Background: DARA, a human, CD38-targeting, IgGκ monoclonal antibody, is approved in many countries for use as monotherapy in relapsed/refractory MM (RRMM), and in combination with standard-of-care regimens in RRMM and transplant-ineligible NDMM. Given the initial safety and efficacy observed with DARA plus VRd (D-VRd) in the safety run-in cohort of the ongoing phase 2 GRIFFIN study in TE NDMM pts, the phase 3 PERSEUS study will evaluate the efficacy and safety of D-VRd versus VRd alone in TE NDMM. Methods: This is an ongoing multicenter, open-label, randomized phase 3 study of D-VRd versus VRd alone in TE NDMM pts. Approximately 690 pts across Europe will be stratified by ISS stage and cytogenetic risk (high risk defined as presence of del17p, t[4;14], or t[14;16]) and randomized in a 1:1 ratio. All pts will receive VRd (V: 1.3 mg/m² SC Days 1, 4, 8, 11; R: 25 mg PO Days 1-21; d: 40 mg PO Days 1-4, 9-12) for 4 pre-transplant induction and 2 post-transplant consolidation cycles (all 28-d cycles), followed by R (10 mg PO Days 1-28) maintenance until progressive disease (PD). Pts in the DARA group will also receive subcutaneous DARA (1,800 mg co-formulated with recombinant human hyaluronidase PH20 [rHuPH20; Halozyme]) QW in Cycles 1-2, Q2W in Cycles 3-6, and Q4W in maintenance Cycles 7+ until PD. After induction, pts will undergo melphalan 200 mg/m² conditioning and autologous stem cell transplantation (ASCT). Pts in the DARA group who achieve sustained minimal residual disease (MRD) negativity (10^–5 threshold; assessed by NGS) for 12 months after ≥24 months of maintenance will stop DARA but continue R maintenance until PD; upon loss of CR or MRD-negative status, pts will restart DARA treatment. All pts will receive preinfusion medications. The primary endpoint is progression-free survival (PFS). Secondary endpoints include MRD-negative rate, overall response rate, PFS on next line of therapy, overall survival, time to and duration of response, health-related quality of life, pharmacokinetics, immunogenicity, stem cell yield after mobilization, time to engraftment post-ASCT, and safety. Clinical trial information: NCT03710603