An open-label, single-center phase II trial of mitoxantrone hydrochloride liposome combined with programmed death-1 (PD-1) inhibitors for pretreated recurrent or metastatic nasopharyngeal carcinoma.

6047 Background: Liposomal mitoxantrone (Lipo-MIT) in combination with programmed death-1 (PD-1) inhibitors exhibits potential synergistic antitumor effects. This study aimed to evaluate the efficacy and safety of this regimen in patients with pretreated recurrent/metastatic nasopharyngeal carcinoma (R/M NPC). Methods: This was a single-arm, Simon two-stage clinical study enrolling patients with R/M NPC who were refractory to platinum-based chemotherapy and PD-1 inhibitors. Patients received intravenous infusion of Lipo-MIT (20 mg/m²) combined with a PD-1 inhibitor on Day 1 of each 21-day treatment cycle, for a maximum of 6 cycles. Subsequent maintenance therapy with PD-1 inhibitors alone was administered until disease progression, occurrence of intolerable toxicity, or completion of 2-year treatment. The primary endpoint was objective response rate (ORR). Key secondary endpoints included disease control rate (DCR), progression-free survival (PFS), overall survival (OS), and safety profile. Results: A total of 32 patients were enrolled between February 3, 2024, and July 21, 2025, all of whom were included in the efficacy and safety analysis sets. The ORR was 40.6% (95% confidence interval [CI], 24.2–59.2), and the DCR was 78.1% (95% CI, 59.6–90.1). With a median follow-up duration of 8.1 months (range, 4.7–17.2 months), the median OS was not reached and the median PFS was 7.4 months (95% CI, 6.0–not reached [NR]). Grade 3 or higher treatment-related adverse events (TRAEs) were observed in 18 patients (56.3%), and the most common TRAEs were leukopenia (25.0%), anemia (21.9%), neutropenia (18.8%), pneumonia (15.6%), and thrombocytopenia (12.5%). No treatment-related deaths were observed. Conclusions: Lipo-MIT combined with PD-1 inhibitors demonstrates promising antitumor activity with manageable toxicities in patients with pretreated R/M NPC. Long-term survival data are pending as follow-up is still ongoing. Clinical trial information: NCT06472713 .