A Study of KER-050 to Treat Anemia Due to Very Low, Low, or Intermediate Risk Myelodysplastic Syndromes

Key Inclusion Criteria:

1. Diagnosis of MDS according to World Health Organization (WHO)/French AmericanBritish (FAB) classification that meets Revised International Prognostic ScoringSystem (IPSS-R) classification of very low, low, or intermediate risk disease.

2. < 5% blasts in bone marrow.

3. Peripheral blood white blood cell count <13,000/µL.

4. Anemia defined as:

5. In non-transfused participants, having received no red blood cell (RBC)transfusions within 8 weeks Hgb concentration ≤ 10.0 g/dL OR

6. In LTB participants, having received 1 to 3 units RBCs for Hgb ≤ 9.0 g/dLwithin 8 weeks OR

7. In HTB participants, having received ≥ 4 units of RBCs for Hgb ≤ 9.0 g/dLwithin 8 weeks

8. Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1, or 2 (ifrelated to anemia.

9. Females of child-bearing potential and sexually active males must agree to useeffective methods of contraception.

Key Exclusion Criteria:

1. Any active infection requiring parenteral antibiotic therapy within 28 days prior toCycle 1 Day 1 or oral antibiotics within 14 days of Cycle 1 Day 1.

2. Diagnosis of secondary MDS (i.e., MDS known to have arisen as the result of chemicalinjury or treatment with chemotherapy and/or radiation for other diseases).

3. Vitamin B12 deficiency.

4. Prior treatment with azacitidine, decitabine, lenalidomide, luspatercept, orsotatercept.

5. Treatment within 28 days prior to Cycle 1 Day 1 with:

6. Erythropoiesis stimulating agent (ESA) OR

7. Granulocyte colony-stimulating factor (G-CSF) OR

8. Granulocyte-macrophage colony-stimulating factor (GM-CSF)

9. Iron chelation therapy if initiated within 8 weeks prior to Cycle 1 Day 1.

10. Vitamin B12 therapy within 8 weeks prior to Cycle 1 Day 1.

11. Treatment with another investigational drug or device or approved therapy forinvestigational use < or = 28 days prior to Cycle 1 Day 1, or if the half-life ofthe previous product is known, within 5 times the half-life prior to Cycle 1 Day 1,whichever is longer.

12. Platelet count > 450 x 109/L or < 30 x 109/L.

13. Transferrin saturation < 15%.

14. Ferritin < 50 µg/L.

15. Folate < 4.5 nmol/L (< 2.0 ng/mL).

16. Vitamin B12 < 148 pmol/L (< 200 pg/mL).

17. Estimated glomerular filtration rate (GFR) < 40 mL/min/1.73 m2 (as determined by theChronic Kidney Disease Epidemiology Collaboration [CKD-EPI].

18. Pregnant or lactating females