Recurrent/ Metastatic NPC

This study is to determine the activity and tolerability of JS207 as a single agent and in combination cohort with chemotherapy. This is an open-labelled, phase Ib/II study of JS207 in patients with previously treated recurrent or metastatic nasopharyngeal carcinoma. The study will comprise of two phases: * Phase 1b monotherapy: Consisting of a dose escalation and then expansion phase in patients with recurrent/ metastatic (R/M) NPC, who have failed at least 1 prior line of platinum-based chemotherapy, with or without prior treatment with PD1/ PDL1 inhibitor. * Randomized phase II: Combination of JS207 with capecitabine or paclitaxel in platinum-refractory patients: Patients who have failed one prior line of platinum-based chemotherapy for R/M NPC will be treated with JS207 in combination with capecitabine. As phase I portion of the study was completed, the starting dose of JS207 for phase II portion will be 10mg/kg IV every 3 weeks.