Efficacy and Safety Analysis of Combination Therapy Based on Liposomal Mitoxantrone (Lipo-MIT) in Relapsed/Refractory NK/T-Cell Lymphoma

Background: Currently, there is no standard treatment for relapsed/refractory NK/T-cell lymphoma (NKTCL), which is characterized by highly aggressive and poor prognosis. New drugs are urgently needed to improve the therapeutic effect. Liposomal mitoxantrone (Lipo-MIT) is approved in China for the treatment of relapsed or refractory peripheral T-cell lymphoma patients who have received at least one line standard therapy previously. Phase II study data showed that the objective response rate (ORR) of patients after monotherapy was 41.7% and the complete response rate (CR) was 23.1%. Progression-free survival (PFS) was 8.5 months. Lipo-MIT showed excellent anti-tumor effect in patients with NKTCL subtype, with an ORR of 42.9%, which broke the limitation of natural resistance of NKTCL to anthracyclines. To further improve the efficacy, we tried a combination therapy based on Lipo-MIT in patients with relapsed/refractory NKTCL. Herein we will report its efficacy and safety.

Methods: Nine patients with relapsed/refractory NKTCL were enrolled in this study, all of whom had previously received pegaspargase-based combination chemotherapy. The salvage treatment was a combination regimen based on Lipo-MIT. The efficacy was evaluated after every 2 cycles using PET-CT or MRI scan, and hematological and non-hematological adverse events were collected after treatment. Progression-free survival (PFS) was defined as the time from initiation of Lipo-MIT to disease progression, recurrence, death, or last follow-up. Overall survival time (OS) was defined as the time from initiation of Lipo-MIT to death from all causes or the last follow-up.

Results: The median age of the nine patients was 53 years old (17-67 years old), and the male-female ratio was 7:2. Eight patients had stage IV NKTCL, one was stage II NKTCL, and all patients had an NRI score of ≥3. The median number of previous treatment lines was 2 (1-4). Three patients had recurrent NKTCL, and six patients had refractory disease to previous treatments, among whom two patients had concurrent hemophagocytic syndrome. The salvage treatment regimens were as follows: Lipo-MIT + pegaspargase + dexamethasone (N=3); Lipo-MIT + pegaspargase + dexamethasone +PD1 monoclonal antibody (N=2); Lipo-MIT +PD1 monoclonal antibody + dexamethasone (N=2); Lipo-MIT + etoposide + pegaspargase + dexamethasone (N=2). Efficacy was evaluable in all patients and the median number of treatment cycles was 3 (2-6). The best response rates were as follows: complete response in 3 (33.3%) patients, partial response in 4 (44.4%) patients, stable disease in 1 (11.1%) patient, and progressive disease in 1 (11.1%) patient. At a median follow-up of 4 months (2-13 months), 6 patients died, including 5 from disease progression and 1 from pegaspargase -associated acute pancreatitis, with a median PFS of 5 months and a median OS of 7 months. One patient underwent allogeneic hematopoietic stem cell transplantation after achieving a complete response and has been disease-free for more than 13 months now. The main adverse reactions of Lipo-MIT combination regimen were grade 3 or more bone marrow suppression (N=7), skin cyanosis (N=4), liver insufficiency (N=4), coagulation dysfunction (N=4), acute pancreatitis (N=1). The median recovery time from myelosuppression was 17 days (6-35 days). There was no correlation between skin cyanosis and efficacy.

Conclusion: Combination therapy based on Lipo-MIT has a high remission rate for relapsed/refractory NKTCL, but the duration of remission needs to be further extended, and subsequent allogeneic hematopoietic stem cell transplantation may prolong survival. Lipo-MIT has obvious myelosuppression toxicity, and active supportive therapy should be given when combined with other cytotoxic drugs. In the future, it is worthwhile to conduct prospective clinical trials to explore the optimal combination therapy based on Lipo-MIT in relapsed/refractory NKTCL.