Myeloma patients who develop bortezomib and lenalidomide-resistant disease have a very poor survival of only a median of 9 months, indicating that new agents are urgently needed. Recent studies have shown that daratumumab as a single agent is effective and well tolerated in these heavily pretreated MM patients. However, approximately 60% of patients do not achieve a partial response, and ultimately all patients will develop progressive disease during daratumumab therapy. In less pretreated patients daratumumab-based combinations (daratumumab plus lenalidomide-dexamethasone or daratumumab plus bortezomib-dexamethasone) were very effective and well tolerated. Therefore, in this study, the investigators will combine daratumumab with other agents to improve survival of heavily pretreated MM patients.