Toripalimab Vs. Placebo Wtih GP Induction Chemotherapy in Locoregionally Advanced Nasopharyngeal Carcinoma

"Drug: Toripalimab 240mg will be given every 3 weeks for 3 cycles, started on day 1 of induction chemotherapy.~Other Names:~JS001 PD-1 antibody~Drug: Gemcitabine 1000mg/m2, d1 \& 8 of every cycle, every 3 weeks for 3 cycles before radiation.~Drug: Cisplatin Induction cisplatin 80mg/m2, every 3 weeks for 3 cycles before radiation; Concurrent cisplatin 100mg/m2, every 3 weeks for 3 cycles during radiation~Other Names:~DDP~Radiation: intensity-modulated radiotherapy Definitive intensity-modulated radiotherapy (IMRT) of 70 Gy will be given in 33 fractions.~Other Names:~IMRT"

"Drug: Placebo 240mg will be given every 3 weeks for 3 cycles, started on day 1 of induction chemotherapy.~Drug: Gemcitabine 1000mg/m2, d1 \& 8 of every cycle, every 3 weeks for 3 cycles before radiation.~Drug: Cisplatin Induction cisplatin 80mg/m2, every 3 weeks for 3 cycles before radiation; Concurrent cisplatin 100mg/m2, every 3 weeks for 3 cycles during radiation~Other Names:~DDP Radiation: intensity-modulated radiotherapy Definitive intensity-modulated radiotherapy (IMRT) of 70 Gy will be given in 33 fractions.~Other Names:~IMRT"