Merck reported a better-than-expected quarterly profit, helped by higher gross margins, and the drugmaker also narrowed and raised its revenue and profit forecasts for 2017.
The company's shares rose 1.6 percent in light premarket trading on Tuesday.
Net income attributable to Merck rose to $1.55 billion, or 56 cents per share, in the first quarter, from $1.13 billion, or 40 cents per share, a year earlier.
Excluding items, Merck earned $88 per share, beating the average analyst estimate by 5 cents, according to Thomson Reuters I/B/E/S.
Gross margin rose 68 percent from 61.6 percent, primarily driven by lower costs, the company said.
Merck said its total revenue increased 1.3 percent to $9.43 billion, beating analysts' average estimate of $9.25 billion.
Sales of Keytruda, which works by taking the brakes off the immune system, rose 134 percent to $584 million, but missed Wall Street's consensus estimate of $589 million, according to Barclays.