Effectiveness of liposomal paclitaxel against MCF-7 breast cancer cells

Paclitaxel is an effective chemotherapeutic agent that is widely used for the treatment of several cancers, including breast, ovarian, and non-small-cell lung cancer. Due to its high lipophilicity, paclitaxel is difficult to administer and requires solubilization with Cremophor EL (polyethoxylated castor oil) and ethanol, which often lead to adverse side effects, including life-threatening anaphylaxis. Incorporation of paclitaxel in dimyristoylphosphatidylcholine:dimyristoylphosphatidylglycerol (DPPC:DMPG) liposomes can facilitate its delivery to cancer cells and eliminate the adverse reactions associated with the Cremophor EL vehicle. Accordingly, the effectiveness of liposomal paclitaxel on MCF-7 breast cancer cells was examined. The results from this study showed that (i) the lipid components of the liposomal formulation were nontoxic, (ii) the cytotoxic effects of liposomal paclitaxel were improved when compared with those seen with conventional paclitaxel, and (iii) the intracellular paclitaxel levels were higher in MCF-7 cells treated with the liposomal paclitaxel formulation. The results of these studies showed that delivery of paclitaxel as a liposomal formulation could be a promising strategy for enhancing its chemotherapeutic effects.     

Drug release rate influences the pharmacokinetics, biodistribution, therapeutic activity, and toxicity of pegylated liposomal doxorubicin formulations in murine breast cancer

The pharmacokinetics (PK), biodistribution (BD), and therapeutic activity of pegylated liposomal doxorubicin formulations with different drug release rates were studied in an orthotopic 4T1 murine mammary carcinoma model. The focus of these experiments was to study the effects of different release rates on the accumulation of liposomal lipid and doxorubicin (DXR) into the tumor and cutaneous tissues of mice (skin and paws). These tissues were chosen because the clinical formulation of pegylated liposomal doxorubicin (Caelyx)/Doxi) causes mucocutaneous reactions such as palmar-plantar erythrodysesthesia (PPE). Liposomes with different doxorubicin (DXR) leakage rates were prepared by altering liposome fluidity through changing the fatty acyl chain length and/or degree of saturation of the phosphatidylcholine component of the liposome. Liposomes with fast, intermediate, and slow rates of drug release were studied. The plasma PK of the liposomal lipid was similar for all formulations, while the plasma PK of the DXR component was dependent on the liposome formulation. Liposomal lipid accumulated to similar levels in tumor and cutaneous tissues for all three formulations tested, while the liposomes with the slowest rates of DXR release produced the highest DXR concentrations in both cutaneous tissues and in tumor. Liposomes with the fastest drug release rates resulted in low DXR concentrations in cutaneous tissues and tumor. The formulation with intermediate release rates produced unexpected toxicity that was not related to the lipid content of the formulation. The liposomes with the slowest rate of drug leakage had the best therapeutic activity of the formulations tested.     

Method for rapid separation of liposome-associated doxorubicin from free doxorubicin in plasma

To understand and predict the efficacy and/or toxicity of liposomal drugs in vivo, it is essential to have rapid, reliable methods of separating and quantitating both the free and the liposomal forms of the drug. A method using solid-phase extraction chromatography columns was developed to separate and quantitate unencapsulated doxorubicin and liposome-associated doxorubicin in plasma following the intravenous injection of liposomal doxorubicin. The method facilitated the recovery and quantitation of free and liposomal drug. The separation and recovery of doxorubicin were linear across the entire range of possible mixtures (0 to 100%) of the two forms of the drug in plasma. Free drug and liposomal drug were readily separated for liposomal doxorubicin systems varying in size (0.1-1.0 microns) and lipid composition (egg yolk phosphatidylcholine/cholesterol and distearylphosphatidylcholine/cholesterol). The method is rapid and allows for multiple samples to be processed simultaneously.     

