The goal of this open label, single-arm clinical study is to learn about the safety and efficacy of base-edited autologous hematopoietic stem cell transplantation(CS-101) in treating patients with β-thalassemia major.

CS-101 is an autologous CD34+ cell suspension modified by ex vivo base editing technology, removing the inhibitory effect of BCL11A on the γ-globin coding gene, inducing the production of γ-globin chains, increasing the concentration of fetal hemoglobin (HbF) in the blood, compensating for the loss of adult hemoglobin (HbA) to treat transfusion-dependent type/ Major β - thalassemia. The therapy addresses two major challenges in the treatment of the disease: lack of matching donors and graft-versus-host responses commonly seen in allogeneic hematopoietic stem cell transplantation.

The study consists of the following five phases:

Screening phase: Sign informed consent, complete screening assessments, and confirm the eligibility for enrollment; Baseline: check the subject's baseline status; Mobilization, collection and manufacturing phase: mobilize, collect autologous CD34+ cells and manufacture, release and transport CS-101 product; Conditioning and treatment phase: including myeloablation and CS-101 product infusion; Follow-up phase: 180 days post-infusion.

Inclusion Criteria:

• 3 to 17 years old(inclusive) male or female subjects at the time of informed consenting
• Diagnosis of β-thalassemia, genotypes include but are not limited to β+β0, βEβ0, β0β0, etc
• Generally in good condition, Karnofsky performance score≥60 points for subjects≥16 years old at the time of autologous hematopoietic stem cell collection, or Lansky Play-Performance score≥60 points for subjects under 16 years old, or equivalent clinical evaluation as the investigator site's common practice
• For female subjects of childbearing potential: use effective contraceptive measures for at least 1 month prior to screening and agree to continue using such measures for contraception throughout the study
• For male subjects who have a potential ability to father a child: use condoms or other methods continuously from the start of mobilization to ensure effective contraception for sexual partners during the study period

Exclusion Criteria:

• Treatment with other investigational medications or other experimental interventions 30 days prior to signing informed consent or within 6 half-lives of the drug, whichever is longer.
• Subjects who have received or are receiving thalidomide and/or Luspatercept, when their drug-drug interaction on the efficacy and safety of CS-101 cannot be ruled out, unless at least there are 3 test results showing the total hemoglobin level before transfusion is below 9g/dL in the past 6 months before screening.
• Previously received allogeneic hematopoietic stem cell transplantation or gene(edited) therapy.
• Subjects have available related fully matching donors and are eligible and prepared for allogeneic hematopoietic stem cell transplantation.
• Subjects with coexisting α-thalassemia and more than 2 deletions or non-deletional mutations in the α-globin chain coding genes.
• Known to be allergic to drugs used during autologous hematopoietic stem cell transplantation (including but not limited to granulocyte colony-stimulating factor, busulfan, dextran), excipients(such as dimethyl sulfoxide), or instruments(such as intravenous catheters) as determined by the investigator are deemed unsuitable to participate in this study.
• Those with active infections, including but not limited to: HIV, hepatitis B, hepatitis C, cytomegalovirus, Epstein-Barr virus and treponema pallidum test positive, or known tuberculosis, parasitic infection, etc. who are judged by the investigator to be unsuitable to participate in this study
• Echocardiography results with ejection fraction below 45%
• Subjects who are febrile (temperature over 37.3° C) should be held back from enrolment.
• Advanced liver disease, defined as aspartate aminotransferase (AST), alanine aminotransferase (ALT) >3 × upper limit of normal (ULN) or baseline International Normalized Ratio (INR) >1.5 × ULN
• MRI during the screening period showed heavy iron overload and is judged by the investigator to be unable to participate in the study.
• Patients with past/present history of cancer
• Known neurological disorders, psychological problems or mental illness, and is judged by the investigator to be unable to cooperate with the study procedures
• Known history of uncontrolled epileptic seizures and is judged by the investigator to be unfit to participate in this study
• Known history of other serious cardiovascular, pulmonary, renal diseases, digestive tract conditions, liver diseases and / or other conditions, etc., and are judged by the investigator to be intolerable or inappropriate for autologous hematopoietic stem cell mobilization, collection, and myeloablative conditioning and infusion
• Pregnant or lactating women