Amgen Inc.’s leukemia drug Blincyto has become the first drug to be approved by the Food and Drug Administration for use in a subgroup of leukemia patients who are at a high risk of relapse following initial treatment.

Previously approved for the treatment for adults and children with refractory B-cell precursor acute lymphoblastic leukemia - an aggressive blood cancer that involves the white blood cells of the bone marrow - Blincyto can now be used in patients who are in remission but still have remaining cancer cells, or “minimal residual disease.” The presence of minimum residual disease means patients are more likely to relapse, according to the FDA.

Amgen received approval to expand the indications of Blincyto under the FDA’s “accelerated approval pathway,” through which the agency evaluates drugs for conditions that otherwise have few treatment options. The medication must be shown through clinical trials to have effects that are reasonably likely to be beneficial to patients, according to the FDA.

In a clinical trial on the drug’s effectiveness in leukemia patients with minimal residual disease, 81 percent of those who took Blincyto tested negative for the condition following a single cycle of treatment, Amgen said. The drug will be further studied to verify that it actually improves overall survival in the population.

Nearly 6,000 people in the U.S. will be diagnosed with acute lymphoblastic leukemia this year, according to the National Cancer Institute.

Sales of Blincyto were $175 million last year, according to Amgen, a 52 percent increase over the year prior. Amgen is based in Thousand Oaks, where it employs around 5,400 workers.

Shares of Amgen (AMGN) rose 2 cents, or less than 1 percent, on Thursday to close at $170.48 on the Nasdaq.