The Use of Transmembrane pH Gradient-Driven Drug Encapsulation in the Pharmacodynamic Evaluation of Liposomal Doxorubicin

Abstract

The toxicity and efficacy properties of doxorubicin entrapped inside liposomes are sensitive to the physical characteristics of the vesicle carrier system. Studies addressing such relationships must use preparation procedures with the ability to independently vary vesicle size, lipid composition and drug to lipid ratio while maintaining high trapping efficiencies. The transmembrane pH gradient-driven encapsulation technique allows such liposomal doxorubicin formulations to be prepared. Pharmacokinetic, toxicology and antitumour studies with these systems have revealed several important relationships between liposome physical properties and biological activity. The acute toxicity of liposomal doxorubicin is related primarily to the ability of the liposomes to retain doxorubicin after administration. Including cholesterol and increasing the degree of acyl chain saturation of the phospholipid component in the liposomes significantly decreases drug leakage in the blood, reduces cardiac tissue accumulation of doxorubicin and results in increased LD₅₀ values. In contrast, the efficacy of liposomal doxorubicin is most influenced by liposome size. Specifically, liposomes with a diameter of approximately 100 nm or less exhibit enhanced circulation lifetimes and antitumour activity. While these relationships appear to be rather straightforward, there exist anomalies which suggest that a more thorough evaluation of liposomal doxorubicin pharmacokinetics may be required in order to fully understand its mechanism of action. A key feature in this regard is the ability to differentiate between non-encapsulated and liposome encapsulated doxorubicin pools in the circulation as well as in tumours and normal tissues. This represents a major challenge that must be addressed if significant advances in the design of more effective liposomal doxorubicin formulations are to be achieved.     

Pharmacokinetics,Brain Delivery,and Efficacy in Brain Tumor-Bearing Mice of Glutathione Pegylated Liposomal Doxorubicin (2B3-101)

Brain cancer is a devastating disease affecting many people worldwide. Effective treatment with chemotherapeutics is limited due to the presence of the blood-brain barrier (BBB) that tightly regulates the diffusion of endogenous molecules but also xenobiotics. Glutathione pegylated liposomal doxorubicin (2B3-101) is being developed as a new treatment option for patients with brain cancer. It is based on already marketed pegylated liposomal doxorubicin (Doxil®/Caelyx®), with an additional glutathione coating that safely enhances drug delivery across the BBB.Uptake of 2B3-101 by human brain capillary endothelial cells in vitro was time-, concentration- and temperature-dependent, while pegylated liposomal doxorubicin mainly remained bound to the cells. In vivo, 2B3-101 and pegylated liposomal doxorubicin had a comparable plasma exposure in mice, yet brain retention 4 days after administration was higher for 2B3-101. 2B3-101 was overall well tolerated by athymic FVB mice with experimental human glioblastoma (luciferase transfected U87MG). In 2 independent experiments a strong inhibition of brain tumor growth was observed for 2B3-101 as measured by bioluminescence intensity. The effect of weekly administration of 5 mg/kg 2B3-101 was more pronounced compared to pegylated liposomal doxorubicin (p<0.05) and saline (p<0.01). Two out of 9 animals receiving 2B3-101 showed a complete tumor regression. Twice-weekly injections of 5 mg/kg 2B3-101 again had a significant effect in inhibiting brain tumor growth (p<0.001) compared to pegylated liposomal doxorubicin and saline, and a complete regression was observed in 1 animal treated with 2B3-101. In addition, twice-weekly dosing of 2B3-101 significantly increased the median survival time by 38.5% (p<0.001) and 16.1% (p<0.05) compared to saline and pegylated liposomal doxorubicin, respectively.Overall, these data demonstrate that glutathione pegylated liposomal doxorubicin enhances the effective delivery of doxorubicin to brain tumors and could become a promising new therapeutic option for the treatment of brain malignancies.     

