Dr Hunter on the Ongoing Investigation into JAK Inhibitors in Myelofibrosis

Anthony M. Hunter, MD, assistant professor, Department of Hematology and Medical Oncology, Emory University School of Medicine, medical director, Immediate Care Center, Winship Cancer Institute of Emory University, discusses the evolution of JAK inhibitors in myelofibrosis, a topic that was highlighted in a presentation at the 2023 SOHO Annual Meeting.

The primary objective of the presentation was to delve into the historical and emerging data regarding JAK inhibitors, he begins. JAK inhibitors have had a part in the therapeutic arsenal for myelofibrosis for approximately 12 years, starting with the introduction of ruxolitinib (Jakafi). However, there has been a notable expansion in the range of available options, such as momelotinib (Ojjaara), which was approved by the FDA in September 2023 for patients with intermediate- or high-risk primary or secondary myelofibrosis and anemia.

In the presentation, Hunter assessed the data related to the clinically available and forthcoming JAK inhibitors, exploring the unique distinctions among them and identifying their potential roles within specific patient subgroups, as well as the practical aspects of utilizing these drugs. One of the key elements of JAK inhibitors that sets them apart from other agents is their suitability for patients with baseline low blood counts or cytopenias, Hunter emphasizes. Treatment alternatives are emerging for patients with cytopenias, who have historically been difficult to treat with original JAK inhibitors. Pacritinib (Vonjo) is designed for patients with lower platelet counts, specifically those with platelet counts less than 50 x 109/L, a group that had been historically excluded from JAK inhibitor treatment, he explains. Furthermore, data indicate that pacritinib may have the potential to ameliorate anemia in these patients. In addition, data have shown improved outcomes with momelotinib vs danazol in patients with anemia, Hunter continues.

A pivotal factor in choosing between JAK inhibitors for patients with myelofibrosis is the presence of baseline cytopenias. Overall, these agents exhibit substantial spleen response and symptom reduction, he says. However, there is a lack of comprehensive data to guideoncologists on which specific patient subgroups should transition between JAK inhibitors, aside from patients with cytopenias in the frontline setting, Hunter says. Therefore, the rest of these agents remain viable options across the myelofibrosis population, he concludes.