Maintenance therapy improves the survival outcomes of patients with metastatic nasopharyngeal carcinoma responding to first-line chemotherapy: a multicentre, randomized controlled clinical study.

PURPOSE: To explore the safety and role of tegafur/gimeracil/oteracil (S1) maintenance therapy (MT) in metastatic nasopharyngeal carcinoma (NPC) patients after response to first-line chemotherapy and to assess outcome-associated biomarkers. METHODS: This was a multicentre, open-label, randomized controlled study involving metastatic NPC patients recruited (from May 2015 to May 2019) at five hospitals in China. The participants were randomized to S1-MT (receiving S1 MT until disease progression or intolerance) or non-MT (followed up until disease progression) groups. The primary endpoint was the progression-free survival (PFS). The secondary endpoints were the overall survival (OS), the correlation between EBV-DNA, serum amyloid A (SAA) status, and outcomes after the first-line chemotherapy, and safety. RESULTS: The median follow-up was 24.3 months; 88 and 95 participants were evaluable in the S1-MT and non-MT groups, respectively. Compared with non-MT, S1-MT prolonged PFS (16.9 vs. 9.3 months, P < 0.001) and OS (33.6 vs. 20.6 months, P < 0.001). Regardless of their EBV-DNA status after first-line chemotherapy, participants were able to benefit from S1 MT, but EBV-DNA-positive participants benefited more significantly (PFS: HR = 0.600, 95% CI = 0.373-0.965, P = 0.035; OS: HR = 0.393, 95% CI = 0.227-0.681, P = 0.001). MT only improved PFS and OS in patients with an SAA decline after first-line chemotherapy (PFS: HR = 0.570, 95% CI = 0.350-0.919, P = 0.021; OS: HR = 0.404, 95% CI = 0.230-0.709, P = 0.002). The median S1 treatment was 23 cycles. Grade 1-2 skin pigmentation, oral mucositis, and hand and foot syndrome were the main adverse reactions. CONCLUSION: For metastatic NPC patients with first-line chemotherapy response, S1 MT can improve PFS and OS, with good tolerability. EBV-DNA and SAA can better help us identify patients who can benefit from MT after standard treatment. TRIAL REGISTRATION: The study protocol was registered at the Chinese Clinical Trial Registry (ChiCTR-IOR-16007939).