A Phase 2a Study To Evaluate The Pharmacokinetics, Safety, Efficacy, Tolerability, And Pharmacodynamics of Sotatercept (ACE-011) for the Correction of Anemia in Subjects With End-stage Renal Disease on Hemodialysis.

Part 1:

Approximately 8 subjects will be randomized to receive either a single 0.1 mg/kg
subcutaneous dose of sotatercept or matching placebo in a 3:1 ratio

Part 2:

Approximately 8 subjects will be randomized to each of the 3 sequential dose groups
(0.3mg/kg or 0.5mg/kg or 0.7 mg/kg) with a 3:1 ratio of sotatercept or placebo (6 subjects
in the sotatercept arm and 2 in the placebo arm). A total of 24-36 subjects may be
randomized in the 3 dose groups.

Inclusion Criteria:

- Males or females ≥18 years of age.

- Subjects on hemodialysis for at least 12 weeks before screening

- Subjects on a stable dose of Erythrocyte Stimulating Agents product to maintain
Hemoglobin (Hb) for at least 6 weeks prior to screening.

- 3 consecutive pre-dialysis Hb concentrations with a mean ≥10 to ≤ 12 g/dL (≥100 to
≤120 g/L) at screening and one pre-dialysis Hb concentration ≥8 to < 10 g/dL (≥ 80 to
< 100 g/L) before randomization.

- Adequate iron status defined as serum transferrin saturation ≥ 20% before
randomization.

Exclusion Criteria:

- Non renal causes of anemia.

- Subjects on peritoneal dialysis.

- Systemic hematological disease

- High sensitivity C-reactive protein >50mg/L at screening.

- Alanine transaminase (ALT) or aspartate transaminase (AST) laboratory values > 2
times the upper limit of normal (ULN) at screening.

- Uncontrolled diabetes mellitus (HbA1c > 9) at screening.

- Uncontrolled hypertension.

- Red Blood Count (RBC) transfusions within 8 weeks prior to screening.

- Active serious infection or history of recurrent serious infection likely to recur
during the study

- History of severe allergic or anaphylactic reactions or hypersensitivity to
recombinant proteins or excipients in the investigational product or to the iron
products needed to normalize iron levels for subjects.

- Subjects that received treatment with another investigational drug or device within
28 days prior to Day 1

- Pregnant or lactating females.