Patient-reported outcomes from the phase II FAST trial of zolbetuximab plus EOX compared to EOX alone as first-line treatment of patients with metastatic CLDN18.2+ gastroesophageal adenocarcinoma

Background Zolbetuximab plus first-line EOX (epirubicin, oxaliplatin, capecitabine; ZOL/EOX) significantly prolonged progression-free survival and overall survival in the FAST trial vs EOX alone. We report the patient-reported outcomes (PROs) of FAST in patients with advanced gastroesophageal adenocarcinoma. Methods Patients were randomized to ZOL/EOX or EOX alone. Patients could receive ≤ 8 EOX cycles and remained on zolbetuximab until disease progression. PROs were collected using the EORTC QLQ-C30 and QLQ-STO22 before drug administration at day 1/cycle 1, day 1/cycle 5, end of EOX treatment, and q12w thereafter until disease progression. Time to deterioration (TTD), defined as the first meaningful worsening from baseline, in the individual QLQ-C30/QLQ-STO22 scores was analyzed. Longitudinal changes in scores from baseline were analyzed using a mixed-effects model for repeated measures (MMRM). Results The per protocol population included 143 (ZOL/EOX: 69; EOX: 74) patients. Baseline QLQ-C30 and STO22 scores were comparable between arms and denoted intermediate-to-high quality of life (QoL), intermediate-to-low global health status (GHS) and low symptom burden. Descriptive analyses showed no differences between arms until end of EOX but maintenance therapy with zolbetuximab was associated with better QoL and less symptom burden thereafter. TTD for most scores favored ZOL/EOX over EOX and reached statistical significance for GHS ( p = 0.008). MMRM results support TTD findings; no statistically significant differences were observed between arms in any score except for nausea and vomiting ( p = 0.0181 favoring EOX). Conclusions ZOL/EOX allowed patients to maintain good QoL and low symptom burden for longer than EOX alone.