Benzinga | Oct 1, 2021 04:38PM EDT

Mereo BioPharma And Ultragenyx Present Data From Phase 2b ASTEROID Study Of UX143 (setrusumab) In Osteogenesis Imperfecta (OI) At American Society For Bone And Mineral Research (ASBMR) 2021 Annual Meeting

Ultragenyx Pharmaceutical Inc. (NASDAQ:RARE), a biopharmaceutical company focused on the development and commercialization of novel products for serious rare and ultra-rare diseases, and Mereo BioPharma Group plc (NASDAQ:MREO), a clinical stage biopharmaceutical company focused on oncology and rare diseases, today presented secondary endpoint data on UX143 (setrusumab) from the Phase 2b ASTEROID study for the Treatment of Osteogenesis Imperfecta (OI). Data were presented at the American Society for Bone and Mineral Research (ASBMR) 2021 Annual Meeting in an oral presentation by Suzanne Jan de Beur, M.D., an associate professor of medicine at The Johns Hopkins University School of Medicine and president of ASBMR.

Previously reported analyses of pre-specified endpoints in the Phase 2b ASTEROID study demonstrated a clear, dose-dependent, statistically significant bone-building effect at multiple anatomical sites in adult patients with OI that was consistent across all subtypes of OI studied, including Types I, III and IV. This effect was determined by evaluating areal bone mineral density (BMD) over baseline at the lumbar spine, as measured by DXA and reaching 8.97% at 12 months in the highest dose cohort (p<0.001). The data also show a statistically significant and consistent improvement in bone strength (stiffness) over baseline at the wrist and tibia measured by Finite Element Analysis (FEA) in both medium and high dose cohorts (p<0.05). There was also a statistically significant improvement in bone strength (failure load) at the wrist at the highest dose (p<0.01). New data presented today at ASBMR demonstrate that treatment with UX143 resulted in dose-dependent increase in P1NP serum levels, a marker of bone formation, and decrease in CTx serum levels, a marker of bone resorption, confirming the mechanism of action of sclerostin inhibition. These changes peaked at month one and declined thereafter, an expected effect based on data from prior clinical studies of sclerostin antibodies tested in osteoporosis. Observed improvements in BMD were continuous, with comparable gains achieved in the first and second 6 months of treatment in the high dose group despite temporal changes in biomarkers.

"The continuous gains in BMD over the twelve months of the ASTEROID study clearly warrant further investigation of the longer-term treatment effect of UX143 in patients with osteogenesis imperfecta," stated Francis Glorieux, M.D., Ph.D., Founding Director of the Genetics Unit at the Shriners Hospital for Children in Montreal and one of the study's co-ordinating PIs.

"These data analyses provide a clear picture of the sclerostin-inhibition effect of UX143 that resulted in both a statistically significant bone building effect and a significant increase in bone strength based on pre-specified measures in adults across all subtypes of OI studied. With Ultragenyx, we plan to advance UX143 into a comprehensive late-stage program in pediatric and adult patients across OI sub-types I, III and IV," said Denise Scots-Knight, Ph.D., Chief Executive Officer of Mereo. "We would like to thank Dr. Jan de Beur for today's presentation, and the co-ordinating Primary Investigators Dr. Glorieux, Dr. Kassim Javaid and Dr. Jay Shapiro for their work on the study."

Top-line 12-month data from the ASTEROID study were reported in November 2019, with full data, including secondary endpoint analyses, reported in January 2020.