A phase II study evaluating the tolerability and efficacy of CAELYX (liposomal doxorubicin, Doxil) in the treatment of unresectable pancreatic carcinoma

siRNA-Encapsulated Biomimetic Liposomes Effectively Inhibit Tumor Cells' Hexosamine Biosynthesis Pathway for Attenuating Hyaluronan Barriers to Pancreatic Cancer Chemotherapy

Pancreatic ductal adenocarcinoma (PDAC) poses significant therapeutic challenges due to excessive hyaluronic acid (HA) accumulation, which impedes drug delivery. Here, we present a targeted approach to reduce HA production by specifically silencing glutamine-fructose-6-phosphate aminotransferase 1 (GFAT1), a key enzyme of the hexosamine biosynthesis pathway (HBP) in pancreatic cancer cells. An engineered liposomal system for siGFAT1 delivery, PMLip@siGFAT1, characterized by macrophage membrane camouflage, LFC131 peptide-mediated targeting, and calcium phosphate (CaP) as the core, was designed to ensure prolonged circulation, enhanced inflamed vascular endothelial penetration, and subsequent effective tumor cell uptake and endosomal escape. Consequently, PMLip@siGFAT1 markedly downregulated the HA level in the PDAC microenvironment, decompressing the tumor vasculature and weakening the stromal barrier, which in turn improved the permeability of chemotherapeutics. In combination with Doxil, PMLip@siGFAT1 demonstrated potent antitumor efficacy with minimal systemic toxicity. Importantly, unlike PEGPH20 (hyaluronidase), PMLip@siGFAT1 reduced tumor invasiveness, while preserving skeletal muscle integrity. These findings highlight that PMLip@siGFAT1 holds great potential to revitalize HA downregulation strategies in pancreatic cancer for enhanced drug delivery and efficacy.

Enzyme-responsive liposomes for controlled drug release

Compared to other nanovectors, liposomes exhibit unique advantages, such as good biosafety and high drug-loading capacity. However, slow drug release from conventional liposomes makes most payloads unavailable, restricting the therapeutic efficacy. Therefore, in the last ∼20 years, enzyme-responsive liposomes have been extensively investigated, which liberate drugs under the stimulation of enzymes overexpressed at disease sites. In this review, we elaborate on the research progress on enzyme-responsive liposomes. The involved enzymes mainly include phospholipases, particularly phospholipase A2, matrix metalloproteinases, cathepsins, and esterases. These enzymes can cleave ester bonds or specific peptide sequences incorporated in the liposomes for controlled drug release by disrupting the primary structure of liposomes, detaching protective polyethylene glycol shells, or activating liposome-associated prodrugs. Despite decades of efforts, there are still a lack marketed products of enzyme-responsive liposomes. Therefore, more efforts should be made to improve the safety and effectiveness of enzyme-responsive liposomes and address the issues associated with production scale-up.

Dual Enzyme Cascade-Activated Popcorn-Like Nanoparticles Efficiently Remodeled Stellate Cells to Alleviate Pancreatic Desmoplasia

In pancreatic cancer, excessive desmoplastic stroma severely impedes drug access to tumor cells. By reverting activated pancreatic stellate cells (PSCs) to quiescence, all-trans retinoic acid (ATRA) can attenuate their stromal synthesis and remodel the tumor-promoting microenvironment. However, its modulatory effects have been greatly weakened due to its limited delivery to PSCs. Therefore, we constructed a tripeptide RFC-modified gelatin/oleic acid nanoparticle (RNP@ATRA), which delivered ATRA in an enzyme-triggered popcorn-like manner and effectively resolved the delivery challenges. Specifically, surface RFC was cleaved by aminopeptidase N (APN) on the tumor endothelium to liberate l-arginine, generating nitric oxide (NO) for tumor-specific vasodilation. Then, massive nanoparticles were pushed from the vessels into tumors, showing 5.1- and 4.0-fold higher intratumoral accumulation than free ATRA and APN-inert nanoparticles, respectively. Subsequently, in the interstitium, matrix metalloproteinase-2-induced gelatin degradation caused RNP@ATRA to rapidly release ATRA, promoting its interstitial penetration and PSC delivery. Thus, activated PSCs were efficiently reverted to quiescence, and stroma secretion and vascular compression were reduced, thereby enhancing intratumoral delivery of small-molecule or nanosized chemotherapeutics. Ultimately, RNP@ATRA combined with chemotherapeutics markedly suppressed tumor growth and metastasis without causing additional toxicities. Overall, this work provides a potential nanoplatform for the efficient delivery of PSC-modifying agents in pancreatic cancer and other stroma-rich tumors.

The Evolution and Recent Trends in Acoustic Targeting of Encapsulated Drugs to Solid Tumors: Strategies beyond Sonoporation

Despite recent advancements in ultrasound-mediated drug delivery and the remarkable success observed in pre-clinical studies, no delivery platform utilizing ultrasound contrast agents has yet received FDA approval. The sonoporation effect was a game-changing discovery with a promising future in clinical settings. Various clinical trials are underway to assess sonoporation's efficacy in treating solid tumors; however, there are disagreements on its applicability to the broader population due to long-term safety issues. In this review, we first discuss how acoustic targeting of drugs gained importance in cancer pharmaceutics. Then, we discuss ultrasound-targeting strategies that have been less explored yet hold a promising future. We aim to shed light on recent innovations in ultrasound-based drug delivery including newer designs of ultrasound-sensitive particles specifically tailored for pharmaceutical usage.

Non-pegylated Liposomal Doxorubicin as Palliative Chemotherapy in pre-Treated Advanced Pancreatic Cancer: A Retrospective Analysis of Twenty-Eight Patients

Background: Pancreatic cancer carries a devastating prognosis and is the fourth leading cause for cancer-related death in the United States and most European countries. Although one-third of patients receive a palliative third line therapy, the benefit of systemic therapy beyond second-line remains unclear. A plethora of clinical trials investigating novel drugs have failed over the past years. Due to the lack of established treatment regimens beyond second line, we offered nonpegylated liposomal doxorubicin, well known in other tumor entities, to pretreated pancreatic cancer patients requesting systemic therapy. Material and Methods: In this retrospective analysis, 28 patients with pancreatic carcinoma treated with nonpegylated liposomal doxorubicin (Myocet®) between 2012 and 2018 at our department were included. Results: For the majority of patients (n = 18, 64%), nonpeglyted liposomal doxorubicin was offered as a third-line therapy. Five patients received it as second line, four patients as fourth line, and one patient as fifth line of therapy. Half of the patients received at least a therapy cycle. The objective response rate to treatment was 7.1%. One patient had a period of radiologically confirmed stable disease with stable tumor markers. Another patient experienced partial remission. Conclusion: According to our findings the benefit of nonpegylated liposomal doxorubicin in pancreatic cancer beyond second line is limited.

