structurally/analytically identical to those produced via solid phase synthesis. The biggest difference will be in the impurity profile, thanks to the introduction of the enzyme. In turn, this will behoove companies to justify their control strategies — namely to clearly define GMP principles and the manufacturing parameters necessary to achieve a consistently high-quality product.
Though Alnylam may have its work cut out for it (and the industry), I appreciated Maines’ optimism about the work ahead. Though I may have started part 1 of this article series with the phrase, “Success breeds its fair share of challenges,” Maines took his own spin to this:
“Everything here is solvable,” Maines concluded. “We can figure out the answers to these questions with the regulators and internally with our scientists and manufacturing experts. I stand by the importance of taking this hybrid approach; success here will breed future success.”
Missed part 1? You can check it out here: The "Middle Ground" Advantage: Why Alnylam Is Betting Big On Chemoenzymatic Ligation
For more on enzymatic ligation & related topics, please check out more of our articles: