Why Is Mereo BioPharma Stock Trading Higher Today?

Ultragenyx Pharmaceutical Inc RARE and Mereo BioPharma Group plc MREO released interim data from the Phase 2 portion of the Phase 2/3 Orbit study of setrusumab.

The data demonstrated that treatment with setrusumab (UX143) significantly reduced the incidence of fractures in patients with osteogenesis imperfecta (OI) with at least six months of follow-up and continues to demonstrate ongoing and meaningful improvements in lumbar spine bone mineral density (BMD). 

The data were presented at the American Society for Bone and Mineral Research 2023 Annual Meeting.

The annualized fracture rate across all 24 patients in the Phase 2 portion of the study was reduced by 67%. 

In the two years before treatment with setrusumab all patients experienced at least one fracture. 

The median annualized fracture rate of 0.72 in the two years before treatment was reduced to 0.00 during the mean treatment duration period of 9 months. 

Following initiation of treatment with setrusumab, 20 patients experienced no radiographic-confirmed fractures, and 4 patients experienced 7 radiographic-confirmed fractures in 5 separate events. These fractures exclude fractures of the fingers, toes, skull, and face, consistent with the Phase 3 study design.

At the 6-month timepoint, treatment with setrusumab resulted in a mean increase in lumbar spine BMD from baseline of 13% at 20 mg/kg (n=11) and 16% at 40 mg/kg (n=8), which represents the same substantial mean improvement in Z-score of +0.85 for both dose groups at 6 months compared to a combined mean baseline Z-score of –1.68. 

The small difference in BMD change from baseline is likely related to differences in patients assigned to the two treated groups. There was no statistically significant difference in BMD percent change or Z-score change from baseline between the 20 and 40 mg/kg dosing cohorts.

As of the data cut-off, no treatment-related serious adverse events were observed in the study. 

The Phase 3 portion of the study is currently enrolling approximately 195 patients.

Price Action: MREO shares are up 31.78% at $1.70, and RARE shares are up 13.26% at $38.02 on the last check Monday.