VTD indicates bortezomib, thalidomide, and dexamethasone; TD, thalidomide and dexamethasone; RVD, bortezomib, lenalidomidee, and dexamethasone; Rd, lenalidomide and dexamethasone; V, bortezomib; PVD, pomalidomide, bortezomib, and dexamethasone; CRd, carfilzomib, lenalidomide, and dexamethasone; CPd, carfilzomib, pomalidomide, and dexamethasone; C, carfilzomib; Pd, pomalidomide and dexamethasone; PR, partial response; VGPR, very good partial response; PFS, progression-free survival; TTP, time to progression; OS, overall survival; f/u, follow-up; and NR, not reported.

* p < 0.05.