Improving the therapeutic index of anthracycline chemotherapy: focus on liposomal doxorubicin (Myocet)

Preclinical evaluation of a urokinase plasminogen activator receptor-targeted nanoprobe in rhesus monkeys

Purpose

To translate a recombinant peptide containing the amino-terminal fragment (ATF) of urokinase plasminogen activator receptor-targeted magnetic iron oxide (IO) nanoparticles (uPAR-targeted human ATF-IONPs) into clinical applications, we conducted a pilot study to evaluate the toxicity and pharmacokinetics of this nanoparticle in normal rhesus monkeys.

Methods

We assessed the changes in the following: magnetic resonance imaging (MRI) signals from pretreatment stage to 14 days posttreatment, serum iron concentrations from 5 minutes posttreatment to 12 weeks posttreatment, routine blood examination and serum chemistry analysis results from pretreatment stage to 12 weeks after administration, and results of staining of the liver with Perls’ Prussian Blue and hematoxylin–eosin at 24 hours and 3 months posttreatment in two rhesus monkeys following an intravenous administration of the targeted nanoparticles either with a polyethylene glycol (ATF-PEG-IONP) or without a PEG (ATF-IONP) coating.

Results

The levels of alkaline phosphatase, alanine transaminase, and direct bilirubin in the two monkeys increased immediately after the administration of the IONPs but returned to normal within 20 days and stayed within the normal reference range 3 months after the injection. The creatinine levels of the two monkeys stayed within the normal range during the study. In addition, red blood cells, white blood cells, hemoglobin level, and platelets remained normal during the 3 months of the study.

Conclusion

All of the results suggest that a transient injury in terms of normal organ functions, but no microscopic necrotic lesions, was observed at a systemic delivery dose of 5 mg/kg of iron equivalent concentration in the acute phase, and that no chronic toxicity was found 3 months after the injection. Therefore, we conclude that uPAR-targeted IONPs have the potential to be used as receptor-targeted MRI contrasts as well as theranostic agents for the detection and treatment of human cancers in future studies.

HPTLC Analysis of Bioactivity Guided Anticancer Enriched Fraction of Hydroalcoholic Extract of Picrorhiza kurroa

Objective. Hydroalcoholic extract of Picrorhiza kurroa and its fractions were subjected to in vitro screening for cytotoxicity; further best active fraction (BAF) obtained was tested against Ehrlich ascites carcinoma (EAC) model in Balb/c mice after its quality control analysis. Methods. Cytotoxicities of all the fractions and mother extract of P. kurroa were determined, using MTT assay on breast cancer (MCF-7, MDA-MB 231) and cervical cancer (HeLa, SiHa) cell lines. Metabolic fingerprinting was developed using HPTLC with quantification of biomarkers (cucurbitacins B and E; betulinic acid; picrosides 1 and 2; and apocynin) in BAF. The EAC tumor-bearing mice were used for in vivo anticancer activity after oral administration (50 mg Kg⁻¹) for 10 days. Results. Cytotoxicity assay of mother extract and its fractions over breast cancer and cervix cancer cell lines showed that dichloromethane (DCM) fraction was most cytotoxic (IC₅₀ 36.0–51.0 µg mL⁻¹ at 72 h). Oral administration of DCM fraction showed significant reduction in tumor regression parameters, viable tumor cell count and restoration of hematological parameters may be due to presence of cucurbitacins B and E; betulinic acid; picrosides 1 and 2; and apocynin, as compared to the untreated mice of the control group. Conclusion. The DCM fraction of P. kurroa displayed potent anticancer activity and can be further explored for the development of a potential candidate for cancer therapy.

Hypothalamic energy metabolism is impaired by doxorubicin independently of inflammation in non-tumour-bearing rats

We sought to explore the effects of doxorubicin on inflammatory profiles and energy metabolism in the hypothalamus of rats. To investigate these effects, we formed two groups: a control (C) group and a Doxorubicin (DOXO) group. Sixteen rats were randomly assigned to either the control (C) or DOXO groups. The hypothalamus was collected. The levels of interleukin (IL)-1β, IL-6, IL-10, TNF-α and energy metabolism (malate dehydrogenase, complex I and III activities) were analysed in the hypothalamus. The DOXO group exhibited a decreased body weight (p < 0.01). Hypothalamic malate dehydrogenase activity was reduced when compared with control (p < 0.05). In addition, pro-inflammatory cytokine levels were unchanged. Therefore, our results demonstrate that doxorubicin leads to an impairment of \hypothalamic energy metabolism, but do not affect the inflammatory pathway. SIGNIFICANCE PARAGRAPH: The hypothalamus is a central organ that regulates a great number of functions, such as food intake, temperature and energy expenditure, among others. Doxorubicin can lead to deep anorexia and metabolic chaos; thus, we observed the effect of this chemotherapeutic drug on the inflammation and metabolism in rats after the administration of doxorubicin in order to understand the central effect in the hypothalamus. Drug treatment by doxorubicin is used as a cancer therapy; however the use of this drug may cause harmful alterations to the metabolism. Thus, further investigations are needed on the impact of drug therapy over the long term.

Phase I study of non-pegylated liposomal doxorubicin in children with recurrent/refractory high-grade glioma

PURPOSE

To determine the maximum recommended dose (RD) and pharmacokinetics of Myocet®, a non-pegylated liposomal doxorubicin, in children.

