The use of lenalidomide in frontline therapy for patients with newly diagnosed multiple myeloma (MM) has increased the number of those who become refractory to lenalidomide at second line. In this context, we assessed the efficacy of daratumumab in combination with ixazomib and dexamethasone (Dara-Ixa-dex) in the prospective phase 2 study DARIA. Eligible patients had relapsed/refractory MM (RRMM) after one prior line with a lenalidomide-based regimen. The primary endpoint was overall response rate (ORR). Secondary endpoints included survival outcomes, safety and changes in biomarkers of bone metabolism. Overall, 50 patients were enrolled (median age 69 years, 56% males). 32 (64%) patients were refractory to lenalidomide, and 17 (34%) had undergone autologous transplant. The ORR was 64% (n = 32); whereas 17 (34%) had a very good partial response or better. The median time to first response was 1.0 month. After a median follow-up of 23.4 months, the median PFS and OS were 8.1 and 39.2 months, respectively. Furthermore, significant changes in markers of bone metabolism became evident as early as at 6 months on treatment. Regarding safety, 21 (42%) patients had ≥1 grade 3/4 adverse event (AE); the most common was thrombocytopenia (n = 9, 18%). 14 (28%) patients had ≥1 serious AE (SAE), the most common being acute kidney injury and pneumonia (n = 2, each). Four patients died due to infections. In conclusion, second-line treatment with Dara-Ixa-dex in patients with RRMM pre-treated with a lenalidomide-based regimen resulted in rapid responses along with a favorable effect on bone metabolism.