The purpose of this study is to determine the safety and clinical effects of SCD-101 when given to adults with sickle cell disease.

This is single site, dose- escalation study of SCD-101 in participants with homozygous sickle cell disease (S/S) or S/beta 0 Thalassemia. All participants will be monitored for safety, tolerability, and dose-limiting toxicities.

The study is divided into two parts. Part A is an open-label, non-randomized, non-placebo-controlled dose escalation study with a 28-day treatment phase and 14-day follow-up phase with five cohorts . Part B is a randomized, placebo-controlled, confirmatory 2x2 crossover cohort with a 28 day washout between periods, and a 28-day follow-up phase.

Inclusion Criteria:

1. Male or female, 18-55 years of age
2. Homozygous sickle cell disease or S/beta 0 thalassemia
3. Hemoglobin F ≤10%
4. Hemoglobin ≥ 6.0 g/dL and ≤ 9.5 g/dL
5. Female participants of child bearing potential and male participants whose partner is a female of child bearing potential must be willing to use approved contraception during the trial and for 3 months following the end of treatment. Only barrier methods or complete abstinence are acceptable for this study. Participants using hormonal contraception (including morning-after-pill) and IUD are excluded unless willing/able to change to an acceptable form of contraception.
6. Ability to adhere to the study visit schedule and other protocol requirements
7. Ability to understand and the willingness to sign an informed consent document

Exclusion Criteria:

1. Red blood cell transfusion within 3 months of enrollment
2. Hydroxyurea treatment within 6 months of enrollment
3. Painful or other acute sickle cell event that required a hospitalization within 4-weeks of enrollment
4. AST and/or ALT >3x upper limit of normal and/or creatinine >2x upper limit of normal or any other significant renal or hepatic impairment
5. Estimated creatinine clearance (CrCl) < 60 mL/min (Cockcroft- Gault formula) at screening.
6. QTc interval of >470 msec at trial entry and participant with congenital long QT syndrome.
7. No other significant sickle cell or non-sickle cell illness that would confound the results of the trial
8. Any condition that, in the view of the investigator, places the participant at risk because of participation in the trial, or may influence the result of the trial or the participant's ability to participate in the trial
9. Participant pregnant or nursing an infant or planning pregnancy during the course of the trial
10. History of allergic reactions attributed to sorghum or compounds of similar chemical or biologic composition (such as Nicosan, Niprisan, Jobelyn or Xickle).
11. Other investigational drug use within 3 months of enrollment
12. PROMIS Fatigue Questionnaire 8a T-score ˂ 44.3