GBT021601-022: A Study of GBT021601 in Participants With Sickle Cell Disease (SCD)

Inclusion Criteria:

1. Male or female aged 6 months or older with SCD who participated and received studydrug or placebo in a previous osivelotor clinical study and completed the end oftreatment visit. Note: Participants who discontinued study drug in the originating study due to anTEAE, but who remained on study, may be eligible for treatment in this studyprovided the TEAE does not pose a risk for treatment with osivelotor.

2. Females of childbearing potential are required to have a negative urine pregnancytest prior to dosing on Day 1. Note: Females who become of childbearing potential during the study must be willingto have negative urine pregnancy tests to remain in the study.

3. If sexually active, females of childbearing potential must consistently use highlyeffective methods of contraception consistently throughout the study and for atleast 120 days after the last dose of study drug. If sexually active, maleparticipants must use barrier methods of contraception until 84 days after the lastdose of study drug. Male participants are eligible to participate if they agree tothe following requirements during the study intervention period and for 84 daysafter the last dose of study intervention:

• Refrain from donating sperm PLUS either

• Be abstinent from heterosexual intercourse as their preferred and usuallifestyle OR

• Must agree to use a male condom when engaging in any activity that allows forpassage of ejaculate to another person

4. Participant has provided written informed consent/assent. For underage participants,both the consent of the participant's legal representative or legal guardian and theparticipant's assent (where applicable) must be obtained based on localrequirements.

Exclusion Criteria:

• Participant withdrew consent or was noncompliant from the originating osivelotorclinical study

• Current or recent use of voxelotor. Recent use is defined as within 10 days prior toDay 1

• Current or recent use of crizanlizumab. Recent use is defined as within 90 daysprior to Day 1

• Participant has any medical, psychological, safety, or behavioral conditions that,in the opinion of the Investigator, may confound safety interpretation, interferewith compliance, or preclude informed consent

• Has received an investigational drug (including investigational vaccines) within 5times the elimination half-life (if known) or within 30 days (if the eliminationhalf-life- is unknown) prior to study drug administration or is concurrentlyenrolled in any research judged not to be scientifically or medically compatiblewith this study