CS-206 in Patients With Sickle Cell Disease

Inclusion Criteria: * Participants must be between 12 to 18 years old (inclusive). Participants or their legal guardians (for participants below 18 years old) must provide written informed consent before any study-related procedures. * Participants must have a Documented βS/βS, βS/β0 or βS/β+ genotype. * Participants must have at least one of the following conditions 1. At least 2 occurrences of any of the following events within 2 years prior to screening. 1. Acute pain crisis: requiring a visit to a medical facility and administration of pain medications (opioids or intravenous NSAIDs) or red blood cell transfusions. 2. Acute chest syndrome: defined by the presence of a new pulmonary infiltrate on a chest X-ray, associated with pneumonia-like symptoms, including chest pain, fever, or respiratory distress. 3. Priapism lasting more than 2 hours and necessitating a visit to a medical facility for intervention. 4. Stroke or transient ischemic attack (TIA): confirmed by imaging studies (e.g., MRI or CT scan), including silent stroke, and overt stroke leading to neurological deficits lasting \>24 hours. 2. Presence of red cell alloimmunization (\>2 antibodies) and the need for ongoing chronic transfusions. 3. Participants who have failed, not tolerated, refused the standard of care for Sickle Cell Disease (SCD), or are unable to access the standard of care due to the availability 4. Other situations deemed appropriate for hematopoietic stem cell transplantation according to the sickle cell anemia treatment guidelines, as determined by the investigator. * Laboratory Parameters: 1. Documented Hemoglobin S (HbS) level ≥30% of total hemoglobin (Hb) concentration prior to transfusion. 2. HbF at screening \< 20% * Participants must have a Karnofsky Performance Status (KPS for participants above 16 years old, inclusive) or Lansky Play-Performance Scale (LPPS for participants below 16 years old) score of ≥70, indicating sufficient functional status to undergo the intervention. * Willing to comply with the protocol requirements, use contraception as required, attend regular follow-up visits, and cooperate with examinations Exclusion Criteria: * Female participants who are pregnant, breastfeeding, or planning pregnancy during the study period are excluded. * Participation in another investigational drug trial within 30 days prior to screening or within 5 half-lives (whichever is longer). * Subjects who have received or are receiving luspatercept treatment within 3 months prior to screening. * Subjects who have previously received any gene therapy for the disease. * Subjects with a fully matched related donor who are already scheduled for allogeneic hematopoietic stem cell transplantation. * More than 10 unplanned hospitalizations or emergency visits within 12 months prior to screening, which the investigator believes are related to significant chronic pain rather than acute pain crisis (VOC). * Severe liver dysfunction: 1. Aspartate aminotransferase (AST) or alanine aminotransferase (ALT) \>3× the upper limit of normal (ULN) or: 2. International Normalized Ratio (INR) \>1.5× ULN * Severe renal impairment (creatinine clearance \<30 mL/min/1.73 m²) are excluded. * Subjects with HIV, cytomegalovirus (CMV), Epstein-Barr virus (EBV), or Treponema pallidum infection during the screening period; those with active HBV or HCV infection; or known tuberculosis or parasitic infection, etc. Excludes subjects with stable hepatitis B (HBV-DNA negative) after treatment and those cured of hepatitis C (HCV-RNA negative). Known active bacterial, viral, or fungal infections. * Deemed unsuitable for autologous hematopoietic stem cell transplantation procedures as determined by the investigator. * Other situations deemed unsuitable for this study as determined by the investigator.