Maintenance capecitabine after first-line platinum-based chemotherapy in advanced oesophagogastric adenocarcinoma: final analysis from the PLATFORM trial

BACKGROUND: PLATFORM is an adaptive phase II trial assessing maintenance therapies in advanced oesophagogastric adenocarcinoma (OGA). We evaluated maintenance capecitabine in patients with disease control after first-line chemotherapy. METHODS: HER2-negative patients with advanced OGA who had response or stable disease after 18 weeks of first-line chemotherapy were randomised (1:1) to surveillance or capecitabine. The primary endpoint was progression-free survival (PFS); secondary endpoints included overall survival (OS) and safety. RESULTS: Between May 2015 and May 2024, 266 patients were randomised (129 surveillance, 137 capecitabine). Median follow up was 70.7 months. Capecitabine significantly improved PFS (HR 0.69; 95% CI 0.54-0.89; p = 0.002), with median PFS of 5.0 vs 2.8 months. One-year PFS rates were 19.9% vs 6.8%; and two-year rates 8.1% vs 4.3%. No OS difference was observed (median OS: 10.5 vs 10.0 months; HR 0.87; 95% CI 0.67-1.12; p = 0.143). One and two-year OS rates were similar (1-year: 44.1% vs 45.7%; 2-year: 18.8% vs 16.8%). Grade ≥3 adverse events were more frequent with capecitabine (46% vs 29%), with 21% experiencing grade 3 treatment related events. DISCUSSION: Maintenance capecitabine significantly prolonged PFS compared to surveillance, meeting the primary endpoint and supporting its use to extend disease control in advanced OGA.