Mereo BioPharma : first patient dosed in phase 2 alpha-1 antitrypsin deficiency study

London, 5 November 2018 – Mereo BioPharma Group plc (AIM: MPH), a clinical stage UK based biopharmaceutical company focused on rare diseases, is pleased to announce that the first patient has been dosed in its Phase 2 clinical study of MPH-966 (alvelestat) for the treatment of alpha-1 antitrypsin deficiency (AATD). The study is being conducted in the United States and Europe with top line data expected in H2 2019.

The Company also announced today a collaboration with and investment from the venture philanthropy arm of the Alpha-1 Foundation, The Alpha-1 Project, Inc. (TAP). TAP is investing in Mereo’s MPH-966 development programme subject to the Company meeting agreed development milestones. The Company has also agreed to issue warrants to TAP, on future dates, to subscribe for shares in the Company subject to TAP making the agreed investments in the programme with the first such investment milestone being the dosing of the first patient in the MPH-966 development programme.

AATD is a potentially life-threatening rare, genetic condition, with an estimated 50,000 patients in North America and 60,000 patients in Europe suffering from a severe form of the disease. It can cause severe debilitating conditions such as chronic liver disease but, most notably, pulmonary emphysema, which is a life-threatening disease. Current standard of care for AATD often involves protein replacement therapy, which requires weekly intravenous infusions of plasma-derived alpha 1 antitrypsin, however, fewer than 10,000 patients are currently treated with this therapy in the U.S. and it is not currently available in some European countries. MPH-966 is an oral neutrophil elastase inhibitor that specifically targets the neutrophil elastase which is primarily responsible for the lung degradation in AATD patients. Mereo therefore believes MPH-966 is highly differentiated from protein replacement therapy.

The Phase 2 study is a 12-week randomized, placebo controlled, clinical trial evaluating two doses of MPH-966 in approximately 165 patients with the PiZZ or NULL genetic mutations. These mutations are associated with the more severely affected patients who have very low (PiZZ) or zero (NULL) alpha-1 antitrypsin levels. The primary endpoint of the study is the change from baseline on biomarkers of neutrophil activity through the measurement of desmosine/isodesomine at 12 weeks compared to placebo. Desmosine has been shown to correlate with deterioration of lung tissue as determined by CT scans in previous studies in AATD patients. If the results of this trial are positive, Mereo intends to seek regulatory advice on the design of a pivotal trial.

Jean-Marc Quach, President and CEO of The Alpha-1 Project said:

‘We are very pleased that the first patient has been successfully dosed in this phase 2 study in alpha-1 antitrypsin deficiency. We are excited by the potential for a new oral therapeutic to improve the lives of our patients with this debilitating disease and are pleased to be supporting Mereo with this phase 2 study.’

Dr Denise Scots-Knight, Chief Executive Officer of Mereo BioPharma Group plc commented:

‘We are happy to announce today, both that the first patient has been dosed in this clinical study and that we have agreed an investment from the Alpha-1 Foundation through TAP. We strive to work closely with patient groups who support those with the orphan and rare diseases we are targeting and are delighted to be working with the Foundation on this study. We will continue to enrol patients over the coming months and look forward to reporting top line data in the second half of 2019.’