Mereo BioPharma releases 'encouraging' data from setrusumab study
Clinical stage biopharmaceutical company Mereo BioPharma Group announced encouraging six-month data from the open label arm of its phase 2b dose-ranging clinical study in adults with type I, III or IV osteogenesis imperfecta (OI) treated with BPS-804 (‘setrusumab’), or the ‘ASTEROID’ study, on Thursday.
The AIM-traded firm said the primary endpoint of the study was the percentage change over baseline in trabecular volumetric bone mineral density (Tr vBMD) of the wrist radius at 12 months, assessed using high resolution peripheral quantitative computed tomography (HR-pQCT), with a hierarchical analysis of change over baseline in radius bone strength on finite element analysis (FEA).
As it announced in October, the phase 2b study had completed patient enrollment with 112 patients, of which 69 had type I, 29 had type IV and 14 had type III OI.
It said that in the open label arm of the study, patients received the highest of the three prospectively defined doses of setrusumab used in the blinded arms of the study.
The change over patients' baseline Tr vBMD was assessed at three and six months, with patients of all three major phenotypes represented in the open label arm.
At the time of the interim data cut-off, 12 patients had Tr vBMD measurements of the radius available at baseline and three months, and 11 at baseline and six months.
Mereo said those patients showed a mean increase of 1.4% over baseline in Tr vBMD at the radius at three months, and a 3.2% increase over baseline at six months.
Thus, increases in Tr vBMD in OI patients in the open label study compared “very favourably” to the increases seen in Tr vBMD at the radius in osteoporosis patients of approximately 1% at 24 months with ‘alendronate’ and approximately 1% and approximately 1.5% increases seen in Tr vBMD at the radius in osteoporosis patients at 12 months observed with ‘teraparitide’ or ‘denosumab’, respectively.
Given the small sample size, the company said it would not expect to see statistical significance, and it would therefore perform and report the FEA when it reported the 12 month data set in the fourth quarter of 2019.
Change from baseline at six and 12 months for areal bone mineral density (BMD) at the lumbar spine, as measured by dual energy x-ray absorptiometry (DXA), was a secondary endpoint of the phase 2b study.
In the open label arm, at the time of the interim data cut-off, there were 12 patients whose areal BMD at the lumbar spine DXA measurements at baseline and six months were available, with a mean increase of 3.5% over baseline.
The firm said it would continue to analyse the results from the patients in the open label arm in the coming weeks, and expected to see further increases in the Tr vBMD and BMD at the lumbar spine in the 12 month data.
Of the 112 patients enrolled in the phase 2b study, to date there had been nine discontinuations.
At the time of the last Drug Monitoring Committee evaluation, 33 patients had been on setrusumab for 12 months and 102 patients had been on setrusumab for more than six months.
Mereo said the most frequently-reported adverse event (AE) to-date was headache, adding that there had been no drug-related cardiovascular serious adverse events (SAEs) or AEs.
The company said it was continuing to expect 12-month headline data from the blinded arms of the study to be available in the fourth quarter.
“The data from this open label arm of our phase 2b study is clear and encouraging and in line with our expectations,” said Mereo BioPharma chief executive officer Dr Denise Scots-Knight.
“With 11 patients, we would not expect to see statistical significance and we believe the improvements in bone mineral density observed across patients with all osteogenesis Imperfecta subtypes included in the trial, bodes well for a positive outcome from the blinded dose arms of the study and we continue to expect headline data from these to be available in the fourth quarter of 2019.”
Dr Scots-Knight said osteogenesis Imperfecta was “quite distinct” from osteoporosis, and was a “rare and devastating” orphan disease, where there existed a significant need for an effective treatment.
“We are committed to advancing setrusumab for both adult and paediatric patients with this condition.
“As we have previously announced, the European Medicines Agency has approved our pediatric investigation plan for setrusumab and the drug candidate is now phase 3 ready, with a registration study design agreed for a pediatric population.”