Update on Phase III trial for Odanacatib, Merck’s investigational cat-K inhibitor for Osteoporosis

Merck (NYSE: MRK), known as MSD outside the United States and Canada, announced today an update on the Phase III trial assessing fracture risk reduction with odanacatib, Merck’s investigational cathepsin K (cat-K) inhibitor. 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.

Merck anticipates submitting regulatory applications for approval of odanacatib in the U.S., European Union (EU) and Japan in the first half of 2013.

“We are encouraged by the Data Monitoring Committee’s recommendation to close the trial early,” said Peter S. Kim, Ph.D., executive vice president, Merck and president, Merck Research Laboratories, “and look forward to reviewing the data with the scientific community to bring forward this innovation.”

The Phase III 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 percent of the targeted number of hip fractures had been reported.

Merck expects the process of closing this large, multi-center trial to take a number of months. Trial investigators will schedule final assessments for trial participants at 387 sites in 40 countries. Data from these visits will be collected and reviewed to allow a full and complete analysis, and final results of the study will be submitted for presentation and publication in 2013 once the analysis is complete.

About Odanacatib

In osteoporosis, bone loss occurs because of an imbalance in bone remodeling (the rate of bone resorption exceeds that of bone formation). Osteoclasts, cells that resorb bone, secrete signaling factors to stimulate osteoblasts, cells that form bone. 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.