'Adhesion and release' nanoparticle-mediated efficient inhibition of platelet activation disrupts endothelial barriers for enhanced drug delivery in tumors

Activated platelets can maintain tumor vessel integrity, thereby leading to limited tumor perfusion and suboptimal antitumor efficacy of nanoparticle-based drugs. Herein, to disrupt the tumor vascular endothelial barriers by inhibiting the transformation of resting platelets to activated platelets, a TM33 peptide-modified gelatin/oleic acid nanoparticle loaded with tanshinone IIA (TNA) was constructed (TM33-GON/TNA). TM33-GON/TNA could adhere to activated platelets by specifically binding their superficial P-selectin and release TNA into the extracellular space under matrix metalloproteinase-2 (MMP-2) stimulation, leading to local high TNA exposure. Thus, platelet activation, adhesion, and aggregation, which occur in the local environment around the activated platelets, were efficiently inhibited, leading to leaky tumor endothelial junctions. Accordingly, TM33-GON/TNA treatment resulted in a 3.2-, 4.0-, and 11.2-fold increase in tumor permeation of Evans blue (macromolecule marker), small-sized Nab-PTX (~10 nm), and large-sized DOX-Lip (~100 nm), respectively, without elevating drug delivery to normal tissues. Ultimately, TM33-GON/TNA plus Nab-PTX exhibited superior antitumor efficacy with minimal side effects in a murine pancreatic cancer model. In addition, the TM33-GON/TNA-induced disrupted endothelial junctions were reversibly restored after the treatment because the number of platelets was not reduced, which implies a low risk of the undesirable systemic bleeding. Hence, TM33-GON/TNA represents a clinically translational adjuvant therapy to magnify the antitumor efficacy of existing nanomedicines in pancreatic cancer and other tumors with tight endothelial lining.

Evaluation of Phase II Trial Design in Advanced Pancreatic Cancer

OBJECTIVES

We evaluated how well phase II trials in locally advanced and metastatic pancreatic cancer (LAMPC) meet current recommendations for trial design.

METHODS

We conducted a systematic review of phase II first-line treatment trial for LAMPC. We assessed baseline characteristics, type of comparison, and primary end point to examine adherence to the National Cancer Institute recommendations for trial design.

RESULTS

We identified 148 studies (180 treatment arms, 7505 participants). Forty-seven (32%) studies adhered to none of the 5 evaluated National Cancer Institute recommendations, 62 (42%) followed 1, 31 (21%) followed 2, and 8 (5%) followed 3 recommendations. Studies varied with respect to the proportion of patients with good performance status (range, 0%-80%) and locally advanced disease (range, 14%-100%). Eighty-two (55%) studies concluded that investigational agents should progress to phase III testing; of these, 24 (16%) had documented phase III trials. Three (8%) phase III trials demonstrated clinically meaningful improvements for investigational agents. One of 38 phase II trials that investigated biological investigational agents was enriched for a biomarker.

CONCLUSIONS

Phase II trials do not conform well to current recommendations for trial design in LAMPC.

Combination Therapies and Drug Delivery Platforms in Combating Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC), the fourth leading cause of cancer-related death in the United States, is highly aggressive and resistant to both chemo- and radiotherapy. It remains one of the most difficult-to-treat cancers, not only due to its unique pathobiological features such as stroma-rich desmoplastic tumors surrounded by hypovascular and hypoperfused vessels limiting the transport of therapeutic agents, but also due to problematic early detection, which renders most treatment options largely ineffective, resulting in extensive metastasis. To elevate therapeutic effectiveness of treatments and overt their toxicity, significant enthusiasm was generated to exploit new strategies for combating PDAC. Combination therapy targeting different barriers to mitigate delivery issues and reduce tumor recurrence and metastasis has demonstrated optimal outcomes in patients' survival and quality of life, providing possible approaches to overcome therapeutic challenges. This paper aims to provide an overview of currently explored multimodal therapies using either conventional therapy or nanomedicines along with rationale, up-to-date progress, as well as the key challenges that must be overcome. Understanding the future directions of the field may assist in the successful development of novel treatment strategies for enhancing therapeutic efficacy in PDAC.

Ratiometric delivery of doxorubicin and berberine by liposome enables superior therapeutic index than DoxilⓇ

Although the appearance of Doxil alleviated the cardiotoxicity of DOX, the progression-free survival of patients was not prolonged compared with traditional medication regimens, and side effects such as hand-foot syndrome has occurred. In order to solve this dilemma, we have designed a novel co-delivery strategy to construct a co-loaded liposome of berberine (BER) and doxorubicin (DOX), which was called LipoBeDo. The optimal synergistic ratio of the two drugs was screened by cell cytotoxicity experiments in vitro, and the optimal attenuation ratio was further determined by in vivo cardiac H&E staining pathological sections. The optimal combination treatment caused a robust increase in apoptotic cells of 4T1, as compared to drug alone treatment. The prepared co-loaded liposome, LipoBeDo, had high encapsulation efficiency and good stability. The nanoliposome carrier controlled the biological fate of the drugs and maintained a pre-defined optimal ratio in vivo. The LipoBeDo significantly inhibited tumor growth in 4T1 murine mammary carcinoma model compared with Doxil (P < 0.05), and completely overcame the myocardial rupture toxicity caused by Doxil in mice. Our co-loaded liposome delivery platform technology provided a new direction for the clinical treatment of triple-negative breast cancer and the safe application of DOX.

