Mitoxantrone and Etoposide for the Treatment of Acute Myeloid Leukemia Patients in First Relapse

Scaffold Hopping and Structural Modification of NSC 663284: Discovery of Potent (Non)Halogenated Aminobenzoquinones

The development of new anticancer drugs is still ongoing as a solution to the unsatisfactory results obtained by chemotherapy patients. Our previous studies on natural product-based anticancer agents led us to synthesize a new series of Plastoquinone (PQ) analogs and study their anticancer effects. Four members of PQ analogs (PQ1-4) were designed based on the scaffold hopping strategy; the design was later completed with structural modification. The obtained PQ analogs were synthesized and biologically evaluated against different cancer genotypes according to NCI-60 screening in vitro. According to the NCI results, bromo and iodo-substituted PQ analogs (PQ2 and PQ3) showed remarkable anticancer activities with a wide-spectrum profile. Among the two selected analogs (PQ2 and PQ3), PQ2 showed promising anticancer activity, in particular against leukemia cell lines, at both single- and five-dose NCI screenings. This compound was also detected by MTT assay to reveal significant selectivity between Jurkat cells and PBMC (healthy) compared to imatinib. Further in silico studies indicated that PQ2 was able to occupy the ATP-binding cleft of Abl TK, one of the main targets of leukemia, through key interactions similar to dasatinib and imatinib. PQ2 is also bound to the minor groove of the double helix of DNA. Based on computational pharmacokinetic studies, PQ2 possessed a remarkable drug-like profile, making it a potential anti-leukemia drug candidate for future studies.

Analysis of Quinolinequinone Analogs with Promising Cytotoxic Activity against Breast Cancer

It is quite challenging to find out bioactive molecules in the vast chemical universe. Quinone moiety is a unique structure with a variety of biological properties, particularly in the treatment of cancer. In an effort to develop potent and secure antiproliferative lead compounds, five quinolinequinones (AQQ1-5) described previously have been selected and submitted to the National Cancer Institute (NCI) of Bethesda to envisage their antiproliferative profile based on the NCI Developmental Therapeutics Program. According to the preliminary in vitro single-dose anticancer screening, four of five quinolinequinones (AQQ2-5) were selected for five-dose screening and they displayed promising antiproliferative effects against several cancer types. All AQQs showed a excellent anticancer profile with low micromolar GI50 and TGI values against all leukemia cell lines, some non-small cell lung and ovarian cancer, most colon, melanoma, and renal cancer, and in addition to some breast cancer cell lines. AQQ2-5 reduced the proliferation of all leukemia cell lines at a single dose and five additional doses, as well as some non-small cell lung and ovarian cancer, the majority of colon cancer, melanoma and renal cancer, and some breast cancer cell lines. This motivated us to use in vitro, in silico, and in vivo technologies to further investigate their mode of action. We investigated the in vitro cytotoxic activities of the most promising compounds, AQQ2 and AQQ3, in HCT-116 colon cancer, MCF7 and T-47D breast cancer, and DU-145 prostate cancer cell lines, and HaCaT human keratinocytes. Concomitantly, IC50 values of AQQ2 and AAQ3 against MCF7 and T-47D cell lines of breast cancer, DU-145 cell lines of prostate cancer, HCT-116 cell lines of colon cancer, and HaCaT human keratinocytes were determined. AQQ2 exhibited anticancer activity through the induction of apoptosis and caused alterations in the cell cycle. In silico pharmacokinetic studies of all analogs have been carried out against ATR, CHK1, WEE1, CDK1, and CDK2. In addition to this, in vitro ADME and in vivo pharmacokinetic profiling for the most effective AAQ (AAQ2) have been studied.

Molecular determinants of etoposide resistance in HL60 cells

Chemotherapy resistance is the main reason for treatment failure in acute myeloid leukemia (AML) and the major cause of its mortality. Etoposide is a DNA topoisomerase-II inhibitor that is used either as a single agent or in combination with cytarabine, azacytidine, vinca alkaloids, and anthracyclines for the treatment of relapsed /refractory AML. In this study, we sought to determine and understand the mechanism of etoposide resistance in AML using the HL60 cell line.HL60 cells were treated with incremental doses of etoposide and resistant colonies were isolated by culturing the resistant cells in semi-solid culture media. Three clones were selected for etoposide resistance namely, HL60-EtopR H1A, HL60-EtopR H1B, and HL60-EtopR H1C which demonstrated 4.78, 2.39, and 4.42-fold higher resistance to etoposide compared with the parental cells. To determine molecular differences between the etoposide-resistant HL60-EtopR cells and the parental cells, microarray-based gene expression profiling was performed. We found up regulation of members of the src tyrosine kinase family genes in the etoposide resistant cells. Further studies are required to evaluate the role of Src inhibitors in targeting etoposide resistant cells.

