Treatment approaches in first relapse. Dara-Rd, daratumumab-lenalidomide-dexamethasone; Dara-Vd, daratumumab-bortezomib-dexamethasone; Elo-Rd, elotuzumab-lenalidomide-dexamethasone; IMiD, immunomodulatory drugs; Ixa-Rd, ixazomib-lenalidomide-dexamethasone; Kd, carfilzomib-dexamethasone; PI, proteasome inhibitors; Pom-Vd, pomalidomide-bortezomib-dexamethasone.