Primrose Bio Launches Prima RNApols™ ExTend Cap AU, a Next-Gen RNA Polymerase for Self-Amplifying mRNA

Maximize capping efficiency and minimize double-stranded RNA ("dsRNA") in the manufacturing of self-amplifying mRNA

SAN DIEGO, Nov. 10, 2025 /PRNewswire/ -- Primrose Bio, Inc. ("Primrose"), a company with proprietary therapeutic manufacturing technologies, today announced the launch of Prima RNApols^™ ExTend Cap AU, an RNA polymerase engineered to significantly improve manufacturing of self-amplifying mRNA vaccines and therapeutics.

ExTend Cap AU enables high-yield, fully capped self-amplifying mRNA with less capping reagent, template DNA and RNA polymerase. Built specifically for AU cap analogs, dsRNA reduction combined with lower reagent needs delivers higher quality, more cost-effective mRNA.

Key Features & Benefits

• High AU capping efficiency: Achieves high capping efficiency with less cap, lowering reagent requirements
• Ultra-low dsRNA: Minimizes unwanted IVT byproducts, reducing downstream purification needs
• Higher yield of saRNA: Maximizes yield while maintaining integrity and fidelity compared to T7 polymerases
• Cost-efficient manufacturing: Uses less template, enzyme, and cap analog for significant cost savings

"Although saRNA products have already achieved regulatory approval in Japan and Europe, developers need improved tools to produce long template mRNA with higher fidelity and purity, while reducing reagent and downstream purification costs," said Drew Burch, CEO of Primrose. "Primrose's enzyme evolution toolkit enables this new solution, so our customers can develop better saRNA products with more efficient manufacturing to address infectious disease, oncology, and other disease states."

Prima RNApols ExTend Cap AU is available for research use applications. GMP-grade Prima RNApols manufactured and released under ISO 13485:2016 certified quality systems are available for clinical and commercial mRNA manufacturing. For more information, please visit www.prima.primrosebio.com.

About Primrose Bio, Inc.
Primrose Bio is focused on developing and commercializing its validated technologies that address industry gaps in production systems and deliver scalable, efficient manufacturing solutions. Primrose major offerings include Prima RNApols^™: improved enzymes for mRNA manufacturing; Pfenex Expression Technology^®: a proprietary production system used in six approved products with up to 20x higher yields and unparalleled success in making complex proteins; and PeliCRM197^®: a commercially validated CRM197 carrier protein used for conjugate vaccines. Several of the world's leading pharmaceutical companies use Primrose's technologies, including Merck, Jazz Pharmaceuticals, Alvogen, Serum Institute of India, Arcellx, Arcturus and others. For more information, please visit www.primrosebio.com.

SOURCE Primrose Bio