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Arcturus is a leading RNA therapeutics company specializing in the treatment of rare diseases, based in San Diego, California. Beginning as a startup company only last year, they occupied a 1,500 square feet space in Torrey Pines Mesa, but following a rapid expansion from 2 to 13 employees, they recently made the decision to relocate to a 10,000 square feet area located in the Torrey Ridge Science Center. The move to a larger headquarters is in preparation for the expansion of their operations, which predicts to increase their number of employees again to around 35 within the following year, to help develop premier RNA medicines.

Arcturus’ leading RNA medicine is an UNA-modified, LUNAR-formulated siRNA targeting transthyretin (TTR) for the treatment of TTR-mediated amyloidosis.  This genetic, slowly progressive disease causes a buildup of the protein amyloid in various tissues and organs, most frequently in the peripheral nervous system. This often fatal condition is caused by mutations in the TTR gene which causes protein misfolding and deposits to build in the peripheral nerves and heart. With approximately 10,000 people worldwide affected, the need for an effective medicine is evident.

LUNAR is a proprietary lipid-enabled delivery system for RNA medicines including small interfering RNA, messenger RNA, antisense and microRNA oligotherapeutics. Any gene within the human genome can be targeted with this form of medicine by incorporating UNA (Unlocked Nucleic Acid) into the oligonucleotide drug candidate. Arcturus aims to produce a leading TTR medicine by developing a drug with superior safety profile, potency and dosing regimen.

The uptake of RNA by cells usually presents itself as a challenge which is why the development of a lipid-enabled delivery system is of great importance. Encasing the RNA within a lipid molecule allows the RNA to be taken up by the cell via endocytosis (see Figure A). The encapsulated RNA is then released into the cytosol following degradation of the lipid particle, taking advantage of its biodegradable properties.

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(Figure A): RNA encased inside a lipid particle for delivery. (courtesy of

Currently Arcturus is in development of the RNA medicine, LUNAR-101, which is entering its final clinical stage, aiming to treat cardiomyopathy from TTR, which affects around 40,000 people worldwide. Another RNA medicine, LUNAR-102, is entering the research stage, aiming to treat polyneuropathy from TTR, which affects around 10,000 people worldwide.