Lili Nsongo

Yasmeen Rahimi

Thomas Shrader

Yale Jen

Yanan Zhu

Yigal Nochomovitz

Myles Minter

Pete Stavropoulos

Whitney Ijem

Angela Qian

Ed Arce

Evan Wang

Jake Roberge

Joohwan Kim

Kuan-Hung Lin

Samantha Schaeffer

Sarah Medeiros

Seamus Fernandez

Wing Yip

- Arcturus Therapeutics' shares plunged between **50% and 61%** following interim Phase 2 trial results for its inhaled mRNA therapy ARCT-032, which showed **no meaningful improvement in lung function (FEV1)** from Day 1 to Day 28 in cystic fibrosis patients.  **[1768224_821d6de583344ce386ce6e9b208349c6]** 
- A post hoc exploratory analysis, however, suggested some lung function improvements at Day 42, with an average absolute increase of **3.8%** and a relative increase of **5.1%** in percent predicted FEV1, and **four of six participants experienced reductions in mucus plugs and volume**.  **[1768224_821d6de583344ce386ce6e9b208349c6]** 
- The company is currently recruiting additional patients for higher dose testing and plans a **12-week safety and efficacy study in up to 20 cystic fibrosis patients in the first half of 2026**.  **[1768224_821d6de583344ce386ce6e9b208349c6]**

Arcturus Therapeutics Shares Decline Following Interim Cystic Fibrosis Trial Results

- Arcturus Therapeutics announced **interim Phase 2 clinical trial results** for its investigational inhaled mRNA therapy, **ARCT-032**, for cystic fibrosis, indicating it was generally safe and well tolerated.  **[1768224_0001193805-25-001499_e664913_ex99-2.htm:0]** 
- In the ARCT-032 trial, **4 out of 6 Class I CF participants** treated with 10 mg daily over 28 days exhibited encouraging **reductions in mucus plug number and volume**.  **[1768224_0001193805-25-001499_e664913_ex99-2.htm:0]** **[1768224_0001193805-25-001499_e664913_ex99-2.htm:1]**  A 12-week safety and preliminary efficacy study is planned for the **first half of 2026**.  **[1768224_0001193805-25-001499_e664913_ex99-2.htm:0]** **[1768224_0001193805-25-001499_e664913_ex99-2.htm:1]** 
- On **October 14, 2025**, the **FDA requested additional clinical endpoint efficacy study data** for the Biologics License Application (BLA) of KOSTAIVE, the company's COVID-19 vaccine, revising previous guidance and delaying the submission.  **[1768224_0001193805-25-001499_e664913_8k-arct.htm:2]** 
- CSL Seqirus submitted a Marketing Authorization Application (MAA) for KOSTAIVE to the UK MHRA in **June 2025**, with approval anticipated in the **first quarter of 2026**.  **[1768224_0001193805-25-001499_e664913_8k-arct.htm:2]** 
- Arcturus filed a **lawsuit on September 23, 2025**, against AbbVie Inc., Capstan Therapeutics, Inc., and others for trade secret misappropriation and breach of contract.  **[1768224_0001193805-25-001499_e664913_8k-arct.htm:2]**

Arcturus Therapeutics Reports Interim ARCT-032 Phase 2 Data and KOSTAIVE Regulatory Updates

- Arcturus Therapeutics announced **interim Phase 2 clinical trial results** for ARCT-032, an investigational inhaled mRNA therapy for cystic fibrosis.  **[1768224_cea30822443b42cc8645356d99a3fa6c_0]** 
- ARCT-032 was **generally safe and well tolerated** in the second cohort of six Class I CF adults.  **[1768224_cea30822443b42cc8645356d99a3fa6c_0]** 
- **Four out of six Class I CF participants** treated with 10 mg of ARCT-032 showed encouraging reductions in mucus plug number and volume after 28 days.  **[1768224_cea30822443b42cc8645356d99a3fa6c_0]** 
- Exploratory analysis also suggested lung function improvements in these four participants, with an average absolute increase of **3.8%** and a relative increase of **5.1%** in percent predicted FEV1.  **[1768224_cea30822443b42cc8645356d99a3fa6c_1]** 
- A **12-week safety and preliminary efficacy study** in up to 20 CF participants is planned to commence in the **first half of 2026**.  **[1768224_cea30822443b42cc8645356d99a3fa6c_0]** **[1768224_cea30822443b42cc8645356d99a3fa6c_1]**

Arcturus Therapeutics Reports Interim Phase 2 Data for Cystic Fibrosis Program

- Arcturus Therapeutics Holdings Inc.'s partner, Meiji Seika Pharma Co., Ltd., received **manufacturing and marketing approval in Japan** for **KOSTAIVE® (ARCT-2301)**, a **two-dose vial self-amplifying mRNA COVID-19 vaccine**.  **[1768224_0001193805-25-001247_e664805_ex99-1.htm:0]** **[1768224_0001193805-25-001247_e664805_8k-arct.htm:1]** 
- The vaccine targets the **SARS-CoV-2 Omicron sub lineage JN.1 variant XEC** and demonstrated neutralizing antibodies against multiple circulating variants in non-clinical studies.  **[1768224_0001193805-25-001247_e664805_ex99-1.htm:0]** **[1768224_0001193805-25-001247_e664805_8k-arct.htm:1]** 
- Meiji Seika Pharma anticipates **supplying the product starting in late September 2025**.  **[1768224_0001193805-25-001247_e664805_ex99-1.htm:0]**

Arcturus Therapeutics' Partner Receives Japanese Approval for COVID-19 Vaccine

Arcturus Therapeutics Holdings (ARCT)