Arcturus Therapeutics’ 2026 Q2 Call: Regulatory Path Clarity, CF Data Timelines, and Safety Disclosure Shifts Don’t Align

Date of Call: Aug 6, 2026

Financials Results

• Revenue: $3M for Q2 2026, $5M for H1 2026, compared to $28.3M and $57.7M in the comparable periods last year

Guidance:

• Decision to advance ARCT 032 (CF) program into Phase 3 expected in Q4 2026.
• Expect to communicate ARCT 810 (OTC deficiency) Phase 2 clinical study data and regulatory path forward in Q3 2026.
• Cash runway of over two and a half years through year-end 2028.

Business Commentary:

Rare Disease Pipeline Progress:

• Arcturus Therapeutics advanced its Phase 2 study for ARCT 032, an inhaled mRNA therapeutic for cystic fibrosis (CF), with active enrollment in the U.S., Israel, and Turkey.
• The decision to proceed to Phase 3 is expected in Q4 2026, contingent on data from the ongoing study.
• The expansion into Israel and Turkey aids recruitment due to higher prevalence of Class 1 CF mutations.

OTC Deficiency Program Update:

• Enrollment and dosing in the Phase 2 study for ARCT 810, an mRNA therapeutic for ornithine transcarbamylase deficiency (OTC), have been completed.
• Regulatory discussions and data readout are planned for Q3 2026.
• The focus is on evaluating the totality of data, including biomarkers and patient-reported outcomes, to inform the regulatory path forward.

Vaccine Franchise and Strategic Developments:

• Arcturus regained global rights to its COVID vaccine, CoStave, and the broader infectious disease vaccine portfolio from CSL Securus.
• The company received a $12 million payment and is released from liabilities worth approximately $16 million.
• Having strategic control of the validated SA mRNA platform presents opportunities for commercialization and partnerships.

Financial Position and Resource Allocation:

• Cash and cash equivalents were $191.5 million as of June 30, 2026, with a decrease of $39.3 million over the first half of the year.
• The company is focused on disciplined execution and capital allocation to advance its rare disease programs.
• The strong balance sheet provides a cash runway of over two and a half years, supporting the achievement of key milestones.

Sentiment Analysis:

Overall Tone: Positive

• "The second quarter of 2026 was marked by continued execution... and important strategic developments." "We are pleased to regain global rights... to our commercial COVID vaccine product... Having strategic control of this validated vaccine platform is an exciting opportunity." "We remain focused on advancing important clinical, regulatory, and corporate milestones."

Q&A:

• Question from Lily Nosongo (Lyric Partners): Could you provide detail on the data expected for the OTC program readout later this quarter? Will it include U.S. pediatric, adolescent, adult, and longer-term European patient updates?
  Response: The update will include the full Phase 2 clinical data (U.S. and European datasets) and supplementary data requested by the FDA, along with details on the regulatory path forward.

• Question from Lily Nosongo (Lyric Partners): For the OTC program, do you view diet liberalization as the bar for success, or should we look at biomarker levels?
  Response: Success will be assessed based on the totality of data, including biomarkers (ammonia, glutamine, urea), patient-reported quality of life, and functional measures.

• Question from Pete Staropoulos (Cantor Fitzgerald): On the CF program, how has enrollment cadence been, will you wait for all patients to complete before data disclosure, and are there plans to adjust the protocol for dosing past 12 weeks?
  Response: Enrollment confidence is high due to expanded international sites. The decision to proceed (triggering Thermo Fisher support) is the key milestone guided for Q4, not a specific data disclosure.

• Question from Pete Staropoulos (Cantor Fitzgerald): Can you discuss the sensitivity and variability of LCI testing used in the CF Phase 2 study?
  Response: LCI provides a more sensitive measure of changes in small airways for sicker patients. Access to normative data from the REACH study will help with interpretation, and the test adds nuanced information beyond traditional spirometry.

• Question from Quan (Wells Fargo): For the CF program, what kind of dataset is expected by Q4 to make a Phase 3 decision, and are there any safety updates?
  Response: The decision will consider FEV1, LCI, high-res CT, and quality of life data. No safety signals have been observed; confidence in safety is high based on over 50 participants dosed up to 15mg for 28 days.

• Question from Quan (Wells Fargo): Has the EOP2 meeting with FDA for OTC been scheduled, and what are potential outcomes?
  Response: A fulsome data and regulatory path update is guided for later this quarter, which will provide details on the EOP2 meeting and its outcomes.

• Question from Juwan Kim (Citigroup): Can you discuss the collaboration with Thermo Fisher and whether they saw interim Phase II data or 15mg data ahead of the deal?
  Response: Thermo Fisher became the exclusive commercial manufacturing partner due to competitive interest. They had access to all clinical data, including internal safety data, under a CDA.

• Question from Jay Gon (William Blair): What are the baseline hyperammonemic crisis rates in the OTC Phase 2 study, and what is the regulatory path for CoStave approval in the U.S.?
  Response: The Phase 2 study isn't designed to capture hyperammonemic events; focus is on stable patients to assess biomarker impact. For CoStave, the regulatory path in the U.S. is clear, with specific requirements communicated by the FDA.

• Question from Whitney Isham (Concord Genuity): How are you thinking about quantitative endpoints for the CF Phase 3 decision, and can you move forward without an FEV benefit?
  Response: Thresholds of success will be set by Arcturus, not historical precedents. A positive outcome on any collected data (FEV, LCI, CT, quality of life) would be a win. Stabilizing lung function and improving patient well-being are key.

• Question from Whitney Isham (Concord Genuity): What is the impact of the CSL relationship change on CoStave in Japan?
  Response: Profit share for Japan will now be split two ways (Arcturus and Meiji). Active conversations are ongoing, and manufacturing/ shipping support continues for the upcoming season.