Mitochondrial metabolism as a target for acute myeloid leukemia treatment

Acute myeloid leukemias (AML) are a group of aggressive hematologic malignancies resulting from acquired genetic mutations in hematopoietic stem cells that affect patients of all ages. Despite decades of research, standard chemotherapy still remains ineffective for some AML subtypes and is often inappropriate for older patients or those with comorbidities. Recently, a number of studies have identified unique mitochondrial alterations that lead to metabolic vulnerabilities in AML cells that may present viable treatment targets. These include mtDNA, dependency on oxidative phosphorylation, mitochondrial metabolism, and pro-survival signaling, as well as reactive oxygen species generation and mitochondrial dynamics. Moreover, some mitochondria-targeting chemotherapeutics and their combinations with other compounds have been FDA-approved for AML treatment. Here, we review recent studies that illuminate the effects of drugs and synergistic drug combinations that target diverse biomolecules and metabolic pathways related to mitochondria and their promise in experimental studies, clinical trials, and existing chemotherapeutic regimens.

Co-Encapsulation of Mitoxantrone and β-Elemene in Solid Lipid Nanoparticles to Overcome Multidrug Resistance in Leukemia

Multidrug resistance (MDR) due to P-glycoprotein (P-gp) overexpression is a major obstacle to successful leukemia chemotherapy. The combination of anticancer chemotherapy with a chemosensitizer of P-gp inhibitor is promising to overcome MDR, generate synergistic effects, and maximize the treatment effect. Herein, we co-encapsulated a chemotherapeutic drug of mitoxantrone (MTO) and a P-gp inhibitor of β-elemene (βE) in solid lipid nanoparticles (MTO/βE-SLNs) for reversing MDR in leukemia. The MTO/βE-SLNs with about 120 nm particle size possessed good colloidal stability and sustained release behavior. For the cellular uptake study, doxorubicin (DOX) was used as a fluorescence probe to construct SLNs. The results revealed that MTO/βE-SLNs could be effectively internalized by both K562/DOX and K562 cells through the pathway of caveolate-mediated endocytosis. Under the optimized combination ratio of MTO and βE, the in vitro cytotoxicity study indicated that MTO/βE-SLNs showed a better antitumor efficacy in both K562/DOX and K562 cells than other MTO formulations. The enhanced cytotoxicity of MTO/βE-SLNs was due to the increased cellular uptake and blockage of intracellular ATP production and P-gp efflux by βE. More importantly, the in vivo studies revealed that MTO/βE-SLNs could significantly prolong the circulation time and increase plasma half-life of both MTO and βE, accumulate into tumor and exhibit a much higher anti-leukemia effect with MDR than other MTO formulations. These findings suggest MTO/βE-SLNs as a potential combined therapeutic strategy for overcoming MDR in leukemia.

Etoposide Combined with FLAG Salvage Therapy Is Effective in Multiple Relapsed/Refractory Acute Myeloid leukemia

Managing acute myeloid leukemia (AML) is often hampered by repeated failure to achieve complete remission as well as recurrent relapse that causes an emergent need for alternative salvage therapies. The efficacy of most salvage therapies is based on anthracycline combinations. In highly pretreated patients who are not eligible for anthracycline-based protocols therapeutic alternatives are limited. For this particular group we evaluated the efficacy and safety of fludarabine, cytarabine, granulocyte colony-stimulating factor (FLAG) in combination with etoposide (FLAG-Eto) in 36 patients. The complete remission rate (CR) was 25.7% with a median overall survival of 6 months (95% CI 4.5-7.7). The median disease-free survival for CR/CRi/MLFS (CR/CR with incomplete he-matological recovery/morphologic leukemia-free state) patients was 8 months (95% CI 0.6-15.5). The mortality rate on day 30 was 8% and increased on day 60 to 17%. Our results show meaningful anti-leukemic activity of the FLAG-Eto regimen with a moderate toxicity profile in heavily pretreated relapsed/refractory AML patients enabling consolidating allogeneic stem cell transplantation.

FLAG salvage therapy combined with idarubicin in relapsed/refractory acute myeloid leukemia

Acute myeloid leukemia (AML) is characterized by a high failure rate to achieve complete remission as well as high relapse rates that cause an emergent need for efficient and tolerable salvage therapies. The combination of FLAG with idarubicin (FLAG-Ida) is a widely used protocol. However, its efficacy has been analyzed in only a limited number of studies with majorly small patient cohorts. Here, we analyzed 132 patients with largely primary refractory or first-time relapsed AML treated according to the FLAG-Ida protocol. The overall complete remission rate (CR + CRi) was 56% with a median overall survival of 15 months (95% CI, 5.7-25.1). The median disease-free survival for CR/CRi-patients was not reached. The mortality rate on day 30 was 9% and increased on day 60 to 16%. Our results show in relapsed/refractory AML patients a high efficacy and compatibility for the FLAG-Ida regimen.