Arcturus Therapeutics is a biotechnology company developing mRNA medicines and vaccines, including self-amplifying mRNA platforms, targeting infectious diseases and rare genetic disorders affecting organs such as the lungs and liver.
It has been one year since the commercialization of Arcturus’ self-amplifying mRNA COVID vaccine. What real-world implications have you observed so far?
Self-amplifying mRNA is ideally designed for vaccines. It expresses antigens very efficiently at low doses and has shown superiority in multiple Phase 3 trials compared to conventional mRNA. The mRNA enters muscle cells, which then produce antigens in a more efficient and superior manner, and we’ve now validated that.
That has two major implications. First, pandemic preparedness. Countries learned from COVID that another outbreak is inevitable, so there are serious conversations about being better prepared. Second, oncology. Conventional mRNA is being explored in cancer vaccines, and self-amplifying mRNA could help develop superior approaches. In COVID specifically, it’s a dynamic and politicised space, but we have a product in 31 countries, partnered with CSL and Meiji in Japan, and we continue to monitor how that evolves.
Are you planning to move into oncology?
We have early research exploring self-amplifying mRNA across infectious disease and oncology. However, oncology is not a core focus for Arcturus.
If self-amplifying mRNA advances in oncology, it would likely be through partnership with companies that specialise in cancer drug development. That’s where it fits strategically for us.
Turning to rare disease, you had interim Phase 2 readouts in cystic fibrosis. What stood out, and why is 2026 pivotal?
2026 has the potential to be the most pivotal year in our 13-year history. In cystic fibrosis, we demonstrated safety and tolerability for daily inhaled mRNA dosing and escalated successfully to 15 milligrams, which is significant. For decades, the challenge has been delivering meaningful doses of inhaled mRNA because the lungs don’t tolerate foreign substances easily.
What’s exciting is that at these dose levels, we began seeing structural changes in the lung. In Class 1 CF patients, we observed reductions in mucus plugs over 28 days, measured through high-resolution CT scans. The key question now is whether that mucus reduction translates into lung function improvement. If it does, that validates not just the drug but the entire inhaled mRNA platform.
What comes next in that program?
We’re moving into a 12-week study with 20 patients, rather than a small short-duration cohort. The study is designed to be statistically sound, with stronger baselines and historical lung function data built in.
The goal is clear: confirm safety and tolerability over 12 weeks and determine whether mucus plug reduction leads to measurable improvements in lung function. For Class 1 CF, where there is currently no treatment, that would be extraordinary.
What about your OTC deficiency program?
We have a program for ornithine transcarbamylase deficiency, or OTC deficiency, a rare liver disease. Unlike the inhaled CF therapy, this mRNA drug is administered intravenously and designed to efficiently deliver RNA to the liver.
Last year we established safety and tolerability and saw biomarkers normalised—not just reduced, but returning to normal levels. We normalised ammonia and glutamine, which is particularly meaningful. That programme has important milestones coming up in 2026 as well.
How has your broader strategy evolved as these programs mature?
Now that self-amplifying mRNA in vaccines has been partnered, we’ve increased our focus internally on rare diseases of the lung and liver.
The mRNA field is at a turning point—moving beyond infectious disease vaccines into broader therapeutic applications.
If we deliver strong data this year in both CF and OTC deficiency, it significantly expands the applicability of mRNA into major organ systems, with the potential to address many diseases.
Has the change in the White House affected your plans, particularly around mRNA?
We’ve felt the impact. A planned BLA filing in the vaccine space was delayed due to changes in philosophy and messaging around vaccines. That directly affected our U.S. strategy.
At the same time, the administration has emphasised accelerating therapies for children with fatal rare diseases. That could benefit programmes like OTC deficiency and CF. We’re preparing multiple Type C meetings with the FDA to discuss regulatory pathways, especially for young children with OTC deficiency, where the unmet need is severe. We’re cautiously optimistic.
One year from now, what would success look like?
For OTC deficiency, success means clarity—a defined regulatory path and line of sight to approval so we can get this drug to children as quickly as possible.
For cystic fibrosis, success means confirming safety and tolerability over 12 weeks and demonstrating lung function improvement alongside mucus reduction. If that happens, it would be a first in Class 1 CF and would validate inhaled mRNA as a transformative platform.