TPGS-grafted and acid-responsive soy protein nanogels for efficient intracellular drug release, accumulation, penetration in 3D tumor spheroids of drug-resistant cancer cells

The frequent occurrence of multidrug resistance (MDR) in solid tumors is the major obstacle for nano-drug delivery systems (nDDS) to realize the successful cancer chemotherapy. Herein, we had prepared pH-responsive nanogels via cross-linking TPGS-grafted soy protein with an acid-labile ortho ester cross-linker (OEAM) to realize the efficient intracellular drugs release and accumulation, and subsequently enhance therapeutic effect in MDR tumor cells. These nanogels displayed a uniform size (~200 nm) and morphology, and the introduction of ortho ester bonds endowed nanogels stability in neutral environment and acid-degradability in acidic conditions. Cisplatin (CDDP) was successfully loaded into nanogels, which exhibited an accelerated drug release at low pH. The modification of TPGS efficiently improved cellular internalization and drug accumulation in A549/DDP cells by inhibiting the function of drug efflux pumps (MRP2 and ATP7A/7B), leading to higher cytotoxicity and apoptosis. Moreover, TPGS-grafted nanogels also showed better drug accumulation and penetration in tumor-like spheroids, and then remarkably inhibited tumor growth owing to the rapid drug release in acidic organelles. As a result, the TPGS-grafted and pH-sensitive soy protein nanogels have a great potential as a drugs carrier for the efficient cancer treatment.

Aptamer-functionalized liposomes for targeted cancer therapy

Accumulation of chemotherapeutic agents in the tumor tissue while reducing adverse effects and drug resistance are among the major goals in cancer therapy. Among nanocarriers, liposomes have been found to be more effective in the passive targeting of cancer cells. A promising recent development in targeted drug delivery is the use of aptamer-functionalized liposomes for cancer therapy. Aptamer-targeted liposomes have enhanced uptake in tumor cells as shown in vitro and in vivo. Here, we discuss the aptamer-functionalized liposome platforms and review functionalization approaches as well as the factors affecting antitumor efficiency of aptamer-targeted liposomal systems. Finally, we provide a comprehensive overview of aptamer-targeted liposomes based on the molecular targets on the surface of cancer cells.

Pharmacokinetics and pharmacodynamics of liposomal chemophototherapy with short drug-light intervals

Chemophototherapy (CPT) merges photodynamic therapy with chemotherapy and can substantially enhance drug delivery. Using a singular liposomal formulation for CPT, we describe a semi-mechanistic pharmacokinetic-pharmacodynamic (PK/PD) model to investigate observed antitumor effects. Long-circulating, sterically-stabilized liposomes loaded with doxorubicin (Dox) stably incorporate small amounts of a porphyrin-phospholipid (PoP) photosensitizer in the bilayer. These were administered intravenously to mice bearing low-passage, patient-derived pancreatic cancer xenografts (PDX). Dox PK was described with a two-compartment model and tumor drug disposition kinetics were modeled with first-order influx and efflux rates. Tumor irradiation with 665 nm laser light (200 J/cm2) 1 h after liposome administration increased tumor vascular permeabilization and drug accumulation, which was accounted for in the PK/PD model with increased tumor influx and efflux rates by approximately 12- and 4- fold, respectively. This modeling approach provided an overall 7-fold increase in Dox area under the curve in the tumor, matching experimental data (7.4-fold). A signal transduction model based on nonlinear direct cell killing accounted for observed tumor growth patterns. This PK/PD model adequately describes the CPT anti-PDX tumor response based on enhanced drug delivery at the short drug-light interval used.

Silk Fibroin-Coated Nanoagents for Acidic Lysosome Targeting by a Functional Preservation Strategy in Cancer Chemotherapy

Background: Premature drug leakage and inefficient cellular uptake are stand out as considerable hurdles for low drug delivery efficiency in tumor chemotherapy. Thus, we established a novel drug delivery and transportation strategy mediated by biocompatible silk fibroin (SF)-coated nanoparticles to overcome these therapeutic hurdles. Methods: we first synthesised a TME-responsive biocompatible nanoplatform constructed of amorphous calcium carbonate (ACC) cores and SF shells for enhanced chemotherapy by concurrently inhibiting premature drug release, achieving lysosome-targeted explosion and locally sprayed DOX, and monitoring via PAI, which was verified both in vitro and in vivo. Results: The natural SF polymer first served as a "gatekeeper" to inhibit a drug from prematurely leaking into the circulation was demonstrated both in vitro and in vivo. Upon encountering TMEs and targeting to the acidic pH environments of lysosomes, the sensitive ACC nanoparticles were gradually degraded, eventually generating a large amount of Ca2+ and CO2, resulting in lysosomal collapse, thus preventing both the efflux of DOX from cancer cells and the protonation of DOX within the lysosome, releasing multiple hydrolytic enzyme to cytoplasm, exhibiting the optimal therapeutic dose and remarkable synergetic therapeutic performance. In particular, CO2 gas generated by the pH response of ACC nanocarriers demonstrated their imaging capability for PAI, providing the potential for quantifying and guiding drug release in targets. Conclusion: In this work, we constructed TME-responsive biocompatible NPs by coating DOX-preloaded ACC-DOX clusters with SF via a bioinspired mineralization method for efficient therapeutics. This functional lysosome-targeted preservation-strategy-based therapeutic system could provid novel insights into cancer chemotherapy.

Reviewing two decades of nanomedicine implementations in targeted treatment and diagnosis of pancreatic cancer: An emphasis on state of art

Pancreatic cancer is nowadays the most life-threatening cancer type worldwide. The problem of poor diagnosis, anti-neoplastics resistance and biopharmaceutical drawbacks of effective anti-cancer drugs lead to worsen disease state. Nanotechnology-based carrier systems used in both imaging and treatment procedures had solved many of these problems. It is critical to develop advanced detection method to save patients from being too late diagnosed. Targeting the pancreatic cancer cells as well helped in decreasing the side effects associated with normal cells destruction. Drug resistance is another challenge in pancreatic cancer management that can be solved by thorough understanding of the microenvironment associated with the disease to design creative nanocarriers. This is the first article to review multifaceted approaches of nanomedicine in pancreatic cancer detection and management. Additionally, mortality rates in selected Arab and European countries were illustrated herein. An emphasis was given on therapeutic and diagnostic challenges and different nanotechnologies adopted to overcome. The four main approaches encompassed nanomedicine for herbal treatment, nanomedicine of synthetic anti-cancer drugs, metal nanoparticles as a distinct treatment policy and nanotechnology for cancer diagnosis. Future research perspectives have been finally proposed.

