Protagonist Therapeutics wants to take the lead in a genetic iron disease, delivering midphase data on a hormone replacement therapy it envisages offering an alternative to blood draws.
Rusfertide is Protagonist’s attempt to improve on the druglike properties of the hormone hepcidin to alter the regulation of iron homeostasis. In people with hereditary hemochromatosis, who absorb too much iron from food, the mechanism of action could enable physicians to stop excessive iron accumulation—and the negative outcomes it causes—without relying solely on blood draws.
The 16 subjects in the phase 2 clinical trial self-administered a subcutaneous dose of rusfertide once or twice a week, with physicians adjusting the dose based on disease biomarkers over the course of the six-month study.
Average serum iron and the ratio of serum iron to total iron-binding capacity, the primary endpoints of the study, fell from baseline, with the p-values coming in at 0.0106 and 0.0051, respectively. Drops in serum iron and the transferrin saturation ratio were seen 24 hours after the first rusfertide dose.
The improvements correlated to less need for the blood draws, known medically as phlebotomies, that are the main treatment for the disease today. Participants were averaging 0.28 phlebotomies per month pre-study. That fell to 0.009 phlebotomies per month during the study.
“Rusfertide has the potential to offer a treatment option for patients in whom phlebotomy may be difficult or contraindicated,” Kris Kowdley, M.D., the Washington State University physician who served as the study’s principal investigator, said in a statement.
Most participants experienced a treatment-emergent adverse event, but the only report higher than Grade 2 was a preexisting case of pancreatic cancer deemed unrelated to the drug. Around half of the subjects suffered mild or moderate treatment-emergent injection site reactions.
Protagonist now plans to talk to clinical investigators and regulatory agencies to determine the next steps.