A Phase 2 Study to Evaluate the Safety and Efficacy of Pacritinib in Relapsed or Refractory Waldenström Macroglobulinemia

This is a single-arm, open-label, Phase II study to evaluate the safety and efficacy of pacritinib in participants with symptomatic Waldenström macroglobulinemia (WM). Pacritinib is a targeted therapy that blocks a protein called JAK2 that helps cells live and grow. It also inhibits IRAK1, which is important for the survival of WM cells. By blocking JAK2 \& IRAK1, pacritinib may kill abnormal cells or stop them from growing. The U.S. Food and Drug Administration (FDA) has not approved pacritinib for WM but it has been approved for Myelofibrosis. The research study procedures include screening for eligibility, in-clinic visits, questionnaires, blood tests, urine tests, Computerized Tomography (CT) scans, X-rays, echocardiograms (ECGs), bone marrow biopsies and aspirations Participants will receive study treatment for up to 4 years and will be followed for 2 years, or until there is start of a new treatment. It is expected that about 30 people will take part in this research study. Sobi AG, Inc. is supporting this research study by providing study drug and funding.