The U.S. Food and Drug Administration announced Thursday its approval allowing Jakafi (ruxolitinib) to be used for treating a chronic disease affecting the bone marrow.

Polycythemia vera causes an overabundance of red blood cells in the bone's marrow, leading as well to a spike in the number of platelets and white blood cells in patients. Due to having too many blood cells in the body, the spleen swells and blood clots close to the skin's surface and bleeding problems occur. Additionally, polycythemia vera increases risks of heart attacks and strokes in patients.

The first to be approved by the FDA for the condition, Jakafi is geared for use towards those who cannot tolerate or manifested inadequate responses to hydroxyurea, another drug aimed at reducing the level of platelets and red blood cells in the blood. It is able to do the same by targeting enzymes known as Janus Associated Kinase 1 and 2 and inhibiting their function. JAK 1 and 2 regulate immunological and blood functions in the body. Using Jakafi is seen as a means of reducing cases of spleen enlargement as well as the need to draw out excess blood in the body.

"The approval of Jakafi for polycythemia vera underscores the importance of developing drugs matched to our increasing knowledge of the mechanisms of diseases," said Richard Pazdur, M.D., Office of Hematology and Oncology Products director from the FDA, adding the trial used for evaluating the medication led to reductions in the sizes of spleens and the need for phlebotomies to manage the condition that are meaningful in a clinical setting.

A clinical trial was used to evaluate the effectiveness and safety of Jakafi in treating polycythemia vera, working with 222 participants, all diagnosed with the condition for a minimum of 24 weeks, manifested enlarged spleens, had undergone phlebotomies (the process of drawing out excess blood in the body) and could not tolerate or exhibited inadequate responses to hydroxyurea.

According to results, 21 percent of those given Jakafi had reduced need for phlebotomies and has smaller spleens by Week 32 of the study. This is compared to the 1 percent of subjects who were administered best available treatments at the time.

The FDA had earlier approved Jakafi in 2011 for use in patients with high-risk or intermediate myelofibrosis, another bone marrow disease. For this approval, the medication underwent priority review because of the promise it held as a dramatic improvement in efficacy or safety compared to available treatment options. Jakafi was also designated an orphan product because it was intended for treating a rare condition.