METHODS

Eligible patients were children with refractory high-grade glioma who had received prior chemotherapy and radiotherapy but no anthracyclines. Cohorts of at least three patients each received escalating doses of Myocet® starting at 60 mg/m(2) at 3-week intervals, administered intravenously over 1 h, and then doses were escalated to 75 mg/m(2) corresponding to the adult RD. Periodic blood samples were collected, and plasma doxorubicin and doxorubicinol concentrations were quantified to characterise the pharmacokinetics of Myocet®.

RESULTS

Between October 2010 and January 2013, 13 children aged 6-17 years were treated. In total, 27 courses were administered, at the 60 mg/m(2) dose level in seven patients without dose-limiting toxicity (DLT), and at 75 mg/m(2) in six patients of whom two experienced DLT (grade 4 neutropenia). The most common grade 3-4 toxicities reported for all courses were neutropenia (35 and 38 %, respectively), thrombocytopenia (12 and 4 %, respectively); and grade 3 vomiting, nausea, mucositis, and fever (4 % each). Mean estimates of central volume of distribution at steady state, clearance, and elimination half-life of doxorubicin were 24.8 L, 15 L/h/m(2), and 34.8 h, respectively, with a large interpatient variability.

CONCLUSION

The RD of Myocet® administered every 3 weeks to paediatric patients was 60 mg/m(2). The efficacy of Myocet® in paediatric patients with high-grade glioma remains to be determined and should be studied in Phase II trials.

Pegylated liposomal doxorubicin (Lipo-Dox®) combined with cyclophosphamide and 5-fluorouracil is effective and safe as salvage chemotherapy in taxane-treated metastatic breast cancer: an open-label, multi-center, non-comparative phase II study

Background

Anthracycline and taxane are classes of drugs that are frequently used in the adjuvant and palliative settings of metastatic breast cancer (MBC); however, treatment failure occurs in most cases. Limited data demonstrated favorable response in MBC after previous taxane-based treatment. The aim of this study was to evaluate the efficacy and safety of pegylated liposomal doxorubicin (Lipo-Dox®) used as part of a combination salvage therapy for patients with MBC whose tumors progressed during or after taxane-based treatment.

Methods

Patients with MBC who failed to respond to previous taxane-based treatments were recruited. Treatment with pegylated liposomal doxorubicin (40 mg/m²), cyclophosphamide (500 mg/m²), and 5-fluorouracil (500 mg/m²) was administered every 3 weeks. Tumor response to treatment was determined by using the Response Evaluation Criteria in Solid Tumor criteria version 1.0, and left ventricular ejection fraction was measured before and after treatment using echocardiography. Each patient was followed for 30 days after the last dose of study medication or until resolution/stabilization of any drug-related adverse event.

Results

Forty-five patients were recruited. As of December 2012, the median follow-up duration was 29.8 months, the overall response rate was 41.9 %, the median progression-free survival was 8.2 months, and the median overall survival was 36.6 months for all treated patients. Grade 3/4 neutropenia, leucopenia, and neutropenic fever were observed in 14 %, 9 %, and 1 % of the cycles, respectively. Other non-hematologic adverse effects were mild to moderate and were manageable. No decrease in left ventricular ejection function was noted.

Conclusion

This regimen of combined of pegylated liposomal doxorubicin, cyclophosphamide, and 5-fluorouracil exhibited a promising overall response rate, progression-free survival rate, and overall survival rate, with a safe cardiac toxicity profile and manageable adverse effects. This regimen could be considered as a treatment option for patients with MBC whose tumors progressed during or after taxane-based treatment.

Antiproliferative and Apoptosis Induction Potential of the Methanolic Leaf Extract of Holarrhena floribunda (G. Don)

Natural plant products with potent growth inhibition and apoptosis induction properties are extensively being investigated for their cancer chemopreventive potential. Holarrhena floribunda (HF) is used in a wide range of traditional medicine practices. The present study investigated the antiproliferative and apoptosis induction potential of methanolic leaf extracts of HF against breast (MCF-7), colorectal (HT-29), and cervical (HeLa) cancer cells relative to normal KMST-6 fibroblasts. The MTT assay in conjunction with the trypan blue dye exclusion and clonogenic assays were used to determine the effects of the extracts on the cells. Caspase activities were assayed with Caspase-Glo 3/7 and Caspase-9 kits. Apoptosis induction was monitored by flow cytometry using the APOPercentage and Annexin V-FITC kits. Reactive oxygen species (ROS) was measured using the fluorogenic molecular probe 5-(and-6)-chloromethyl-2′,7′-dichlorofluorescein diacetate acetyl ester and cell cycle arrest was detected with propidium iodide. Dose-response analyses of the extract showed greater sensitivity in cancer cell lines than in fibroblast controls. Induction of apoptosis, ROS, and cell cycle arrest were time- and dose-dependent for the cancer cell lines studied. These findings provide a basis for further studies on the isolation, characterization, and mechanistic evaluation of the bioactive compounds responsible for the antiproliferative activity of the plant extract.

