Background: The aim of this trial was to investigate the addition of the anti-SLAMF7 monoclonal antibody elotuzumab to lenalidomide, bortezomib, and dexamethasone (RVd) in induction and consolidation therapy as well as to lenalidomide maintenance treatment in transplant-eligible patients with newly diagnosed multiple myeloma., Methods: GMMG-HD6 was a phase 3, randomised trial conducted at 43 main trial sites and 26 associated trial sites throughout Germany. Adult patients (aged 18-70 years) with previously untreated, symptomatic multiple myeloma, and a WHO performance status of 0-3, with 3 being allowed only if caused by myeloma disease and not by comorbid conditions, were randomly assigned 1:1:1:1 to four treatment groups. Induction therapy consisted of four 21-day cycles of RVd (lenalidomide 25 mg orally on days 1-14; bortezomib 1·3 mg/m 2 subcutaneously on days 1, 4, 8, and 11]; and dexamethasone 20 mg orally on days 1, 2, 4, 5, 8, 9, 11, 12, and 15 for cycles 1-2) or, RVd induction plus elotuzumab (10 mg/kg intravenously on days 1, 8, and 15 for cycles 1-2, and on days 1 and 11 for cycles 3-4; E-RVd). Autologous haematopoietic stem-cell transplantation was followed by two 21-day cycles of either RVd consolidation (lenalidomide 25 mg orally on days 1-14; bortezomib 1·3 mg/m 2 subcutaneously on days 1, 8, and 15; and dexamethasone 20 mg orally on days 1, 2, 8, 9, 15, and 16) or elotuzumab plus RVd consolidation (with elotuzumab 10 mg/kg intravenously on days 1, 8, and 15) followed by maintenance with either lenalidomide (10 mg orally on days 1-28 for cycles 1-3; thereafter, up to 15 mg orally on days 1-28; RVd/R or E-RVd/R group) or lenalidomide plus elotuzumab (10 mg/kg intravenously on days 1 and 15 for cycles 1-6, and on day 1 for cycles 7-26; RVd/E-R or E-RVd/E-R group) for 2 years. The primary endpoint was progression-free survival analysed in a modified intention-to-treat (ITT) population. Safety was analysed in all patients who received at least one dose of trial medication. This trial is registered with ClinicalTrials.gov, NCT02495922, and is completed., Findings: Between June 29, 2015, and on Sept 11, 2017, 564 patients were included in the trial. The modified ITT population comprised 559 (243 [43%] females and 316 [57%] males) patients and the safety population 555 patients. After a median follow-up of 49·8 months (IQR 43·7-55·5), there was no difference in progression-free survival between the four treatment groups (adjusted log-rank p value, p=0·86), and 3-year progression-free survival rates were 69% (95% CI 61-77), 69% (61-76), 66% (58-74), and 67% (59-75) for patients treated with RVd/R, RVd/E-R, E-RVd/R, and E-RVd/E-R, respectively. Infections (grade 3 or worse) were the most frequently observed adverse event in all treatment groups (28 [20%] of 137 for RVd/R; 32 [23%] of 138 for RVd/E-R; 35 [25%] of 138 for E-RVd/R; and 48 [34%] of 142 for E-RVd/E-R). Serious adverse events (grade 3 or worse) were observed in 68 (48%) of 142 participants in the E-RVd/E-R group, 53 (39%) of 137 in the RVd/R, 53 (38%) of 138 in the RVd/E-R, and 50 (36%) of 138 in the E-RVd/R (36%) group. There were nine treatment-related deaths during the study. Two deaths (one sepsis and one toxic colitis) in the RVd/R group were considered lenalidomide-related. One death in the RVd/E-R group due to meningoencephalitis was considered lenalidomide and elotuzumab-related. Four deaths (one pulmonary embolism, one septic shock, one atypical pneumonia, and one cardiovascular failure) in the E-RVd/R group and two deaths (one sepsis and one pneumonia and pulmonary fibrosis) in the E-RVd/E-R group were considered related to lenalidomide or elotuzumab, or both., Interpretation: Addition of elotuzumab to RVd induction or consolidation and lenalidomide maintenance in patients with transplant-eligible newly diagnosed multiple myeloma did not provide clinical benefit. Elotuzumab-containing therapies might be reserved for patients with relapsed or refractory multiple myeloma., Funding: Bristol Myers Squibb/Celgene and Chugai., Competing Interests: Declaration of interests EKM reports consulting or advisory role with Bristol Myers Squibb (BMS)/Celgene, GlaxoSmithKline, Janssen-Cilag, Sanofi Aventis, Stemline, and Takeda; honoraria from BMS/Celgene, GlaxoSmithKline, Janssen-Cilag, Sanofi Aventis, Stemline, and Takeda; research funding from Sanofi Aventis; and travel accommodation