This is a non-randomized, open label, multi-site, single-dose, phase 1/2 study in up to 18
participants (including at least 3 adolescents between 12 and 17 years of age, inclusive)
with β-thalassemia major. The study will evaluate the safety and efficacy of autologous
hematopoietic stem cell transplantation (HSCT) using LentiGlobin BB305 Drug Product
[autologous CD34+ hematopoietic stem cells transduced with LentiGlobin BB305 lentiviral
vector encoding the human βA-T87Q-globin gene].