Analysis of doxorubicin distribution in MCF-7 cells treated with drug-loaded nanoparticles by combination of two fluorescence-based techniques, confocal spectral imaging and capillary electrophoresis

The intracellular distribution of the antiancer drug doxorubicin (DOX) was followed qualitatively by fluorescence confocal spectral imaging (FCSI) and quantitatively by capillary electrophoresis (CE). FCSI permits the localization of the major fluorescent species in cell compartments, with spectral shifts indicating the polarity of the respective environment. However, distinction between drug and metabolites by FCSI is difficult due to their similar fluorochromes, and direct quantification of their fluorescence is complicated by quantum yield variation between different subcellular environments. On the other hand, capillary electrophoresis with fluorescence detection (CE-LIF) is a quantitative method capable of separating doxorubicin and its metabolites. In this paper, we propose a method for determining drug and metabolite concentration in enriched nuclear and cytosolic fractions of cancer cells by CE-LIF, and we compare these data with those of FCSI. Significant differences in the subcellular distribution of DOX are observed between the drug administered as a molecular solution or as a suspension of drug-loaded iron oxide nanoparticles coated with polyethylene glycol. Comparative analysis of the CE-LIF vs FCSI data may lead to a tentative calibration of this latter method in terms of DOX fluorescence quantum yields in the nucleus and more or less polar regions of the cytosol.

Leukocytes as carriers for targeted cancer drug delivery

INTRODUCTION

Metastasis contributes to over 90% of cancer-related deaths. Numerous nanoparticle platforms have been developed to target and treat cancer, yet efficient delivery of these systems to the appropriate site remains challenging. Leukocytes, which share similarities to tumor cells in terms of their transport and migration through the body, are well suited to serve as carriers of drug delivery systems to target cancer sites.

AREAS COVERED

This review focuses on the use and functionalization of leukocytes for therapeutic targeting of metastatic cancer. Tumor cell and leukocyte extravasation, margination in the bloodstream, and migration into soft tissue are discussed, along with the potential to exploit these functional similarities to effectively deliver drugs. Current nanoparticle-based drug formulations for the treatment of cancer are reviewed, along with methods to functionalize delivery vehicles to leukocytes, either on the surface and/or within the cell. Recent progress in this area, both in vitro and in vivo, is also discussed, with a particular emphasis on targeting cancer cells in the bloodstream as a means to interrupt the metastatic process.

EXPERT OPINION

Leukocytes interact with cancer cells both in the bloodstream and at the site of solid tumors. These interactions can be utilized to effectively deliver drugs to targeted areas, which can reduce both the amount of drug required and various nonspecific cytotoxic effects within the body. If drug delivery vehicle functionalization does not interfere with leukocyte function, this approach may be utilized to neutralize tumor cells in the bloodstream to prevent the formation of new metastases, and also to deliver drugs to metastatic sites within tissues.

Dexrazoxane

Anthracyclines are a fundamental part of many childhood cancer therapy regimens; however, the discovery of anthracycline-induced cardiotoxicity has raised concern and led to dose limitation. The cardiotoxicity of anthracyclines has resulted in an increased demand for cardioprotectants. Dexrazoxane is the only cardioprotectant that has proven efficacy in reducing cardiotoxic effects when given prior to the administration of anthracyclines. Currently, it is still considered an “off-label” use due to a paucity of data in the literature on dexrazoxane administration in children. Nevertheless, through evaluation of the available data, dexrazoxane is observed to be safe, tolerable, and efficacious in mitigating the cardiotoxic effects of anthracycline in children, without jeopardizing its antineoplastic activity or increasing the risk of developing secondary malignant neoplasms.

Cardiotoxicity and cardioprotection in childhood cancer

Children diagnosed with cancer are now living longer as a result of advances in treatment. However, some commonly used anticancer drugs, although effective in curing cancer, can also cause adverse late effects. The cardiotoxic effects of anthracycline chemotherapy, such as doxorubicin, and radiation can cause persistent and progressive cardiovascular damage, emphasizing a need for effective prevention and treatment to reduce or avoid cardiotoxicity. Examples of risk factors for cardiotoxicity in children include higher anthracycline cumulative dose, higher dose of radiation, younger age at diagnosis, female sex, trisomy 21 and black race. However, not all who are exposed to toxic treatments experience cardiotoxicity, suggesting the possibility of a genetic predisposition. Cardioprotective strategies under investigation include the use of dexrazoxane, which provides short- and long-term cardioprotection in children treated with doxorubicin without interfering with oncological efficacy, the use of less toxic anthracycline derivatives and nutritional supplements. Evidence-based monitoring and screening are needed to identify early signs of cardiotoxicity that have been validated as surrogates of subsequent clinically significant cardiovascular disease before the occurrence of cardiac damage, in patients who may be at higher risk.

Anthracycline-related cardiotoxicity in childhood cancer survivors

PURPOSE OF REVIEW

Anthracyclines have markedly improved the survival rates of children with cancer. However, anthracycline-related cardiotoxicity is also well recognized and can compromise the long-term outcome in some patients. The challenge remains of how to balance the chemotherapeutic effects of anthracycline treatment with its potentially serious cardiovascular complications. Here, we review the pathophysiology, risk factors, clinical manifestations, prevention, and treatment of anthracycline-related cardiotoxicity.

RECENT FINDINGS

Some risk factors and biomarkers associated with an increased probability of anthracycline-related cardiotoxicity have been identified. Modifying the structural forms and dosages of anthracyclines and coadministering cardioprotective agents may prevent some of these cardiotoxic effects. Cardiovascular complications have also been treated with angiotensin-converting enzyme inhibitors, β-blockers, and growth hormone replacement therapy. Cardiac transplantation remains the treatment of last resort.

SUMMARY

Despite major advances in cancer treatment, anthracycline-related cardiotoxicity remains a major cause of morbidity and mortality in survivors of childhood cancer. Promising areas of research include: use of biomarkers for early recognition of cardiac injury in children receiving chemotherapy, development and application of cardioprotective agents for prevention of cardiotoxicity, and advancements in therapies for cardiac dysfunction in children after anthracycline treatment.

