The GMP generation of Human T lymphoid Progenitors (HTLP) that are competent to rapidly become in vivo differentiated functional and thymic-educated T-cells may overcome the post-transplant delayed immune reconstitution... First infusions of HTLP in both clinical trials confirmed the safety and reproducible GMP manufacturing. HLTP offers an exciting perspective for improving immune reconstitution in alternative hematopoietic transplants.