The aim of this study is to investigate the efficacy and safety of the "capecitabine combined with toripalimab maintenance regimen" in improving the first-line treatment of recurrent and metastatic nasopharyngeal carcinoma after receiving remission through chemotherapy combined with anti PD-1 monoclonal antibody standard regimen.

Inclusion Criteria:

1. The age at the time of diagnosis is 18-75 years old, regardless of gender;
2. Histologically confirmed nasopharyngeal carcinoma;
3. Confirm the presence of distant metastasis in advanced nasopharyngeal carcinoma patients or recurrent nasopharyngeal carcinoma patients who cannot receive local treatment. ;
4. After receiving standard treatment for 4-6 cycles, the disease is control;
5. ECOG score 0-1;
6. Expected survival time of at least 12 weeks;
7. Patients who have not received systemic chemotherapy within 6 months prior to diagnosis ;
8. According to RECIST 1.1 standard, at least 1 measurable lesion;
9. Enough organ function;
10. Sign an informed consent form;
11. Female participants with fertility and male participants with fertility partners must agree to use reliable contraceptive measures within 6 months after screening and the last treatment.

Exclusion Criteria:

1. Patients who are known to be intolerant to capecitabine or allergic to any therapeutic drug, or who are participating in clinical studies of other new drugs;
2. Diseases that may interfere with oral medication treatment, including but not limited to swallowing difficulties, chronic diarrhea, or intestinal obstruction;
3. Previous or current history of other tumors, excluding cured cervical carcinoma in situ, skin basal cell carcinoma, and thyroid papillary carcinoma;
4. Sever heart disease;
5. Central nervous system metastasis with clinical symptoms;
6. Serious infections ;
7. Within 4 weeks of signing the informed consent form, receive systemic hormone or other immunosuppressive therapy with an equivalent dose greater than 10mg prednisone per day. Subjects with a systemic hormone dose ≤ 10mg prednisone per day or inhaled/topical corticosteroids can be enrolled in the study;
8. Patients with active chronic hepatitis B or active hepatitis C.
9. A history of interstitial pneumonia or other autoimmune diseases.
10. HIV infection;
11. Individuals with significant organ dysfunction or uncontrollable comorbidities, including but not limited to uncontrollable hypertension, decompensated liver cirrhosis, active peptic ulcer, or hemorrhagic disease;
12. Less than 6 weeks after major organ surgery;
13. Pregnant or breast feeding;
14. Patients with mental illness, those with a history of alcohol or drug abuse, or those who are unable to obtain informed consent;
15. Other researchers have determined that it is not suitable to participate in this trial.
16. Those who refuse or are unable to sign the informed consent form.