Amgen Inc.’s leukemia drug Blincyto has received full approval from the U.S. Food and Drug Administration, the company has announced.

The Thousand Oaks biotech’s product was previously assigned breakthrough therapy designation and was accelerated for approval. It is the first single-agent immunotherapy that will treat patients with a specific type of the disease called refractory acute lymphoblastic leukemia, or ALL, which is often lethal and has a median survival rate of just four months.

In Blincyto’s phase 3 trial, the drug proved to have improved outcomes over standard chemotherapy.

“We are pleased that the FDA has granted full approval for Blincyto, marking a significant milestone for certain patients with relapsed or refractory ALL,” Sean E. Harper, executive vice president of research and development, said in a statement.

The announcement was made on Tuesday after the market closed. Shares of Amgen (AMGN) on Wednesday closed down 5 cents or less than 1 percent to $173.27 on the Nasdaq.