Liposomal nitrooxy-doxorubicin: one step over caelyx in drug-resistant human cancer cells

In this work we prepared and characterized two liposomal formulations of a semisynthetic nitric oxide (NO)-releasing doxorubicin (Dox), called nitrooxy-Dox (NitDox), which we previously demonstrated to be cytotoxic in Dox-resistant human colon cancer cells. Liposomes with 38.2% (Lip A) and 19.1% (Lip B) cholesterol were synthesized: both formulations had similar size and zeta potential values and caused the same intracellular distribution of free NitDox, but Lip B accumulated and released NitDox more efficiently. In Dox-resistant human colon cancer cells, Lip A and Lip B exhibited a more favorable kinetics of drug uptake and NO release, and a stronger cytotoxicity than Dox and free NitDox. While Caelyx, one of the liposomal Dox formulations approved for breast and ovary tumors treatment, was ineffective in Dox-resistant breast/ovary cancer cells, Lip B, and to a lesser extent Lip A, still exerted a significant cytotoxicity in these cells. This event was accompanied in parallel by a higher release of NO, which caused nitration of P-glycoprotein (Pgp) and multidrug resistance related protein 1 (MRP1), two transporters involved in Dox efflux, and impaired their pump activity. By doing so, the efflux kinetics of Dox after treatment with Lip B was markedly slowed down and the intracellular accumulation of Dox was increased in breast and ovary drug-resistant cells. We propose these liposomal formulations of NitDox as new tools with a specific indication for tumors overexpressing Pgp and MRP1.

Nanopharmacology in translational hematology and oncology

Nanoparticles have displayed considerable promise for safely delivering therapeutic agents with miscellaneous therapeutic properties. Current progress in nanotechnology has put forward, in the last few years, several therapeutic strategies that could be integrated into clinical use by using constructs for molecular diagnosis, disease detection, cytostatic drug delivery, and nanoscale immunotherapy. In the hope of bringing the concept of nanopharmacology toward a viable and feasible clinical reality in a cancer center, the present report attempts to present the grounds for the use of cell-free nanoscale structures for molecular therapy in experimental hematology and oncology.

Synergistic nanoparticulate drug combination overcomes multidrug resistance, increases efficacy, and reduces cardiotoxicity in a nonimmunocompromised breast tumor model

Anthracyclines, commonly employed for cancer chemotherapy, suffer from dose-limiting cardiotoxicity and poor efficacy due to multidrug resistance (MDR). We previously demonstrated that simultaneous delivery of the synergistic drugs doxorubicin (DOX) and mitomycin C (MMC) by polymer-lipid hybrid nanoparticles (PLN) circumvented MDR, increased efficacy, and reduced cardiotoxicity in immuncompromised mice superior to poly(ethylene glycol)-coated (PEGylated) lipososmal DOX (PLD). Herein it is shown that the DOX-MMC combination was also synergistic in MDR EMT6/AR1 murine breast cancer cells and that their nanoparticle formulations were able to overcome the MDR phenotype. In contrast PLD exhibited little or no effect on the MDR cells. For the first time, these differences in in vitro efficacy are shown to be strongly correlated with cellular uptake and intracellular distribution of DOX brought about by DOX formulations (e.g., free solution, PLN vs PLD). To take into consideration the role of an intact immune system and tumor stroma in the response of host and tumor to chemotherapy, use was made of nonimmunocomprised mouse models to study the dose tolerance, cardiotoxicity, and efficacy of DOX-MMC coloaded PLN (DMsPLN) compared to PLD. DMsPLN treatment at 50 mg/m(2) DOX and 17 mg/m(2) of MMC singly or once every 4 days for 4 cycles were well tolerated by the mice without elevated systemic toxicity blood markers or myocardial damage. In contrast, PLD was limited to a single treatment due to significant total weight loss. The DMsPLN treatment delayed tumor growth up to 312% and 28% in EMT6/WT and EMT6/AR1 models, respectively. This work supports the translational value of DMsPLN for the aggressive management of either naïve or anthracycline-resistant tumors.

PEG-PLGA Nanoparticles Entrapping Doxorubicin Reduced Doxorubicin-Induced Cardiotoxicity in Rats

Aim:Doxorubicin-induced cardiotoxicity limited its clinical utilization in oncology. In this study, Dox was entrapped into PEG-PLGA Nanoparticles, cardiotoxicity of Dox or PEG-PLGA-Dox was investigated in rats. Materials and methods :PEG-PLGA-Dox was prepared via modified single emulsion method. Its characterization including size, Drug loading capacity (DLC), entrapment efficiency (EE) were estimated. The cardiotoxicity of PEG-PLGA-Dox was assessed on SD rats via echocardiography and biochemical indicators compare to free Dox and physical sodium. Results:The average diameter of PEG-PLGA-Dox is around 200 nm, with DLC about 10%.After administered PEG-PLGA-Dox, the ratio of heart weight to body weight decreased not as significant as Dox group, level of serum parameters and echocardiography parameter also decreased little compared to the Dox group. Conclusions:After entrapped into PEG-PLGA nanoparticle, Dox-induced cardiotoxicity was reduced significantly.

