Mereo BioPharma Receives FDA Rare Pediatric Disease Designation

Mereo BioPharma Group plc recently announced that the US FDA has granted Rare Pediatric Disease designation to setrusumab for the treatment of osteogenesis imperfecta (OI). Setrusumab is a fully humanized monoclonal antibody that inhibits sclerostin, a protein which inhibits the activity of bone-forming cells. OI is a genetic rare disorder with no approved treatments that is characterized by reduced bone mass and fragile bones that break easily. In Mereo’s Phase 2b ASTEROID study, setrusumab demonstrated a dose-dependent bone building effect and a trend of reduction in fractures in addition to being safe and well tolerated in adults with OI.

The FDA grants Rare Pediatric Disease Designation for serious and life-threatening diseases that primarily affect children aged 18 years or younger and fewer than 200,000 people in the US. If a Biologics License Application (BLA) in the US for setrusumab is approved, Mereo may be eligible to receive a priority review voucher from the FDA, which can be redeemed to obtain priority review for any subsequent marketing application and may be sold or transferred to other companies for their programs, as has been done by other voucher recipients.

“Receiving Rare Pediatric Disease designation from the FDA highlights the significant unmet medical need facing children with OI and underscores the potential of setrusumab to become the first approved treatment option specifically for these patients,” said Dr. Denise Scots-Knight, Chief Executive Officer of Mereo. “Following the completion of our Phase 2b ASTEROID study, we are pleased that both the FDA and EMA have agreed on the principles of a design of a single Phase 3 pivotal pediatric study in OI. We believe there is a clear path forward for setrusumab in OI and are continuing discussions with potential partners prior to the initiation of a Phase 3 study consistent with our Company strategy.”

Osteogenesis Imperfecta (OI) is a rare genetic disorder that is characterized by fragile bones and reduced bone mass resulting in bones that break easily, loose joints and weakened teeth. In severe cases, those with OI may experience hundreds of fractures in a lifetime. In addition, people with OI often suffer muscle weakness, early hearing loss, fatigue, curved bones, scoliosis, respiratory problems and short stature, leading to significant impacts on overall health and quality of life. The majority of cases of OI (estimated at approximately 90%) are caused by a dominant mutation in a gene coding for type I collagen, a key component of healthy bone. Current treatment of OI is supportive, focusing on minimizing fractures and maximizing mobility, but to date, there are no FDA or EU approved treatments.

Setrusumab is a fully humanized monoclonal antibody that inhibits sclerostin, a protein which inhibits the activity of bone-forming cells. The mechanism of action of setrusumab could be particularly well suited for the treatment of OI and setrusumab has the potential to become the first approved treatment option that could reduce fractures and improve the quality of life for individuals with OI. Mereo has obtained orphan drug designation in OI for setrusumab in both the United States and the EU. Setrusumab was accepted into the EMA’s Adaptive Pathways program in the EU and was accepted into the EMA’s Priority Medicines scheme (PRIME). In the Phase 2b ASTEROID study, setrusumab demonstrated a dose-dependent bone building effect and a trend of reduction in fractures in addition to being safe and well tolerated adults with OI. Following the review of the data from the Phase 2b ASTEROID study, the FDA agreed on the principles of a design of a Phase 3 pediatric study in OI to be completed prior to the submission of a BLA in the United States, which is also in line with Mereo’s proposed pivotal pediatric study design that has been agreed to in principle with the European Medicines Agency (EMA). Mereo intends to partner setrusumab prior to conducting a pivotal trial of setrusumab in children with severe OI.

Mereo BioPharma is a biopharmaceutical company focused on the development and commercialization of innovative therapeutics that aim to improve outcomes for oncology and rare diseases. Mereo’s lead oncology product candidate, etigilimab (Anti-TIGIT), has completed a Phase 1a dose escalation clinical trial in patients with advanced solid tumors and has been evaluated in a Phase 1b study in combination with nivolumab in select tumor types. Mereo’s rare disease product portfolio consists of setrusumab, which has completed a Phase 2b dose-ranging study in adults with OI, as well as alvelestat, which is being investigated in a Phase 2 proof-of-concept clinical trial in patients with alpha-1 antitrypsin deficiency (AATD) and in a Phase 1b/2 clinical trial in COVID-19 respiratory disease.