8-K: Mereo BioPharma and Ultragenyx Announce Positive Phase 2 Data for Setrusumab in Osteogenesis Imperfecta

Interim data from the Phase 2 portion of the Phase 2/3 Orbit study shows setrusumab significantly reduced fracture rates and improved bone mineral density in patients with osteogenesis imperfecta.

Summary

• Mereo BioPharma and Ultragenyx have announced positive 14-month results from the Phase 2 portion of the ongoing Phase 2/3 Orbit study for setrusumab (UX143) in patients with osteogenesis imperfecta (OI).
• The study demonstrated a 67% reduction in the median annualized fracture rate, decreasing from 0.72 to 0.00 (p=0.0014) after a mean treatment duration of 16 months.
• Treatment with setrusumab also resulted in a 22% mean increase in lumbar spine bone mineral density (BMD) from baseline at 12 months (p<0.0001).
• The mean lumbar spine BMD Z-score improved from -1.73 at baseline to -0.49 at 12 months, a substantial normalization of +1.25 (p<0.0001).
• These improvements in BMD and Z-scores were consistent across all OI sub-types studied.
• No treatment-related serious adverse events were observed, with common adverse events being infusion-related events and headaches.

Sentiment

Score: 9

Explanation: The document presents very positive clinical trial results with significant improvements in fracture rates and bone mineral density, with no serious adverse events reported. This suggests a high likelihood of success for the drug and a positive outlook for the company.

Positives

• The 67% reduction in annualized fracture rate is a significant improvement for patients with OI.
• The increase in bone mineral density (BMD) and Z-score indicates a positive impact on bone health.
• The improvements were consistent across all OI sub-types, suggesting broad applicability.
• The safety profile of setrusumab appears favorable, with no serious treatment-related adverse events reported.
• The study results suggest a sustained response over the long term.

Negatives

• The most common adverse events were infusion-related events and headaches, which may require management.
• The study is still ongoing, and long-term data is needed to confirm the sustained benefits and safety of setrusumab.

Risks

• The clinical development process is inherently uncertain, and future results may differ from current findings.
• The companies rely on third parties to conduct and fund clinical trials, which introduces potential risks.
• Patient enrollment in clinical trials is crucial, and delays could impact timelines.
• The companies are dependent on key executives, and their loss could affect operations.
• There is a risk of smaller than anticipated market opportunities for the product.

Future Outlook

The companies are moving forward with the Phase 3 portion of the Orbit study and the Phase 3 Cosmic study, with the goal of bringing setrusumab to a larger number of patients with OI. More detailed 14-month data will be presented at a future scientific meeting.

Management Comments

• Gary S. Gottesman, M.D., stated that setrusumab is safely reducing the incidence of fractures and improving BMD in patients with OI, with patients continuing to make measurable gains.
• Eric Crombez, M.D., noted that the clinically meaningful continued improvement in BMD suggests that new and stronger bone is being created, resulting in an important reduction in fractures.

Industry Context

This announcement is significant in the rare disease space, as there are currently no globally approved treatments for OI. The positive results for setrusumab could position it as a potential first-in-class therapy for this condition. The collaboration between Ultragenyx and Mereo BioPharma highlights the trend of partnerships in rare disease drug development.

Comparison to Industry Standards

• The 67% reduction in fracture rate is a substantial improvement compared to the natural history of OI, where patients experience frequent fractures.
• The 22% increase in BMD is also significant, as many OI patients have low bone density.
• Current treatments for OI, such as bisphosphonates, have limited efficacy and are not globally approved for the condition.
• The results from the Asteroid study in adults with OI showed a dose-dependent effect on bone formation and density, which is consistent with the current findings in the pediatric population.
• Other companies developing treatments for OI include Ascendis Pharma with TransCon CNP, which is in Phase 2 trials, and Amgen with romosozumab, which is being investigated in adults with OI.

Stakeholder Impact

• Shareholders are likely to react positively to the strong clinical data.
• Patients with OI and their families will be encouraged by the potential for a new and effective treatment.
• Employees of both companies may feel more optimistic about the future of the drug development program.
• The positive results could lead to increased interest from potential partners and investors.

Next Steps

• The companies will continue with the Phase 3 portion of the Orbit study and the Phase 3 Cosmic study.
• More detailed 14-month data will be presented at a future scientific meeting.

Key Dates

Keywords

setrusumab, osteogenesis imperfecta, OI, fracture rate, bone mineral density, BMD, clinical trial, Ultragenyx, Mereo BioPharma, rare disease