Smart Nanoparticles Undergo Phase Transition for Enhanced Cellular Uptake and Subsequent Intracellular Drug Release in a Tumor Microenvironment

Inefficient cellular uptake and intracellular drug release at the tumor site are two major obstacles limiting the antitumor efficacy of nanoparticle delivery systems. To overcome both problems, we designed a smart nanoparticle that undergoes phase transition in a tumor microenvironment (TME). The smart nanoparticle is generated using a lipid-polypetide hybrid nanoparticle, which comprises a PEGylated lipid monolayer shell and a pH-sensitive hydrophobic poly-l-histidine core and is loaded with the antitumor drug doxorubicin (DOX). The smart nanoparticle undergoes a two-step phase transition at two different pH values in the TME: (i) At the TME (pH_e: 7.0-6.5), the smart nanoparticle swells, and its surface potential turns from negative to neutral, facilitating the cellular uptake; (ii) After internalization, at the acid endolysosome (pH_endo: 6.5-4.5), the smart nanoparticle dissociates and induces endolysosome escape to release DOX into the cytoplasm. In addition, a tumor-penetrating peptide iNRG was modified on the surface of the smart nanoparticle as a tumor target moiety. The in vitro studies demonstrated that the iNGR-modified smart nanoparticles promoted cellular uptake in the acidic environment (pH 6.8). The in vivo studies showed that the iNGR-modified smart nanoparticles exerted more potent antitumor efficacy against late-stage aggressive breast carcinoma than free DOX. These data suggest that the smart nanoparticles may serve as a promising delivery system for sequential uptake and intracellular drug release of antitumor agents. The easy preparation of these smart nanoparticles may also have advantages in the future manufacture for clinical trials and clinical use.

Secretory phospholipase A2 responsive liposomes exhibit a potent anti-neoplastic effect in vitro, but induce unforeseen severe toxicity in vivo

The clinical use of liposomal drug delivery vehicles is often hindered by insufficient drug release. Here we present the rational design of liposomes optimized for secretory phospholipase A₂ (sPLA₂) triggered drug release, and test their utility in vitro and in vivo. We hypothesized that by adjusting the level of cholesterol in anionic, unsaturated liposomes we could tune the enzyme specificity based on membrane fluidity, thus obtaining liposomes with an improved therapeutic outcome and reduced side effects. Cholesterol is generally important as a component in the membranes of liposome drug delivery systems due to its stabilizing effects in vivo. The incorporation of cholesterol in sPLA₂ sensitive liposomes has not previously been possible due to reduced sPLA₂ activity. However, in the present work we solved this challenge by optimizing membrane fluidity. In vitro release studies revealed enzyme specific drug release. Treatment of two different cancer cell lines with liposomal oxaliplatin revealed efficient growth inhibition compared to that of clinically used stealth liposomes. The in vivo therapeutic effect was evaluated in nude NMRI mice using the sPLA₂ secreting mammary carcinoma cell line MT-3. Three days after first treatment all mice having received the novel sPLA₂ sensitive liposome formulation were euthanized due to severe systemic toxicity. Thus the present study demonstrates that great caution should be implemented when utilizing sPLA₂ sensitive liposomes and that the real utility can only be disclosed in vivo. The present studies have clinical implications, as sPLA₂ sensitive formulations are currently undergoing clinical trials (LiPlaCis®).

Targeting reactive oxygen species in development and progression of pancreatic cancer

INTRODUCTION

Pancreatic ductal adenocarcinoma (PDA) is characterized by expression of oncogenic KRas which drives all aspects of tumorigenesis. Oncogenic KRas induces the formation of reactive oxygen species (ROS) which have been implicated in initiation and progression of PDA. To facilitate tumor promoting levels and to avoid oncogene-induced senescence or cytotoxicity, ROS homeostasis in PDA cells is balanced by additional up-regulation of antioxidant systems. Areas covered: We examine the sources of ROS in PDA, the mechanisms by which ROS homeostasis is maintained, and the biological consequences of ROS in PDA. Additionally, we discuss the potential mechanisms for targeting ROS homoeostasis as a point of therapeutic intervention. An extensive review of the relevant literature as it relates to the topic was conducted using PubMed. Expert commentary: Even though oncogenic mutations in the KRAS gene have been detected in over 95% of human pancreatic adenocarcinoma, targeting its gene product, KRas, has been difficult. The dependency of PDA cells on balancing ROS homeostasis could be an angle for new prevention or treatment strategies. These include use of antioxidants to prevent formation or progression of precancerous lesions, or methods to increase ROS in tumor cells to toxic levels.

Nanomedicine strategies to overcome the pathophysiological barriers of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is one of the leading causes of cancer- related deaths. PDAC remains one of the most difficult-to-treat cancers, owing to its unique pathobiological features: a nearly impenetrable desmoplastic stroma, and hypovascular and hypoperfused tumour vessels render most treatment options largely ineffective. Progress in understanding the pathobiology and signalling pathways involved in disease progression is helping researchers to develop novel ways to fight PDAC, including improved nanotechnology-based drug-delivery platforms that have the potential to overcome the biological barriers of the disease that underlie persistent drug resistance. So-called 'nanomedicine' strategies have the potential to enable targeting of the Hedgehog-signalling pathway, the autophagy pathway, and specific RAS-mutant phenotypes, among other pathological processes of the disease. These novel therapies, alone or in combination with agents designed to disrupt the pathobiological barriers of the disease, could result in superior treatments, with increased efficacy and reduced off-target toxicities compared with the current standard-of-care regimens. By overcoming drug-delivery challenges, advances can be made in the treatment of PDAC, a disease for which limited improvement in overall survival has been achieved over the past several decades. We discuss the approaches to nanomedicine that have been pursued to date and those that are the focus of ongoing research, and outline their potential, as well as the key challenges that must be overcome.

Interventional Nanotheranostics of Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) accounts for over 90% of all pancreatic cancer. Nanoparticles (NPs) offer new opportunities for image-guided therapy owing to the unique physicochemical properties of the nanoscale effect and the multifunctional capabilities of NPs. However, major obstacles exist for NP-mediated cancer theranostics, especially in PDAC. The hypovascular nature of PDAC may impede the deposition of NPs into the tumor after systemic administration, and most NPs localize predominantly in the mononuclear phagocytic system, leading to a relatively poor tumor-to-surrounding-organ uptake ratio. Image guidance combined with minimally invasive interventional procedures may help circumvent these barriers to poor drug delivery of NPs in PDAC. Interventional treatments allow regional drug delivery, targeted vascular embolization, direct tumor ablation, and the possibility of disrupting the stromal barrier of PDAC. Interventional treatments also have potentially fewer complications, faster recovery, and lower cost compared with conventional therapies. This work is an overview of current image-guided interventional cancer nanotheranostics with specific attention given to their applications for the management of PDAC.