and expenses from BMS/Celgene, GlaxoSmithKline, Janssen-Cilag, Sanofi Aventis, Stemline, and Takeda. HG reports support for the present manuscript from BMS/Celgene, Chugai, and HD6 funding; consulting or advisory role with Amgen, BMS, Janssen, Sanofi, and Adaptive Biotechnology; honoraria from Amgen, BMS, Chugai, GlaxoSmithKline, Janssen, Novartis, Sanofi, and Pfizer; research funding from Amgen, BMS, Celgene, GlycoMimetics, GlaxoSmithKline, Heidelberg Pharma, Hoffmann-La Roche, Karyopharm, Janssen, Incyte Corporation, Millenium Pharmaceuticals, Molecular Partners, Merck Sharp and Dohme, MorphoSys, Pfizer, Sanofi, Takeda, and Novartis; travel accommodations and expenses from Amgen, BMS, GlaxoSmithKline, Janssen, Novartis, Sanofi, and Pfizer; and grants or provision of Investigational Medicinal Products from Amgen, Array Biopharma/Pfizer, BMS/Celgene, Chugai, Dietmar-Hopp-Foundation, Janssen, Johns Hopkins University, Mundipharma, and Sanofi. MHä reports consulting or advisory role with Novartis, BMS/Celgene, Gilead Sciences, Sanofi/Aventis, Roche, Amgen, SOBI, Janssen, Takeda, GlaxoSmithKline, Jazz Pharmaceuticals, Bayer Vital, and BMS. RF reports Honoraria from Amgen, BMS/Celgene, Janssen, Sanofi, and Takeda; and travel accommodations and expenses from BMS/Celgene, Janssen, and GSK. MM reports consulting or Advisory Role with Janssen, BMS, Abbvie, Sanofi, GlaxoSmithKline, Oncopeptides, Takeda, and Stemline; honoraria from Amgen, BMS, GlaxoSmithKline, Janssen, and Takeda; and travel accommodations and expenses from Amgen. JD reports honoraria from Sanofi, BMS, Janssen, AstraZeneca, Beigene; and travel accommodation and expenses from Amgen, BMS, Beigene, and Amgen. CM reports Consulting or Advisory Role from Celgene, BMS, and Janssen. CS reports consulting or advisory role from BMS, GlaxoSmithKline, Janssen, Pfizer, Roche, and Takeda; honoraria from Amgen, BMS/GlaxoSmithKline, Janssen, MSD, Novartis, Roche, Sanofi, and Takeda; research funding from Janssen, and Takeda; and travel accommodation and expenses from BMS, Janssen, Sanofi Aventis, and Takeda. RS reports consulting or advisory role with BMS/Celgene, GlaxoSmithKline, Janssen, Kite/Gilead, and Sanofi; and honoraria from Amgen, BMS/Celgene, GlaxoSmithKline, Janssen, Kite/Gilead, Sanofi, and Takeda. IvM reports consulting or advisory role with Sanofi, Amgen, Janssen, Takeda, Stemline, GSK, BMS, Oncopeptides, Pfizer, and AstraZeneca. PR reports honoraria from BMS and travel accommodation and expenses from BMS. UG reports consulting or advisory role with Amgen, Boehringer Ingelheim, BMS, Celtrion, Ipsen, Sanofi, and MSD; and honoraria from Amgen, AstraZeneca, and Novartis. SK reports travel accommodation and expenses from AbbVie. UMM reports consulting or advisory role with Sanofi-Aventis, BMS, Roche, GSK, Novartis, Pierre Fabre, MSD, and Guardant Health; and travel accommodation and expenses from Pierre Fabre, Ipsen, and Janssen. CK reports travel accommodation and expenses from European Hematology Association. KCW reports consulting or advisory role with Abbvie, Amgen, Adaptive Biotech, BMS/Celgene, BeiGene, Janssen, GlaxoSmithKline, Karyopharm, Oncopeptides, Pfizer, Roche Pharma, Sanofi, Takeda, and Menarini; honoraria from Abbvie, Amgen, Adaptive Biotech, Astra Zeneca, BMS/Celgene, BeiGene, Janssen, GlaxoSmithKline, Karyopharm, Novartis, Oncopeptides, Pfizer, Roche Pharma, Sanofi, Stemline, Takeda, and Menarini; and research funding from Abbvie, Amgen, BMS/Celgene, Janssen, GlaxoSmithKline, Sanofi, and Takeda. MSR reports consulting or advisory role with BMS, Amgen, GSK, Janssen, Sanofi, Pfizer, AbbVie, Novartis, and Roche; research funding from Sanofi; travel accommodation and expenses from BMS, AbbVie, Janssen, Sanofi, GSK; Honoraria from BMS, Janssen, GSK, AbbVie, and Sanofi; and receipt of equipment, materials, drugs, medical writing, gifts or other services from Novartis, Sanofi. HJS reports consulting or advisory role with Amgen, AstraZeneca, BMS/Celgene, Genzyme, GSK, Janssen Cilag, Oncopeptides, Pfizer, Sanofi, and Stemline; honoraria from Abbvie, Amgen, AstraZeneca, BMS/Celgene, Genzyme, GSK, Janssen Cilag, Oncopeptides, Pfizer, Roche, Sanofi, Stemline, and Takeda; and travel accommodation and expenses from Amgen, BMS/Celgene, Janssen Cilag, and Sanofi. All other authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license. Published by Elsevier Ltd.. All rights reserved.)