Phase II Study Shows Hopeful Results for Blood Cancer Therapy

Protagonist Therapeutics recently reported that rusfertide, an experimental peptide therapy, has successfully achieved its main goal in the Phase II REVIVE trial. The therapy was found to be effective in controlling the overproduction of red blood cells, a condition known as erythrocytosis, in individuals with polycythemia vera.

The study, detailed in The New England Journal of Medicine, indicated that the average maximum hematocrit level decreased to 44.5% following rusfertide treatment, a significant reduction from the initial 50% recorded during the first 28 weeks of the trial. Notably, 60% of the participants who received rusfertide experienced a treatment response, which is defined as maintaining a hematocrit level below 45% without the need for bloodletting, compared to only 17% in the placebo group. This outcome was statistically significant, with a p-value of 0.002.

Protagonist's Chief Medical Officer, Arturo Molina, highlighted that the REVIVE trial's findings could establish rusfertide as an innovative treatment for polycythemia vera patients, particularly those who struggle with the side effects of conventional treatments. The company is committed to further evaluating the long-term safety and sustained efficacy of rusfertide in the ongoing REVIVE study.

Additionally, Protagonist is conducting the Phase III VERIFY trial, an international, placebo-controlled study involving 250 participants. This trial aims to assess the weekly subcutaneous self-injection of rusfertide in terms of efficacy, symptom relief, and safety. The results from VERIFY are anticipated in 2025.

Polycythemia vera, a blood cancer affecting roughly 160,000 people in the U.S., is characterized by an excess of red blood cells. Patients often face an elevated risk of cardiovascular events and various systemic symptoms such as itching, night sweats, fatigue, and concentration difficulties. If untreated, this condition can result in severe consequences like heart attacks, strokes, and even death.

Currently, there is no cure for polycythemia vera, and management typically involves medications and interventions aimed at keeping hematocrit levels below 45%. These treatments can include bloodletting, which may also lead to iron deficiency.

Rusfertide functions as a peptide mimetic of the hormone hepcidin, which plays a crucial role in regulating iron balance and the proper development of red blood cells. Its mechanism of action is designed to reduce hematocrit levels to acceptable ranges without increasing the risk of iron deficiency.

Recently, Takeda recognized the potential of rusfertide and invested $300 million in Protagonist for a worldwide license to develop and market the therapy. While Protagonist retains responsibility for the Phase III VERIFY trial and U.S. regulatory approval, Takeda will manage ex-U.S. development and lead global commercialization efforts.