IntroductionThe prognosis of relapsed or refractory mature T- and natural killer (NK)-cell lymphoma remains dismal. Novel agents are urgently needed to improve the outcomes for this population.MethodsIn this phase 2, multicenter, open-label, single-arm study (NCT03776279), the authors report the efficacy and safety of liposomal mitoxantrone (Lipo-MIT) monotherapy in patients with relapsed or refractory mature T- and NK-cell lymphoma. Lipo-MIT was administered intravenously at 20 mg/m2 once every 4 weeks. The primary end points were the objective response rate (ORR) determined by the independent review committee (IRC) and investigators. Secondary end points included duration of response (DoR), progression-free survival (PFS), overall survival (OS), and safety.ResultsFrom April 26, 2018, to August 10, 2022, 108 eligible patients were enrolled and treated at 26 study centers in China. The ORRs were 41.7% (95% confidence interval [CI], 32.3-51.5%) per IRC and 46.3% (95% CI, 36.7%-56.2%) per investigators; 25 (23.1%) and 15 (13.9%) patients, respectively, achieved complete response. With a median follow-up of 29.5 months, median PFS per IRC was 8.5 months (95% CI, 6.0-11.9); median OS was 23.3 months (95% CI, 12.0-not evaluable); median DoR per IRC was not reached. The most frequent treatment-emergent adverse events were decreased white blood cell count (75, 69.4%), decreased neutrophil count (73, 67.6%), and decreased platelet count (47, 43.5%).ConclusionsLipo-MIT monotherapy showed robust and durable antitumor activity with a manageable safety profile, representing a new therapeutic option in relapsed or refractory mature T- and NK-cell lymphoma.