Merck announced an update on their Phase 3 trial assessing fracture risk reduction with odanacatib for osteoporosis.

The Data Monitoring Committee (DMC) for the study recently completed its first planned interim analysis for efficacy and recommended that the study be closed early due to robust efficacy and a favorable benefit-risk profile. As a result, Merck will begin taking steps to close the trial. The DMC noted that safety issues remain in certain selected areas and made recommendations with respect to following up on them. Merck’s previously announced plan to conduct a blinded extension trial will allow further monitoring of the issues. The extension trial will also continue to measure efficacy.

The randomized, placebo-controlled trial with over 16,000 patients was designed to assess the safety and efficacy of odanacatib in reducing fracture risk in post-menopausal women with osteoporosis. This event-driven trial started in 2007 and was expected to continue until hip fractures had been reported in a total of 237 patients. The interim analysis was conducted by the DMC as planned when approximately 70% of the targeted number of hip fractures had been reported.

Odanacatib selectively inhibits cat-K, the primary enzyme in the osteoclast that digests proteins during bone resorption, while maintaining the number of osteoclasts. This novel mechanism of action of odanacatib leads to improved balance in bone remodeling and bone formation is preserved while bone resorption is reduced, resulting in progressive increases in bone mineral density over time.

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