• Question from Adam Walsh (Roth Capital Partners): Given the lack of tolerability disclosure for ARCT 032 so far, can we read into that or are we over our skis?
  Response: Management will comment on safety and tolerability when appropriate, likely after a larger body of data over more patients and longer exposure, as the trial is open-label.

• Question from Jenny Kim (BTIG): With global vaccine rights regained, how are you thinking about the cost to maintain and monetize CoStave and the broader portfolio, and does this change R&D expense trajectory?
  Response: Focus is on commercialization (expanding in Europe, UK) and business development/partnership pathways for the validated platform to fund further development, not a significant change to R&D expense.

• Question from Yale Jen (LifeSci Capital): Besides CoStave, what is the clinical stage of other vaccines (flu, RSV, EBV)?
  Response: Most data is undisclosed/preclinical. Phase 1 for pandemic flu (ARCT 2304) is completed, with results to be published and scientific advice with EMA planned for Q4. Other programs (seasonal flu, RSV, EBV) will be disclosed under CDA.

• Question from Yale Jen (LifeSci Capital): If MAGIE chooses to develop a COVID vaccine for the next season, will Arcturus be involved?
  Response: Arcturus will support MAGIE in any way possible, especially in manufacturing and timely delivery of materials.

Contradiction Point 1

Regulatory Path Clarity for CoStave (KOSTAIVE) in the U.S.

The certainty of the regulatory pathway for U.S. approval appears to shift between calls.

Juwan Kim (Citigroup) - Juwan Kim (Citigroup)

2026Q2: The regulatory path for CoStave U.S. approval is clear based on ongoing discussions with the FDA. - Joe Payne(CEO)

Can you discuss the collaboration with Thermo Fisher, including how it came about and whether they reviewed any interim Phase II data (e.g., 15 mg) prior to the deal? - Whitney Isham (Concord Genuity)

2026Q2: The path is clear based on interactions with the U.S. FDA. - Joseph Payne(CEO)

Contradiction Point 2

Safety/Tolerability Data Disclosure for ARCT-032 (CF) Program

The company's stance on when to disclose detailed safety/tolerability data appears inconsistent.

Adam Walsh (Roth Capital Partners) - Adam Walsh (Roth Capital Partners)

2026Q2: The company will disclose any material safety issues as required. However, they prefer to wait for an appropriate time to share detailed safety and tolerability data... - Joe Payne(CEO) and Dr. Alan Cohen(CMO)

"Does the lack of tolerability data for Cohort 4 of ARCT-032, which began dosing in March 2026, indicate a concern or is it premature to assume anything?" - Adam Walsh (Roth Capital Partners)

2026Q2: The company will disclose any material safety issues as required. - Joe Payne(CEO) and Dr. Alan Cohen(CMO)

Contradiction Point 3

Regulatory Pathway and Data Requirements for OTC (ARCT-810)

Contradiction on the clarity and status of the regulatory path forward.

Quan (Wells Fargo) - Quan (Wells Fargo)

2026Q2: The company will provide a fulsome update on the OTC program, including details about the EOP2 meeting, later in Q3 2026. This will be the appropriate time to discuss the meeting's outcomes and the regulatory path forward. - Joe Payne(CFO)

Has the End-of-Phase-Two (EOP2) meeting with the FDA for the OTC program (ARCT-810) been scheduled, and what are the potential outcomes? - Lily Nzunga (Leerink Partners)

2026Q1: The FDA's Type C meeting provided clear regulatory direction toward a pivotal pediatric study... An End of Phase II meeting is planned for H2 2026 to discuss... needed to justify a pediatric trial... - Dr. Alan Cohen(CFO), Joe Payne(CFO)

Contradiction Point 4

Timeline and Nature of Data Disclosure for CF (ARCT-032)

Contradiction on the basis for proceeding to Phase III and the disclosure strategy.

What did Pete Staropoulos discuss regarding Cantor Fitzgerald's earnings? - Pete Staropoulos (Cantor Fitzgerald)

2026Q2: The decision to proceed to Phase III (planned for Q4 2026) will be based on the accumulated dataset, not on enrollment completion. The positive data generated to date... is expected to be sufficient for an informed decision. - Joe Payne(CFO), Dr. Alan Cohen(CFO)

Regarding the CF program (ARCT-032), could you provide updates on enrollment cadence and the timeline for data disclosure, including whether interim results might be available? - Mayank Mantani (B. Riley Securities)

2026Q1: By the end of this calendar year, the company expects to have sufficient data to comment on the program's future direction. - Dr. Alan Cohen(CFO), Joe Payne(CFO)

Contradiction Point 5

Decision-Making Criteria for CF Phase III

Contradiction on whether a positive signal in FEV1 is a requirement for proceeding to Phase III.

Whitney Isham (Concord Genuity) - Whitney Isham (Concord Genuity)

2026Q2: Any positive data across the collected measures (FEV1, LCI, CT, quality of life) would be a significant win. Stabilizing or improving lung function (FEV1 decline is ~1-2% annually) and improving patient-reported outcomes will be key factors in the decision. - Joe Payne(CFO) and Dr. Alan Cohen(CFO)

For the CF program, how are you thinking about the quantitative endpoints for the Phase III decision, and could you move forward based on LCI or CT data if FEV1 isn't showing a benefit? - Adam Walsh (ROTH Capital)

20260304-2025 Q4: The exact question about OTC (functional data vs. biomarkers) is on the agenda for the upcoming Type C meetings. The company will be able to provide a detailed answer on the importance of functional endpoints versus biomarker packages after consulting with the FDA in a few months. - Joseph Payne(CFO)