ATG indicates anti-thymocyte globulin; Bu, busulfan; Conv, conventional-intensity conditioning; Cy, cyclophosphamide; DFS, disease-free survival; DLT, dose-limiting toxicity; Flu, fludarabine; GVHD, graft-versus-host disease; Mel, melphalan; MUD, matched unrelated donor; NRM, non-relapse mortality; OS, overall survival; RIC, reduced-intensity conditioning, R/R, relapsed/refractory; TBI, total body irradiation; TRM, treatment-related mortality; TT, thiotepa.