NEW YORK (CNNMoney.com) -- Amgen Inc. Thursday reported a surge in second-quarter earnings and sales, soundly beating Wall Street forecasts.

Amgen, the world's biggest biotechnology company, said earnings excluding stock-option expense and other items rose nearly 12 percent to about $1.2 billion, or $1.05 a share, for the quarter. Sales jumped 14 percent to $3.6 billion.

Analysts had forecast earnings of 94 cents a share and sales of $3.5 billion, according to Thomson First Call.

Amgen (Charts) stock rallied, climbing about 4.5 percent in after-hours trading after falling 1 percent during regular trading on Nasdaq.

"I wasn't surprised at the fact that they beat the numbers, but I am surprised that the numbers are so huge," said Shiv Kapoor, analyst for Montgomery & Co.

Sales of Amgen's top-selling drug, Aranesp, a treatment for anemia and kidney disease, jumped 26 percent to $1.1 billion.

Combined sales of Neulasta and Neupogen, drugs used with chemotherapy to fight infection, rose 12 percent to about $1.1 billion. Sales for Enbrel, a treatment for rheumatoid arthritis, rose 13 percent to $724 million.

Chief executive Kevin Sharer said he hopes to have the experimental colorectal cancer drug panitumumab on the market by the third quarter. The biotech is also testing denosumab as a treatment for bone cancer and other diseases, though analysts say that drug might not enter the market until 2009.

Amgen's 2005 acquisition of another biotech, Abgenix, took a big bite out of net profit. Charges related to the merger, as well as stock-options expenses and other costs, totaled $1.1 billion, reducing net income to $14 million for the latest quarter.

Amgen could use some good news. The Thousand Oaks, Calif.-based biotech, was once considered an expensive stock, but it has watched its stock price plunge 18 percent this year, making it more affordable.

"I think it's one of the better, cheaper plays in the space right now," said Edward Nash, analyst for Stifel Nicolaus & Co.

The analysts interviewed for this story do not own shares of companies mentioned here, and their firms do not conduct banking business with them.

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