Background: VTd is a standard of care (SoC) for TE NDMM. CD38 mAb DARA significantly reduced the risk of progression/death and improved CR and MRD-negative rates in relapsed refractory MM or transplant-ineligible NDMM in phase 3 studies. We report the primary and final analysis of Part 1 of CASSIOPEIA. Methods: In Part 1, TE NDMM pts 18-65 y were randomized 1:1 to VTd (6 28-day cycles [C; 4 pre-ASCT induction, 2 post-ASCT consolidation] of V 1.3 mg/m² SC BIW Week [W] 1-2; T 100 mg PO QD; d 40-80 mg/week PO or IV W 1-4 C 1-2, W 1-3 C 3-6) ± DARA (16 mg/kg IV QW C 1-2, Q2W C 3-6). Melphalan 200 mg/m² was pre-ASCT HDT. The primary endpoint, post-consolidation sCR rate, was assessed at Day [D] 100 post-ASCT. Part 2 (maintenance) is ongoing.Results: A cohort of 1085 pts (D-VTd, 543; VTd, 542) was randomized. The D 100 post-ASCT sCR rate was significantly higher for D-VTd vs VTd (28.9% vs 20.3%; P = 0.0010; Table). At 18.8-mo median follow-up, PFS from first randomization favored D-VTd with HR 0.47 (95% CI, 0.33-0.67; P<0.0001). With median PFS NR in either arm, 18-mo PFS rates were 92.7% vs 84.6% for D-VTd vs VTd. Rates of ≥CR, ≥VGPR, and MRD negativity supported sCR results (Table). OS is immature with 46 deaths on study (D-VTd, 14; VTd, 32; HR, 0.43; 95% CI, 0.23-0.80). The most common (≥10%) grade 3/4 TEAEs (D-VTd/VTd) were neutropenia (27.6%/14.7%), lymphopenia (17.0%/9.7%), stomatitis (12.7%/16.4%), and thrombocytopenia (11.0%/7.4%). In the D-VTd arm, infusion-related reactions occurred in 35.4% of pts. Conclusions: D-VTd in induction prior to and consolidation after ASCT improved depth of response (sCR, ≥CR, and MRD negativity) and PFS with acceptable safety. The favorable benefit-risk profile supports the use of D-VTd in TE NDMM. CASSIOPEIA is the first study to demonstrate clinical benefit of DARA + SoC in TE NDMM. Clinical trial information: NCT02541383