Strategies for Optimizing Liposomal Doxorubicin

Abstract

Liposome encapsulation of doxorubicin can dramatically alter its biological activity, resulting in decreased toxicity and equivalent or increased antitumor potency. Since the physical characteristics of the liposome carrier system (size, lipid composition, and lipid dose) can have profound effects on the pharmacologic properties of vesicles administered intravenously, it may be expected that the therapeutic activity of liposomal doxorubicin will be sensitive to these properties. To determine the influence of these variables on the toxicity and efficacy properties of liposomal doxorubicin, transmembrane pH gradient-dependent active encapsulation techniques have been utilized to generate liposomal doxorubicin preparations in which the vesicle size, lipid composition, and drug to lipid ratio can be independently varied. these studies indicate that the toxicity of liposomal doxorubicin is related to the stability of the preparation in the circulation. This property is dictated primarily by vesicle lipid composition, although the drug to lipid ratio can also exert an influence. In contrast, the antitumor activity of liposomal doxorubicin appears most sensitive to the size of the vesicle system. Specifically, antitumor drug potency increases as the vesicle size is decreased. these studies demonstrate that manipulating the physical characteristics of liposomal anticancer pharmaceuticals can lead to preparations with optimized therapeutic activity.     

多柔比星脂质体单药和联合洛铂方案治疗复发卵巢癌的临床研究

目的:评价盐酸多柔比星脂质体单药(PLD)与盐酸多柔比星脂质体联合洛铂治疗复发性卵巢癌的安全性和临床疗效。方法:收集2012年4月至2015年10月我科收治的31例复发晚期上皮性卵巢癌患者,根据患者是否存在铂类耐药分为多柔比星组(单药组)15例及多柔比星+洛铂组(对照组)16例。单药组给盐酸多柔比星脂质体50 mg/m~2,静滴;对照组给盐酸多柔比星脂质体20-30 mg/m~2,洛铂30-50 mg/m~2,静脉滴注,两组每21-28天重复一次,观察和比较两组的临床疗效和毒性反应的发生情况。结果:所有患者完成3-8周期,客观有效率(ORR)为38.7%。单药组为33.3%,对照组为占43.8%,两组ORR比较差异无统计学意义(P=0.411)。单药组骨髓抑制的毒副作用较对照组发生率显著升高高(P=0.019),两组其他毒副反应的发生情况比较差异无统计学意义(P0.05)。单药组和对照组中位生存时间(MST)分别为10个月(95%CI:1.242-18.758)、18个月(95%CI:8.261-27.739),中位无进展生存期(PFS)分别为7个月(95%CI:2.210-13.797)、13个月(95%CI:4.368-21.632),两组MST、PFS比较差异均无统计学意义(P0.277)。结论:聚乙二醇脂质体阿霉素单体或聚乙二醇脂质体阿霉素联合洛铂治疗复发性卵巢癌的疗效相当,而聚乙二醇脂质体阿霉素单体的安全性更高。     

Liposomal daunorubicin overcomes drug resistance in human breast,ovarian and lung carcinoma cells

Multi-drug resistance due in part to membrane pumps such as P-glycoprotein (Pgp) is a major clinical problem in human cancers. We tested the ability of liposomally-encapsulated daunorubicin (DR) to overcome resistance to this drug. A widely used breast carcinoma cell line originally selected for resistance in doxorubicin (MCF7ADR) was 4-fold resistant to DR compared to the parent MCF7 cells (IC50 79 nM vs. 20 nM). Ovarian carcinoma cells (SKOV3) were made resistant by retroviral transduction of MDR1 cDNA and selection in vinblastine. The resulting SKOV3MGP1 cells were 130-fold resistant to DR compared to parent cells (IC50 5700 nM vs. 44 nM). Small-cell lung carcinoma cells (H69VP) originally selected for resistance to etoposide were 6-fold resistant to DR compared to H69 parent cells (IC50 180 nM vs. 30 nM). In all three cases, encapsulation of DR in liposomes as Daunoxome (Gilead) did not change the IC50 of parent cells relative to free DR. However, liposomal DR overcame resistance in MCF7ADR breast carcinoma cells (IC50 20 nM), SKOV3MGP1 ovarian carcinoma cells (IC50 237 nM) and H69VP small-cell lung carcinoma cells (IC50 27 nM). Empty liposomes did not affect the IC50 for free DR in the three resistant cell lines, nor did empty liposomes affect the IC50 for other drugs that are part of the multi-drug resistance phenotype (etoposide, vincristine) in lung carcinoma cells. These data indicate the possible value of liposomal DR in overcoming Pgp-mediated drug resistance in human cancer.     

