Arcturus Therapeutics Q1 Earnings Call Highlights

Key Points

• ARCT-032, the inhaled mRNA cystic fibrosis candidate, has entered a 12-week Phase II open-label study with dosing "well beyond one month" — a milestone the company attributes to its LUNAR delivery lipids and purification process and which allowed initiation at 10 mg daily after favorable safety monitoring.
• ARCT-810 (OTC deficiency) received clear regulatory guidance from an FDA Type C meeting on a pediatric development path, with ammonia and glutamine biomarkers endorsed; Arcturus is continuing adult dosing and plans an end-of-Phase II meeting in H2 2026 to align on a pivotal pediatric study.
• Arcturus reported $213.4 million in cash as of March 31, 2026 and says its cash runway extends beyond the second quarter of 2028, supporting near-term milestones, while partner Meiji is manufacturing the self-amplifying mRNA COVID vaccine KOSTAIVE for the 2026/2027 season amid lower revenue and reduced R&D/G&A expenses.

Arcturus Therapeutics NASDAQ: ARCT executives highlighted progress in two rare-disease clinical programs and outlined a strengthened cash runway during the company’s first-quarter 2026 earnings call, while also discussing ongoing partner activity for its self-amplifying mRNA COVID-19 vaccine in Japan.

CF program enters longer repeat-dosing study

President and CEO Joe Payne said the company’s inhaled mRNA cystic fibrosis (CF) candidate, ARCT-032, has moved into what he described as “new uncharted territory” as Arcturus began enrolling a 12-week, open-label Phase II study during the first quarter and is “well beyond one month of dosing.” Payne said continuous dosing beyond a month “has never been successfully tolerated in the history of inhaled mRNA therapeutics,” and argued that chronic dosing is important in Class 1 CF because of what he described as pulmonary congestion requiring “consistent chronic dosing that is reasonably well-tolerated.”

Payne attributed the company’s ability to dose beyond a month to two factors: Arcturus’ inhaled LUNAR particle technology, which he said uses delivery lipids “chemically different from all other technologies” in the space, and a proprietary manufacturing process intended to remove undesired impurities. He also said the CF community’s awareness of ARCT-032’s safety and tolerability profile contributed to initiating enrollment “earlier than originally anticipated.”

Chief Medical Officer Dr. Alan Cohen said the 12-week Phase II study is designed to monitor safety and tolerability and assess “evidence of early clinical benefit,” including changes in percent predicted FEV1 and lung clearance index (LCI). He said the company is also evaluating two validated quality-of-life measures and changes in high-resolution CT imaging to provide a more comprehensive assessment of potential clinical effects.

In the Q&A, management said the current study does not include a placebo arm. Cohen emphasized steps taken to improve spirometry reliability, noting that many CF patients have long experience performing spirometry and that the protocol includes screening and baseline parameters to limit excessive variability. He also pointed to the need for additional natural-history data in adults for LCI, and said the Cystic Fibrosis Foundation is conducting a prospective study in a similar population, with data expected to be shared later this year going into 2027 at the North American Cystic Fibrosis Conference (NACFC). Cohen said Arcturus expects access to that dataset.

Payne added that the FDA has not defined a threshold of success for FEV1 or LCI for Arcturus’ program and said “anything positive would be viewed seriously” for a new modality like inhaled mRNA in Class 1 CF.

On enrollment, Payne said the cadence “is being determined in the upcoming weeks,” and that the company expects to provide a clearer timeline for enrollment completion later this year. He also reminded listeners that Arcturus enrolled about 13 subjects in 2025 across three cohorts in the U.S. and is now expanding enrollment outside the U.S.

Asked about a competitor discontinuing an inhaled CFTR mRNA trial, Payne said Arcturus has not seen similar manifestations and cited differences in delivery technology and mRNA purification. He highlighted that Arcturus has used “no steroids as a co-treatment” and has been approved for unsupervised dosing at home, which he contrasted with other companies. Cohen added that following completion of cohort 3 dosing up to 15 mg daily for 28 days, the safety monitoring committee “saw nothing clinically worrisome” and permitted a longer 12-week study at 10 mg or 15 mg daily; the company is initiating the 12-week study at 10 mg once daily.