DAFODIL: A novel liposome-encapsulated synergistic combination of doxorubicin and 5FU for low dose chemotherapy

PEGylated liposomes have transformed chemotherapeutic use of doxorubicin by reducing its cardiotoxicity; however, it remains unclear whether liposomal doxorubicin is therapeutically superior to free doxorubicin. Here, we demonstrate a novel PEGylated liposome system, named DAFODIL (Doxorubicin And 5-Flurouracil Optimally Delivered In a Liposome) that inarguably offers superior therapeutic efficacies compared to free drug administrations. Delivery of synergistic ratios of this drug pair led to greater than 90% reduction in tumor growth of murine 4T1 mammary carcinoma in vivo. By exploiting synergistic ratios, the effect was achieved at remarkably low doses, far below the maximum tolerable drug doses. Our approach re-invents the use of liposomes for multi-drug delivery by providing a chemotherapy vehicle which can both reduce toxicity and improve therapeutic efficacy. This methodology is made feasible by the extension of the ammonium-sulfate gradient encapsulation method to nucleobase analogues, a liposomal entrapment method once conceived useful only for anthracyclines. Therefore, our strategy can be utilized to efficiently evaluate various chemotherapy combinations in an effort to translate more effective combinations into the clinic.

Improvement in the drug delivery and anti-tumor efficacy of PEGylated liposomal doxorubicin by targeting RNA aptamers in mice bearing breast tumor model

Targeted delivery by ligands such as aptamers, is a promising method to increase the efficiency of PEGylated-liposomal doxorubicin (PL-Dox). In this study, we have successfully conjugated our recently developed anti-breast cancer RNA aptamer (TSA14) to the surface of PL-Dox and characterized for their size, zeta potential, Dox percent encapsulation and release properties in the presence of fetal bovine serum. In vitro experiments showed that aptamer could improve cellular uptake and cytotoxicity of PL-Dox in TUBO breast cell line. In mice bearing TUBO breast tumor, although, the doxorubicin plasma level of liposomal doxorubicin did not significantly change after modification of nanoparticles with aptamer, however, much higher tumor accumulation of Dox as compared with non-targeted liposomes proved the tumor-targeting capability of aptamers. In the same way, aptamer-PL-Dox improved anti-tumor efficiency of liposomes in TUBO breast tumor in mice compared to non-targeted liposomes. Overall, the results showed that aptamer decoration of PL-Dox could significantly improve selectivity and the therapeutic efficacy of liposomal DOX and merits further investigation.

IGF1 Receptor Targeted Theranostic Nanoparticles for Targeted and Image-Guided Therapy of Pancreatic Cancer

Overcoming resistance to chemotherapy is a major and unmet medical challenge in the treatment of pancreatic cancer. Poor drug delivery due to stromal barriers in the tumor microenvironment and aggressive tumor biology are additional impediments toward a more successful treatment of pancreatic cancer. In attempts to address these challenges, we developed IGF1 receptor (IGF1R)-directed, multifunctional theranostic nanoparticles for targeted delivery of therapeutic agents into IGF1R-expressing drug-resistant tumor cells and tumor-associated stromal cells. These nanoparticles were prepared by conjugating recombinant human IGF1 to magnetic iron oxide nanoparticles (IONPs) carrying the anthracycline doxorubicin (Dox) as the chemotherapeutic payload. Intravenously administered IGF1-IONPs exhibited excellent tumor targeting and penetration in an orthotopic patient-derived xenograft (PDX) model of pancreatic cancer featuring enriched tumor stroma and heterogeneous cancer cells. IGF1R-targeted therapy using the theranostic IGF1-IONP-Dox significantly inhibited the growth of pancreatic PDX tumors. The effects of the intratumoral nanoparticle delivery and therapeutic responses in the orthotopic pancreatic PDX tumors could be detected by magnetic resonance imaging (MRI) with IONP-induced contrasts. Histological analysis showed that IGF1R-targeted delivery of Dox significantly inhibited cell proliferation and induced apoptotic cell death of pancreatic cancer cells. Therefore, further development of IGF1R-targeted theranostic IONPs and MRI-guided cancer therapy as a precision nanomedicine may provide the basis for more effective treatment of pancreatic cancer.

Towards Optimal Design of Cancer Nanomedicines: Multi-stage Nanoparticles for the Treatment of Solid Tumors

Conventional drug delivery systems for solid tumors are composed of a nano-carrier that releases its therapeutic load. These two-stage nanoparticles utilize the enhanced permeability and retention (EPR) effect to enable preferential delivery to tumor tissue. However, the size-dependency of the EPR, the limited penetration of nanoparticles into the tumor as well as the rapid binding of the particles or the released cytotoxic agents to cancer cells and stromal components inhibit the uniform distribution of the drug and the efficacy of the treatment. Here, we employ mathematical modeling to study the effect of particle size, drug release rate and binding affinity on the distribution and efficacy of nanoparticles to derive optimal design rules. Furthermore, we introduce a new multi-stage delivery system. The system consists of a 20-nm primary nanoparticle, which releases 5-nm secondary particles, which in turn release the chemotherapeutic drug. We found that tuning the drug release kinetics and binding affinities leads to improved delivery of the drug. Our results also indicate that multi-stage nanoparticles are superior over two-stage nano-carriers provided they have a faster drug release rate and for high binding affinity drugs. Furthermore, our results suggest that smaller nanoparticles achieve better treatment outcome.

pH-triggered echogenicity and contents release from liposomes

Liposomes are representative lipid nanoparticles widely used for delivering anticancer drugs, DNA fragments, or siRNA to cancer cells. Upon targeting, various internal and external triggers have been used to increase the rate for contents release from the liposomes. Among the internal triggers, decreased pH within the cellular lysosomes has been successfully used to enhance the rate for releasing contents. However, imparting pH sensitivity to liposomes requires the synthesis of specialized lipids with structures that are substantially modified at a reduced pH. Herein, we report an alternative strategy to render liposomes pH sensitive by encapsulating a precursor which generates gas bubbles in situ in response to acidic pH. The disturbance created by the escaping gas bubbles leads to the rapid release of the encapsulated contents from the liposomes. Atomic force microscopic studies indicate that the liposomal structure is destroyed at a reduced pH. The gas bubbles also render the liposomes echogenic, allowing ultrasound imaging. To demonstrate the applicability of this strategy, we have successfully targeted doxorubicin-encapsulated liposomes to the pancreatic ductal carcinoma cells that overexpress the folate receptor on the surface. In response to the decreased pH in the lysosomes, the encapsulated anticancer drug is efficiently released. Contents released from these liposomes are further enhanced by the application of continuous wave ultrasound (1 MHz), resulting in substantially reduced viability for the pancreatic cancer cells (14%).

