Jakafi Risks Require Monitoring of Dose During First Three Months: Study

In response to concerns about the potential risks associated with Jakafi, researchers warn that doctors should closely monitor patients during the first three months they are on the myelofibrosis drug.

A study published this month in the medical journal Haematologica indicates that doctors should be on the lookout for signs of anemia and thrombocytopenia during the first three months a patient is on Jakafi treatment. After that time period, they determined that the drug was overall safe and effective.

Researchers from a number of universities and clinics across the U.S. conducted a randomized, double-blind clinical trial of Jakafi (ruxolitinib), a drug approved in 2011 by the FDA to treat myelofibrosis. Also known as Jakavi, it is manufactured and distributed by Incyte Pharmaceuticals and Novartis.

Myelofibrosis is a bone disease that results in bone marrow being replaced with scar tissue, impairing red blood cell regeneration. This causes blood to form in other areas, like the liver and spleen, which causes them to enlarge. The average life span after diagnosis is five years.

According to the study’s findings, the first 8-12 weeks often causes a platelet count decrease, but after that the platelets remain relatively stable. The drug’s label warns about both anemia and thrombocytopenia.

Survivability was increased among patients who were given the drug, and when anemia and thrombocytopenia occurred they rarely led to patients dropping treatment, the researchers reported. Two patients given Jakafi developed acute myleloid leukemia (AML). However, two patients given placebos also developed AML.

An earlier study’s findings suggest that side effects of Jakafi may also increased the risk of a deadly brain disease, known as progressive multifocal leukoencephalopathy or PML.

Progressive multifocal leukoencephalopathy (PML) is an aggressive brain disease that is believed to be caused by the common JC virus. Many suspect that the virus becomes active after drugs suppress the immune system. In many cases, the infection results in death.

Symptoms of PML could include changes in mood, unusual behavior, confusion, memory loss, weakness or loss of strength on one side of the body, or problems with vision, speech or walking.

Other drugs linked to PML, such as Tysabri and Gilenya, have been highly restricted by the FDA due to the risk to patients. Tysabri was recalled at one point before being re-released under more stringent safety measures.