Dr. Oh on the Development of JAK Inhibitors in Myelofibrosis

Stephen Oh, MD, PhD, assistant professor of medicine, Division of Hematology, Washington University School of Medicine, Siteman Cancer Center, discusses the development of JAK inhibitors in myelofibrosis.

Each of the JAK inhibitors, apart from ruxolitinib (Jakafi), has raised concerns over safety, explains Oh. The first of the 3 investigational JAK inhibitors is momelotinib, which seems to improve anemia in a subset of patients. Since Gilead discontinued the development of that agent, Sierra Oncology has acquired the rights to the drug. It looks like it will move forward in development, states Oh.

Pacritinib is another JAK inhibitor that seems to be safe in patients with a low platelet count. The FDA hold on that agent has since been lifted, and there is an ongoing study to determine the lowest dose that can be safely and effectively administered in patients with myelofibrosis, says Oh. Fedratinib, the last JAK inhibitor, had been put on FDA hold due to concerns over Wernicke’s-like encephalopathy syndrome. The FDA hold has also been lifted, and the drug is being redeveloped by Celgene.