Phase II study of GEN-001 in combination with avelumab in patients with PD-L1–positive locally advanced, or metastatic gastric cancer (GC) or gastroesophageal junction cancer (GEJC) who have progressed after second-line (2L) and beyond (GEN001-201 study).

Abstract

368 Background: The relationship between gut microbiota and the response to immune checkpoint inhibitors is likely due to cross-reactivity between microbial and tumor antigens, enhancing dendritic cell (DC) activation, antigen presentation, and inflammatory cytokine production. GEN-001 is a live biotherapeutic product (LBP) consisting of a lyophilized formulation of a strain of Lactococcus lactis. This study is designed to investigate the safety and efficacy of GEN-001 in combination with avelumab (the PD-L1 inhibitor) for patients with PD-L1 positive advanced GC/GEJC. Methods: This is an open-label, single arm, phase II clinical trial for PD-L1 positive (CPS ≥1) patients with unresectable, locally advanced, or metastatic GC/GEJC who have progressed after second-line and beyond. All patients were treated with GEN-001 (9x1011 CFU, administered as oral once daily) in combination with avelumab (800 mg, administered as an intravenous infusion every two weeks) until progressive disease, unacceptable toxicity, death, or withdrawal. Tumor response was assessed every 8 weeks for 6 months and every 12 weeks thereafter. The primary endpoint was objective response (OR); secondary endpoints included progression-free survival (PFS), overall survival (OS) and safety. Results: As of August 31, 2023, a total of 42 patients were enrolled. 37 patients have been assessed for response. The confirmed partial response (PR) and unconfirmed PR were achieved by 5 patients and 1 patient respectively, 8 patients have experienced as stable disease (SD). Median PFS and median OS were 1.73 months (95% confidence interval [CI]: 1.67-2.37 months) and 7.9 months (95% [CI]: 6.07-NE months). Treatment-related adverse events (TRAEs) of any grade occurred in 12 patients (28.6%) and Grade ≥3 TRAEs occurred in 2 patients (4.8%) out of 42 patients. Conclusions: Treatment of patients with GC/GEJC with GEN-001 in combination with avelumab in the ≥ 3L setting showed promising antitumor activities with an overall manageable safety profile. The results from this trial will be updated about its effects on clinical outcome, including survival, safety, and biomarker findings. Clinical trial information: NCT05419362 .