Study to Evaluate Effect of a Single Dose of Sotatercept (ACE-011) on Red Blood Cell Mass and Plasma Volume in Subjects With Solid Tumors

Inclusion Criteria:

1. Men and women ≥ 18 years of age.

2. Histologically confirmed diagnosis of a solid tumor malignancy documented by cytology
or biopsy.

3. Presence of metastatic disease.

4. Hemoglobin value between ≥ 8.0 to < 11.0 g/dL (≥ 80 to < 110 g/L).

5. ≥ 28 days must have elapsed (prior to pre-dose RBC mass / PV test) since previous
treatment with erythropoiesis-stimulating agent (including concurrent treatment with
IV iron).

6. ≥ 28 days must have elapsed (prior to Day 1) since the last RBC blood transfusion and
receipt of ≤ 2 units of blood in the past 56 days (prior to Day 1).

7. Eastern Cooperative Oncology Group (ECOG) Performance status of 0 - 1.

Exclusion Criteria:

At the time of screening, subjects who have any grade ≥ 3 toxicity (according to the
currently active minor version of NCI CTCAE v4.0, except for the following disease related
toxicities:

- Hematological events - anemia, thrombocytopenia, neutropenia

- Non-hematological events - nausea, vomiting, fatigue, muscle or bone/joint pain