A Study to Evaluate the Pharmacokinetics and Safety of Etavopivat in Pediatric Patients With Sickle Cell Disease

Inclusion Criteria:

• Type of Participant and Disease Characteristics

1. Patient has confirmed diagnosis of SCD • Documentation of SCD genotype (HbSS, HbSβ0-thalassemia or other sickle cellsyndrome variants) based on prior history of laboratory testing. Moleculargenotyping is not required. SCD genotype may be determined from the results ofHb electrophoresis, high-performance liquid chromatography (HPLC), or similartesting. Note that Hb electrophoresis is performed by the local laboratory atScreening.

2. Hemoglobin greater than or equal to (≥) 5.5 and less than (<) 10.5 grams perdeciliter (g/dL)

3. Adolescent patients with severe SCD, as defined by at least 1 of the following:

• Two or more VOCs in the past 12 months, defined as a previously documentedepisode of acute chest syndrome (ACS) or acute painful crisis (for whichthere was no explanation other than VOC) which required prescription orhealthcare professional-instructed use of analgesics for moderate tosevere pain
• Hospitalization for any SCD-related complication in the last 12 months
• Proteinuria, defined as an albumin:creatinine ratio (ACR) > 100 milligramsper gram (mg/g) on 2 measures (separated by ≥ 1 month) as an indicator ofearly renal disease
• History of a conditional TCD in the last 12 months, but not currentlybeing treated with chronic transfusion therapy. Conditional TCD is definedas a TAMMV of 170-199 centimeters per second (cm/s) by TCD or 155-184 cm/sby imaging TCD (TCDi).

4. For participants taking hydroxyurea (HU), the dose of HU (mg/kg) must be stable (no more than a 20% change in dosing) for at least 90 days prior to start ofstudy treatment with no anticipated need for dose adjustments during the study,in the opinion of the Investigator

5. Patients on crizanlizumab or L-glutamine treatment at the time of consent maybe eligible if they:

• Have been on a stable dose for ≥ 12 months at the time of consent (ie, nochanges to the dose except for changes to weight or for safety reasons)
• For patients on crizanlizumab, have been ≥ 80% compliant with the plannedregimen during the 12 months prior to the time of consent

Exclusion Criteria:

• Medical Conditions

1. More than 10 VOCs within the past 12 months that required a hospital, emergencyroom (ER), or clinic visit

2. Hospitalized for sickle cell crisis or other vaso-occlusive event within 14days of Screening

3. Abnormal TCD in the prior 12 monthsPrior/Concomitant Therapy

4. Patients receiving regularly scheduled blood (RBC) transfusion therapy (alsotermed chronic, prophylactic, or preventive transfusion)

5. Received any blood products within 30 days of starting study treatment

6. Receiving or use of concomitant medications that are strong inducers ofcytochrome P450 (CYP) 3A4/5 within 2 weeks of starting study treatment

7. Use of voxelotor within 28 days prior to starting study treatment oranticipated need for this agent during the study

8. Receipt of erythropoietin or other hematopoietic growth factor treatment within 28 days of starting study treatment or anticipated need for such agents duringthe study

9. Receipt of prior cellular based therapy (eg, hematopoietic cell transplant,gene modification therapy)