A mathematical model of the enhanced permeability and retention effect for liposome transport in solid tumors

The discovery of the enhanced permeability and retention (EPR) effect has resulted in the development of nanomedicines, including liposome-based formulations of drugs, as cancer therapies. The use of liposomes has resulted in substantial increases in accumulation of drugs in solid tumors; yet, significant improvements in therapeutic efficacy have yet to be achieved. Imaging of the tumor accumulation of liposomes has revealed that this poor or variable performance is in part due to heterogeneous inter-subject and intra-tumoral liposome accumulation, which occurs as a result of an abnormal transport microenvironment. A mathematical model that relates liposome accumulation to the underlying transport properties in solid tumors could provide insight into inter and intra-tumoral variations in the EPR effect. In this paper, we present a theoretical framework to describe liposome transport in solid tumors. The mathematical model is based on biophysical transport equations that describe pressure driven fluid flow across blood vessels and through the tumor interstitium. The model was validated by direct comparison with computed tomography measurements of tumor accumulation of liposomes in three preclinical tumor models. The mathematical model was fit to liposome accumulation curves producing predictions of transport parameters that reflect the tumor microenvironment. Notably, all fits had a high coefficient of determination and predictions of interstitial fluid pressure agreed with previously published independent measurements made in the same tumor type. Furthermore, it was demonstrated that the model attributed inter-subject heterogeneity in liposome accumulation to variations in peak interstitial fluid pressure. These findings highlight the relationship between transvascular and interstitial flow dynamics and variations in the EPR effect. In conclusion, we have presented a theoretical framework that predicts inter-subject and intra-tumoral variations in the EPR effect based on fundamental properties of the tumor microenvironment and forms the basis for transport modeling of liposome drug delivery.

Liposome based delivery systems in pancreatic cancer treatment: from bench to bedside

Despite rapid advances in cancer diagnosis and treatment, pancreatic cancer remains one of the most difficult human malignancies to be treated, with a mortality rate nearly equal to its incidence. Although gemcitabine has been established as the standard first-line treatment for advanced pancreatic cancer, gemcitabine-based combination chemotherapy showed either marginal or no improvement in survival. Developments in liposomal delivery systems have facilitated the targeting of specific agents for cancer treatment. Such systems could be developed as platforms for future multi-functional theranostic nanodevices tailor-made for the combined detection of early cancer and functional drug delivery. We systemically review liposome based drug-delivery systems, which can provide improved pharmacokinetics, reduced side effects and potentially increased tumor uptake, for pancreatic cancer therapy. Novel liposomal formulations allowing for higher tumor targeting efficiencies and used in current clinical trials to treat this challenging disease are emphasized.

Nanovector-based therapies in advanced pancreatic cancer

Systemic therapy for advanced pancreatic cancer has been largely disappointing owing to the unfavorable pharmacokinetic profile and poor penetration of current chemotherapeutic agents ,as well as the fragile patient population with compromised tolerance to toxic chemotherapies. Nanovectors can provide passive drug delivery through abnormal tumor neo-vasculature microanatomy or active targeting via binding to receptors or macromolecules associated with the tumor. In such a manner, nanovector-based therapy may not only modulate the pharmacokinetics and therapeutic index of chemotherapeutic agents but also provide new treatment options in patients with advanced pancreatic cancer. In this article, we present the rationale and currently available clinical results of nanovector-based therapies to highlight the potential use of this class of agent in patients with advanced pancreatic cancer.

An imaging-driven model for liposomal stability and circulation

Simultaneous labeling of the drug compartment and shell of delivery vehicles with optical and positron emission tomography (PET) probes is developed and employed to inform a hybrid physiologically based pharmacokinetic model. Based on time-dependent estimates of the concentration of these tracers within the blood pool, reticuloendothelial system (RES) and tumor interstitium, we compare the stability and circulation of long-circulating and temperature-sensitive liposomes. We find that rates of transport to the RES for long-circulating and temperature-sensitive particles are 0.046 and 0.19 h(-1), respectively. Without the application of exogenous heat, the rates of release from the long-circulating and temperature-sensitive particles circulating within the blood pool are 0.003 and 0.2 h(-1), respectively. Prolonged lifetime in circulation and slow drug release from liposomes result in a significantly greater drug area under the curve for the long-circulating particles. Future studies will couple these intrinsic parameters with exogenous heat-based release. Finally, we develop a transport constant for the transport of liposomes from the blood pool to the tumor interstitium, which is on the order of 0.01 h(-1) for the Met-1 tumor system.

Phase I trial of doxorubicin-containing low temperature sensitive liposomes in spontaneous canine tumors

PURPOSE

To determine the maximum tolerated dose, dose-limiting toxicities, and pharmacokinetic characteristics of doxorubicin encapsulated in a low temperature sensitive liposome (LTSL) when given concurrently with local hyperthermia to canine solid tumors.

EXPERIMENTAL DESIGN

Privately owned dogs with solid tumors (carcinomas or sarcomas) were treated. The tumors did not involve bone and were located at sites amenable to local hyperthermia. LTSL-doxorubicin was given (0.7-1.0 mg/kg i.v.) over 30 minutes during local tumor hyperthermia in a standard phase I dose escalation study. Three treatments, given 3 weeks apart, were scheduled. Toxicity was monitored for an additional month. Pharmacokinetics were evaluated during the first treatment cycle.

RESULTS

Twenty-one patients were enrolled: 18 with sarcomas and 3 with carcinomas. Grade 4 neutropenia and acute death secondary to liver failure, possibly drug related, were the dose-limiting toxicities. The maximum tolerated dose was 0.93 mg/kg. Other toxicities, with the possible exception of renal damage, were consistent with those observed following free doxorubicin administration. Of the 20 dogs that received > or = 2 doses of LTSL-doxorubicin, 12 had stable disease, and 6 had a partial response to treatment. Pharmacokinetic variables were more similar to those of free doxorubicin than the marketed liposomal product. Tumor drug concentrations at a dose of 1.0 mg/kg averaged 9.12 +/- 6.17 ng/mg tissue.

CONCLUSION

LTSL-doxorubicin offers a novel approach to improving drug delivery to solid tumors. It was well tolerated and resulted in favorable response profiles in these patients. Additional evaluation in human patients is warranted.

