Amgen Inc. announced on Monday positive human trial results for a cancer drug that was the focus of a multibillion dollar acquisition last year.

The Thousand Oaks biotech said that Phase 3 trials showed patients with multiple myeloma who used Kyprolis had a longer lifespan than patients using treatments currently on the market.

Amgen obtained Kyprolis, a pipeline drug, as part of its acquisition of Onyx Pharmaceuticals Inc. last year. Amgen paid $10.4 billion for the South San Francisco company.

Kyprolis is an injectable drug for myeloma patients who have tried at least two other therapies without showing an improvement. The drug works by blocking certain enzymes needed for cell maintenance, thus killing the cancer cells.

Amgen Chief Executive Robert Bradway said Kyprolis is one of a new crop of drugs that the company has already submitted or plans to submit for government approval.

“Kyprolis is an important building block in our robust, differentiated pipeline,” Bradway said in a statement.

Shares closed up $3.10 or 2.5 percent, to $128.65 on the Nasdaq.