Amgen's bone drug beats Lilly's Forteo in a Phase III osteoporosis trial

Amgen's ($AMGN) investigational bone-growing drug met its main goal in a late-stage trial, clearing its first Phase III hurdle by besting an Eli Lilly ($LLY) blockbuster for osteoporosis.

The antibody, romosozumab, hit its primary endpoint of significantly beating Lilly's bone-building Forteo over 12 months, Amgen said. In a study on 436 postmenopausal women with osteoporosis, patients getting a monthly injection of romosozumab experienced a higher average change in hip bone mineral density than those getting a daily subcutaneous dose of Lilly's drug, according to the company.

Amgen is keeping detailed trial results under wraps until a later medical meeting, saying only that the side effect profiles were "generally balanced" between the two drugs.

The UCB-partnered romosozumab is designed to block the protein sclerostin, which stands in the way of bone production, and thereby boost osteo density. Amgen and UCB are now working through a pair of larger Phase III studies on more than 10,000 women to see how well the antibody can prevent osteoporosis-related bone fractures. The first, pitting romosozumab against placebo, is expected to read out final data in the first half of next year, while the second, comparing Amgen's drug with the now-generic Fosamax, will wrap up in 2017.

Amgen and UCB first planned to develop romosozumab as a bone-healing agent but ditched that indication in 2013 in light of the antibody's Phase II performance, pivoting to the more lucrative osteoporosis market. Forteo, approved for men and women, brought in $1.3 billion for Lilly last year.

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