Alexion, AstraZeneca’s rare disease subsidiary, is licensing specialized gene therapy vehicles from the Japanese firm JCR Pharmaceuticals.
The deal, announced on 8th June 2025, gives Alexion access to JCR’s JUST-AAV capsids to use in up to five of Alexion’s genomic medicines programs. In exchange, Alexion will pay JCR an undisclosed upfront fee plus up to 225 million USD in milestone payments related to research and development, as well as an additional 600 million USD in sales milestones. JCR will also get tiered royalties related to sales, though no specifics were given.
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What is JUST-AAV Capsids?
JUST-AAV is a proprietary platform technology that utilizes modified adeno-associated virus (AAV) vectors.
The technology entails insertion of miniaturized antibodies against receptors on selected tissues, organs or the blood-brain barrier onto the capsid surface, enhancing targeted delivery to those tissues and organs.
Further capsid modifications minimize off-target effects and improve safety. The name is derived from “JCR” “Ultimate destination of organ” “Safeguarding against off-target delivery” and “Transformative technology” reflecting its potential for broad application across various diseases.
JUST-AAV Capsids May be Used for Duchenne Cures
What indications Alexion would use the capsids for was also not specified. AstraZeneca’s rare disease pipeline is full of mid- to late-stage assets in diseases like myasthenia gravis and lupus nephritis.
JCR boasts that its proprietary JUST-AAV capsids come in several varieties, specifically highlighting “liver-sparing,” muscle-targeting and brain-targeting variants. Injuries to the liver from gene therapies have been under intense scrutiny lately, due to the deaths of two patients from liver injury after receiving Sarepta’s gene therapy for Duchenne muscular dystrophy, Elevidys, earlier this year. – Read More: Elevidys Gene Therapy will not be used in non-ambulatory patients –
Pre Clinical Trials of JUST-AAV Capsids
Researchers successfully created a brain-targeting AAV vector (brain-targeting JUST-AAV) by incorporating a miniaturized antibody that binds to the transferrin receptor, into the AAV capsid. Furthermore, unique modifications to the AAV capsid sequence significantly reduced AAV vector accumulation in the liver, a known source of adverse effects.
In mouse studies, the JUST-AAV vector achieved 77-fold higher expression of green fluorescent protein (GFP) in the brain compared to AAV9, while reducing the tropism to the liver by 99%. To further enhance brain targeting and BBB permeability, the researchers incorporated additional molecules that bind to receptors other than the transferrin receptor into the AAV capsid.
In monkey studies, this bispecific vector demonstrated an improved gene delivery efficiency to the brain by several orders of magnitude compared with AAV9, while reducing infection in potentially problematic tissues such as the liver and dorsal root ganglia by more than 90%.
Application of JUST-AAV to a mouse model of neuronal ceroid lipofuscinosis resulted in the disappearance of symptoms such as seizures and prolonged lifespan to an extent of a functional cure. These results suggest that the newly developed JUST-AAV technology offers the potential for safer and more efficient gene therapy than conventional gene delivery vectors. – Learn More: JCR Pharmaceuticals presents preclinical gene therapy data –
