PTG-300 in Subjects With Hereditary Hemochromatosis

Inclusion Criteria: * Men and women aged 18 and older * Confirmed diagnosis of HFE-related hereditary hemochromatosis with prior genotype testing * Documented stable phlebotomy for ≥ 6 months * Screening hemoglobin \>11.5 g/dL * Documented evidence of prior serum ferritin ≥500 ng/mL * Serum ferritin \>50 ng/mL and \<300 ng/mL at screening Exclusion Criteria: * Clinically meaningful laboratory abnormality * Receiving iron chelation therapy * Receiving erythrocytapheresis * Pregnant or lactating females * Infection requiring hospitalization or intravenous antimicrobial therapy, or opportunistic infection within 3 months of dosing; any infections requiring antimicrobial therapy within 4 weeks of dosing. * Serious or unstable medical or psychiatric condition that would prevent subject providing informed consent * Organ damage from iron overload * Primary or secondary immunodeficiency * Positive hepatitis B or hepatitis C or known human immunodeficiency virus infection * Known history of autoimmune/inflammatory diseases * Any surgical procedures requiring general anesthesia within 1 month prior to screening or planned surgery during study * History of invasive malignancies within last 2 years, except non-malignant skin cancer and local cured prostate cancer, cervical cancer, or ductal carcinoma in situ * Receipt of an investigational agent within 30 days of screening