Arcturus will enroll up to 20 participants with Class 1 cystic fibrosis mutations in a 12-week open-label Phase 2 study of ARCT-032, initiating treatment at 10 mg daily based on established safety and early clinical signals. The trial will evaluate spirometry (% predicted FEV1), Lung Clearance Index, quality-of-life scores and serial CT imaging, with an option to escalate dosing to 15 mg and tightened enrollment criteria to reduce measurement variability.

The ARCT-810 mRNA therapeutic for ornithine transcarbamylase deficiency is advancing toward Type C regulatory meetings with health authorities in the first half of 2026. Management plans to discuss separate adult and pediatric trial designs, focusing on endpoints like reductions in dietary restrictions and standard-of-care measures under recent FDA guidance for ultra-rare populations.

In January 2026 the UK Medicines and Healthcare Products Regulatory Agency approved KOSTAIVE, Arcturus’s self-amplifying mRNA COVID-19 vaccine for adults, while U.S. licensure discussions with CSL continue. The BARDA-funded ARCT-2304 H5N1 STARR vaccine completed a Phase 1 study in 212 young and 80 older adults, showing durable immune responses and favorable tolerability across all dose levels.

Arcturus reported a $70.3 million annual revenue decline driven by reduced CSL collaboration revenue and milestone achievements, with quarterly revenue down $15.6 million year-over-year. Annual R&D expenses fell by $83 million due to program transitions, extending the company’s cash runway into 2028, although upcoming Phase 2 costs will partially offset these savings.