Chemotherapy-induced dermatological toxicity: frequencies and impact on quality of life in women’s cancers. Results of a prospective study

PURPOSE

The study aimed to determine the prevalence of dermatological side effects and its impact on quality of life in patients receiving systemic chemotherapy for women's cancers.

MATERIALS AND METHODS

A prospective study was conducted on patients with histologically confirmed advanced women's cancers who were deemed candidates for adjuvant or palliative chemotherapy. Patients were systemically examined for skin, hair, and nail side effects. The impact of those side effects on their quality of life was assessed using the health-related quality of life score (HRQL).

RESULTS

Between April 2001 and October 2001, 91 patients received 1 to 17 (median 4) courses of chemotherapy. Malignancies included breast cancer (n = 39, 43%), ovarian cancer (n = 32, 35%), cervical cancer (n = 12, 13%), endometrial cancer (n = 5, 6%), fallopian tube cancer (n = 2, 2%), and vaginal cancer (n = 1, 1%). Chemotherapy agents included taxanes (n = 42, 46%), PEG doxorubicin (n = 17, 7%), other anthracyclines (epirubicin and doxorubicin; n = 6, 19%), topotecan (n = 13, 14%), and other agents (n = 13, 14%). Overall incidence of skin, nail, and hair side effects was 86.8% (n = 79). Seventeen patients (18.7%) developed a palmo-plantar erythrodysesthesia (PPE), and nine of those (53%) were of grade 3 in common toxicity criteria scale (NCI). Twenty-one patients (23.1%) developed nail changes such as subungual hematomas, onycholysis, and leukonychias or nail loss, while 69 (75.8%) developed hair loss. There was a higher incidence of PPE in patients receiving chemotherapy for palliation rather than cure (percent over percent, p < 0.001, Fisher's exact test). Using the HRQL score, skin changes were the most frequently reported unpleasant side effect (34.1%), and of those patients who developed PPE, this was reported by n = 8 (47%) as the most unpleasant.

CONCLUSIONS

Dermatological chemotherapy side effects are frequent after treatment of women's cancers and have a major impact on quality of life as assessed by HRQL. Counseling of patients with women's cancers and the profile of side effects of chemotherapeutic agents should be considered before considering an adjuvant or palliative chemotherapy regimen.

Advanced strategies in liposomal cancer therapy: problems and prospects of active and tumor specific drug release

Tumor specific drug delivery has become increasingly interesting in cancer therapy, as the use of chemotherapeutics is often limited due to severe side effects. Conventional drug delivery systems have shown low efficiency and a continuous search for more advanced drug delivery principles is therefore of great importance. In the first part of this review, we present current strategies in the drug delivery field, focusing on site-specific triggered drug release from liposomes in cancerous tissue. Currently marketed drug delivery systems lack the ability to actively release the carried drug and rely on passive diffusion or slow non-specific degradation of the liposomal carrier. To obtain elevated tumor-to-normal tissue drug ratios, it is important to develop drug delivery strategies where the liposomal carriers are actively degraded specifically in the tumor tissue. Many promising strategies have emerged ranging from externally triggered light- and thermosensitive liposomes to receptor targeted, pH- and enzymatically triggered liposomes relying on an endogenous trigger mechanism in the cancerous tissue. However, even though several of these strategies were introduced three decades ago, none of them have yet led to marketed drugs and are still far from achieving this goal. The most advanced and prospective technologies are probably the prodrug strategies where non-toxic drugs are carried and activated specifically in the malignant tissue by overexpressed enzymes. In the second part of this paper, we review our own work, exploiting secretory phospholipase A2 as a site-specific trigger and prodrug activator in cancer therapy. We present novel prodrug lipids together with biophysical investigations of liposome systems, constituted by these new lipids and demonstrate their degradability by secretory phospholipase A2. We furthermore give examples of the biological performance of the enzymatically degradable liposomes as advanced drug delivery systems.

Efficacy and safety of liposomal anthracyclines in Phase I/II clinical trials

Preclinical studies have established the pharmacologic advantages of liposomal anthracyclines, including pharmacokinetic profiles after bolus dosing that resemble continuous infusion of conventional anthracyclines, increased drug concentrations in tumor cells compared with the surrounding tissues, and reduced toxicity relative to conventional anthracycline treatment. Based on these studies, many phase I and phase II clinical trials were conducted to assess the safety and potential activity of liposomal anthracyclines in the management of both solid and hematologic tumors. These studies provided valuable insight into the safety of pegylated liposomal doxorubicin (Doxil/Caelyx [PLD]), nonpegylated liposomal doxorubicin (Myocet [NPLD]), and liposomal daunorubicin (DaunoXome [DNX]) over a range of doses, either as single-agent therapy or in combination with other cytotoxic agents. Other liposomal anthracyclines in development may be well tolerated but their activity remains to be elucidated by clinical trials. The available data also suggest that liposomal anthracyclines have activity not only against tumor types with known sensitivity to conventional anthracyclines, but also potentially for tumors that are typically anthracycline-resistant. Despite the availability of clinical data from a wide variety of tumor types and patient populations, further studies of liposomal anthracycline therapy are needed to fully establish their safety, efficacy, and dosing in the treatment of these patients.

Pegylated liposomal doxorubicin in combination with mitomycin C, infusional 5-fluorouracil and sodium folinic acid. A phase-I-study in patients with upper gastrointestinal cancer

Mitomycin C (MMC) in combination with infusional 5-fluorouracil (FU) plus folinic acid (FA) is an effective treatment for metastatic gastrointestinal cancer. Anthracyclines are commonly used in the treatment of upper gastrointestinal cancer. The aim of this study was to determine the maximum tolerated dose of liposomal, pegylated doxorubicin (Caelyx) in combination with infusional 5-FU/sodium FA and MMC. Escalating doses of Caelyx (15 – 25 – 30 – 35 mg m⁻² corresponding to dose levels I–IV) were applied on days 1 and 29, given to fixed doses of 24-h 5-FU (2000 mg m⁻²) and sodium FA (500 mg m⁻², mixed with 5-FU in one pump) weekly for 6 weeks, and MMC 7 mg m⁻² on days 8 and 36. At least three patients were treated at each dose level. A total of 25 patients are evaluable. No dose-limiting toxicity (DLT) was observed on level I (n=3). On level II, DLT occurred in three out of five patients (mucositis and leucopenia). Owing to the early DLTs at this dose, we added a 20 mg m⁻² Caelyx dose level (Ia). In total, 17 patients were treated at this dose level. Among these, only two patients experienced DLT in cycle one and 37 complete cycles have been administered in association with a low toxicity profile. The median dose intensity was 100% for each drug during the first course and no treatment delay exceeding 7 days was required. The recommended dose of 4-weekly Caelyx in combination with weekly 24-h 5-FU/sodium FA and 4-weekly MMC is 20 mg m⁻². Preliminary antitumour activity has been observed in patients with pretreated pancreatic cancer and in untreated gastric cancer.