Clinical Studies with Liposomal Doxorubicin

Abstract

To present data on a continuing phase I study of liposomal doxorubicin at this time may seem like a giant leap backwards. Liposomally encapsulated doxorubicin has been available for clinical use for some years. Phase I studies have been completed, and phase II studies have been conducted in patients with breast cancer (1,2). Two major obstacles to the commercial exploitation of drugs encapsulated in liposomes were evident. the first was to find a preparation that could be given safely to humans. the second was to develop a pharmaceutical preparation that could be commercially exploited by fulfilling the requirements for manufacture and sale as a drug. the first of these problems was solved a number of years ago, but only recently have we had preparations that fulfilled the second requirement. Two of these have entered clinical trials at Roswell Park Memorial Institute (RPMI). One of these, the liposomally encapsulated muramyl tripeptide derivative (MTP-PE), has been presented previously (3,4). Accordingly, in this paper we will focus on our studies of liposomally encapsulated doxorubicin.     

Characterization of liposomal systems containing doxorubicin entrapped in response to pH gradients

Studies from this laboratory (Mayer et al. (1986) Biochim. Biophys. Acta 857, 123-126) have shown that doxorubicin can be accumulated into liposomal systems in response to transmembrane pH gradients (inside acidic). Here, detailed characterizations of the drug uptake and retention properties of these systems are performed. It is shown that for egg phosphatidylcholine (EPC) vesicles (mean diameter of 170 nm) exhibiting transmembrane pH gradients (inside acidic) doxorubicin can be sequestered into the interior aqueous compartment to achieve drug trapping efficiencies in excess of 98% and drug-to-lipid ratios of 0.36:1 (mol/mol). Drug-to-lipid ratios as high as 1.7:1 (mol/mol) can be obtained under appropriate conditions. Lower drug-to-lipid ratios are required to achieve trapping efficiencies in excess of 98% for smaller (less than or equal to 100 nm) systems. Doxorubicin trapping efficiencies and uptake capacities are related ito maintenance of the transmembrane pH gradient during encapsulation as well as the interaction between doxorubicin and entrapped citrate. This citrate-doxorubicin interaction increases drug uptake levels above those predicted by the Henderson-Hasselbach relationship. Increased drug-to-lipid ratios and trapping efficiencies are observed for higher interior buffering capacities. Retention of a large transmembrane pH gradient (greater than 2 units) after entrapment reduces the rate of drug leakage from the liposomes. For example, EPC/cholesterol (55:45, mol/mol) liposomal doxorubicin systems can be achieved which released less than 5% of encapsulated doxorubicin (drug-to-lipid molar ratio = 0.33:1) over 24 h at 37 degrees C. This pH gradient-dependent encapsulation technique is extremely versatile, and well characterized liposomal doxorubicin preparations can be generated to exhibit a wide range of properties such as vesicle size, lipid composition, drug-to-lipid ratio and drug release kinetics. This entrapment procedure therefore appears well suited for use in therapeutic applications. Finally, a rapid colorimetric test for determining the amount of unencapsulated doxorubicin in liposomal systems is described.     

In vitro cytotoxic study of immunoliposomal doxorubicin targeted to human CD34(+) leukemic cells

The expression of CD34 antigen in acute myelogenous leukemias is considered an unfavourable prognosis marker for response to anticancer drugs and duration of remission. This study investigated the applicability of long-circulating immunoliposomes loaded with doxorubicin targeted to CD34 antigen present on MDR(+) human myelogenous leukemia KG-1a cell line. Immunoliposomal doxorubicin showed a higher cytotoxicity against KG-1a cells than non-targeted liposomal doxorubicin, but it did not improve over that of free drug. Although no reversal of doxorubicin resistance was found to occur through its liposomal encapsulation, a therapeutic benefit can be obtained by the selective cytotoxicity observed. Endocytosis studies demonstrated that, after binding to CD34 antigen, the immunoliposomes are not internalized by the KG-1a cells and so the cytotoxic effect might be due to drug released into the space near the cell membrane. Thus, immunotargeting of liposomal doxorubicin to CD34(+) leukemic cells may only provide an ex vivo strategy for site-selective CD34(+) leukemia cell killing.     

