Neoadjuvant docetaxel, oxaliplatin, and s-1 plus surgery and adjuvant s-1 for resectable advanced gastric cancer: Final survival outcomes of the randomized phase 3 PRODIGY trial

30 Background: The phase 3 PRODIGY study compared neoadjuvant docetaxel, oxaliplatin and S-1 (DOS) chemotherapy followed by surgery followed by adjuvant S-1 with surgery followed by adjuvant S-1 for Korean patients with resectable locally advanced gastric cancer (LAGC) (Kang et al. J Clin Oncol. 2021). The planned analysis of the primary endpoint of PRODIGY showed that the addition of neoadjuvant DOS to surgery and adjuvant S-1 improved progression-free survival (PFS). We herein report the long-term follow-up outcomes, including overall survival (OS), from this trial. Methods: Patients with histologically confirmed primary gastric or gastroesophageal junction adenocarcinoma with clinical T2-3N+ or T4Nany disease were enrolled from 18 Korean study sites. Patients were randomly assigned to D2 surgery followed by adjuvant S-1 (40–60 mg orally twice a day, days 1–28 q6w for eight cycles; SC group) or neoadjuvant DOS (docetaxel 50 mg/m 2 , oxaliplatin 100 mg/m 2 intravenously day 1, S-1 40 mg/m 2 orally twice a day, days 1–14 q3w for three cycles) before D2 surgery, followed by adjuvant S-1 (CSC group). The primary endpoint was PFS. OS was the secondary endpoint. This analysis presents the final assessment of the outcomes after 5 years. Results: A total of 266 and 264 patients were randomly assigned to the CSC and SC arms, respectively, among which 238 and 246 patients were treated and included in the full analysis set. As of the data cut-off date (SEP-2022), the median follow-up duration of the surviving patients was 99.5 months (range, 68.6–127.7 months). As compared to SC, CSC significantly increased the OS (adjusted hazard ratio, 0.72; 95% CI, 0.54 to 0.97; stratified log-rank P=0.028) with a 5-year OS rate of 66.8% and 63.0% for the CSC and SC arms, respectively. CSC also significantly improved the PFS (adjusted hazard ratio, 0.71; 95% CI, 0.53 to 0.94; stratified log-rank P=0.019) with a 5-year PFS rate of 60.6% and 56.9% for the CSC and SC arms, respectively. Among the patient subgroups determined based on different clinical T/N categories, a patient subgroup with cT4Nany disease showed the greatest relative risk reduction in OS with neoadjuvant chemotherapy (HR 0.69, 95% CI 0.51–0.95). Conclusions: The addition of neoadjuvant docetaxel, oxaliplatin and S-1 (DOS) chemotherapy, as part of perioperative chemotherapy, to surgery and adjuvant S-1 prolonged the OS and PFS of Asian patients with LAGC relative to patients treated with surgery and adjuvant S-1 alone. Neoadjuvant DOS chemotherapy should be considered one of the standard treatment options for patients with LAGC in Asia. Unlike in the Western setting, neoadjuvant chemotherapy may be preferentially considered for patients with cT4 disease in Asia. Clinical trial information: NCT01515748 .