Potential Unlocked!

August 13, 2025 by Derek Jacobs

Expanding mRNA capabilities with Codex® HiCap RNA Polymerase

From pandemic-era vaccines to next-generation cancer immunotherapies, mRNA-based therapeutics are transforming the pharmaceutical landscape. But as the field matures, so do the challenges, particularly around manufacturing efficiency, regulatory scrutiny, and product safety.

In our whitepaper, Enabling mRNA Therapeutic Development Through Enhanced IVT Capping Efficiency, we discuss those challenges and explore how Codex® HiCap RNA Polymerase, a novel engineered enzyme, addresses these critical hurdles by enabling enhanced in vitro transcription (IVT) capping efficiency.

Why does the 5’ cap matter?

One of the most critical components of mRNA production is the 5’ cap structure. Without it, mRNA is unstable, poorly translated, and highly immunogenic. The 5’ cap is a critical structure attached to every eukaryotic mRNA molecule. It plays a vital role in:

• Stabilizing the transcript
• Initiating translation
• Facilitating nuclear export
• Reducing immune activation

In synthetic mRNA production, the cap must be added during or after the IVT reaction. Traditional post-transcriptional capping methods are inefficient and add complexity to the manufacturing process. Co-transcriptional capping, adding the cap during IVT, is more streamlined, but it requires high capping efficiency to be effective.

Traditional enzyme challenges

Wild-type T7 RNA polymerase (WT T7) has long been the workhorse of IVT, but it comes with limitations:

• Lower capping efficiency, especially with expensive cap analogs
• Higher levels of double-stranded RNA (dsRNA), which can trigger unwanted immune responses
• Reduced yields when using high concentrations of cap analogs

These issues not only compromise therapeutic performance but also introduce manufacturing inefficiencies, elevate regulatory risks and increase production costs; all these pose barriers in adopting mRNA-based therapies.

Engineering improved efficiency and quality

Enter Codex® HiCap RNA Polymerase, a novel enzyme engineered to dramatically improve the efficiency and quality of mRNA synthesis. By enabling superior co-transcriptional capping, this innovation is helping developers produce safer, more potent mRNA therapeutics while reducing costs and simplifying workflows.

HiCap was engineered through directed evolution to address these challenges head-on. It selectively incorporates di- and tri-nucleotide cap analogs with exceptional efficiency: achieving >95% capping efficiency across a range of cap analog types, including CleanCap AG, ARCA, and sCap.

In comparative studies, HiCap consistently outperformed WT T7:

• Higher capping efficiency at lower cap analog concentrations
• No loss in overall mRNA yield
• Significantly reduced dsRNA byproducts

This means developers can use less of the costly cap analogs while still producing high-quality, therapeutically relevant mRNA.

Here in the real world: Cost, safety, speed

Benefits of HiCap extend beyond the lab bench, with up to 62% reduction in cap analog usage, translating to substantial cost savings. Additional benefits include:

• Elimination of downstream purification steps, such as HPLC, thanks to lower dsRNA levels
• Improved safety and potency, with reduced immunogenicity and enhanced translation efficiency

These advantages are especially critical as regulatory agencies increase scrutiny on mRNA purity and as developers seek to scale production for clinical and commercial use.

Building for mRNA’s future

HiCap goes beyond just an improved enzyme; it’s a strategic enabler for the next generation of mRNA therapeutics. Its compatibility with modified uridines and high transcriptional fidelity make it ideal for applications ranging from vaccines to gene editing.

As the mRNA field continues to evolve, innovations like Codex HiCap RNA Polymerase will be essential for overcoming manufacturing bottlenecks, reducing costs, and accelerating time to clinic.

Download the Whitepaper to see how Codex HiCap can help redefine mRNA manufacturing

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