Background: The standard treatment for localized/locally advanced gastroesophageal adenocarcinoma (GEA) is radical surgery and peri-operative FLOT treatment (5-fluorouracil plus leucovorin, oxaliplatin, and docetaxel), but around half patients still experience disease relapse. In gastrointestinal cancers, the presence of circulating tumor DNA (ctDNA) after surgery is associated with a high risk of relapse, and the lack of ctDNA clearance after post-operative treatment is strongly associated with early relapse. Therefore, liquid biopsy may guide the selection of patients with micrometastatic disease after preoperative chemotherapy and surgery for non-cross resistant regimens in the post-operative setting. Trastuzumab deruxtecan (T-DXd) is approved in patients with HER2-positive advanced gastric or gastroesophageal adenocarcinoma after failure of at least one prior trastuzumab-based regimen. The DESTINY-Gastric01 and 02 trials showed remarkable activity and efficacy of T-DXd, thus supporting the investigation of this agent in early-stage disease to increase the chance of achieving disease eradication. Finally, the DESTINY-Gastric03 trial showed the safety profile and feasibility, with preliminary promising activity results of the combination of T-DXd with a fluoropyrimidine.
Trial design: TRINITY is an ongoing multicentre, randomized, open-label, interventional phase II study which will enroll approximately 46 patients with HER2-positive GEA, treated with pre-operative FLOT and radical surgery, and with the persistence of minimal residual disease detected by the Signatera™ assay in a liquid biopsy collected between 2 and 6 weeks after surgery. The trial is designed with an observational phase enrolling patients with HER2-positive GEA eligible for standard treatment with peri-operative FLOT and surgery. Eligible patients will be randomized on a 1:1 basis to the experimental treatment arm consisting of adjuvant T-DXd (6.4 mg/kg IV on day 1) plus either capecitabine (1000 mg/sqm BID orally on days 1-14) or 5-fluorouracil (600 mg/sqm continuous IV infusion on days 1-5) Q3 W for 6 cycles, or to the control arm with standard post-operative FLOT (at the same dose used during the last pre-operative cycle) for 4 cycles. Patients non-eligible for the interventional trial will continue the standard therapy and follow-up in the frame of the observational phase with collection of exploratory longitudinal liquid biopsies. The primary objective is ctDNA clearance at 1 year after randomization. Considering alpha- and beta-errors of 0.10 and 0.20 and hypothesizing a ctDNA clearance of 10% and 35% in the control and experimental arm, respectively, 23 patients per arm are required to prove the superiority of the experimental strategy. Secondary endpoints include disease-free survival, overall survival, metastases-free survival, patient-reported outcomes and safety. The trial also represents a translational platform, including extensive analysis of circulating, tissue, and immune biomarkers as exploratory endpoints. Enrollment is active and ongoing.
Trial registration: TRINITY is registered at ClinicalTrials.gov (NCT06253650).
Keywords: Esophageal cancer; Gastric cancer; HER2; Liquid biopsy; Trastuzumab-deruxtecan.
© 2025. The Author(s).