ORPH.L Regulatory News (ORPH)

Open Orphan plc

("Open Orphan" or the "Company")

Positive results from RSV Human Challenge Study

Data on Phase 2a study published in New England Journal of Medicine

Open Orphan plc (AIM: ORPH), a rapidly growing specialist contract research organisation (CRO) and world leader in testing infectious and respiratory disease products using human challenge clinical trials, notes the announcement dated February 17 2022 from Enanta Pharmaceuticals, Inc. (NASDAQ: ENTA), a clinical stage biotechnology company dedicated to creating small molecule drugs for viral infections and liver diseases, on positive results from a human challenge study assessing its respiratory syncytial virus ("RSV") antiviral candidate, EDP-938. The results from this human challenge study have been published in The New England Journal of Medicine. hVIVO, a subsidiary of Open Orphan, conducted the Phase 2a, double-blind, placebo-controlled trial using its RSV Human Challenge Study Model.

The trial enrolled 178 healthy adult volunteers across two parts, 18-55 years of age, who were intranasally challenged with RSV-A Memphis 37b ("M37b"). Volunteers received either a dose of EDP-938 or placebo for five days after infection, with different dose levels of EDP-938 being assessed. The study demonstrated that both viral load and clinical symptoms were significantly lower in volunteers that received EDP-938 than those that received placebo, with similar safety profiles between placebo and the antiviral regimens. Importantly, no serious adverse events occurred.

RSV is a contagious, common respiratory virus that usually causes mild, cold-like symptoms and affects the respiratory tract of children and at-risk older adults; in severe cases, it can cause pneumonia and other life-threatening breathing difficulties. RSV is a significant public health threat and is one of the leading causes of hospitalisation to at-risk older adults.

hVIVO has two decades of experience and expertise in safely conducting challenge studies across a range of respiratory and infectious disease viruses, including various strains of influenza, RSV, HRV, asthma and malaria, etc.

Dr Andrew Catchpole, Chief Scientific Officer of hVIVO said: "It's pleasing to see another of our clients getting such positive results from a human challenge study that we conducted, and that the data has been published in The New England Journal of Medicine. EDP-938 is a potentially important medicine that could help reduce the global impact of RSV, and I look forward to following Enanta's continued progression of the candidate through further clinical trials."

Cathal Friel, Executive Chairman of Open Orphan, said: "We are delighted to see that this important Phase 2a study of EDP-938 has yielded such positive results. We are a world leader in testing infectious and respiratory disease products using challenge studies such as this, and RSV is just one portion of our portfolio of challenge models, which also includes influenza, HRV, malaria, asthma, and now SARS-CoV-2. We look forward to continue offering our world class services to partners as we look to meet the growing demand from the infectious disease market."

Interested in becoming a volunteer?

hVIVO recruits many of its volunteers for its challenge study clinical trials through its dedicated volunteer recruitment website, www.flucamp.com. By volunteering to take part in one of our studies in a safe, controlled, clinical environment under expertly supervised conditions you are playing your part to further medical research and help increase the understanding of respiratory illnesses.

Individuals interested in taking part in COVID-19 human challenge study research can learn more at www.UKCovidChallenge.com.

For further information please contact:

Notes to Editors

Open Orphan plc

Open Orphan plc (London and Euronext: ORPH) is a rapidly growing contract research company that is a world leader in testing vaccines and antivirals using human challenge clinical trials. The Company provides services to Big Pharma, biotech and government/public health organisations.

Open Orphan runs challenge studies in London from both its 19-bedroom Whitechapel quarantine clinic and its state-of-the-art 24-bedroom QMB clinic with its highly specialised on-site virology and immunology laboratory. The Company has a leading portfolio of human challenge study models for infectious and respiratory diseases and is developing a number of new models. There has been an explosion in the growth of the infectious disease market, which is estimated to grow to in excess of $250bn by 2025. The Group is focused on refreshing its existing challenge models and develop new models, such as Malaria, to address the dramatic growth potential of the global infectious disease market.

Building upon its many years of challenge studies and virology research, the Company is developing an in-depth database of infectious disease progression data. Based on the Company's Disease in Motion® platform, this unique dataset includes clinical, immunological, virological and digital (wearable) biomarkers. The Disease in Motion platform has many potential applications across a wide variety of end users including big technology, wearables, pharma and biotech companies.

Open Orphan's Paris office has been providing biometry, data management and statistics to its many European pharmaceutical clients for over 20 years. For over 15 years, the Company's Netherlands office has been providing drug development consultancy and services, including CMC (chemistry, manufacturing and controls), PK and medical writing, to a broad range of European clients. Both offices are now also fully integrated with the London office and working on challenge study contracts as well as supporting third party trial contracts.