Reduced-dose RT With/Without CCT Versus Standard CCRT for High-risk LANPC Who Achieved CR Post Induction Chemotherapy

Inclusion Criteria:

1. Histologically confirmed non-keratinizing nasopharyngeal carcinoma (differentiated orundifferentiated type, i.e., WHO type II or type III).
2. Tumor staged as III-IVA (AJCC 8th, except T3N0).
3. Patients who achieved both radiological and biological CR according to the RECISTcriteria on the basis of MRI, PET-CT and endoscopic biopsy, and EBV DNA load =0copies/mL (or lower than the test line) after 3 cycles of induction therapy ofplatinum-based chemotherapy plus immunotherapy.
4. Eastern Cooperative Oncology Group performance status ≤1.
5. Adequate organ function: Adequate marrow function: neutrocyte count≥4×10e9/L, hemoglobin ≥90g/L and plateletcount ≥100×10e9/L. Adequate liver and kidney function: Alanine Aminotransferase (ALT)/AspartateAminotransferase (AST) ≤2.5×upper limit of normal (ULN), and bilirubin ≤ 2.5×ULN.;creatinine clearance rate ≥ 60 ml/min or creatinine of no more than 1.5 times theupper normal limit.
6. Patients must be informed of the investigational nature of this study and give writteninformed consent.

Exclusion Criteria:

1. Patients who are evaluated as PR or SD or PD or EBV DNA load of >0 copies/mL after 3cycles of induction therapy of platinum-based chemotherapy plus PD-1/PD-L1 blockades.
2. The laboratory examination value does not meet the relevant standards within 7 daysbefore enrollment.
3. Patients have received prior chemotherapy, immunotherapy, targeted therapy, or surgery (other than diagnostic treatment).
4. Subjects who underwent anti-PD-1 /PD-L1 antibody or anti-CTLA-4 antibody (or any otherantibody acting on T cell synergistic stimulation or checkpoint pathway) andanti-angiogenic drugs.
5. Active central nervous system (CNS) metastases (indicated by clinical symptoms,cerebral edema, steroid requirement, or progressive disease).
6. Grade ≥2 epistaxis (defined as the need for medical intervention such as nasaltamponade, cautery, topical vasoconstrictors, according to CTCAE 5.0) within 1 monthprior to enrollment; Macroscopic hemoptysis or hematemesis) is defined as ≥1/2teaspoon of bright red blood, or a blood clot with little/no sputum on each cough). (Patients with mixed sputum-blood occasionally may be enrolled).
7. Patients with hypertension who cannot be reduced to the normal range byantihypertensive drug treatment (systolic blood pressure > 140 mmHg/diastolic bloodpressure > 90 mmHg), patients with ≥ grade II coronary heart disease, arrhythmia (including QTc interval prolongation > 450 ms in men and > 470 ms in women) andcardiac insufficiency.
8. Patients currently take warfarin, heparin, aspirin (> 325 mg/day) or other NSAIDsknown to inhibit platelet function, ticlopidine, clopidogrel, or cilostazol. (Patientscan be enrolled if they discontinue these drugs 10 days prior to the commence of studyand meet the requirements of coagulation in the enrollment criteria).
9. Patients with other malignancies (except for cervical cancer, basal cell carcinoma orsquamous cell carcinoma of the skin, localized prostate cancer, and ductal carcinomain situ who have undergone curative treatment).
10. Has a known history of interstitial lung disease.
11. Known history of hypersensitivity to any components of the PD-1/PD-L1 blockadesformulation or other monoclonal antibodies.
12. Has a known history of allergic reactions to the drugs in the study (gemcitabine,cisplatin, docetaxel, abraxane, paclitaxel ).
13. Has active autoimmune disease or any condition that requires systemic corticosteroidor immunosuppressive therapy, including but not limited to the following: rheumatoidarthritis, pneumonitis, colitis (inflammatory bowel disease), hepatitis, hypophysitis,nephritis, hyperthyroidism, and hypothyroidism, except for subjects with vitiligo orresolved childhood asthma/atopy. Subjects with the following conditions will not beexcluded from this study: asthma that requires intermittent use of bronchodilators,hypothyroidism stable on hormone replacement, vitiligo, Graves' disease, orHashimoto's disease. Additional exceptions may be made with medical monitor approval.
14. Complications requiring long-term use of immunosuppressive drugs or systemic or localuse of immunosuppressive-dose corticosteroids.
15. HIV positive; HBsAg positive and HBV DNA copy number positive (quantitative detection ≥ 1000 cps/ml); chronic hepatitis C with blood screening positive (HCV antibodypositive).
16. Has a known history of active TB (bacillus tuberculosis) within 1 year; anti-TBtreatment is ongoing or within 1 year prior to screening.
17. Has received a live vaccine; or a systematic glucocorticoid therapy ; or anyanti-infective vaccine (e.g. influenza vaccine, varicella vaccine, etc.) ; any Chineseanti-tumor herbs within 4 weeks prior to enrollment.
18. Pregnancy or breastfeeding.
19. Other patients who were considered unsuitable by the treating physicians.