This study aimed to investigate the value of a novel strategy of intermittent systematic chemotherapy (ISC) in widely metastatic nasopharyngeal carcinoma (wmNPC) patients who achieve objective response after systematic chemotherapy (SC).

Widely metastatic nasopharyngeal carcinoma (wmNPC) represented a particular subgroup of patients with the worst prognosis, of which palliative systematic chemotherapy(SC) was recommended as initial treatment, however, palliative systematic treatment was often required to be stopped due to the cumulative toxicities while stopping SC may lead to disease progression, a 'stop and go' approach, namely chemotherapy 'holidays', was a new strategy which may keep a good balance of benefit and risk. This study aimed to investigate the value of a novel strategy of intermittent systematic chemotherapy (ISC) in wmNPC patients who achieve objective response after SC.

Inclusion Criteria:

1. Patients with multiple metastases at first diagnosis or multiple metastases after treatment(multiple metastases were defined as more than 5 lesions and/or more than 2 metastasis organs); Histologically or cytologically confirmed multiple metastatic NPC.
2. Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2 at trial entry, and life expectancy ≥ 6 months as judged by the Investigator;
3. The disease must be measurable with at least 1 unidimensional measurable lesion by Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1; Adequate organ function;
4. Take adequate contraceptive measures throughout the study, and contraception continues until 12 months after treatment;
5. Able and willing to provide a signed informed consent form, and able to comply with all procedures.
6. The time from the last chemotherapy and/or radiotherapy to randomization must be ≥6 months.

Exclusion Criteria:

1. Patients with a hypersensitivity to any of the drugs used in our study;
2. With any active autoimmune disease or history of autoimmune disease;
3. Clinically significant cardiovascular and cerebrovascular diseases;
4. Have or are suffering from other malignant tumors within 5 years (except non-melanoma skin cancer or pre-invasive cervical cancer);
5. Active systemic infection;
6. Drug or alcohol abuse;
7. No or limited capacity for civil conduct;
8. The patient has a physical or mental disorder, and the researcher considers that the patient is unable to fully or fully understand the possible complications of this study;
9. History of immunodeficiency including seropositive for human immunodeficiency virus (HIV), or other acquired or congenital immune-deficient disease, or any active systemic viral infection requiring therapy；
10. Use cortisol or other systematic immunosuppressive medications within 4 weeks before the study treatment, and the subject requiring hormone therapy during trials.
11. Pregnancy or breastfeeding.