OTC program: FDA Type C meeting supports pediatric path

Arcturus also provided an update on ARCT-810, its mRNA therapeutic candidate for ornithine transcarbamylase (OTC) deficiency. Payne said the company met with the FDA to discuss a pediatric clinical development strategy and received “clear regulatory direction on a path toward a pivotal pediatric study.” He said the company is collecting additional exploratory data and anticipates further alignment with the FDA at an end-of-Phase II meeting planned for the second half of 2026.

During Q&A, Cohen said the company has completed the first of two Type C meetings, which focused on using adult Phase II data to support moving into pediatrics. He said the FDA highlighted the “utility of the biomarkers,” including ammonia and glutamine, and that Arcturus has greater clarity on which biomarkers to use going forward. Cohen said ureagenesis remains “a biomarker in development,” and the degree of reliance on it will depend on additional data being generated.

Cohen said the company is continuing enrollment in adult dosing groups, including 0.3 and 0.5 mg/kg, and intends to bring a completed dataset to the end-of-Phase II meeting. He said the goal is to demonstrate safety and tolerability and “enough evidence of clinical efficacy” to justify studies in young children and newborns. On patient segmentation, Cohen said the highest unmet-need group is generally under age six, noting that severe early-presenting patients may require transplant or face mortality if not stabilized. He said the pediatric focus would be on “children in the first weeks and months of life up through probably age six.”

Asked whether ARCT-810 would be a stopgap ahead of transplant or potentially longer-term, Cohen said the company’s hope is not only to forestall liver transplant but “keep these children from requiring… liver transplants lifelong” if intervention occurs early enough.

Partner activity: Meiji manufacturing KOSTAIVE for 2026/2027 season

Payne said partner Meiji in Japan is actively manufacturing KOSTAIVE, Arcturus’ self-amplifying mRNA COVID-19 vaccine, for the 2026/2027 season using a two-dose vial presentation. He noted that commercial guidance for KOSTAIVE in Japan will be provided by Meiji.

Financial update: revenue down, expenses lower, runway extended

Chief Financial Officer Dennis Mulroy, who recently joined the company, reviewed first-quarter results. Mulroy said cash, cash equivalents, and restricted cash totaled $213.4 million as of March 31, 2026, compared with $232.8 million as of December 31, 2025.

Mulroy said quarterly revenue decreased year-over-year by $27.3 million, driven by reductions in revenue from the company’s CSL collaboration as Arcturus refocuses on rare disease clinical programs.

On expenses, Mulroy said R&D costs decreased year-over-year by $13.4 million, driven primarily by lower manufacturing and clinical trial costs related to LUNAR-COV19 and BARDA, along with lower payroll and benefits tied to reduced stock-based compensation and headcount reductions. He said these reductions were partially offset by higher manufacturing costs related to LUNAR-OTC.

Mulroy said G&A expenses decreased year-over-year by $1.8 million due to reduced share-based compensation and lower payroll and benefits associated with headcount reductions.

He added that Arcturus has maintained a cash runway “extending beyond the second quarter of 2028,” which he said supports multiple near-term milestones for the company’s therapeutic programs.

Leadership changes and 2026 priorities

Payne said Arcturus expanded its executive leadership team with the appointments of Mulroy as CFO and Cohen as CMO. In closing remarks, Payne said the company remains focused on clinical and regulatory milestones throughout 2026, supported by what management characterized as a strong balance sheet and a more experienced leadership team.

About Arcturus Therapeutics NASDAQ: ARCT

Arcturus Therapeutics Holdings Inc is a clinical-stage biotechnology company dedicated to developing messenger RNA (mRNA) medicines that address a range of diseases. The company leverages its proprietary STARR® mRNA platform to enable precise control over mRNA expression, supported by its lipid nanoparticle delivery technology, LUNAR®. Arcturus's approach is designed to address both therapeutic and prophylactic applications, with an emphasis on vaccines and treatments for rare genetic and infectious diseases.

The company's pipeline includes ARCT-810, an mRNA therapeutic candidate for phenylketonuria (PKU), and ARCT-021 (also known as LUNAR-COV19), a COVID-19 vaccine candidate developed in collaboration with Duke-NUS Medical School in Singapore.

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