Incyte is celebrating after US regulators gave the green light to Jakafi for patients suffering with myelofibrosis.

The US Food and Drug Administration has approved Jakafi (ruxolitinib) for the treatment of patients with intermediate or high-risk myelofibrosis (MF). It is the first product to be approved by the agency for MF, and the first in a new class of drugs, JAK inhibitors, to be approved for any indication.

MF is an uncommon, life-threatening blood cancer characterised by bone marrow failure and enlarged spleen (splenomegaly). Symptoms including fatigue, night sweats and pruritus, poor quality of life, weight loss and shortened survival and Incyte believes it affects about 16,000-18,500 people in the USA.

The approval was based on results from two Phase III trials (one carried out by Incyte, the other by partner Novartis), which demonstrated that patients treated with Jakafi experienced significant reductions in splenomegaly, or enlarged spleen.

Richard Pazdur, director of the Office of Hematology and Oncology Drug Products in the FDA’s Center for Drug Evaluation and Research, said that Jakafi "represents another example of an increasing trend in oncology where a detailed scientific understanding of the mechanisms of a disease allows a drug to be directed toward specific molecular pathways". Incyte chief executive Paul Friedman said the thumbs-up "marks a tremendous achievement" for his firm "because a scientific discovery from our research laboratories has become the first JAK inhibitor to reach the market".

As part of their collaboration signed in 2009, Incyte retained exclusive rights to develop ruxolitinib in the USA, while Novartis can sell the drug in all haematology-oncology indications elsewhere.