Joe Payne
Analyst · Leerink Partners. Please go ahead
Thank you, Neda. It's good to be with you again everybody. Over the last few months, there has been elevated interest in our mRNA therapeutics pipeline, given that we have meaningful clinical data sets forth coming. So, I will begin today's call with updates pertaining to our mRNA therapeutics pipeline. I will begin with an update on ARCT-032. This is our messenger RNA therapeutic candidate for cystic fibrosis. Arcturus is advancing at the moment in the open-label Phase 2 multiple ascending dose CF study in adults with CF, who are not eligible for CFTR modulator therapy, or are not taking CFTR modulators due to drug intolerance, poor response, or lack of access to modulators. Each adult participant in the Phase 2 CF study is expected to receive daily inhaled treatments of ARCT-032 over a period of 28 days. The study began last December, and to date, the study continues in multiple subjects without safety or tolerability issues. The company expects to complete Phase 2 enrollment by the end of the year, and provide Phase 2 interim data for the first two cohorts in mid-2025. I will now move on to our ARCT-810 program. This is our messenger RNA therapeutic candidate for Ornithine Transcarbamylase, or OTC deficiency. Arcturus continues to enroll participants in the open-label Phase 2 OTC deficiency study, with five intravenous infusions of ARCT-810 over a period of two months. The company previously completed the dosing phase, involving a cohort of eight people, and the dosing was at 0.3 mg/kg of placebo-controlled European study, enrolling OTC deficient individuals. The company expects to provide Phase 2 interim data this quarter, or Q2 2025. The U.S. Phase 2 study evaluates several biomarkers, including glutamine and ammonia. Elevated glutamine levels can occur when ammonia scavengers are used, particularly in individuals with urea cycle disorders such as OTC deficiency. While ammonia scavengers reduce circulating ammonia, glutamine may still be elevated due to its role as a temporary ammonia repository and therefore may be used as a useful biomarker to ascertain proper urea cycle function in OTC deficient individuals. We are also utilizing a newly-developed and improved 15N ureagenesis assay. This is supported by a newly-published paper out of Haverly's Lab at the University of Zurich. This 15N ureagenesis assay is expected to provide important data for monitoring the effect of ARCT-810 in the company's clinical development program. We are encouraged by the comprehensive data we have collected to date with our CF and OTC programs. And given the current market conditions, we have made a strategic decision to focus our resources toward our mRNA therapeutics pipeline. I now shift your attention to our partnered COVID-19 vaccine program. We are pleased about the recent EU approval of KOSTAIVE. This is our self-amplifying mRNA COVID-19 vaccine. Arcturus received an initial milestone payment from CSL, our global vaccine partner, in relation to the EU approval of KOSTAIVE. We continue to make progress expanding the global KOSTAIVE franchise. Company anticipates a marketing authorization application or MAA filing in the United Kingdom in Q2 2025, followed by a U.S. BLA filing in Q3 2025. The WHO is expected to announce the updated COVID strain later this week, and we, along with our partner CSL Seqirus, will update KOSTAIVE accordingly to support Meiji's distribution efforts in Japan this upcoming season. Our STARR self-amplifying mRNA platform continues to benefit from meaningful publications. The company recently published a comprehensive analysis of safety data for KOSTAIVE, with a 12-month follow-up from the pivotal clinical study in Vietnam, which had over 17,000 participants who received at least one dose of the study vaccine. The study confirmed the favorable reactogenicity profile, acceptable tolerability of ARCT-154 was also observed in older participants and individuals at high risk of severe COVID-19 due to underlying medical conditions. Long-term data from this large trial suggests that the sa-mRNA COVID vaccine is safe and well-tolerated, and did not include any reports of myocarditis or pericarditis. In April, Arcturus' Japanese partner, Meiji Seika Pharma, published an analysis characterizing the distribution and clearance of ARCT-154 encoded spike protein and non-structural proteins in the lymph nodes and injection site muscle in mice, following a single intramuscular vaccination. The study showed the encoded spike protein reached its highest level approximately three days after vaccination, and quickly disappeared from the injection site muscle. The spike protein persisted up to 28 days in lymph nodes after vaccination, and the data suggests that this prolonged spike protein expression may be credited for the observed higher immunogenicity. And as expected, the study also confirmed that the replication is limited. Now moving to ARCT-2304, this is our sa-mRNA vaccine candidate for Pandemic Influenza A, which is also known as H5N1, or the bird flu virus. In April, Arcturus received U.S. FDA fast track designation for ARCT-2304. As a reminder, this project has been supported in whole with federal funds from the HHS, ASPR, and BARDA. The company recently completed the recruitment of 212 adults, which included 80 participants over the age of 60 years old, in a randomized placebo-controlled Phase 1 trial being conducted here in the U.S. The company expects interim Phase 1 data in the second-half of 2025. And with that, I will now pass the call to Andy.