A Study to Evaluate Safety, Pharmacokinetic, and Biological Activity of INCB059872 in Subjects With Sickle Cell Disease

Inclusion Criteria:

- Diagnosis of SCD (sickle cell SS) confirmed through hemoglobin electrophoresis.

- Must be red blood cell (RBC) transfusion-independent (not currently on regularly
scheduled transfusions) for ≥ 3 months from the time of first dose of study drug.

- No RBC transfusion within 30 days of first dose of study drug.

- Hydroxyurea (HU) refractory

-Must not have received HU therapy during the 3 months before receiving study drug.

- Creatinine clearance ≥ 60 mL/min based on the institutional formula.

- Willingness to avoid pregnancy or fathering children.

Exclusion Criteria:

- Any unresolved toxicity ≥ Grade 2 from previous therapy except for stable chronic
toxicities not expected to resolve.

- Pregnant or nursing women or participants expecting to conceive or father children
within the projected duration of the study, starting with screening visit through
completion of safety follow-up.

- Received an investigational study drug within 28 days or 5 half-lives (whichever is
longer) before receiving the first dose of study drug (requirement may be waived with
medical monitor approval).

- Chronic or current active infectious disease requiring systemic antibiotics,
antifungal, or antiviral treatment.

- Prior receipt of LSD1 inhibitor therapy for any indication.