Bendamustine and its role in the treatment of unfit patients with chronic lymphocytic leukaemia: a perspective review

Oral formulation of bendamustine hydrochloride for patients with advanced solid tumors; a phase 1 study

To determine the maximum tolerated dose (MTD) and recommended dose (RD) of orally-administered bendamustine in Japanese patients with advanced solid tumors. The optimal dosing schedule, safety, pharmacokinetics, and preliminary antitumor effects were also evaluated. A multicenter, open-label trial with a standard 3 + 3 design and dose escalation by dose-limiting toxicity (DLT) was conducted. The treatment schedules were once daily for 7, 14, and 21 days every 3 weeks as one cycle. The total dose per cycle was increased from 175 to 840 mg/m². Eighteen patients were enrolled in this study. DLT occurred in one of six patients at 75 mg/m²/day × 7 days, and one of three patients at 37.5 mg/m²/day × 14 days and 25 mg/m²/day × 21 days. However, the delayed recovery from a decrease in neutrophil or platelet count hampered the start of subsequent treatment cycles, and the trend was more prominent at 37.5 mg/m²/day × 14 days and 25 mg/m²/day × 21 days than in 75 mg/m²/day × 7 days. MTD was determined as 75 mg/m²/day × 7 days to allow acceptable hematologic recovery. The pharmacokinetics of orally-administered bendamustine were generally dose-dependent; however, the inter-individual variability is relatively large. The major adverse events were hematologic toxicities; gastrointestinal disorders were generally mild. Adverse drug reactions did not lead to the discontinuation of the drug. A partial response was observed in two of six patients (prostatic small cell carcinoma and thymic carcinoma) at 75 mg/m²/day × 7 days. The RD and optimal dosing schedule of orally-administered bendamustine was 75 mg/m² once daily for 7 days every 3 weeks for the treatment of advanced solid tumors. (Trial registration number ClinicalTrials.gov NCT03604679. Registration date July 27, 2018).

Efficacy of bendamustine and rituximab in unfit patients with previously untreated chronic lymphocytic leukemia. Indirect comparison with ibrutinib in a real-world setting. A GIMEMA-ERIC and US study

Limited information is available on the efficacy of front‐line bendamustine and rituximab (BR) in chronic lymphocytic leukemia (CLL) with reduced renal function or coexisting conditions. We therefore analyzed a cohort of real‐world patients and performed a matched adjusted indirect comparison with a cohort of patients treated with ibrutinib. One hundred and fifty‐seven patients with creatinine clearance (CrCl) <70 mL/min and/or CIRS score >6 were treated with BR. The median age was 72 years; 69% of patients had ≥2 comorbidities and the median CrCl was 59.8 mL/min. 17.6% of patients carried TP53 disruption. The median progression‐free survival (PFS) was 45 months; TP53 disruption was associated with a shorter PFS (P = 0.05). The overall survival (OS) at 12, 24, and 36 months was 96.2%, 90.1%, and 79.5%, respectively. TP53 disruption was associated with an increased risk of death (P = 0.01). Data on 162 patients ≥65 years treated with ibrutinib were analyzed and compared with 165 patients ≥65 years treated with BR. Factors predicting for a longer PFS at multivariable analysis in the total patient population treated with BR and ibrutinib were age (HR 1.06, 95% CI 1.02‐1.10, P < 0.01) and treatment with ibrutinib (HR 0.55, 95% CI 0.33‐0.93, P = 0.03). In a post hoc analysis of patients in advanced stage, a significant PFS advantage was observed in patient who had received ibrutinib (P = 0.03), who showed a trend for OS advantage (P = 0.08). We arrived at the following conclusions: (a) BR is a relatively effective first‐line regimen in a real‐world population of unfit patients without TP53 disruption, (b) ibrutinib provided longer disease control than BR in patients with advanced disease stage.

