The results demonstrated that mice treated with a soluble form of the ActRIIA receptor increases trabecular bone volume by 45%, 120%, 130% and 248% compared to untreated animals two, four, six and 12 weeks, respectively. Furthermore, measurements of the growth of new bone indicate an increase in the rate of bone formation resulting in increased bone strength.
Additionally, a study was conducted in a mouse model of osteoporosis and the results were similarly encouraging. Bone mineral density increased 12% in the treated mice compared to a 15% decrease in untreated animals. The increases in bone mass along with improvements in bone architecture led to significant increases in bone strength in the treated osteoporotic animals compared to the untreated animals. The results of these studies also show that the mechanism of bone formation to be fundamentally different than parathyroid hormone, the only anabolic bone therapy approved by a regulatory agency.
John Knopf, CEO of Acceleron, said: “Following the successful completion of our single dose study in postmenopausal healthy volunteers in 2007, Acceleron initiated a Phase Ib multiple dose study which is ongoing. We look forward to continuing the development of this compound by beginning a Phase IIa study in multiple myeloma patients with osteolytic bone lesions this summer.”