* Regulatory filings planned for first-half 2013
* Merck shares rise 3.1 percent in after-hours trade
July 11 (Reuters) - A pivotal trial of Merck & Co's experimental osteoporosis drug odanacatib has shown that it reduces fracture risk, prompting outside monitors to recommend that the study be stopped early.
News that the novel drug was shown to be effective sent shares of Merck up more than 3 percent.
The company said it expects to take a number of months to wind up the trial, which began in 2007, but will continue with an extension trial to follow up on certain safety issues flagged by the Data Monitoring Committee.
Merck said it expects to submit regulatory applications for U.S., European and Japanese approval of odanacatib in the first half of next year.
The oral drug, taken weekly, is considered more convenient than an older class of osteoporosis drugs known as bisphosphonates. Sales of Merck's bisphosphonate drug Fosamax reached $3 billion in 2007, but that revenue has plunged since emergence of generic competition in early 2008.
Bisphosphonate use has also declined due to safety concerns including the risk of osteonecrosis of the jaw, a severe bone disease.
Wall Street analysts, on average, have forecast annual sales of odanacatib at $402 million by 2016, according to Thomson Pharma.
Credit Suisse analyst Catherine Arnold recently raised her 2020 sales estimate for the drug to $1.1 billion from $350 million, citing meaningful differences in fracture rates to bisphosphonates and the likelihood that more osteoporosis sufferers would take medication if a potentially safer option were available.
Odanacatib is designed to block cathepsin K, the major enzyme in osteoclasts that is responsible for breakdown of existing bone tissue.
The pivotal study involved over 16,000 post-menopausal women with osteoporosis. It was expected to continue until hip fractures had been reported in 237 patients. Merck said the interim analysis was conducted when around 70 percent of the targeted number of hip fractures had been reported.
The company said it expects to report final results from the study next year.
Shares of Merck rose more than 3 percent in after-hours trading to $42.49. Earlier, the stock closed at $41.21 on the New York Stock Exchange.