Bridging cancer biology and the patients' needs with nanotechnology-based approaches

Cancer remains as stressful condition and a leading cause of death in the western world. Actual cornerstone treatments of cancer disease rest as an elusive alternative, offering limited efficacy with extensive secondary effects as a result of severe cytotoxic effects in healthy tissues. The advent of nanotechnology brought the promise to revolutionize many fields including oncology, proposing advanced systems for cancer treatment. Drug delivery systems rest among the most successful examples of nanotechnology. Throughout time they have been able to evolve as a function of an increased understanding from cancer biology and the tumor microenvironment. Marketing of Doxil® unleashed a remarkable impulse in the development of drug delivery systems. Since then, several nanocarriers have been introduced, with aspirations to overrule previous technologies, demonstrating increased therapeutic efficacy besides decreased toxicity. Spatial and temporal targeting to cancer cells has been explored, as well as the use of drug combinations co-encapsulated in the same particle as a mean to take advantage of synergistic interactions in vivo. Importantly, targeted delivery of siRNA for gene silencing therapy has made its way to the clinic for a "first in man" trial using lipid-polymeric-based particles. Focusing in state-of-the-art technology, this review will provide an insightful vision on nanotechnology-based strategies for cancer treatment, approaching them from a tumor biology-driven perspective, since their early EPR-based dawn to the ones that have truly the potential to address unmet medical needs in the field of oncology, upon targeting key cell subpopulations from the tumor microenvironment.

Monitoring tumor response with radiolabeled nucleoside analogs in a hepatoma-bearing mouse model early after doxisome(®) treatment

PURPOSE

This study aims to demonstrate that 3'-deoxy-3'-(18)F-fluorothymidine ((18)F-FLT) positron emission tomography (PET) is a promising modality for noninvasively monitoring the therapeutic efficacy of Doxisome(®) in a subcutaneous hepatoma mouse model.

PROCEDURES

Male BALB/c nu/nu mice were inoculated with HepG2 hepatoma xenograft in the right flank. Doxisome(®) (5 mg/kg, three times a week for 2 weeks) was intravenously administrated for treatment. (18)F-FLT-microPET, biodistribution studies, and immunohistochemistry of Ki-67 were performed.

RESULTS

A significant difference (p < 0.05) in tumor volume was observed on day 5 between treated and control groups. The tumor-to-muscle ratio derived from (18)F-FLT-PET and (123)I-ICdR-microSPECT images of Doxisome(®)-treated mice dropped from 12.55 ± 0.76 to 3.81 ± 0.31 and from 2.48 ± 0.42 to 1.59 ± 0.08 after a three-dose treatment, respectively, while that of the control group remained steady. The retarded proliferation rate of treated xenograft was confirmed by Ki-67 immunohistochemistry staining.

CONCLUSIONS

This study clearly demonstrated that Doxisome(®) is an effective anti-cancer drug against the growth of HepG2 hepatoma and that (18)F-FLT-PET could provide early information of tumor response during treatment.

Nanoparticles containing insoluble drug for cancer therapy

Nanoparticle drug formulations have been extensively researched and developed in the field of drug delivery as a means to efficiently deliver insoluble drugs to tumor cells. By mechanisms of the enhanced permeability and retention effect, nanoparticle drug formulations are capable of greatly enhancing the safety, pharmacokinetic profiles and bioavailability of the administered treatment. Here, the progress of various nanoparticle formulations in both research and clinical applications is detailed with a focus on the development of drug/gene delivery systems. Specifically, the unique advantages and disadvantages of polymeric nanoparticles, liposomes, solid lipid nanoparticles, nanocrystals and lipid-coated nanoparticles for targeted drug delivery will be investigated in detail.

Doxorubicin-antioxidant co-drugs

Doxorubicin-antioxidant multitarget compounds 6 and 7 were obtained by combining doxorubicin (DOX) with caffeic and ferulic acids through an ester linkage at C-14. The products were studied in in vitro models of cardiomyocytes and breast cancer cells, characterized by different degrees of resistance to DOX, due to different expressions of ATP binding cassette (ABC) transporters. Compound 7 was found to be less toxic than DOX in cardiomyocytes and to display the same possibly higher toxicity against the resistant breast cancer cells. This result shows that appropriate DOX-antioxidant co-drugs can limit the onset of cardiac damage, a significant side-effect of DOX, without impairing the antitumor activity of the parent antibiotic.

Comparative cardiac toxicity of anthracyclines in vitro and in vivo in the mouse

Purpose

The antineoplastic efficacy of anthracyclines is limited by their cardiac toxicity. In this study, we evaluated the toxicity of doxorubicin, non-pegylated liposomal-delivered doxorubicin, and epirubicin in HL-1 adult cardiomyocytes in culture as well as in the mouse in vivo.

Methods

The cardiomyocytes were incubated with the three anthracyclines (1 µM) to assess reactive oxygen generation, DNA damage and apoptotic cell death. CF-1 mice (10/group) received doxorubicin, epirubicin or non-pegylated liposomal-doxorubicin (10 mg/kg) and cardiac function was monitored by Doppler echocardiography to measure left ventricular ejection fraction (LVEF), heart rate (HR) and cardiac output (CO) both prior to and 10 days after drug treatment.

Results

In HL-1 cells, non-pegylated liposomal-doxorubicin generated significantly less reactive oxygen species (ROS), as well as less DNA damage and apoptosis activation when compared with doxorubicin and epirubicin. Cultured breast tumor cells showed similar sensitivity to the three anthracyclines. In the healthy mouse, non-pegylated liposomal doxorubicin showed a minimal and non-significant decrease in LVEF with no change in HR or CO, compared to doxorubicin and epirubicin.

