AbbVie's venetoclax has picked up another breakthrough therapy status in the US, this time in combination with Roche's rituximab as a treatment for patients with relapsed/refractory chronic lymphocytic leukaemia.

The drug, an inhibitor of the B-cell lymphoma-2 (BCL-2) protein being developed with Roche and Genentech, was previously assigned breakthrough status for the treatment of patients with R/R CLL who carry the 17p deletion.

The new designation comes on the back of early-stage study results showing that patients with R/R CLL taking venetoclax in combination with rituximab had an overall response rate of 84 percent, while six patients stopped therapy after achieving either a complete response or CR with incomplete marrow recovery. 

"This second Breakthrough Therapy Designation for venetoclax granted by the FDA underscores the significant potential of this therapy in treating relapsed/refractory CLL patients,” said Michael Severino, executive vice president of research and development and chief scientific officer at AbbVie. 

CLL is a slow-progressing and difficult-to-treat cancer of the bone marrow and blood, in which the bone marrow makes too many lymphocytes, a type of white blood cell. It is the most common type of leukaemia in the Western world, with more than 14,000 cases in the US diagnosed every year. 

Regulators on both sides of the Atlantic are currently reviewing a marketing application for the drug. The FDA is considering its use in patients who have received at least one prior therapy, including those with 17p deletion, while in Europe the target population is those carrying either the 17p deletion or TP53 mutations.