INTRODUCTION: Cytogenetic analysis performed by FISH at diagnosis of Multiple Myeloma (MM) allows to stratify patients in groups at different risk of progression or death. We analyzed a large cohort of patients with newly diagnosed MM to evaluate the prognostic impact of multiple high-risk cytogenetic abnormalities (HRAs), detected either as a single lesion (e.g. isolated) or multiple lesions (e.g. co-segregated). METHODS: Probes for FISH analysis of CD138+ bone marrow plasma cells were chosen to detect t(4;14), t(6;14), t(11,14), t(14;16), t(14;20), deletion of 1p32, 13q14, 17p13, gain of 1q21 and hyperdiploidy (HD). HRAs were defined by the presence of one or more of t(4;14), t(14;16), t(14;20), del(17p), gain(1q) and del(1p). The analysis was performed in a large cohort of patients who received the diagnosis of MM in Italian centers and were enrolled in the phase III EMNO2/HO95 study. By study design, patients were randomized to receive either standard-dose intensification treatment with bortezomib-melphalan-prednisone (VMP) or high-dose intensification treatment with melphalan at 200 mg/m2 (HDM) plus autotransplantation (ASCT), either single (ASCT-1) or double(ASCT-2). A second randomization to receive or not receive consolidation therapy was planned after the intensification phase, followed by lenalidomide maintenance in both arms. RESULTS: A total of 461 patients were evaluable for all HRAs listed above. 151 of them were randomly assigned (stratification by ISS stage) to VMP and 310 to ASCT-1 or ASCT-2. HRAs were detected in 233/461 patients (50.5%): 155 (33.6%) gain(1q), 51 (11.1%) del(1p), 46 (10.0%) del(17p), 58 (12.6%) t(4;14), 20 (4.3%) t(14;16) and 6 (1.3%) t(14;20). 141/461 patients (30.6%) showed an isolated HRA: 76 (53.9%) gain(1q), 27 (19.1%) a high-risk translocation (HRT), 21 (14.9%) del(17p) and 17 (12.1%) del(1p). 81/461 patients (17.6%) carried 2 HRAs, most frequently a HRT co-segregating with gain(1q) (detected in 48.2%), while 3 HRAs were found in the remaining 11 (2.4%). With a median follow-up of 37.8 months, 3-year PFS estimates for patients without HRA or with 1, 2 and 3 HRAs were 80.3%, 53.5%, 45% and 21.8%, respectively (P CONCLUSIONS: 50% of patients with NDMM presented with one or more HRA and 20% with two or more of them. In patients with at least 1 HRA, randomization to ASCT-2 was superior over ASCT-1 in terms of prolonged PFS and OS. The association of gain(1q) with a HRT was the most frequently observed co-segregation of 2 HRAs and was correlated with significantly shorter PFS and OS compared with isolated gain(1q) and gain(1q) plus del(1p). The association of HD with del(17p) mitigated the adverse PFS of del(17p). Disclosures Offidani:celgene: Honoraria, Membership on an entity9s Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity9s Board of Directors or advisory committees. Sonneveld:Celgene Corporation, Amgen, Janssen, Karyopharm, PharmaMar, SkylineDx: Honoraria; Celgene, Amgen, Janssen, Karyopharm, Takeda: Consultancy, Honoraria, Research Funding; Celgene Corporation, Amgen, Janssen, Karyopharm, SkylineDx, PharmaMar: Consultancy. Boccadoro:Novartis: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Sanofi: Honoraria, Research Funding; AbbVie: Honoraria; Amgen: Honoraria, Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Mundipharma: Research Funding.