BPS-804 (setrusumab) is a fully human monoclonal antibody designed to inhibit sclerostin, thereby improving bone strength and therefore reduce fractures in patients with osteogenesis imperfecta (OI) and improve quality of life.

OI is a rare genetic disorder, commonly known as brittle bone disease, which is characterized by fragile bones that fracture easily. In addition to fractures, individuals with OI often have muscle weakness, hearing loss, fatigue, joint laxity, curved bones, scoliosis, and short stature. The majority of cases of OI (up to 90 %) are caused by a dominant mutation in the genes coding for type I collagen, a key component of healthy bone. Current treatment of OI is based on supportive care, focusing on treating fractures and maximizing mobility. To date, there are no FDA or EMA approved treatments.

Clinical Status

We have enrolled 112 adult patients in the US and Europe into a Phase 2b study designed to measure increase in bone density measured by HRpQCT, as well as other aspects of OI. The study has 3 blinded dose-ranging arms and an open-label arm at the top dose.  The open-label arm reported six-month open-label data on the top dose on 30 May 2019.  Top-line 12-month data from the other three blinded dose-ranging arms of the study are expected in Q4 2019. A Paediatric Investigation Plan (PIP) has been approved by the European Medicines Agency (EMA) in approximately 165 children with severe disease aged 5-18 years old.

BPS-804 (setrusumab) has been granted Orphan Designation in both the US and EU. It has also been accepted into the EMA’s Adaptive Pathways Programme and granted PRIority MEdicines (PRIME) designation by the Agency.

BPS-804 was well tolerated by the 83 subjects who have received it across the 4 Phase 1/2 studies completed to date.

Click here for the BPS-804 adult clinical trial website


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Bringing the patient perspective into our work

Nothing about us without us


Mereo is committed to developing and making available therapies in collaboration with all stakeholders, most importantly, the people who we are seeking to serve.  This means that we are committed to ensuring that the patient voice is included in every step of the way;  and we actively seek opportunities for having leadership from the OI community as part of our development programme for setrusumab.

Rare diseases, individually, each affect small numbers of people.  This means that patients are rare but it also means that expertise and experience is rare, too.  A primary care physician might never see one case of a given rare disease.  Patients and their families, on the other hand, are often extremely well-informed – more often than not becoming experts in their condition.  This means that their point of view and their experience is crucially important in all decision-making, because they have the lived experience and are able to point to what will make a real and meaningful difference in their lives.

The respect for and inclusion of the rare disease patients’ point of view is also recognised by Regulatory, Health Technology Assessment and Pricing & Reimbursement authorities, who are increasingly including patient representation in their evaluation and decision-making processes, both in the USA and in Europe.  Mereo is committed to maximising those opportunities to include the patient voice, while respecting the independence of patient representatives and community leaders.  Conflict of interest policies and procedures are in place to respect the different roles and responsibilities of all actors in such processes and Mereo adheres to these.  We also make available all financial support that we provide to patient organisations via our transparency reporting

Multi-stakeholder collaboration is a fundamental condition to achieving patient access to rare disease medicines


In addition to the formal external engagements, we also believe that it is important for all of our team members at Mereo to be able to feel and understand the potential benefits that our shared work is providing for patients.  We are proud that organisations from the Osteogenesis Imperfecta community spend time with our broad company team in order to secure that we are always keeping the patient perspective in our minds.

Osteogenesis Imperfecta Community Representation Organisations 

Osteogenesis Imperfecta Federation Europe (OIFE) 
Osteogenesis Imperfecta Foundation (OIF)


14-15 June 2019:  See, Hear, Smile:  Topical Meeting on Osteogenesis Imperfecta 

9-12 July 2020:  50 th Anniversary of the OIF – OIF National Conference

Scientific publications

1. Shapiro J (2014) Osteogenesis Imperfecta: A Translational Approach to Brittle Bone Disease.community
Academic Press. Chapter 2: p15-22
2. Glorieux et al (2017) BPS-804 Anti-Sclerostin Antibody in Adults With Moderate
Osteogenesis Imperfecta: Results of a Randomized Phase 2a Trial. JBMR 32: 1496-1504


View clinical studies