PDCD1 and nasopharyngeal carcinoma: Hence, we analyzed the data of patients with RM-NPC from a prospective clinical study (POLARIS-02) with the largest cohort to date of patients with RM-NPC treated with anti–PD-1 monotherapy, and we aimed to explore the role that plasma EBV DNA titers and their dynamics play in prognosis prediction and surveillance of disease progression for patients with RM-NPC who are receiving anti–PD-1 monotherapy in the era of immunotherapy.