Rockville-based Micromet, a biopharmaceutical firm that creates antibody-based cancer treatments, agreed to be bought Thursday for $1.16 billion by Amgen, a biotechnology company in Thousand Oaks, Calif.

The sale price equates to $11 per share, a 33 percent premium over the stock’s closing price on Wednesday. The deal has been approved by the board of directors at both companies and is slated to close in the first quarter.

The main drug in Micromet’s development pipeline, blinatum­omab, aims to treat patients with a progressive form of cancer called acute lymphoblastic leukemia. The drug’s underlying technology uses the human body’s T cells to kill cancer cells.

Christian Itin, Micromet’s president and chief executive, said in a statement that “Amgen’s extensive resources and experience in the development and commercialization of biologics promise to speed blinatumomab’s path to market.”

Two trials of blinatumomab in patients with acute lymphoblastic leukemia are in their second phase. The drug is being tested as a possible treatment for other diseases as well, including non-Hodgkin’s lymphoma.

The company employs 32 people at its Rockville offices and has not determined whether local operations will be affected by the sale, a spokeswoman said.

Jason Kantor, a biotechnology analyst with RBC Capital Markets, said that the drug eventually could be approved to treat multiple diseases but that Micromet probably would have struggled to make that happen using its resources alone. A partnership or acquisition seemed inevitable.

“I think it’s good for the drug and the technology because it puts a lot more financial muscle, and clinical and regulatory bandwidth, behind a program that has a lot of opportunity and potential,” Kantor said.

“You can argue you should have made more money, but at the end of the day you need a buyer and a seller, and it seems like a fair price,” he added.

Micromet joins a number of other Maryland biotechnology companies that in recent years have been the target of high-priced buyouts. Columbia-based Martek, which makes nutrients for baby formula and other products, was sold for $1.1 billion at the end of 2010 to Netherlands-based Royal DSM, the world’s largest vitamin supplier.

Big-ticket acquisitions have occasionally lifted the local economy. After Gaithersburg-based MedImmune was bought by AstraZeneca for $15.6 billion in 2007, the parent company used the purchase to create a research-and-development hub here.

“I think it’s hard for us to anticipate at this stage [what will happen with Micromet], but I would say for the industry itself, a billion-dollar acquisition is an affirmation of the value of what companies are pursuing in the eyes of others,” said Judy Britz, executive director of the Maryland Biotechnology Center.