AbbVie Inc. and Roche Holding AG’s treatment for a type of leukemia won U.S approval almost three months ahead of schedule.

The Food and Drug Administration approved Venclexta, known chemically as venetoclax, for patients with chronic lymphocytic leukemia who have tried at least one other therapy, according to a statement from the agency on Monday. Chronic lymphocytic leukemia is one of the most common types of blood cancer in adults, according to the National Cancer Institute.

The approval is for Venclexta’s use by patients with missing genes called a 17p deletion who are considered hard to treat.

“For certain patients with CLL who have not had favorable outcomes with other therapies, Venclexta may provide a new option for their specific condition,” Richard Pazdur director of the Office of Hematology and Oncology Products at the FDA, said in a statement.

AbbVie’s drug Imbruvica is approved as a first-line therapy for chronic lymphocytic leukemia patients with 17p deletion.

The FDA granted the drug breakthrough status to expedite its approval. Breakthrough status means the drug treats a life-threatening condition and early evidence indicates it may be a substantial improvement over existing therapies. Of 107 patients in a trial, all but one of whom had 17p deletion, 79 percent responded to the treatment, Roche’s Genentech unit said when the FDA granted the drug priority review in January.