Conclusion

This study provides evidence for reduced cardiac toxicity of non-pegylated-liposomal doxorubicin characterized by attenuation of ROS generation, DNA damage and apoptosis in comparison to epirubicin and doxorubicin.

Oxidative stress, redox signaling, and metal chelation in anthracycline cardiotoxicity and pharmacological cardioprotection

SIGNIFICANCE

Anthracyclines (doxorubicin, daunorubicin, or epirubicin) rank among the most effective anticancer drugs, but their clinical usefulness is hampered by the risk of cardiotoxicity. The most feared are the chronic forms of cardiotoxicity, characterized by irreversible cardiac damage and congestive heart failure. Although the pathogenesis of anthracycline cardiotoxicity seems to be complex, the pivotal role has been traditionally attributed to the iron-mediated formation of reactive oxygen species (ROS). In clinics, the bisdioxopiperazine agent dexrazoxane (ICRF-187) reduces the risk of anthracycline cardiotoxicity without a significant effect on response to chemotherapy. The prevailing concept describes dexrazoxane as a prodrug undergoing bioactivation to an iron-chelating agent ADR-925, which may inhibit anthracycline-induced ROS formation and oxidative damage to cardiomyocytes.

RECENT ADVANCES

A considerable body of evidence points to mitochondria as the key targets for anthracycline cardiotoxicity, and therefore it could be also crucial for effective cardioprotection. Numerous antioxidants and several iron chelators have been tested in vitro and in vivo with variable outcomes. None of these compounds have matched or even surpassed the effectiveness of dexrazoxane in chronic anthracycline cardiotoxicity settings, despite being stronger chelators and/or antioxidants.

CRITICAL ISSUES

The interpretation of many findings is complicated by the heterogeneity of experimental models and frequent employment of acute high-dose treatments with limited translatability to clinical practice.

FUTURE DIRECTIONS

Dexrazoxane may be the key to the enigma of anthracycline cardiotoxicity, and therefore it warrants further investigation, including the search for alternative/complementary modes of cardioprotective action beyond simple iron chelation.

Safety and efficacy of metronomic non-pegylated liposomal encapsulated doxorubicin in heavily pretreated advanced breast cancer patients

PURPOSE

Metronomic administration of the same chemotherapy agents (lower doses with closer intervals) may optimize their antiangiogenic properties. The aim of our study was to determine the efficacy and safety of a metronomic regimen based in non-pegylated liposomal doxorubicin (NPLD) in advanced breast cancer patients.

METHODS

Clinical records of patients with pretreated advanced breast cancer and who were treated with the Metronomic-Cooper-type regimen consisting of weekly fixed doses of NPLD (30 mg IV) plus 5-Fluorouracil (5-FU) (500 mg IV) plus vincristine (0.25 mg IV) and daily oral cyclophosphamide (50 mg) plus prednisone (20 mg) were reviewed.

RESULTS

In 84 pretreated patients, a tumor response was observed in 38 patients (45 %); stable disease was observed in 23 patients (27 %). Median progression-free survival (PFS) time to progression was 8.4 months and median overall survival (OS) was 21 months. The most common grade 2-3 hematologic adverse event was neutropenia, which was observed in 47 patients (56 %). Febrile neutropenia was observed in 10 patients (12 %). The most common non-hematologic adverse events were asthenia and mucositis which were observed in 60 patients (71 %) and 26 patients (31 %), respectively. Three patients (4 %) experienced an asymptomatic decline of the left ventricular ejection fraction.

CONCLUSIONS

NPLD-based metronomic regimen was effective and safe in pretreated advanced breast cancer patients. It could be considered as an appealing option to treat patients previously exposed to anthracyclines.

How circulating tumor cells escape from multidrug resistance: translating molecular mechanisms in metastatic breast cancer treatment

Resistance to anthracyclines is responsible for treatment failure in most patients with metastatic breast cancer. According to recent studies, the expression of specific drug transporters (MRPs) on circulating tumor cells is predictive of prognosis in different cancer types. We observed that patients whose circulating tumor cells expressed MRP1 and MRP2, two drug-export pumps responsible for anthracyclines efflux, who received conventional anthracyclines had a significantly shorter time to progression compared with patients sharing same characteristics who received non pegylated liposomal doxorubicin (P < 0.005). These results may highlight a new appealing role of the liposomal doxorubicin formulation, not only because of its reduced cardiac toxicity but especially referring to its theoretical efficacy in anthracycline-resistant breast cancer patients.

Photothermal-chemotherapy with doxorubicin-loaded hollow gold nanospheres: A platform for near-infrared light-trigged drug release

