An experimental treatment for chronic lymphocytic leukemia (CLL) from GlaxoSmithKline (NYSE:GSK) and drug partner Genmab has been granted status by the Food and Drug Administration that smooths the regulatory path for the drug.

Designation as a “breakthrough therapy” should speed up the FDA’s evaluation of Arzerra in combination with another drug, chlorambucil, to treat CLL, the most common form of leukemia in adults. The partners are studying the drug combination in patients who have not received prior treatment and cannot be treated by the chemotherapy drug fludarabine, which is used to treat blood cancers such as leukemia.

The FDA created the breakthrough designation to expedite review of drugs developed to treat serious or life-threatening medical conditions. The FDA grants this status when preliminary clinical evidence shows the drug may offer substantial improvement by at least one clinically significant measure over existing therapies.

CLL is the most common form of leukemia in adults. The American Cancer Society estimates that in 2013 CLL will account for more than 15,680 new cases and more than 4,580 deaths in the United States. No curative chemotherapy is available for the disease.

The partnership between British pharma GSK and Danish drug developer Genmab dates to 2006 when the companies entered an agreement to co-develop and commercialize ofatumumab, the compound that is now called Arzerra. Ofatumumab is an antibody that targets the CD20 molecule. The agreement gave GSK exclusive worldwide rights to ofatumumab as well as any other antibodies that Genmab may develop targeting that molecule.

GSK operates its U.S. headquarters in Research Triangle Park.