Background: R/R DLBCL treatment remains challenging. Atezolizumab (ATE) and obinutuzumab (OBI) are monoclonal antibodies acting respectively to inhibit T-lymphocyte exhaustion or by inducing lymphoma cells cytotoxicity, whereas venetoclax (VEN) is a small molecule inhibiting BCL-2. Combining tumor-targeted therapies with agents that enhance anti-tumor immunity represents an attractive treatment paradigm. This LYSA sponsored multicenter phase 2 trial (NCT03276468) evaluate the combination of ATE, OBI and VEN in R/R B lymphomas, we present here primary efficacy and safety data fromthe DLBCL cohort. Methods: Patients ≥18 years with biopsy-confirmed R/R DLBCL who failed at least one line of therapy were eligible. OBI was given IV at the dose of 1 g on day (D) 1, 8 and 15 of cycle (C) 1 and on D1 from C2 to C8 every 3 weeks. ATE was given IV, 1.2 g every 3 weeks, started at D2 of C1, then administered at D2 of each cycle for 24 cycles. VEN was given orally at 800 mg/D at full dose, started on D8C1 for 24 cycles. The primary endpoint wasthe Overall Metabolic Response Rate (OMRR) by Lugano criteria at the end of induction (EOI) after 8 cycles of ATE, OBI and VEN (M6) or at premature treatment discontinuation. Results: At the time of the primary analysis (03 Jan 2020), 58 pts were enrolled and the median follow-up was 9 months [6.9-11.8]. Baseline characteristics were: median age, 70 years; male, 53.4%; Ann Arbor Stage IV, 84.5%; aaIPI (≥2), 63.2%; > 2 prior lines of therapy, 83.6%; and refractory to last line of prior regimen, 63.6%. The OMRR at EOI was measured at 23.6% [14.58%-34.93%], including 18% of CMR. To date, these responses seem durable with only 3 reported relapses. According to the highest diameter mass, OMRR was 38.5% versus 10.3%, < 5cm and > 5cm respectively; P = 0,02. All three treatments were stopped in 78% of patients, mostly for progressive disease. At the time of analysis, a median of 4 cycles [1-8] has been administered. A total of 48 (84.2%) pts experienced grade 3–4 adverse event (AE) and 6 (10.5%) had an AE that led to discontinuation of any drug.AE of grade 3 or more reported in at least 20% of patients were neutropenia (33.3%) and lymphopenia (35.1%). Of note, a grade 3 autoimmune colitis and a grade 1 hypothyroidism were reported during induction. Conclusions: The ATE, OBI and VEN combinationappears to be well tolerated. The OMRR rate at EOI is comparable with currently available treatment options in this population, with durable responses. The OMRR seems better in patients with a low tumor burden. Clinical trial information: NCT03276468.