A Study of Anti-PD-1 Antibody With or Without BL-B01D1 as Maintenance Therapy Following Anti-PD-1 Antibody Plus Chemotherapy for the First-line Treatment of Recurrent or Metastatic Nasopharyngeal Carcinoma (PANKU-NPC02)

Inclusion criteria

• Voluntarily sign the informed consent form and comply with the protocol requirements;
• Age ≥ 18 years;
• Expected survival time ≥ 3 months;
• Trial participants with nasopharyngeal carcinoma confirmed by histopathology and/or cytology, either initially diagnosed with metastatic disease or relapsed after curative-intent treatment;
• Agree to provide tumor tissue samples obtained at or after the diagnosis of recurrent or metastatic disease;
• Must have at least one measurable lesion as defined by RECIST v1.1;
• Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1;
• Toxicities from prior anti-tumor therapy must have recovered to ≤ Grade 1 as defined by NCI-CTCAE v6.0;
• No severe cardiac dysfunction, with left ventricular ejection fraction ≥ 50%;
• Organ function levels must meet the required criteria;
• Urine protein ≤ 1+ or < 1000 mg/24h;
• For premenopausal women of childbearing potential, a pregnancy test must be performed within 7 days before starting treatment; serum pregnancy test must rule out pregnancy; they must not be breastfeeding and must use highly effective contraceptive methods throughout the entire treatment period and for 7 months after the last dose. For male trial participants whose partners are women of childbearing potential, adequate barrier contraception must be used throughout the entire treatment period and for 7 months after the end of treatment.

Exclusion criteria

• Trial participants who have received prior systemic therapy;
• Those who have received prior therapy targeting the mechanism of tumor immuno-oncology;
• Those who have previously received antibody-drug conjugates (ADCs) using topoisomerase I inhibitors as the toxin, or EGFR- and/or HER3-targeting antibodies/ADCs;
• Trial participants who have received systemic immunostimulatory agents within 4 weeks prior to the first dose;
• Those who have received radical radiotherapy, major surgery, or extensive-field radiotherapy within 4 weeks prior to study randomization;
• History of severe cardiac or cerebrovascular disease;
• Those receiving long-term systemic corticosteroid therapy (e.g., prednisone >10 mg/day) prior to the first dose;
• Active autoimmune diseases and inflammatory diseases;
• Unstable thrombotic events requiring therapeutic intervention within 6 months prior to screening;
• Prolonged QTc interval, complete left bundle branch block, third-degree atrioventricular block, or frequent and uncontrolled arrhythmias;
• Diagnosis of active malignancy within 3 years prior to study randomization;
• Hypertension inadequately controlled by two antihypertensive agents;
• Trial participants with poorly controlled blood glucose;
• History of interstitial lung disease (ILD) requiring steroid therapy, current ILD, or radiation pneumonitis of Grade ≥2;
• Concurrent pulmonary diseases resulting in clinically severe impairment of respiratory function;
• Active central nervous system (CNS) metastases;
• Severe infection occurring within 4 weeks prior to study randomization;
• Trial participants with massive serosal cavity effusion, symptomatic serosal cavity effusion, or poorly controlled serosal cavity effusion;
• Imaging findings indicating tumor invasion or encasement of abdominal, thoracic, or cervical structures;
• Severe, non-healing wounds, ulcers, or bone fractures within 4 weeks prior to signing informed consent;
• Trial participants with clinically significant bleeding or obvious bleeding tendency within 4 weeks prior to signing informed consent;
• Trial participants with inflammatory bowel disease, history of extensive bowel resection, history of immune-mediated enteritis, intestinal obstruction, or chronic diarrhea;
• Trial participants with a history of allergy to recombinant humanized antibodies or hypersensitivity to the investigational drug;
• History of autologous or allogeneic stem cell transplantation;
• Positive for human immunodeficiency virus (HIV) antibodies, active hepatitis B virus (HBV) infection, or hepatitis C virus (HCV) infection;
• History of severe neurological or psychiatric disorders;
• Receipt of other unapproved investigational drugs or treatments within 4 weeks prior to study randomization;
• Trial participants who plan to receive, or have received, live vaccines within 28 days prior to study randomization;
• Other conditions deemed by the investigator to make the participant unsuitable for participation in this clinical trial due to complications or other circumstances.