Retrospective study on maintenance therapy with PD-1 inhibitor combined with S-1 or capecitabine after first-line treatment for recurrent or metastatic nasopharyngeal carcinoma.

This study aimed to investigate the clinical efficacy and safety of programmed death-1 (PD-1) inhibitor combined with S-1 or capecitabine as maintenance therapy in patients with recurrent or metastatic nasopharyngeal carcinoma (R/M NPC) following first-line systemic treatment. Clinical data of 95 patients diagnosed with R/M NPC were retrospectively analyzed. All patients were pathologically confirmed as having non-keratinizing undifferentiated NPC with metastatic lesions verified by imaging or pathological examination. After receiving at least 4 cycles of first-line treatment with PD-1 inhibitor combined with gemcitabine plus cisplatin chemotherapy regimen, patients entered the maintenance stage and were divided into two groups: the combination maintenance group (PD-1 inhibitor plus S-1 or capecitabine) and the PD-1 inhibitor monotherapy maintenance group. Baseline characteristics, objective response rate (ORR), disease control rate (DCR), changes of Epstein-Barr virus DNA (EBV-DNA) load, inflammatory indicators, nutritional status indicators, quality of life scores, adverse events, and survival outcomes were compared between the two groups. A logistic regression model was adopted to analyze the influencing factors of poor prognosis. After maintenance treatment, the secondary ORR and DCR were slightly higher in the combination maintenance group without statistical significance (both P > 0.05). The EBV-DNA negative conversion rate was significantly elevated in the combination group (P < 0.05). Inflammatory indicators of both groups were remarkably improved after treatment (P < 0.05). No significant inter-group differences were observed in nutritional status indicators, SF-36 quality of life scores, incidence and severity distribution of grade ≥ 3 adverse events, or immune-related adverse events (all P > 0.05). Progression-free survival (PFS) was significantly longer in the combination maintenance group (P < 0.05). Univariate logistic regression analysis showed that treatment regimen, EBV-DNA negative conversion rate and ECOG score were correlated with poor prognosis. Multivariate logistic regression analysis revealed that an ECOG score of 0-1 and EBV-DNA negative conversion rate were independent protective factors against poor prognosis. In conclusion, maintenance therapy with PD-1 inhibitor combined with S-1 or capecitabine after first-line treatment for R/M NPC yields definite therapeutic efficacy. The ORR and DCR showed an upward trend in the combination group, though the difference was not statistically significant. Meanwhile, this regimen can significantly elevate the EBV-DNA negative conversion rate, ameliorate systemic inflammatory responses and prolong PFS without increasing the risk of severe adverse reactions. Combined maintenance therapy did not trigger remarkable declines in most dimension scores of SF-36, and patients' overall quality of life remained relatively stable.