US regulators have approved Novartis and Incyte's JAK 1 and 2 inhibitor Jakavi (ruxolitinib) for another rare blood cancer called polycythemia vera, making it the first specifically approved for the condition in the country.

Polycythemia vera is a chronic and incurable condition characterised by the overproduction of red blood cells in the bone marrow, which can cause the spleen to swell, bleeding problems and blood clots in the veins near the skin surface (phlebitis). It also puts patients at increased risk of stroke or heart attack.

Jakafi, which also carries Orphan Drug status, works by inhibiting enzymes called Janus Associated Kinase (JAK) 1 and 2 that are involved in regulating blood and immunological functioning. 

US Food and Drug Administration approval came on the back of clinical data showing that, compared to best available therapy, the drug maintained red blood cell volume without the need for phlebotomy and reducing spleen size in patients who cannot take the chemotherapy hydroxyurea.

Jakavi was approved by the FDA in 2011 for myelofibrosis and is widely expected to attain blockbuster status; the drug is also being tested in trials for pancreatic cancer.