Background: Venetoclax (Ven) is a selective, potent, oral BCL-2 inhibitor that induces apoptosis in multiple myeloma (MM) cells in vitro. It has shown synergistic activity with bortezomib (V) and dexamethasone (d). Combination of the CD38 monoclonal antibody daratumumab (D) with Ven is hypothesized to further increase anti-myeloma activity based on dual mechanisms of pro-apoptotic effects on tumor cells and enhanced immune stimulation. Methods: This ongoing Phase 1/2, nonrandomized, multicenter study (NCT03314181) is evaluating safety, efficacy and pharmacokinetics (PK) of VenDd +/- V in patients (pts) with relapsed/refractory MM. In Part 1, pts with t(11;14) who received ≥1 prior line of therapy (PI and an immunomodulatory drug) were treated with VenDd [Ven QD + D 16 mg/kg IV + d 40 mg weekly]. In Part 2, pts irrespective of t(11;14) status, non-refractory to PIs and who received 1–3 prior lines of therapy were treated with VenDVd [Ven QD + D 16 mg/kg IV + V (1.3 mg/m²) + d (20 mg)]. A randomized, open-label expansion (Part 3) will further evaluate and compare safety and efficacy of VenDd (400 or 800 mg Ven dose levels) with control DVd in pts with t(11;14). Results: As of Dec 05, 2019, 48 pts were enrolled. Part 1 included 24 pts with t(11;14), median age 63 (range 51–76). Part 2 included 24 pts, median age 65 (range 41–80) of which 6 (25%) had t(11;14). Frequent adverse events (AEs; VenDd/VenDVd) were fatigue (71%/25%), diarrhea (58%/46%), nausea (46%/50%), insomnia (33%/50%), upper respiratory tract infection (33%/21%), cough (42%/9%), and dyspnea (25%/25%). Frequent Grade ≥ 3 AEs in pts on VenDd were neutropenia (17%), hypertension (12%), fatigue and hyperglycemia (8% each), and in pts on VenDVd were insomnia (21%), diarrhea and thrombocytopenia (8% each). Nine pts had infection-related Grade ≥ 3 AEs (5 VenDd, 4 VenDVd). Eighteen pts had a serious AE (11 VenDd, 7 VenDVd) with pyrexia (n = 3) being most common. One pt on VenDVd died of progressive disease. PK analyses showed that addition of D and V did not impact Ven exposure. Median follow-up time (VenDd/VenDVd) was 10 and 9 months. Overall response rate in VenDd/VenDVd was 96%/92% and 96%/79% had ≥ very good partial response rate. Median progression free survival and duration of response were not reached. Conclusions: Pts treated with VenDd +/- V continue to demonstrate a tolerable safety profile with encouraging efficacy, notably among pts with t(11;14) treated with VenDd. Safety, efficacy, PK, and cytogenetics analyses will be updated for presentation. Clinical trial information: NCT03314181.