Identification of novel therapeutic targets in microdissected clear cell ovarian cancers

Clear cell ovarian cancer is an epithelial ovarian cancer histotype that is less responsive to chemotherapy and carries poorer prognosis than serous and endometrioid histotypes. Despite this, patients with these tumors are treated in a similar fashion as all other ovarian cancers. Previous genomic analysis has suggested that clear cell cancers represent a unique tumor subtype. Here we generated the first whole genomic expression profiling using epithelial component of clear cell ovarian cancers and normal ovarian surface specimens isolated by laser capture microdissection. All the arrays were analyzed using BRB ArrayTools and PathwayStudio software to identify the signaling pathways. Identified pathways validated using serous, clear cell cancer cell lines and RNAi technology. In vivo validations carried out using an orthotopic mouse model and liposomal encapsulated siRNA. Patient-derived clear cell and serous ovarian tumors were grafted under the renal capsule of NOD-SCID mice to evaluate the therapeutic potential of the identified pathway. We identified major activated pathways in clear cells involving in hypoxic cell growth, angiogenesis, and glucose metabolism not seen in other histotypes. Knockdown of key genes in these pathways sensitized clear cell ovarian cancer cell lines to hypoxia/glucose deprivation. In vivo experiments using patient derived tumors demonstrate that clear cell tumors are exquisitely sensitive to antiangiogenesis therapy (i.e. sunitinib) compared with serous tumors. We generated a histotype specific, gene signature associated with clear cell ovarian cancer which identifies important activated pathways critical for their clinicopathologic characteristics. These results provide a rational basis for a radically different treatment for ovarian clear cell patients.     

Liposomes with entrapped doxorubicin exhibit extended blood residence times

The blood residence time of liposomes with entrapped doxorubicin is shown to be significantly longer than for identically prepared empty liposomes. Liposomal doxorubicin systems with a drug-to-lipid ratio of 0.2 (w/w) were administered at a dose of 100 mg lipid/kg. Both doxorubicin and liposomal lipid were quantified in order to assess in vivo stability and blood residence times. For empty vesicles composed of phosphatidylcholine (PC)/cholesterol (55:45, mole ratio) and sized through filters of 100 nm pore size, 15-25% of the administered lipid dose was recovered in the blood 24 h after i.v. injection. The percentage of the dose retained in the circulation at 24 h increased 2-3-fold when the liposomes contain entrapped doxorubicin. For 100 nm distearoyl PC/chol liposomal doxorubicin systems, as much as 80% of the injected dose of lipid and drug remain within the blood compartment 24 h after i.v. administration.     

Development of stealth liposome coencapsulating doxorubicin and fluoxetine

Stealth liposomes form an important subset of liposomes, demonstrating prolonged circulation half-life and improved safety in vivo. Caelyx? (liposomal doxorubicin; Merck & Co., Whitehouse Station, New Jersey, USA) is a successful example of the application of stealth liposomes in anticancer treatment. However, multidrug resistance (MDR) to chemotherapy still remains a critical problem, accounting for more than 90% of treatment failure in patients with advanced cancer. To circumvent MDR, fluoxetine and doxorubicin were tested in combination for synergistic activity in MCF-7 (human breast carcinoma) and MCF-7/adr (doxorubicin-resistant human breast carcinoma) cells using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell-viability assay. Coencapsulation of doxorubicin and fluoxetine, using an ammonium sulphate gradient, was investigated, and a factorial experiment was designed to determine the optimal drug-to-lipid (D/L) ratio for coencapsulation. Drug release from Dox-Flu-SL (stealth liposome coencapsulating doxorubicin and fluoxetine) under both in vitro and in vivo conditions was determined. In MCF-7 cells, synergism was demonstrated at specific doxorubicin:fluoxetine ratios of between 0.09 and 0.5 (molar ratio), while MCF/7/adr cells demonstrated synergism across all drug ratios. Coencapsulation of doxorubicin and fluoxetine (Dox-Flu-SL) was successfully achieved (optimal doxorubicin:fluoxetine:lipid molar ratio of 0.02:0.05:1), obtaining a mean concentration of 257 ± 12.1 and 513 ± 29.3 μM for doxorubicin and fluoxetine, respectively. Most important, Dox-Flu-SL demonstrated drug release in synergistic ratios in cell-culture media, accounting for the improved cytotoxicity of Dox-Flu-SL over liposomal doxorubicin (LD) in both MCF-7 and MCF-7/adr cells. Pharmacokinetic studies also revealed that Dox-Flu-SL effectively prolonged drug-circulation time and reduced tissue biodistribution. Dox-Flu-SL presents a promising anticancer formulation, capable of effective reversal of drug resistance, and may constitute a novel approach for cancer therapy.     

