Interim safety analysis of the DANTE trial: Perioperative atezolizumab in combination with FLOT versus FLOT alone in patients with resectable esophagogastric adenocarcinoma—A randomized, open-label phase II trial of the German Gastric Group at the AIO and SAKK.

4549 Background: The DANTE study evaluates atezolizumab in the perioperative treatment of locally advanced, potentially resectable gastric or GEJ adenocarcinoma in combination with perioperative FLOT. Here, we report the protocol-defined interim safety analysis. Methods: DANTE is a multinational, prospective, multicenter, randomized, investigator-initiated, open label phase II trial. Patients (pts) with locally advanced, potentially resectable adenocarcinoma of the stomach and GEJ (≥cT2 and/or N-positive) without distant metastases are enrolled. Pts are randomized 1:1 to 4 pre-operative 2-week cycles of FLOT followed by surgery and 4 additional cycles of FLOT plus atezolizumab at 840 mg every 2 weeks, followed by a total of 8 additional cycles of atezolizumab at 1200 mg every 3 weeks as monotherapy (arm A) or FLOT alone (arm B). Primary endpoint is time to disease progression or relapse after surgery (PFS/DFS). Results: Recruitment started in Sep 2018; by Feb 2020, a total of 175 pts have been randomized. This analysis is based on the first 40 pts (20 pts in each arm). The pts had a median age of 62 y and 75% of pts had an ECOG PS of 0 in both arms. The cohort was well balanced in terms of tumor location and clinical stage. 5% of the 40 patients (overall 7.4% of 175 pts enrolled) showed microsatellite instability. 90% of pts enrolled completed all pre-operative cycles in each arm. Total number of adverse events with relation to study treatment was 154 in arm A and 148 in arm B. Total number of serious adverse events (SAE; related or not) was 16 in Arm A and 14 in arm B. 20% of pts in each arm had an SAE due to perioperative morbidity. No surgical mortality was observed. 18 and 19 pts proceeded to operation in arms A and B, respectively. Premature treatment discontinuation occurred in 2 pts in each arm: disease progression (1) and deterioration of general health condition (1) in arm A; and pts’ wish (1) and death (1) in arm B. Median hospitalization time was 15 days in arm A and 16 days in arm B. Conclusions: Perioperative atezolizumab plus FLOT is feasible and safe. The study continues recruitment. Clinical trial information: NCT03421288 .