This is a phase 3, multi-center, randomized controlled trial, with the purpose to evaluate the therapeutic efficacy and safety of PD-1 blockade (toripalimab) combined with the de-intensified chemoradiotherapy sparing concurrent cisplatin (i.e., toripalimab incorporated into induction chemotherapy and radiotherapy) in high-risk locoregionally advanced nasopharyngeal carcinoma.

This phase 3, multi-center, randomized controlled trial plans to enroll 532 patients with newly-diagnosed, pathologically-proven, untreated locoregionally advanced nasopharyngeal carcinoma (LANPC) at high-risk of distant metastasis (T4N1 and T1-4N2-3, according to American Joint Committee on Cancer [AJCC]/Union for International Cancer Control [UICC] 8th edition clinical staging system). Patients will receive 3 cycles of induction chemotherapy (IC; gemcitabine-cisplatin regimen) followed by 1) experimental arm (de-intensification group): intensity-modulated radiotherapy (IMRT) alone or 2) control arm (standard group): 2 cycles of concurrent cisplatin plus IMRT (CCRT). For both of the two arms, toripalimab will be adopted on day 1 of the first cycle IC and continue every 3 weeks for 6 cycles till the end of IMRT, with the first and last 3 cycles of toripalimab administrated along with IC and CCRT/IMRT, respectively. After three weeks of the completion of IMRT, adjuvant toripalimab will be used every 3 weeks for 11 cycles, and therefore the entire treatment process is expected to last for one year.

Inclusion Criteria:

1. Age: 18 to 65;
2. Pathological type: non-keratinizing carcinoma (World Health Organization criteria);
3. Diagnosed with LANPC (T4N1, T1-4N2-3) according to the 8th edition clinical staging system of the American Joint Committee on Cancer [AJCC]/Union for International Cancer Control [UICC];
4. ECOG performance score: 0 to 1;
5. Normal bone marrow function: white blood cell count > 4×109/L, hemoglobin > 90g/L, platelet count > 100×109/L;
6. Normal values of thyroid function, amylase and lipase examination, pituitary function, inflammation and infection indicators, myocardial enzymes, and ECG results. For patients older than 50 years with a smoking history, normal lung function are required. Patients with abnormal ECG and/or a history of vascular disease (but not meeting the exclusion criteria listed in the exclusion criteria 7) need further testing and require normal results of myocardial function and color Doppler ultrasound.
7. Normal liver and kidney function: total bilirubin ≤ 1.5 × upper limit of normal (ULN); alanine transaminase and aspartate transaminase ≤ 2.5 × ULN; alkaline phosphatase ≤ 2.5 × ULN; creatinine clearance rate ≥ 60 ml/min;
8. Patients must sign informed consent and be willing and able to comply with the requirements of visits, treatment, laboratory tests and other research requirements stipulated in the research schedule;
9. Subjects with pregnancy ability must agree to use reliable contraceptive measures from screening to 1 year after treatment.

Exclusion Criteria:

1. Hepatitis B virus surface antigen (HBsAg) positive and HBV DNA > 1×10E3 copies/ml; anti-hepatitis C virus positive;
2. Anti-human immunodeficiency virus (HIV) positive or diagnosed with acquired immune deficiency syndrome (AIDS);
3. Active tuberculosis: active tuberculosis in the past 1 year should be excluded regardless with treatment; history of active tuberculosis over 1 year should be excluded except that previous regulatory anti-tuberculosis treatment is proved;
4. Active, known or suspected autoimmune disease (including but not limited to uveitis, enteritis, hepatitis, pituitary, nephritis, vasculitis, hyperthyroidism, hypothyroidism and asthma requiring bronchiectasis). Exceptions are type I diabetes mellitus, hypothyroidism requiring hormone replacement therapy, skin disorders requiring no systemic treatment (such as vitiligo, psoriasis or alopecia);
5. Previous interstitial lung disease or pneumonia requiring oral or intravenous steroid therapy;
6. Chronic treatment with systemic glucocorticoid (dose equivalent to or over 10 mg prednisone per day) or any other form of immunosuppressive therapy. Subjects who used inhaled or topical corticosteroids were eligible;
7. Uncontrolled heart disease, for example: 1) heart failure (NYHA level ≥ 2); 2) unstable angina; 3) myocardial infarction in past 1 year; 4) supraventricular or ventricular arrhythmia requiring treatment or intervention;
8. Pregnant or lactating women (pregnancy test should be considered for women with sexual life and fertility);
9. Previous or concurrent with other malignant tumors, except for adequately treated non-melanoma skin cancer, cervical carcinoma in situ and thyroid papillary cancer;
10. Allergy to macromolecular protein preparations, or any component of nivolumab;
11. Active infection requiring systemic treatment;
12. Receiving live vaccine within 30 days of the initial nivolumab;
13. History of organ transplantation;
14. History of psychotropic disease, alcoholism or drug abuse; other situation assessed by the investigators that may compromise the safety or compliance of patients, such as serious disease requiring timely treatment (including mental illness), severe laboratory abnormalities, or family-social risk factors.

Open-label