Protagonist Therapeutics, Inc. announced positive topline results from the blinded, placebo-controlled, randomized withdrawal portion of REVIVE, a study evaluating rusfertide, a subcutaneous injectable hepcidin mimetic, in patients with polycythemia vera (PV). Subjects receiving rusfertide achieved highly statistically significant improvements versus placebo in the primary endpoint. The double-blind, placebo-controlled, 12-week randomized withdrawal phase was included as Part 2 of the REVIVE study to evaluate rusfertide in PV patients with frequent phlebotomy requirements.

In the trial, study subjects were initially enrolled in the 28-week open label dose-titration and efficacy evaluation Part 1 of the study, followed by 1:1 randomization of 53 subjects to placebo versus rusfertide therapy for a subsequent duration of 12 weeks. More subjects receiving rusfertide during the blinded randomized withdrawal portion of the REVIVE study were responders compared with placebo (69.2% versus 18.5%, p=0.0003). A study subject was defined as a responder if the subject completed 12 weeks of double-blind treatment while maintaining hematocrit control without phlebotomy eligibility and without phlebotomy.

During the 12 weeks of the blinded randomized withdrawal, only 2 of 26 subjects on rusfertide were phlebotomized, keeping 92.3% patients phlebotomy free in the rusfertide arm (p=0.0003). In patients with moderate or severe Myeloproliferative Neoplasm-Symptom Assessment Form (MPN-SAF) symptom scores at baseline, the change from baseline was statistically significant in fatigue, problems with concentration, inactivity and itching during the 28-week open label Part 1 of the study. Meaningful comparison of symptom assessments in Part 2 are not possible since a majority of subjects randomized to placebo discontinued prior to the 12-week assessment of MPN-SAF symptoms. Rusfertide was well tolerated, with localized injection site reactions comprising the majority of reported adverse events.