Background: Venetoclax (Ven) is a selective, potent, oral BCL-2 inhibitor. In the Phase 3 BELLINI trial, addition of Ven to bortezomib (B) + dexamethasone (d) significantly improved response rates and progression-free survival (PFS) vs placebo (Pbo) and showed significant efficacy in patients (pts) with either t(11;14) or BCL2high gene expression. Here we present updated safety and efficacy data from the prespecified second interim overall survival (OS) analysis. Methods: In this multicenter, randomized, double-blind study (NCT02755597), pts with relapsed/refractory multiple myeloma (RRMM) with 1-3 prior lines of therapy were randomized 2:1 to Ven (800 mg) or Pbo in combination with B (1.3 mg/m2) and d (20 mg). The primary endpoint was PFS; key secondary endpoints included overall response and overall survival (OS). Results: 291 pts were randomized; 194 to Ven, 97 to Pbo. Pt characteristics were well balanced among arms. In the Ven arm, median age was 66, 17% had high-risk cytogenetics, 11% had t(11;14), and 34% had BCL2high gene expression. As of 13 Sept 2019, 59 pts were still on study, 45 (23%) Ven vs 14 (14%) Pbo. At a median follow-up of 28.6 months, there were 64 (33%) deaths in the Ven arm vs 24 (25%) in Pbo. At the initial data cutoff (26 Nov 2018), PFS HR was 0.63 (0.44,0.90) and OS HR was 2.03 (1.04,3.95). Table shows updated PFS and OS. Most common treatment-emergent adverse events (TEAEs) with Ven were diarrhea (59%), nausea (37%), and constipation (35%). Most common grade 3/4 AEs (Ven/Pbo) were neutropenia (21%/8%), thrombocytopenia (15%/30%), anemia (16%/15%), diarrhea (15%/12%), and pneumonia (18%/13%). Serious AEs occurred in 54% Ven and 52% Pbo pts. 24% discontinued Ven due to AEs vs 12% Pbo. There were 14 treatment-emergent deaths in the Ven arm and 1 in Pbo. Conclusions: The addition of Ven to Bd significantly improves PFS but resulted in increased mortality vs Pbo in the total population. Greatest PFS improvement with Ven was observed in pts with t(11;14) or BCL2high gene expression, where Ven shows a favorable benefit-risk profile. The study continues for final OS analysis. Clinical trial information: NCT02755597.