London, UK-based Mereo BioPharma’s experimental drug targeting brittle bone disease has been designated PRIME status by the European Medicines Agency (EMA).

Brittle bone disease, or osteoporosis imperfecta (OI), is a rare genetic disorder characterised by fragile bones and reduced bone mass resulting in bones that break easily, loose joints and weakened teeth.

In severe cases patients can experience hundreds of fractures in a lifetime, and often suffer muscle weakness, early hearing loss, fatigue, curved bones, scoliosis, respiratory problems and short stature.

As yet there is no approved treatment for the condition, and so care is centred on management strategies that focus on minimising fractures and maximising mobility.

Mereo is currently undertaking a Phase IIb trial for BPS-804 - a human monoclonal antibody targeting sclerostin - in adult patients with OI.

Sclerostin inhibits the activity of bone-forming cells, known as osteoblasts. The firm believes that inhibiting its action will induce or increase osteoblast function and maturation, increasing bone formation and reducing bone resorption, thereby reducing bone fragility and fractures in OI patients.

The EMA introduced its PRIME programme to speed up the regulatory process for investigational medicines that may offer a major therapeutic advantage over existing treatments, or benefit patients without treatment options.

Through the initiative, Mereo will have enhanced support from the regulator, including optimising development pathway for BPS-804, potentially accelerating assessment of the marketing application, and engaging in early discussion with both the EMA and health technology assessments regarding reimbursement pathways.

The firm’s chief executive Denise Scots-Knight said the PRIME designation “is further recognition that OI is a disease with a high unmet medical need and that BPS-804 has the potential to provide a much needed novel treatment option for these patients.

“We look forward to collaborating closely with the EMA through both PRIME and the Adaptive Pathways Programme to expedite the development of BPS-804 and potentially accelerate availability of this therapy for patients.”