Circio and GenAssist have announced a research collaboration aimed at developing next-generation gene therapy candidates for genetic muscle diseases and in vivo cell therapies.

The partnership brings together Circio’s circular RNA-based circVec platform and GenAssist’s tissue-specific adeno-associated virus (AAV) delivery technology. The companies will evaluate whether combining the two platforms can improve gene expression while reducing the high doses currently required for many gene therapies.

Genetic muscle disorders remain an area of significant unmet need. While gene therapies have shown promise, high systemic doses can be associated with serious safety concerns, including toxicity in organs such as the liver. The companies believe their combined technologies could help overcome these challenges by improving targeting and increasing expression efficiency.

According to Circio, its circVec circular RNA platform has demonstrated up to 50-fold enhanced gene expression from AAV vectors in vivo. GenAssist’s proprietary capsids and promoters are designed to target muscle tissue and T-cells while minimising delivery to the liver.

Under the agreement, the companies will initially focus on developing gene therapy approaches for muscle diseases that require broad expression across muscle tissue. The aim is to achieve therapeutic effects at substantially lower doses than conventional AAV-based therapies.

Dr Chunyan He, chief executive officer of GenAssist, said: “We are incredibly impressed by Circio’s unique circular RNA technology and see tremendous potential in how it can dramatically boost gene expression. Our second-generation AAV platform establishes a new benchmark for safety, utilizing highly tissue-specific, de-targeted capsids to dramatically lower systemic dosing while eliminating off-target toxicity.”

She added: “Through our collaboration with Circio, we integrate their unique circular RNA technology—whose exceptional stability and superior transcriptional output ensure robust, sustained expression even at significantly reduced vector loads. This partnership directly addresses the core demands of next-generation genetic medicine, overcoming the traditional dose-expression trade-off to deliver safer and more effective therapies.”

The collaboration will also explore applications in in vivo CAR-T therapy. The companies plan to combine GenAssist’s T-cell-targeting AAV technology with Circio’s circVec expression cassette to generate potential candidates for cancer and autoimmune diseases.

These engineered AAV constructs will be evaluated in laboratory and animal studies. If successful, selected programmes could advance into preclinical development.

Dr Thomas B Hansen, chief technology officer of Circio, said: “The targeted AAVs developed by GenAssist have the ability to specifically and efficiently transduce muscle or T-cells upon systemic delivery with near-complete liver de-targeting.”

He added: “The partnership between Circio and GenAssist will aim to evaluate whether the enhanced circVec expression acts synergistically with these targeted capsids and promoters. This fits perfectly into Circio’s strategy of testing circVec in multiple tissues using different AAV variants, both internally and externally.”

The collaboration forms part of Circio’s broader partnering strategy to identify therapeutic applications where its circular RNA technology may improve the performance and specificity of gene therapy vectors.

GenAssist’s platform has previously generated several experimental AAV capsids designed for muscle, T-cell and central nervous system targeting. The company’s preclinical pipeline includes programmes for Duchenne muscular dystrophy and hypertrophic cardiomyopathy.

While the collaboration remains at the research stage, both companies believe the combination of targeted delivery and enhanced gene expression could help address some of the key limitations currently facing gene therapy development.