Phase I Study of the Combination of Bendamustine, Rituximab, and Pixantrone in Patients With Relapsed/Refractory B-cell Non-Hodgkin Lymphoma

Pixantrone Sensitizes Gram-Negative Pathogens to Rifampin

The emergence of bacterial drug resistance poses a severe threat to global public health. In particular, antimicrobial-resistant pathogens lead to a high rate of treatment failure and significantly increase mortality. Repurposing FDA-approved compounds to sensitize superbugs to conventional antibiotics provides a promising strategy to alleviate such crises. Pixantrone (PIX) has been approved for treating aggressive B-cell non-Hodgkin's lymphoma. By high-throughput drug screening, we profiled the synergistic activity between PIX and rifampin (RFP) against Gram-negative extensively drug-resistant isolates by checkerboard assay. Mechanistic studies demonstrated that PIX impacted the flagellum assembly, induced irreversible intracellular reactive oxygen species accumulation and disrupted proton motive force. In addition, the combination of PIX with RFP possesses effective antimicrobial activity against multidrug-resistant strains in vivo without detected toxicity. Collectively, these results reveal the potential of PIX in combination with RFP as a therapy option for refractory infections caused by Gram-negative pathogens. IMPORTANCE Bacterial resistance has become increasingly serious because of the widespread use and abuse of antibiotics. In particular, the emergence of multidrug-resistant bacteria has posed a serious threat to human public health. Drug repurposing, the process of finding new uses for existing drugs, provide a promising pathway to solve antimicrobial resistance. Compared to the development of novel antibiotics, this strategy leverages well-characterized pharmacology and toxicology of known drugs and is more cost-effective.

Pixantrone, etoposide, bendamustine, rituximab (P[R]EBEN) as an effective salvage regimen for relapsed/refractory aggressive non-Hodgkin lymphoma-Polish Lymphoma Research Group real-life analysis

BACKGROUND

Despite a significant improvement in treatment outcomes, 30-40% of aggressive non-Hodgkin lymphomas (NHL) patients are refractory or relapse after the first line therapy. Half of them are not eligible to autologous stem cell transplantation (ASCT) due to failure of platinum-based salvage regimens. Pixantrone is conditionally approved in Europe in patients with R/R aggressive NHL failing at least 2 previous lines of therapy. Polish Lymphoma Research Group (PLRG) evaluated the efficacy and tolerability of P[R]EBEN combining pixantrone, etoposide, bendamustine with or without rituximab), a new regimen developed recently by Francesco d'Amore, in real-life experience.

METHODS

In this retrospective audit, we analyzed the data of consecutive 25 R/R NHL cases, treated with P[R]EBEN regimen in 9 PLRG centers. Safety and efficacy data, including adverse reactions (AE), response rates, progression-free and overall survival (PFS and OS) were collected.

RESULTS

Overall response rate (ORR) to P[R]EBEN regimen was 68% (40% CR and 28% PR). Most patients responded, relatively early, by second cycle of therapy. P[R]EBEN was effective in 8 out of 15 patients (53%) refractory to previous platinum-based salvage regimens. In 4 patients (16%) stabilization of disease (SD) during therapy was observed and further 4 patients (16%) progressed during the treatment (PD). Response rates were higher in patients, chemosensitive to their prior regimen (ORR - 87.5%, including 50% CR). At the median follow-up of 7.5 months (range 1-16) the median PFS and OS were not reached. Projected PFS and OS at 12 months are 68% and 78% respectively. The P[R]EBEN regimen was well tolerated and most of patients received it as out-patients. AEs grade ≥3 occurred in 17 patients (68%). Most common grade 3-4 AEs were due to hematological toxicity with febrile neutropenia observed in 5 patients (20%). There were no episodes of septic deaths. Six patients (24%) died during treatment and follow-up period, all of them due to lymphoma progression.

CONCLUSION

Our data suggest good efficiency and tolerability of P[R]EBEN regimen as a rescue therapy in patients with R/R aggressive NHL.