Efficacy and Safety of Becotatug Vedotin (MRG003) Combined With Anti-PD1 as Maintenance Therapy for Recurrent and Metastatic Nasopharyngeal Carcinoma

This multicenter randomized controlled Phase III trial assesses the efficacy and safety of becotatug vedotin plus anti-PD-1 antibody as maintenance therapy for recurrent/metastatic nasopharyngeal carcinoma. Eligible patients aged 18-75 must have stable disease or positive plasma EBV DNA after 4-6 cycles of first-line chemoimmunotherapy, with adequate organ function and good physical status. A total of 86 subjects will be randomly split 1:1: the control group receives single anti-PD-1 maintenance, while the experimental group gets anti-PD-1 combined with becotatug vedotin in 21-day cycles for up to 2 years. Regular blood tests and tumor scans will be performed to monitor efficacy and adverse events graded by CTCAE v5.0; biological samples will be collected for biomarker research with consent. The primary endpoint is IRC-reviewed progression-free survival, with secondary endpoints covering overall survival, tumor response rates and safety. Overseen by an independent ethics committee, the trial ensures full data confidentiality. Participants sign informed consent and can withdraw anytime without interference to their routine cancer care, exploring a superior maintenance regimen for this high-risk NPC group.

Inclusion Criteria: * Aged between 18 and 75 years at diagnosis, regardless of gender; * Histologically confirmed nasopharyngeal carcinoma; * Patients with advanced nasopharyngeal carcinoma with confirmed distant metastasis (Stage IVb per AJCC 8th edition; Stage IV per AJCC 9th edition), or recurrent nasopharyngeal carcinoma unsuitable for locoregional or curative therapy; * Achieved stable disease (SD) assessed per RECIST v1.1 or maintained positive plasma EBV DNA after 4 to 6 cycles of first-line chemotherapy combined with immunotherapy; * Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1; * Expected survival of at least 12 weeks; * No prior systemic chemotherapy administered within 6 months before diagnosis (excluding patients with disease progression more than 6 months after neoadjuvant chemotherapy, adjuvant chemotherapy, or definitive concurrent chemoradiotherapy); * At least one measurable lesion as defined by RECIST v1.1; * Adequate organ and bone marrow function as defined below: 1. HGB ≥90 g/L, WBC ≥4×10⁹/L, PLT ≥100×10⁹/L. 2. Liver function: TBIL \