EDIT-301 for Autologous Hematopoietic Stem Cell Transplant (HSCT) in Participants With Transfusion-Dependent Beta Thalassemia (TDT)

Prior treatment

• Prior HSCT or contraindications to autologous HSCT
• Prior receipt of gene therapy
• Any prior or current malignancy, or immunodeficiency disorder,

Other illness

• Participants with associated a history of α-thalassemia and \> 1 alpha chain deletion, or alpha multiplications as documented in medical records
• Participants with a history of other inherited hemoglobinopathy or thalassemic mutation (Hb S, C, D or other) as documented in medical records
• Advanced liver disease
• Immediate family member with a known or suspected Familial Cancer Syndrome
• Clinically significant and active bacterial, viral, fungal, or parasitic infection

Lab values

• Available 10/10 human leukocyte antigen (HLA)-matched related donor
• Inadequate bone marrow function, as defined by white blood cell count of \< 3 x 10\^9/L or a platelet count \< 100 x 10\^9/L (without hypersplenism), per investigator judgement

Other

• Inadequate organ function

• Diagnosis of Transfusion Dependent B-Thalassemia as defined by:
• Documented homozygous β-thalassemia or compound heterozygous β-thalassemia including β-thalassemia/hemoglobin E (HbE) based on historical data in medical records, and
• History of at least 100 mL/kg/year or 10 U/year of packed red blood cell (RBC) transfusions in the 2 years prior to signing informed consent
• Clinically stable and eligible to undergo autologous HSCT
• Karnofsky Performance Status ≥ 70