Nitrogen Mustards as Anticancer Chemotherapies: Historic Perspective, Current Developments and Future Trends

Nitrogen mustards, a family of DNA alkylating agents, marked the start of cancer pharmacotherapy. While traditionally characterized by their dose-limiting toxic effects, nitrogen mustards have been the subject of intense research efforts, which have led to safer and more effective agents. Even though the alkylating prodrug mustards were first developed decades ago, active research on ways to improve their selectivity and cytotoxic efficacy is a currently active topic of research. This review addresses the historical development of the nitrogen mustards, outlining their mechanism of action, and discussing the improvements on their therapeutic profile made through rational structure modifications. A special emphasis is made on discussing the nitrogen mustard prodrug category, with Cyclophosphamide (CPA) serving as the main highlight. Selected insights on the latest developments on nitrogen mustards are then provided, limiting such information to agents that preserve the original nitrogen mustard mechanism as their primary mode of action. Additionally, future trends that might follow in the quest to optimize these invaluable chemotherapeutic medications are succinctly suggested.

Selective BTK inhibition improves bendamustine therapy response and normalizes immune effector functions in chronic lymphocytic leukemia

The Bruton's tyrosine kinase (BTK) inhibitor ibrutinib has been shown to be highly effective in patients with chronic lymphocytic leukemia (CLL) and is approved for CLL treatment. Unfortunately, resistance and intolerance to ibrutinib has been observed in several studies, opening the door for more specific BTK inhibitors. CC-292 (spebrutinib) is a BTK inhibitor with increased specificity for BTK and less inhibition of other kinases. Our in vitro studies showed that CC-292 potently inhibited B-cell receptor signaling, activation, proliferation and chemotaxis of CLL cells. In in vivo studies using the adoptive transfer TCL1 mouse model of CLL, CC-292 reduced tumor load and normalized tumor-associated expansion of T cells and monocytes, while not affecting T cell function. Importantly, the combination of CC-292 and bendamustine impaired CLL cell proliferation in vivo and enhanced the control of CLL progression. Our results demonstrate that CC-292 is a specific BTK inhibitor with promising performance in combination with bendamustine in CLL. Further clinical trials are warranted to investigate the therapeutic efficacy of this combination regimen.

Assays on DNA Damage and Repair in CLL

Assays that measure DNA damage and repair are critical in evaluating the extent to which therapeutic agents damage DNA and in identifying whether DNA repair can limit the toxicity of chemotherapy. The COMET assays described in this guide should help readers evaluate single and double-strand breaks cause by chemotherapeutic agents and also monitor the ability of the cells to repair such damage. The EJDR assay described is a valuable tool to assess the ability of drugs and DNA repair proteins to modulate DNA repair capacity. Finally, the immunofluorescence assay described should allow accurate assessments of DNA damage and the kinetics of repair as measured by Ɣ-H2AX foci. This procedure can also be used to mechanistically investigate the recruitment of specific DNA damage and repair proteins in CLL cells.

Antimalarial drugs trigger lysosome-mediated cell death in chronic lymphocytic leukemia (CLL) cells

Lysosomes are the most acidic vesicles within mammalian cells and are promising targets for the treatment of breast cancer, glioblastomas and acute myeloid leukemia (AML). Our previous studies have shown that chronic lymphocytic leukemia (CLL) cells are also sensitive to lysosome disruption and cell death, by siramesine or chemotherapy. In the present study, we screened the antimalarial drugs, mefloquine, atovaquone, primaquine, and tafenoquine, for their effects on lysosome disruption and cytotoxicity in primary CLL cells. We found that mefloquine and tafenoquine could permeabilize lysosome membranes and induce cell death at doses that are clinically achievable. In contrast, these agents had less effect on normal B cells. Tafenoquine was most effective at inducing cell death, and this was associated with increased formation of reactive oxygen species (ROS) and lipid peroxidation. Addition of ROS scavengers blocked both tafenoquine- and mefloquine-induced cell death. Moreover, blocking the activity of cathepsins released from the lysosomes decreased tafenoquine-induced cell death. Taken together, lysosome disruption using antimalarial drugs is a novel approach for the treatment of CLL.