Exhibit 99.1
Ultragenyx Announces First Patients Dosed in Phase 3 Program
Evaluating Setrusumab (UX143) for the Treatment of Osteogenesis Imperfecta (OI)
Pivotal Phase 3 portion of Orbit study now enrolling approximately 195 pediatric and young adult patients
Newly initiated Phase 3 Cosmic study now enrolling approximately 65 younger pediatric patients
NOVATO, Calif. July 06, 2023 Ultragenyx Pharmaceutical Inc. (NASDAQ: RARE) today announced that the first patients have been dosed in
both of its late-stage clinical trials evaluating setrusumab in pediatric and young adult patients with OI sub-types I, III and IV. The Phase 3 portion of the pivotal Phase 2/3 Orbit study is evaluating
the effect of setrusumab compared to placebo on annualized clinical fracture rate in patients aged 5 to <26 years. The newly initiated Phase 3 Cosmic study is an active-controlled study evaluating setrusumab compared to intravenous
bisphosphonate (IV-BP) therapy on annualized total fracture rate in patients aged 2 to <5 years.
I am
extremely encouraged by the recent data from the Phase 2 portion of the Orbit study, which includes improvement in biochemical markers and bone density measures that reflect the clinical response we have observed in study participants,
stated Thomas Carpenter, M.D., professor of Pediatrics (Endocrinology) and of Orthopaedics and Rehabilitation, Yale School of Medicine. We are looking forward to evaluating the full clinical potential of setrusumab as this important Phase 3
program moves forward, with hopes for improving therapeutic outcomes in OI.
Data from the Phase 2 portion of the Orbit study
demonstrated increases in bone formation and bone mineral density, which are important markers of bone strength, as well as early indications of improved bone health from our investigators, said Eric Crombez, M.D., chief medical officer at
Ultragenyx. Our comprehensive Phase 3 program is designed to study the impact of setrusumab on clinical fracture risk reduction. The two Phase 3 trials will evaluate patients over a broad age range, including the younger pediatric population,
where the risk of fracture is higher and where we can potentially have the greatest impact on their future health.
Ultragenyx is leading the
clinical development of setrusumab as part of a collaboration and license agreement with Mereo BioPharma Group plc (NASDAQ: MREO), a clinical-stage biopharmaceutical company focused on rare diseases. The companies recently announced positive data
from the dose-selection Phase 2 portion of the Orbit study showing that setrusumab rapidly induced bone production in OI-affected patients.
U.S. residents can learn more by visiting ultraclinicaltrials.com.
The Setrusumab Phase 3 Program
The global, seamless
Phase 2/3 Orbit study is evaluating the effect of setrusumab compared to placebo on clinical fracture rate in patients aged 5 to <26 years. In the Phase 2 portion, 24 patients were randomized 1:1 to receive setrusumab at one of two doses
to determine the optimal dosing strategy for Phase 3. The pivotal Phase 3 portion of the study will include approximately 195 patients at more than 40 sites across 12 countries, randomized 2:1 to receive setrusumab or placebo, with a primary
efficacy endpoint of annualized clinical fracture rate. All patients will transition to an extension period and receive open-label setrusumab after the Phase 3 primary analysis is complete.
The global Phase 3 Cosmic study is an open-label, randomized, active-controlled study in patients aged 2 to <5 years evaluating setrusumab compared
to intravenous bisphosphonates (IV-BP) therapy on reduction in total fracture rate, including morphometric vertebral fractures. The Cosmic study will enroll approximately 65 patients at more than 20
sites across 8 countries.