Pharmacokinetics,Biodistribution and Therapeutic Efficacy of Doxorubicin Encapsulated in Stealth® Liposomes (Doxil®)

Abstract

Doxil® (Stealth® liposomal doxorubicin HCl) Injection is doxorubicin HCl incorporated into long circulating liposomes that contain surface-grafted polyoxyethylene chains. These surface-grafted polymer chains reduce the interaction of the liposomes with the mononuclear phagocytic system, accounting for the long circulation and altered biodistribution of Stealth liposomes. They also reduce adhesion of the liposomes to cells, blood vessel walls and other surfaces and result in increased vascular permeability of Stealth liposomes compared to conventional liposomes of equal size. Efficacy studies in several tumor models, including human xenograft models, have demonstrated that Doxil is more effective than unencapsulated doxorubicin (Adriamycin) or doxorubicin encapsulated in non-coated conventional liposomes. Doxil exhibits altered plasma pharmacokinetics, with a longer plasma half-life, large AUC and markedly smaller volume of distribution than Adriamycin. Tissue levels of doxorubicin are generally lower in Doxil-treated animals than in animals that receive an equivalent dose of Adriamycin, and Doxil is less cardiotoxic, myelotoxic and nephrotoxic than Adriamycin. Phase I and II studies evaluating the efficacy of Doxil in AIDS-related Kaposi sarcoma have been encouraging, with evidence of increased delivery of drug to the lesions and an overall good response to therapy. The increased efficacy of Doxil is believed to be related to its increased extravasation through the leaky tumor vasculature and its accumulation in tumor tissue.     

Pegylated liposomal doxorubicin in the treatment of AIDS-related Kaposi's sarcoma

Kaposi's sarcoma is a vascular tumor of skin and viscera first described in 1872. Prior to the 1980s, this disease was rarely seen in the Western world, but was quite prevalent in Sub-Saharan African countries. Since the onset of the HIV pandemic in the 1980s, the incidence of Kaposi's sarcoma has increased markedly in Africa and continues to be a significant problem in association with AIDS in Western countries. Many therapies have been demonstrated to be effective in the treatment of HIV-related Kaposi's sarcoma, including alitretinoin gel, interferon alpha, and various forms of cytotoxic chemotherapy. Antiretroviral therapy combined with cytotoxic agents has yielded significantly greater efficacy than chemotherapy alone. However, as reviewed in this report, pegylated liposomal doxorubicin has been established as the treatment of choice for patients with AIDS-associated Kaposi's sarcoma in Western countries. Compelling preclinical and clinical evidence, reviewed herein, has demonstrated that the nanoparticle (pegylated liposome) delivery system of this formulation leads to greater tumor localization of doxorubicin and consequent improved efficacy, as well as reduced toxicity.     