Photothermal ablation (PTA) is an emerging technique that uses near-infrared (NIR) laser light-generated heat to destroy tumor cells. However, complete eradication of tumor cells with PTA is difficult because of uneven heat distribution in the treatment volume. We hypothesized that combining PTA with chemotherapy using a single multifunctional nanoconstruct that mediates simultaneous photothermal cell killing and drug release (photothermal-chemotherapy) would result in enhanced antitumor activity and reduced toxicity compared to chemotherapy alone. Doxorubicin (DOX) was loaded to hollow gold nanospheres (HAuNS) coated with polyethylene glycol (PEG). The pharmacokinetics and biodistribution of both DOX and HAuNS in the resulting nanoconstruct, DOX@PEG-HAuNS having different DOX:PEG:HAuNS ratios, were evaluated using dual isotope labeling techniques. The antitumor activity of DOX@PEG-HAuNS with DOX:PEG:HAuNS weight ratio of 1:3:1 (NP3) in combination with NIR laser was studied in vitro and in vivo using human MDA-MB-231 breast cancer and A2780 ovarian cancer cells. In vitro, NP3 mediated PTA of both cancer cells and DOX release upon NIR laser treatment. In vivo, NP3 showed slower clearance in blood and greater accumulation in tumors than free DOX. NP3-plus-NIR laser demonstrated greater antitumor activity than free DOX, NP3, or liposomal DOX. Moreover, NP3 displayed significantly decreased systemic toxicity compared to free DOX or liposomal DOX. Enhanced antitumor effect with NP3-plus-laser can be attributed to both the cytotoxic effect of DOX released from NP3 and the photothermal effect mediated by HAuNS. Slow release of DOX from NP3 in normal tissues contributed to reduced systemic toxicity. Photothermal-chemotherapy exemplified by a single-agent nanoconstruct NP3 is a promising approach to anticancer therapy.

Switching of Self-Assembly in a Peptide Nanostructure with a Specific Enzyme

Peptide self-assembly has been shown to be a useful tool for the preparation of bioactive nanostructures, and recent work has demonstrated their potential as therapies for regenerative medicine. In principle, one route to make these nanostructures more biomimetic would be to incorporate in their molecular design the capacity for biological sensing. We report here on the use of a reversible enzymatic trigger to control the assembly and disassembly of peptide amphiphile (PA) nanostructures. The PA used in these studies contained a consensus substrate sequence specific to protein kinase A (PKA), a biological enzyme important for intracellular signaling that has also been shown to be an extracellular cancer biomarker. Upon treatment with PKA, this PA molecule becomes phosphorylated causing the high aspect-ratio filamentous PA nanostructures to disassemble. Treatment with an enzyme to cleave the phosphate group results in reformation of the filamentous nanostructures. We also show that disassembly in the presence of PKA allows the enzyme-triggered release of an encapsulated cancer drug. In addition, these drug-loaded nanostructures were found to induce preferential cytotoxicity in a cancer cell line that is known to secrete high levels of PKA. This ability to control nanostructure through an enzymatic switch could allow for the preparation of highly sophisticated and biomimetic materials that incorporate a biological sensing capability to enable therapeutic specificity.

Reduction-sensitive liposomes from a multifunctional lipid conjugate and natural phospholipids: reduction and release kinetics and cellular uptake

The development of targeted and triggerable delivery systems is of high relevance for anticancer therapies. We report here on reduction-sensitive liposomes composed of a novel multifunctional lipidlike conjugate, containing a disulfide bond and a biotin moiety, and natural phospholipids. The incorporation of the disulfide conjugate into vesicles and the kinetics of their reduction were studied using dansyl-labeled conjugate 1 in using the dansyl fluorescence environmental sensitivity and the Förster resonance energy transfer from dansyl to rhodamine-labeled phospholipids. Cleavage of the disulfide bridge (e.g., by tris(2-carboxyethyl)phosphine (TCEP), dithiothreitol (DTT), l-cysteine, or glutathione (GSH)) removed the hydrophilic headgroup of the conjugate and thus changed the membrane organization leading to the release of entrapped molecules. Upon nonspecific uptake of vesicles by macrophages, calcein release from reduction-sensitive liposomes consisting of the disulfide conjugate and phospholipids was more efficient than from reduction-insensitive liposomes composed only of phospholipids. The binding of streptavidin to the conjugates did not interfere with either the subsequent reduction of the disulfide bond of the conjugate or the release of entrapped molecules. Breast cancer cell line BT-474, overexpressing the HER2 receptor, showed a high uptake of the reduction-sensitive doxorubicin-loaded liposomes functionalized with the biotin-tagged anti-HER2 antibody. The release of the entrapped cargo inside the cells was observed, implying the potential of using our system for active targeting and delivery.

Liposome-encapsulated doxorubicin reverses drug resistance by inhibiting P-glycoprotein in human cancer cells

The most frequent drawback of doxorubicin is the onset of drug resistance, due to the active efflux through P-glycoprotein (Pgp). Recently formulations of liposome-encapsulated doxorubicin have been approved for the treatment of tumors resistant to conventional anticancer drugs, but the molecular basis of their efficacy is not known. To clarify by which mechanisms the liposome-encapsulated doxorubicin is effective in drug-resistant cancer cells, we analyzed the effects of doxorubicin and doxorubicin-containing anionic liposomal nanoparticles ("Lipodox") on the drug-sensitive human colon cancer HT29 cells and on the drug-resistant HT29-dx cells. Interestingly, we did not detect any difference in drug accumulation and toxicity between free doxorubicin and Lipodox in HT29 cells, but Lipodox was significantly more effective than doxorubicin in HT29-dx cells, which are rich in Pgp. This effect was lost in HT29-dx cells silenced for Pgp and acquired by HT29 cells overexpressing Pgp. Lipodox was less extruded by Pgp than doxorubicin and inhibited the pump activity. This inhibition was due to a double effect: the liposome shell per se altered the composition of rafts in resistant cells and decreased the lipid raft-associated amount of Pgp, and the doxorubicin-loaded liposomes directly impaired transport and ATPase activity of Pgp. The efficacy of Lipodox was not increased by verapamil and cyclosporin A and was underwent interference by colchicine. Binding assays revealed that Lipodox competed with verapamil for binding Pgp and hampered the interaction of colchicine with this transporter. Site-directed mutagenesis experiments demonstrated that glycine 185 is a critical residue for the direct inhibitory effect of Lipodox on Pgp. Our work describes novel properties of liposomal doxorubicin, investigating the molecular bases that make this formulation an inhibitor of Pgp activity and a vehicle particularly indicated against drug-resistant tumors.

