Gain of chromosome 1q21 and the gene expression-based GEP70 risk score are established prognostic markers for newly diagnosed Multiple Myeloma (MM) patients. Here we addressed the prognostic impact of these two markers in 81 relapsed/refractory (RR) MM patients treated with the CD38-antibody daratumumab. Fluorescence in situ hybridization for 1q21 was performed at initial presentation, while the GEP70 score was determined at initial presentation and prior to daratumumab treatment. While the GEP70 at initial presentation showed a trend for inferior survival, the GEP70 collected prior to daratumumab treatment was significantly associated with poor outcome (P < 0·05). The worst outcome was seen for patients who were positive for gain(1q) and classified as GEP70 high risk prior to daratumumab [progression-free (PFS) and overall survival (OS) of 0·3 years (95% CI: 0·15-1·4 years) and 0·8 years (95% CI: 0·5-1·9 years) respectively], while the median PFS and OS were not reached by patients without gain(1q) and GEP70 low-risk status. In conclusion, gain(1q) and the GEP70 are powerful prognostic markers for RR MM patients treated with daratumumab, and patients classified as high risk according to these markers experience shorter treatment response.