An independent monitoring board said a large trial of Merck & Co's Vytorin cholesterol drug can continue, suggesting no major safety issues have yet been seen with the pill.
The news eased investor concerns that a safety issue could arise and further hurt sales of already struggling Vytorin. Merck shares were up 3.7 percent in Tuesday morning trading.
"We believe it is increasingly difficult to suggest any safety issues with (Vytorin)," JPMorgan analyst Chris Schott said, in view of the panel's green light to continue with the study.
Such panels of medical experts, which are allowed to examine confidential clinical trial data, are routinely used to assess whether drug studies should continue or be halted because they have already proven a drug is effective, ineffective or has safety problems.
Investors have been avidly awaiting an update from the panel on the study of Vytorin, called IMPROVE-IT, which began in 2005 and involves more than 18,000 patients with well-controlled cholesterol who had heart attacks or the kind of chest pain that can precede heart attacks.
The study will now continue until its planned conclusion in September 2014, Merck said on Tuesday. The study aims to prove conclusively whether Vytorin, whose annual sales total $1.75 billion, can significantly reduce heart attacks, strokes and heart-related deaths compared with Merck's older, generically-available Zocor (simvastatin) cholesterol fighter.
"Getting this interim look out of the way is a positive, given where investor sentiment has been," Sanford Bernstein analyst Tim Anderson said in a research note. He said "a surprising number of investors" have been worried about potential safety issues with Vytorin.
Doubts about the true worth of Vytorin and a related Merck drug called Zetia, and debates about their safety, have hurt sales of the medicines since 2008, after a pair of smaller studies showed unfavorable trends.
Vytorin combines Zocor with Zetia, a $2.6 billion-a-year product that Merck also sells as a standalone treatment. Zetia and Zocor block "bad" LDL cholesterol through different mechanisms, the reason they are paired in Vytorin.
The IMPROVE-IT study was begun in 2005, a year after Vytorin was introduced, to get a far better picture of the combo drug's worth and safety than could be seen in earlier trials that led to its approval.
Merck investors are hoping the final IMPROVE-IT results next year will establish Vytorin's clear effectiveness and safety, and thereby spark revived sales of Vytorin and Zetia.
Merck shares were up $1.60 to $45.26 in morning trading on the New York Stock Exchange.
(Reporting By Ransdell Pierson and Caroline Humer; editing by John Wallace)