The efficacy of immunotherapy combined with capecitabine versus immunotherapy alone as maintenance therapy in patients with de novo metastatic nasopharyngeal carcinoma: a retrospective propensity score matching study.

Background: Chemoimmunotherapy followed by immunotherapy maintenance is recommended as the standard treatment for metastatic nasopharyngeal carcinoma (NPC) patients. While capecitabine maintenance therapy has been shown to improve outcomes in these patients, data on the efficacy of combining capecitabine with immunotherapy maintenance remain limited. This study compared the efficacy of immunotherapy combined with capecitabine maintenance therapy (Immu/Cape) versus immunotherapy maintenance alone (Immu) in patients with de novo metastatic NPC (dmNPC) who received first-line chemoimmunotherapy.

Methods: Patients with dmNPC receiving platinum-based chemoimmunotherapy were included in this study. Propensity score matching (PSM) analysis was employed to balance the baseline characteristics between the two treatment groups.

Results: A total of 287 dmNPC patients were included in the study (100 in the Immu/Cape group and 187 in the Immu group). Patients in the Immu/Cape group demonstrated significantly prolonged progression-free survival (PFS; median PFS 41.5 versus 23.1 months, P < 0.001). After PSM, 83 patients remained in each group. Multivariable analysis indicated that the maintenance regimen was an independent prognostic factor for prolonged PFS (Immu/Cape versus Immu: hazard ratio 0.44, 95% confidence interval 0.26-0.73, P = 0.001). Subgroup analysis revealed that patients with polymetastatic disease (PMD) receiving Immu/Cape had significantly longer PFS compared with those receiving immunotherapy alone (3-year PFS rate: 49.2% versus 26.7%, P = 0.0087). In contrast, no significant benefit was observed in patients with oligometastatic disease (3-year PFS rate: 57.9% versus 54.2%, P = 0.27). Furthermore, in patients with detectable Epstein-Barr virus (EBV) DNA2-6 cycles, the Immu/Cape group exhibited significantly higher 3-year PFS rates compared with the Immu group (34.0% versus 19.8%, P = 0.032), whereas no PFS advantage was noted in patients with undetectable EBV DNA2-6 cycles (65.1% versus 52.6%, P = 0.13).

Conclusions: Immu/Cape maintenance therapy appears to be superior to immunotherapy alone in prolonging PFS in patients with dmNPC, particularly in those with PMD and detectable EBV DNA after two to six cycles of treatment.