The FDA granted fast track designation to momelotinib -- a selection JAK1, JAK2 and ACVR1 inhibitor -- for the treatment of patients with intermediate- or high-risk myelofibrosis who previously received a JAK inhibitor. 

The manufacturer plans to launch a randomized double blind phase 3 trial to evaluate the agent among symptomatic, anemic patients with primary myelofibrosis, post-polycythemia vera myelofibrosis or post-essential thrombocythemia myelofibrosis previously treated with JAK inhibitor therapy.

​Woman looking through microscope. Source: Getty

About 180 patients will be randomly assigned 2:1 to receive momelotinib or danazol. The danazol arm will be allowed to crossover after 24 weeks of treatment. 

Total symptom score response rate will be the primary endpoint. Secondary and exploratory endpoints will include transfusion independence and splenic response rate, duration of total symptom score response, anemia benefit, and patient-reported outcome measures of fatigue and physical function.

“Fast track designation for momelotinib highlights the serious and significant unmet needs of patients with myelofibrosis who have previously received a JAK inhibitor,” Barbara Klencke, MD, chief development officer at Sierra Oncology, said in a company-issued press release. “These patients typically suffer from uncontrolled constitutional symptoms, progressively worsening anemia often resulting in transfusion dependency, and enlarged spleens. Fast track also recognizes the absence of FDA-approved treatments for these patients and that momelotinib has the potential to address their unmet needs.”