Roche said on Tuesday that the U.S. Food and Drug Administration has granted priority review for its venetoclax drug application for blood cancer treatment, which it is developing with partner AbbVie.

Analysts have said the medicine has blockbuster sales potential and U.S. regulators already fast-tracked it for approval last May by designating it a breakthrough therapy.

The companies have said the drug has met its primary treatment goal in patients with chronic lymphocytic leukemia who had a so-called 17p gene deletion.

The mutation has been associated with aggressive cancer and survival of less than two to three years after diagnosis.

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

"Venetoclax is a potential new way to treat this difficult type of chronic lymphocytic leukemia,” Sandra Horning, Roche's chief medical officer and head of global product development, said in a statement.

CLL is a slow-growing cancer of the blood and bone marrow and is one of the most common adult leukemias worldwide. It is generally considered incurable.

Roche is also seeking approval in Europe for the drug, where the European Medicines Agency has validated its marketing authorization application.