The purpose of this study is to explore the efficacy and safety of a combination of GP chemotherapy and tislelizumab in neoadjuvant therapy combined with tislelizumab in adjuvant therapy of locoregionally advanced nasopharyngeal carcinoma patients.

Platinum-based concurrent chemoradiotherapy is the standard of care for patients with locoregionally advanced nasopharyngeal carcinoma(NPC). Gemcitabine plus cisplatin(GP) has been demonstrated an effective chemotherapy regimen for NPC patients in previous studies. The results of GP combined with concurrent chemoradiotherapy in the treatment of locoregionally advanced nasopharyngeal carcinoma showed 10% of locoregionally advanced NPC patients had complete response after three cycles of GP neoadjuvant chemotherapy, and GP neoadjuvant chemotherapy added to chemoradiotherapy significantly improved recurrence-free survival (85.3% vs 76.5%) and overall survival (94.6% vs 90.3%) among locoregionally advanced NPC patients , as compared with chemoradiotherapy alone. Therefore, GP regimen has been established as the highest level of evidence-based neoadjuvant chemotherapy in the 2020 National Comprehensive Cancer Network (NCCN) guidelines. Recently, immune checkpoint inhibitors, such as anti-programmed cell death-1 (PD-1)monoclonal antibody has shown promising efficacy in the treatment of tumor patients. Clinical trials have shown objective response rates of 20.5%-34% in patients with recurrent or metastatic NPC patients receiving anti PD-1 monoclonal antibody immunotherapy including pembrolizumab, nivolumab, camrelizumab, and toripalimab. The current NCCN guidelines recommend anti PD-1 monoclonal antibody as a second-line treatment for recurrent or metastatic NPC. More and more evidence show that immunotherapy combined with chemotherapy has a synergistic effect in treating tumors. GP chemotherapy combined with anti PD-1 antibody has achieved the initial effect in NPC. Phase 1 trials have shown the combination of camrelizumab plus GP chemotherapy in recurrent or metastatic NPC led to a proportion of 91% patients achieving an objective response. In addition, previous studeis showed that PD-1 antibody adjuvant therapy had good feasibility and effectiveness in the treatment of nasopharyngeal carcinoma. Tislelizumab, approved by the National Medical Products Administration in China, is an anti-PD-1 monoclonal IgG4 antibody with higher affinity to PD-1 than pembrolizumab and nivolumab and was engineered to minimize binding to FcγR on macrophages in order to abrogate antibody-dependent phagocytosis, a mechanism of T-cell clearance and potential resistance to anti-PD-1 therapy. Multiple clinical trials have shown strong anti-neoplastic activity of tislelizumab in various tumors including NPC. Clinical trial has shown an objective response rates of 43% in patients with recurrent metastatic nasopharyngeal carcinoma treated with tirelizumab, which is superior to other anti PD-1 monoclonal antibodys. So we hypothesize that GP neoadjuvant chemotherapy combined with tislelizumab and tislelizumab adjuvant therapy could further improve survival of patients with locaregionally advanced NPC. Based on this, this study aims to evaluate the efficacy and safety of gemcitabine plus cisplatin chemotherapy combined with tislelizumab neoadjuvant therapy, followed by cisplatin based concurrent chemoradiotherapy, then followed by tislelizumab adjuvant therapy in the patients with locoregionally advanced nasopharyngeal carcinoma, to provide new evidence for individualized comprehensive treatment in NPC.

Inclusion Criteria:

1. Patients must be informed of the investigational nature of this study and give written informed consent.
2. Age ≥ 18 years and ≤70 years,men or non-pregnant women.
3. Patients with histologically confirmed Nonkeratinizing carcinoma of the nasopharynx (differentiated or undifferentiated type, WHO II or III).
4. Tumor staged as III-IVA (AJCC 8th, except T3N0，T3N1(Only retropharyngeal lymph nodes metastasized).
5. No previous anti-tumor treatment.
6. Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0 or 1.
7. Adequate marrow function:White blood cell count (WBC)≥4.0×109 /L, Hemoglobin ≥ 90g/L, Platelet count ≥100×109/L.
8. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤2×upper limit of normal (ULN),serum total bilirubin (TBIL) ≤2.0 times the upper limit of normal (ULN) .Adequate renal function: creatinine clearance rate≥60 ml/min or Creatinine ≤1.5× upper limit of normal value.

Exclusion Criteria:

1. Patients with recurrent or metastatic nasopharyngeal carcinoma.
2. Histologically confirmed with keratinizing squamous cell carcinoma of the nasopharynx.
3. Prior therapy with radiation or systemic chemotherapy.
4. Women in the period of pregnancy, lactation, or reproductive without effective contraceptive measures.
5. Seropositivity for human immunodeficiency virus (HIV).
6. Known history of other malignancies (except cured basal cell carcinoma or carcinoma in situ of the cervix).
7. Prior exposure to immune checkpoint inhibitors,including anti-PD-1, anti-PD-L1, anti-CTLA-4 antibodies.
8. Patients with immunodeficiency disease or a history of organ transplantation.
9. Received large doses of glucocorticoids, anticancer monoclonal antibodies, or other immunosuppressants within 4 weeks.
10. Patients with severe dysfunction of heart, liver, lung, kidney or marrow.
11. Patients with severe, uncontrolled disease or infections.
12. Received other research drugs or in other clinical trials at the same time.
13. Refuse or fail to sign the informed consent .
14. Patients with other treatment contraindications.
15. Patients with personality or mental disorders, incapacity or limited capacity for civil conduct.
16. Hepatitis B surface antigen (HBsAg) positive and peripheral blood HBV deoxyribonucleic acid (HBV DNA) ≥1000cps/ml.
17. Patients with positive HCV antibody test will only be enrolled in this study if the PCR test for HCV RNA is negative.
18. Patients who were known to be intolerable or allergic to treatment drug.