Rznomics Inc (KOSDAQ: 476830), a South Korea-based biopharmaceutical company specialising in the development of RNA-based gene therapies, on Monday announced a breakthrough in the high-efficiency production of circular RNA (circRNA), a rapidly emerging modality in next-generation RNA therapeutics.

The research was published online in Nucleic Acids Research (NAR), an international journal in the fields of nucleic acid research and molecular biology, under the title 'Target Site Selection and P1 Engineering Enable Highly Efficient Circular RNA Production via End-to-End Self-Targeting and Splicing'.

The company says that the study highlights a substantial enhancement in the circRNA production efficiency of Rznomics' proprietary Self-Targeting and Splicing (STS) technology, which enables RNA molecules to spontaneously form a circular structure during in vitro transcription.

Unlike conventional linear RNA, circRNA features a covalently closed-loop structure, rendering it highly resistant to enzymatic degradation. This stability makes circRNA a highly promising platform for a broad spectrum of RNA-based medicines, including vaccines and protein therapeutics. However, circularisation efficiency generally decreases as RNA length increases. This limitation restricts the size of genes that can be practically accommodated and poses a challenge for efficient large-scale manufacturing.

To address this limitation, the Rznomics research team systematically screened target sites for self-circularisation and implemented an engineering strategy to optimise the P1 construct involved in the self-circularisation reaction.

According to Rznomics, the study revealed that self-circularisation efficiency fluctuates significantly depending on the location of the target site, even within the same RNA sequence, demonstrating that optimal target site selection is a key factor for high-yield circRNA production. The researchers further engineered the P1 construct by sequentially introducing a short polyA10 sequence and an antisense sequence designed to strengthen interaction with the target site, improving self-circularisation efficiency by up to approximately seven-fold compared with the original STS design.

In experiments using Factor VIII RNA approximately 7.8 kilo-nucleotides in length, the optimised STS method achieved approximately a two-fold higher circularisation efficiency than the widely used Permuted Intron–Exon (PIE) method.

Rznomics says that these findings demonstrate that integrating strategic target-site selection with P1 construct engineering enables efficient circRNA production not only for relatively short RNAs but also for large RNAs approaching 8 kilo-nucleotides. Rznomics anticipates that this technology could serve as a broadly applicable platform for the development of circRNA-based therapeutics and vaccines.