Open-Label Extension Study to Pioneer Study 6058-SCD-101

Inclusion Criteria: * Participants aged ≥18 years and older must have previously participated in and successfully completed Study 6058-SCD-101. * Participant has signed and dated the informed consent form (ICF) before any study-specific procedures are performed and is willing and able to comply with the study procedures and restrictions. * Participants who meet all other inclusion and exclusion criteria for this study, and per Investigator's recommendation may continue standard of care as indicated with the exception of hydroxyurea (HU). Participants may continue crizanlizumab, and/or L-glutamine, but must be on a stable dose for at least 6 months. * Participants, who if female and of childbearing potential, agree to use 2 effective methods of contraception, 1 of which must be highly effective, or practice abstinence starting at the time of the ICF signing to 90 days after the last dose of study drug, and, who if male, should use condoms or practice abstinence from the time of ICF signing to 90 days after the last dose of study drug. * Documented HbF benefit, as judged by the Investigator, from prior study. * Participant must meet both of the following laboratory values during Screening: 1. Absolute neutrophil count ≥ 1.5 × 10\^9/liter, 2. Platelets ≥ 80 × 10\^9/liter * Absolute reticulocyte count during Screening \> 100 × 10\^9/liter. Exclusion Criteria: * Major surgery, serious illness (acute or chronic), infection (clinically significant bacterial, fungal, parasitic or viral infection which requires therapy), fever not resolved within 3 days of onset and requiring treatment, significant bleeding, cerebrovascular accident, or seizure within 14 days prior to signing the ICF and 14 days prior to starting study drug. * Sickle cell complication requiring more than 24-hour care from a medical provider in hospital or emergency care setting in the 14 days prior to starting study drug. * Use of medications that are moderate or strong inducers or inhibitors of cytochrome P450 (CYP) 3A4 or CYP2C8, inhibit P-glycoprotein, breast cancer resistance protein, or multidrug and toxin extrusion protein 2-K, or are substrates of CYP2B6 within 14 days prior to first dose of study drug or anticipated need for any of these medications during the study. * Participation in any other study with an investigational agent other than pociredir within the past 60 days prior to the first dose of study drug. * History of bone marrow transplant or hematopoietic stem cell transplant or gene therapies. * Vaccination in the previous 7 days prior to the first dose of study drug. Note: Other protocol specified criteria may apply