hVIVO plc

("hVIVO", the "Company" or the "Group")

Shionogi reports positive results from RSV antiviral human challenge trial conducted by hVIVO

Human challenge trials provide valuable insights to accelerate candidate development

hVIVO plc (AIM: HVO), a fast-growing early-stage Contract Research Organisation ("CRO") and the world leader in human challenge clinical trials, notes the announcement by Shionogi & Co., Ltd. ("Shionogi"), reporting positive results from a Phase 2a Respiratory Syncytial Virus ("RSV") human challenge trial ("HCT") conducted by hVIVO. The trial demonstrated a significant reduction in viral load for Shionogi's investigational oral RSV antiviral candidate, S-337395.

S-337395, which has received Fast Track designation from the U.S. Food and Drug Administration (FDA), was evaluated in a randomised, placebo-controlled, double-blind human challenge trial involving healthy volunteers recruited by hVIVO's volunteer recruitment arm, FluCamp. The antiviral efficacy and safety of S-337395 were evaluated when administered orally once daily for five days.

The S-337395 treatment group showed a statistically significant reduction in viral load compared to the placebo group, achieving the primary endpoint. In the highest dose group of S-337395, there was an 88.94% reduction in viral load (P<0.0001), and also a statistically significant improvement in clinical symptom scores. Additionally, S-337395 was generally safe and well tolerated, there were no serious or severe adverse events, and no dose-dependent increase in incidence or severity of adverse events. No participants discontinued due to adverse events.

These findings reinforce the crucial role of human challenge trials in accelerating drug development by generating rapid efficacy data, reducing risk in later-stage trials. hVIVO has over three decades of expertise and continues to lead in safely conducting HCTs for a range of respiratory viruses, including RSV, influenza, human rhinovirus (HRV - common cold virus), and COVID-19. To date, hVIVO has conducted 30 RSV challenge trials involving approximately 2,000 healthy volunteers, expediting the development of multiple RSV antiviral and vaccine candidates. The Company's RSV challenge model has provided pivotal proof-of-concept data for vaccines and antivirals and has contributed to regulatory designations, product acquisitions, and market approvals.

hVIVO remains committed to advancing antiviral research through its industry-leading human challenge models and looks forward to supporting Shionogi in the continued development of S-337395.

Shionogi's full announcement is available here.

Dr Andrew Catchpole, Chief Scientific Officer of hVIVO, said: "These results demonstrate the power of human challenge trials in accelerating the development of much-needed RSV treatments. The significant reduction in viral load and improvement in clinical symptoms observed with S-337395 demonstrate the potential of this antiviral candidate to address the urgent need for effective RSV therapies. At hVIVO, we are proud to leverage our decades of experience in human challenge trials to support innovative drug development, helping to bring promising new treatments to patients faster. We look forward to seeing continued success for Shionogi and S-337395 going forward."

For further information please contact:

Notes to Editors

hVIVO plc (Ticker: HVO) is a rapidly growing early-stage Contract Research Organisation (CRO) and the global leader in human challenge trials. The company delivers end-to-end clinical development services to a diverse and expanding client base, including seven of the world's ten largest biopharma companies.

hVIVO specialises in conducting human challenge trials across multiple infectious and respiratory indications, leveraging its state-of-the-art quarantine facility in London-the largest of its kind worldwide. The company also offers comprehensive virology and immunology laboratory services under the hLAB brand.

Through its German subsidiary, CRS, hVIVO operates a 120-bed capacity across Mannheim and Kiel, providing early-phase clinical trial services, including first-in-human and proof-of-concept studies. Its second subsidiary, Venn Life Sciences, offers Early Drug Development Consulting and Biometry services to the biopharma sector.

The Group provides fully integrated drug development solutions from preclinical stages through Phase II trials, alongside patient recruitment via FluCamp. Additionally, its five clinical sites support outpatient Phase II and III trials, ensuring a seamless and efficient pathway from discovery to late-stage development.