Cracking the RNA Bottleneck: Codexis and the Enzymatic Synthesis Revolution

REDWOOD CITY, Calif. – September 28, 2026

The biopharmaceutical industry is quietly approaching a manufacturing precipice. As RNA interference (RNAi) therapies graduate from treating rare orphan diseases to tackling mass-market cardiometabolic conditions like hypertension and hypercholesterolemia, the sheer volume of therapeutic material required is skyrocketing. Industry projections suggest that global demand for therapeutic small interfering RNA (siRNA) will surge 30-fold by 2035. Yet, the foundational chemistry used to manufacture these molecules has remained largely unchanged since the 1980s.

Enter Codexis, Inc., a company that is betting its future on a biological solution to a chemical problem. Today, the Redwood City-based enzyme engineering specialist announced a strategic evaluation agreement with an undisclosed "pioneering siRNA drug innovator." Under the terms of the deal, Codexis will leverage its proprietary ECO Synthesis Manufacturing Platform to produce stereo-defined oligonucleotide fragments. The unnamed partner will then assemble these fragments into full siRNA duplexes using enzymatic ligation.

On the surface, it is a standard biotech collaboration announcement. But looking beyond the launch, this partnership serves as a critical stress test for a technology that could fundamentally rewire how the world's most advanced genetic medicines are manufactured. It is a direct head-to-head benchmark between the legacy of chemical synthesis and the promise of enzymatic bioprocessing.

The Stereochemistry Problem: Moving from Noise to Signal

To understand why this collaboration matters, one must understand the inherent flaws of traditional solid-phase oligonucleotide synthesis (SPOS). To prevent RNA therapeutics from being rapidly chewed up by enzymes in the human body, chemists replace non-bridging oxygen atoms in the RNA backbone with sulfur atoms, creating what is known as a phosphorothioate (PS) linkage.

However, every time a sulfur atom is introduced via SPOS, it creates a chiral center, resulting in two possible three-dimensional orientations: "Rp" or "Sp". Because traditional chemistry cannot control which orientation is formed, the process yields a random, stochastic mixture. A standard siRNA molecule with just six of these modifications generates 64 distinct diastereomers. Every FDA-approved siRNA drug on the market today is, in reality, a complex soup of dozens, if not hundreds, of slightly different molecules.

"For decades, the industry accepted this stereochemical soup as an unavoidable cost of doing business," noted one veteran bioprocessing expert familiar with the Codexis platform. "But as we move into larger patient populations, the FDA is looking closer at batch-to-batch consistency. If you have 64 isomers, some are highly potent, some are inactive, and some might be driving off-target toxicity. Controlling that mixture is the holy grail."

This is where Codexis’s StereoSelect technology comes into play. By engineering specific RNA polymerases, the company can force the sulfur addition into a single, defined orientation. The result is a pure, stereo-defined molecule. At the TIDES USA 2026 conference earlier this year, Codexis presented data proving they could achieve this stereochemical control while initiating synthesis from a single nucleotide—eliminating the need for chemical starter primers entirely.

Alison Moore, PhD., President and CEO at Codexis, emphasized this advantage in the company's announcement: “This agreement is an important next step in bringing our latest ECO Synthesis capabilities to a customer. Working with a pioneer in the siRNA field offers an exciting opportunity to demonstrate how ECO Synthesis can deliver stereochemical control, which may offer both superior product quality and therapeutic performance to an innovator’s pipeline over assets produced using traditional solid phase chemistry methods.”

A Greener, Scalable Blueprint

Beyond the clinical advantages of pure stereochemistry, the collaboration highlights a pressing logistical and environmental crisis in pharma manufacturing. Traditional SPOS is a notoriously dirty process. It relies on massive volumes of hazardous organic solvents like acetonitrile and dichloromethane. Scaling SPOS to meet metric-ton commercial demand is not just economically daunting due to the cost of reagents; it is environmentally unsustainable.

The ECO Synthesis platform operates entirely in water. Recent life-cycle assessment data confirmed that this aqueous enzymatic process reduces the Global Warming Potential of oligonucleotide manufacturing by more than 50 percent and lowers the environmental impact of input materials by a factor of 2.7.

Furthermore, the partnership focuses on a "fragment ligation" approach. Synthesizing a long RNA chain nucleotide-by-nucleotide results in cumulative yield losses. By using enzymes to build short, perfect 10- or 12-mer fragments, and then using engineered double-stranded RNA ligases—aided by Codexis's FragLink computational tool—to stitch them together, manufacturers can achieve greater than 90 percent duplex assembly without the need for complex, toxic chromatographic purification steps.

Reading the Tea Leaves: Who is the Partner?

Codexis has kept the identity of its new partner strictly confidential, referring to them only as a "pioneering siRNA drug innovator." However, the breadcrumbs left at recent industry events offer compelling clues.

At the TIDES USA 2026 conference in Boston, Codexis hosted an exclusive expert panel titled “Stereochemistry Control in RNAi Manufacturing: Signal or Noise?” Sitting directly alongside Codexis executives were CMC leaders from Arrowhead Pharmaceuticals and Wave Life Sciences. Arrowhead, in particular, has been openly vocal in its corporate presentations about the necessity of shifting toward block synthesis and enzymatic ligation to overcome multi-kilogram supply bottlenecks for its cardiometabolic pipeline.

Another strong candidate is Alnylam Pharmaceuticals, the undisputed commercial pioneer of RNAi. Codexis has previously highlighted case studies scaling siRNA manufacturing using Alnylam’s vutrisiran as a reference drug construct. Furthermore, the company recently appointed Dr. David Butler to its Strategic Advisory Board—a scientist who spent formative years at Alnylam developing RNA delivery systems before leading chemistry at Wave Life Sciences. Regardless of whether the partner is Arrowhead, Alnylam, or another heavyweight, the collaboration signifies that the industry's top tier is taking enzymatic synthesis seriously.

Validating a Commercial Pivot

For Codexis, this evaluation agreement is more than a scientific milestone; it is a vital validation of the company's recent corporate pivot. Following an operational restructuring in late 2025, the board promoted Dr. Moore—a former Amgen manufacturing executive—to CEO. Under her leadership, the organization has aggressively transitioned ECO Synthesis from an academic proof-of-concept into a commercial licensing engine.

Rather than spending hundreds of millions to build a standalone contract manufacturing organization (CDMO), Codexis is deploying an enzyme-supplier licensing model. They have already initiated technology transfers with entrenched CDMO giants like Nitto Denko Avecia and Axolabs. This capital-efficient strategy has resonated with investors. A successful $25 million equity financing in July 2026 boosted the company's pro-forma cash balance to nearly $80 million, funding operations and a dedicated $25 million GMP enzyme facility buildout through 2028.

The current head-to-head benchmarking against SPOS will evaluate purity, product quality, and ligation performance. If the enzymatically synthesized fragments meet the rigorous analytical standards required for clinical development, the unnamed partner holds the option to integrate ECO Synthesis into its future commercial supply chains.

The transition from chemical to biological manufacturing for oligonucleotides will not happen overnight. The regulatory inertia surrounding established SPOS methods is profound. However, as the demand for RNA therapeutics outstrips the physical and environmental limits of legacy chemistry, innovations like the ECO Synthesis platform are no longer just fascinating science experiments. They are becoming existential necessities for the future of genetic medicine.