Anthracycline-associated cardiotoxicity in survivors of childhood cancer

Anthracycline chemotherapeutic agents are widely used to treat childhood cancers, helping to create an increasing population of childhood cancer survivors. Cardiac complications can occur years after exposure to anthracyclines and are a leading cause of noncancerous morbidity and mortality in this population. The mechanism of its cardiotoxicity is not completely known, although oxidative stress is believed to play a significant role. This pathway and other nonoxidative mechanisms are reviewed. Several risk factors such as age, dose, female gender, and concomitant radiation therapy are known, but the relative risks of many comorbidities such as diabetes and hypertension are not well studied. No standard, evidence-based guidelines for appropriate screening methods to detect cardiotoxicity exist. Periodic imaging with echocardiography or radionuclide angiography is appropriately recommended for long-term survivors but is of limited use during therapy. Biomarkers such as cardiac troponins and brain natriuretic peptides may aid in detecting cardiotoxicity. Studies investigating the use of agents such as angiotensin-converting enzyme (ACE)-inhibitors and beta-blockers to treat anthracycline cardiotoxicity have shown promise, but more data are needed. Structural analogs such as epirubicin were developed to minimize cardiotoxicity but have not sufficiently reduced it. Liposome-encapsulated anthracyclines have shown a considerable decrease of cardiotoxicity in adults without sacrificing efficacy, but the data related to children are sparse. The only agent proven to be cardioprotective is the iron chelator, dexrazoxane. Studies have shown that dexrazoxane is safe and significantly reduces the incidence of cardiotoxicity. Dexrazoxane should be considered for pediatric oncology protocols using anthracyclines that include longitudinal assessment.

Cardiovascular effects in childhood cancer survivors treated with anthracyclines

Anthracyclines are commonly used to treat childhood leukemias and lymphomas, as well as other malignancies, leading to a growing population of long-term childhood cancer survivors. However, their use is limited by cardiotoxicity, increasing survivors' vulnerability to treatment-related complications that can markedly affect their quality of life. Survivors are more likely to suffer from heart failure, coronary artery disease, and cerebrovascular accidents compared to the general population. The specific mechanisms of anthracycline cardiotoxicity are complex and remain unclear. Hence, determining the factors that may increase susceptibility to cardiotoxicity is of great importance, as is monitoring patients during and after treatment. Additionally, treatment and prevention options, such as limiting cumulative dosage, liposomal anthracyclines, and dexrazoxane, continue to be explored. Here, we review the cardiovascular complications associated with the use of anthracyclines in treating malignancies in children and discuss methods for preventing, screening, and treating such complications in childhood cancer survivors.

[Non-pegylated doxorubicin (Myocet®) as the less cardiotoxic alternative of free doxorubicin]

Anthracyclines have probably been considered to be the most active agents for the treatment of breast cancer and some other solid tumors and hematological malignancies. However, they are associated with dose-related cardiotoxicity, which can lead to progressive myocardial damage and limits the maximal cumulative dose that can be given. This review focuses on the non-pegylated liposome-encapsulated doxorubicin (Myocet®), which has been developed to increase the therapeutic index of free doxorubicin. The encapsulation of doxorubicin within a macromolecular vector, such as a liposome ("nanoparticle based drug delivery system") reduces its distribution volume, diminishing its toxicity for healthy tissues while increasing the concentration within the neoplastic tissue. The most common adverse event is neutropenia, which is consistent with previous experience with free doxorubicin. Available evidence suggests that the incidence of hematological toxicity is lower than with conventional doxorubicin. Myocet® both as a single agent and in combination is effective and safe with an associated reduction in incidence and severity of cardiac events. Nagykálnai T. Non-pegylated doxorubicin (Myocet®) as the less cardiotoxic alternative of free doxorubicin.

The application of exosomes as a nanoscale cancer vaccine

Cancer is a leading cause of death globally, and it is predicted and projected to continue rising as life expectancy increases. Although patient survival rates for some forms of cancers are high due to clinical advances in treatment protocols, the search for effective cancer vaccines remains the ultimate Rosetta Stone in oncology. Cervarix^®, Gardasil^®, and hepatitis B vaccines are currently employed in preventing certain forms of viral cancers. However, they are, strictly speaking, not ‘true’ cancer vaccines as they are prophylactic rather than therapeutic, are only effective against the oncogenic viruses, and do not kill the actual cancer cells. On April 2010, a new prostate cancer vaccine Provenge^® (sipuleucel-T) was approved by the US FDA, and it is the first approved therapeutic vaccine that utilizes antigen-presenting cell technology involving dendritic cells in cancer immunotherapy. Recent evidence suggests that the use of nanoscale particles like exosomes in immunotherapy could form a viable basis for the development of novel cancer vaccines, via antigen-presenting cell technology, to prime the immune system to recognize and kill cancer cells. Coupled with nanotechnology, engineered exosomes are emerging as new and novel avenues for cancer vaccine development. Here, we review the current knowledge pertaining to exosome technology in immunotherapy and also seek to address the challenges and future directions associated with it, in hopes of bringing this exciting application a step closer toward an effective clinical reality.