Merck says its antiviral medicine met late-stage primary endpoint

Merck & Co. said Wednesday morning that its investigational antiviral medicine met its primary endpoint in a phase 3 trial. The treatment, letermovir, is being tested to prevent infection in stem cell transplant recipients. The drug has special status in the U.S. and elsewhere as an orphan product intended for a rare disease or condition, and was granted fast track status by the Food and Drug Administration, which speeds up the development and approval process. Merck shares rose 5.9% over the last three months, compared with a 1.1% decline in the S&P 500 .

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