Incyte Corp’s Jakafi (ruxolitinib) has become the first drug to be approved for the treatment of the rare bone marrow disease myelofibrosis.

Myelofibrosis is a disease in which the bone marrow is replaced by scar tissue. This causes an uncontrollable growth of blood cells in organs such as the liver and spleen, which become enlarged as a result.

The US Food and Drug Administration (FDA) approved Jakafi after two clinical trials showed that patients given the drug experienced more than a 35% reduction in spleen size compared to patients receiving placebo.

A greater proportion of patients receiving Jakafi saw more than a 50% reduction in their myelofibrosis-related symptoms, including abdominal discomfort, itching and bone or muscle pain, than was the case in patients receiving placebo.

Jakafi, a pill taken two times a day, inhibits enzymes called JAK 1 and 2, which are involved in regulating blood and immunological functioning.

Richard Pazdur, director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research said, “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.

“The clinical trials leading to this approval focused on problems that patients with myelofibrosis commonly encounter, including enlarged spleens and pain.”