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Ultragenyx, Mereo drug reduces fractures in bone disorder study

Dive Brief:

  • Ultragenyx Pharmaceutical and Mereo BioPharma on Tuesday said their experimental treatment for a rare bone disorder showed prolonged effects in the early part of a Phase 2/3 study.
  • The trial included people with a condition called osteogenesis imperfecta, which impacts bone metabolism and increases the risk of fractures, deformities and other issues. Ultragenyx and Mereo’s drug, setrusumab, is designed to block a protein known as sclerostin that can negatively affect bone formation
  • In October 2023, the companies said setrusumab significantly reduced fractures and built lumbar spine bone mineral density in a group of patients followed for at least six months. The results revealed Tuesday, showed that effect was sustained through at least 14 months of follow-up with ongoing improvement in bone density.

Dive Insight:

The longer-term results offer reassurance to investors who are eagerly awaiting the first readout of the Phase 3 portion of the companies’ “Orbit” trial, analysts said. That interim analysis is expected either at the end of this year or early next year.

Safety results are also encouraging, the companies said. In the time period analyzed, there were no serious treatment-related side effects. The most common adverse events were headaches and infusion-related events, they said.

The initial Phase 2 part of the study included 24 patients between the ages of 5 and 25 who received one of two doses of setrusumab. In the two years before entering the trial, every one of the participants had experienced at least one fracture. Treatment produced a 67% reduction in the annualized fracture rate, the companies said.

Following the initial success of the trial, researchers transitioned to Phase 3, which includes an additional 158 patients who are randomized at a 2:1 ratio to either receive the drug or a placebo. The companies are also conducting a separate Phase 3 trial known as Cosmic in patients under the age of seven.

Ultragenyx and Mereo began working together on the drug in December 2020. The latest results follow another research success for Ultragenyx announced in May. In that case, the company released positive top-line results for a Phase 3 study of a gene therapy for patients with glycogen storage disease.

Shares in Ultragenyx rose by nearly 2% Wednesday, while Mereo stock traded almost 10% higher.