AbbVie on Wednesday said its experimental treatment for a form of leukemia associated with a gene mutation met its primary goal in a mid-stage trial and that the company would seek U.S. approval of the medicine, which analysts have said has blockbuster sales potential.

AbbVie, which is developing the drug venetoclax with Switzerland's Roche Holding AG, said it would unveil data from the Phase II trial at an upcoming medical meeting and will seek U.S. marketing approval for the product before the end of 2015.

The drug was tested in patients with chronic lymphocytic leukemia (CLL) who had a so-called 17p gene deletion that has been associated with aggressive cancer and survival of less than 2 to 3 years after diagnosis.

The trial included patients with relapsed or advanced CLL, or those who had previously been untreated.

Venetoclax achieved its target overall response rate in the study, meaning it reduced the number of cancer cells by at least a predefined margin, the drugmakers said.

Safety of the drug was similar to that seen in earlier trials, with no unexpected new issues, AbbVie said

Brokerage Cowen and Co has predicted the medicine, if approved, could capture annual sales of $2 billion by 2020. It works by blocking BCL-2, a protein that prevents self-destruction of defective or cancerous cells in the body.

"Venetoclax may help restore the natural process that allows these leukemic cells to self-destruct," Sandra Horning, Roche's chief medical officer, said in a release.

The FDA earlier this year granted "breakthrough therapy" status to the drug for previously treated CLL patients with the gene deletion, a designation that can help speed regulatory review.

Chronic lymphocytic leukemia is a slow-progressing blood cancer in which the bone marrow makes too many lymphocytes, a type of white blood cell. AbbVie said about 14,620 new cases of CLL are diagnosed each year in the United States and that it is the most common leukemia seen in adults in western countries.

About 3 to 10 percent of CLL patients have the 17p deletion when diagnosed, but it is found in 30 to 50 percent of patients who have relapsed or advanced disease, AbbVie said.