New approaches to treatment of various cancers based on cytotoxic analogs of LHRH,somatostatin and bombesin

The development of targeted cytotoxic analogs of hypothalamic peptides for the therapy of various cancers is reviewed and various oncological studies on experimental tumors are summarized. Novel therapeutic modalities for breast, prostate and ovarian cancer consist of the use of targeted cytotoxic analogs of LH-RH containing doxorubicin (DOX) or 2-pyrrolino-DOX. The same radicals have been incorporated into cytotoxic analogs of somatostatin which can be also targeted to receptors for this peptide in prostatic, mammary, ovarian, renal and lung cancers, brain tumors and their metastases. A targeted cytotoxic analog of bombesin containing 2-pyrrolino-DOX has also been synthesized and successfully tried in experimental models of prostate cancer, small cell lung carcinoma and brain tumors. The development of these new classes of peptide analogs should lead to a more effective treatment for various cancers.     

A Synthetic Aptamer-Drug Adduct for Targeted Liver Cancer Therapy

AS1411 (previously known as AGRO100) is a 26 nucleotide guanine-rich DNA aptamer which forms a guanine quadruplex structure. AS1411 has shown promising utility as a treatment for cancers in Phase I and Phase II clinical trials without causing major side-effects. AS1411 inhibits tumor cell growth by binding to nucleolin which is aberrantly expressed on the cell membrane of many tumors. In this study, we utilized a simple technique to conjugate a widely-used chemotherapeutic agent, doxorubicin (Dox), to AS1411 to form a synthetic Drug-DNA Adduct (DDA), termed as AS1411-Dox. We demonstrate the utility of AS1411-Dox in the treatment of hepatocellular carcinoma (HCC) by evaluating the targeted delivery of Dox to Huh7 cells in vitro and in a murine xenograft model of HCC.     

Type of chemotherapy has substantial effects on the immune system in ovarian cancer

Chemotherapy induces a variety of immunological changes. Studying these effects can reveal opportunities for successful combining chemotherapy and immunotherapy. Immuno-chemotherapeutic combinations in ovarian cancer are currently not generating the anticipated positive effects. To date, only scattered and inconsistent information is available about the immune-induced changes by chemotherapy in ovarian cancer. In this study, we compared six common chemotherapeutics used in ovarian cancer patients (carboplatin, paclitaxel, pegylated liposomal doxorubicin, gemcitabine, carboplatin-paclitaxel and carboplatin-gemcitabine) and studied their effects on the immune system in an ovarian cancer mouse model. Mice received a single chemotherapy or vehicle injection 21 days after tumor inoculation with ID8-fluc cells. One week after therapy administration, we collected peritoneal washings for flow cytometry, serum for cytokine analysis with cytometric bead array and tumor biopsies for immunohistochemistry. Carboplatin-paclitaxel showed the most favorable profile with a decrease in immunosuppressive cells in the peritoneal cavity and an increase of interferon-gamma in serum. In contrast, carboplatin-gemcitabine seemed to promote a hostile immune environment with an increase in regulatory T-cells in tumor tissue and an increase of macrophage-inflammatory-protein-1-beta in the serum.     

Pros and cons of the liposome platform in cancer drug targeting

Coating of liposomes with polyethylene-glycol (PEG) by incorporation in the liposome bilayer of PEG-derivatized lipids results in inhibition of liposome uptake by the reticulo-endothelial system and significant prolongation of liposome residence time in the blood stream. Parallel developments in drug loading technology have improved the efficiency and stability of drug entrapment in liposomes, particularly with regard to cationic amphiphiles such as anthracyclines. An example of this new generation of liposomes is a formulation of pegylated liposomal doxorubicin known as Doxil or Caelyx, whose clinical pharmacokinetic profile is characterized by slow plasma clearance and small volume of distribution. A hallmark of these long-circulating liposomal drug carriers is their enhanced accumulation in tumors. The mechanism underlying this passive targeting effect is the phenomenon known as enhanced permeability and retention (EPR) which has been described in a broad variety of experimental tumor types. Further to the passive targeting effect, the liposome drug delivery platform offers the possibility of grafting tumor-specific ligands on the liposome membrane for active targeting to tumor cells, and potentially intracellular drug delivery. The pros and cons of the liposome platform in cancer targeting are discussed vis-à-vis nontargeted drugs, using as an example a liposome drug delivery system targeted to the folate receptor.