Anthracyclines: molecular advances and pharmacologic developments in antitumor activity and cardiotoxicity

The clinical use of anthracyclines like doxorubicin and daunorubicin can be viewed as a sort of double-edged sword. On the one hand, anthracyclines play an undisputed key role in the treatment of many neoplastic diseases; on the other hand, chronic administration of anthracyclines induces cardiomyopathy and congestive heart failure usually refractory to common medications. Second-generation analogs like epirubicin or idarubicin exhibit improvements in their therapeutic index, but the risk of inducing cardiomyopathy is not abated. It is because of their janus behavior (activity in tumors vis-à-vis toxicity in cardiomyocytes) that anthracyclines continue to attract the interest of preclinical and clinical investigations despite their longer-than-40-year record of longevity. Here we review recent progresses that may serve as a framework for reappraising the activity and toxicity of anthracyclines on basic and clinical pharmacology grounds. We review 1) new aspects of anthracycline-induced DNA damage in cancer cells; 2) the role of iron and free radicals as causative factors of apoptosis or other forms of cardiac damage; 3) molecular mechanisms of cardiotoxic synergism between anthracyclines and other anticancer agents; 4) the pharmacologic rationale and clinical recommendations for using cardioprotectants while not interfering with tumor response; 5) the development of tumor-targeted anthracycline formulations; and 6) the designing of third-generation analogs and their assessment in preclinical or clinical settings. An overview of these issues confirms that anthracyclines remain "evergreen" drugs with broad clinical indications but have still an improvable therapeutic index.

Assessment of peri-operative quality of life in patients undergoing surgery for gastrointestinal cancer

The purpose of this study was to assess the pre- and postoperative quality of life (QOL) of patients with gastrointestinal cancer and to investigate the relationship between QOL and various psychological and clinical factors. Eighty-five patients who underwent surgery for gastrointestinal cancer and 26 control patients undergoing surgery for digestive diseases other than cancer were interviewed. Two tests were administered to assess QOL and psychological status respectively: the Japanese-language version of the European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30 and the Japanese-language version of the Hospital Anxiety and Depression Scale (HADS). Each test was administered before surgery, before discharge, and 6 months after discharge. Gastrointestinal tumors were localized to the stomach, colon, or rectum in 88% of cases and classified as advanced stage or early stage according to staging protocols. Changes in EORTC QLQ-C30 subscale scores over time were compared among advanced stage, early stage, and control patients. All groups showed significant changes in subscale scores of QOL; the scores of the advanced-stage group indicated worse QOL than the early-stage and control groups in a lot of areas. The physical function (PF2) QOL subscore was influenced by diagnosis, postoperative complications, medical equipment at discharge, and the length of admission and negatively correlated with depression and anxiety. These results suggest that QOL in gastrointestinal cancer patients is variable over time and is influenced by various clinical factors. Therefore, consideration of these clinical factors is paramount to the optimal care of gastrointestinal cancer patients.

Treatment of pancreatic cancer with a combination of irinotecan (CPT-11) and gemcitabine: a multicenter phase II study by the Greek Cooperative Group for Pancreatic Cancer

BACKGROUND

The efficacy and toxicity of gemcitabine (GEM) and irinotecan (CPT-11) is evaluated in previously untreated patients with inoperable or metastatic pancreatic cancer.

PATIENTS AND METHODS

From January 1999 to July 2001, 60 patients with pancreatic cancer (85% stage IV) were enrolled in a two-step extended phase II trial. Patients were treated with gemcitabine (1,000 mg/m2 on days 1 and 8) and CPT-11 (300 mg/m2 on day 8) in cycles of 3 weeks. No prophylactic use of recombinant human granulocyte colony-stimulating factor (rhG-CSF) was initially planned.

RESULTS

In an intention-to-treat analysis one (1.7%) complete and 14 (23.3%) partial responses were achieved [objective response rate (ORR) 24.7%; 95% confidence interval 14.04% to 35.96%]. Twenty-two (36.7%) and 23 (38.3%) patients had stable and progressive disease, respectively. The median duration of response was 5 months, the median time to tumor progression (TTP) was 7 months and the median overall survival 7 months. One-year survival was 22.5%. Pain improvement and asthenia during treatment were observed in 45% and 43% of patients, respectively; weight gain occurred in 19.5% of patients. Grade 3 anemia occurred in three (5%) patients who required transfusion of six packed red blood cell (RBC) units. Ten (16.7%) additional patients with grade 2 anemia were treated with recombinant erythropoietin. Grade 3 thrombocytopenia occurred in seven (11.7%) patients and grades 3 and 4 neutropenia in 27 (45%). Ten patients developed febrile neutropenia, two of whom died due to sepsis. Prophylactic use of rhG-CSF was eventually required in 93 (28.3%) of 329 administered cycles. Other toxicities were mild.

CONCLUSIONS

The combination of gemcitabine and irinotecan is an active chemotherapy regimen against pancreatic cancer with a 25% ORR. Toxicity was acceptable for the great majority of patients but with a high percentage of hematopoietic growth factor administration.

Liposomally targeted cytotoxic drugs for the treatment of cancer

Phospholipid spherules composed of lipid bilayer membranes entrapping a central aqueous core were first described more than 30 years ago (Bangham et al 1965). The term liposome was coined in 1968 (Sessa & Weissmann 1968) and the first suggestions that these vesicles might have potential as vehicles for targeted drug delivery for a range of diseases, including cancer, appeared shortly afterwards (Gregoriades et al 1974; Gregoriades 1976a, b). However, the process of turning this expectation into a clinical reality has suffered a number of setbacks and has taken more than a quarter of a century. In the process, new types of liposomes with favourable in-vivo pharmacokinetics and biodistribution patterns have been generated (Lasic & Papahadjopoulos 1995). Many of these preparations have been subjected to extensive examination and an increasing number of agents have entered clinical trials. In this review, we will trace the development of those liposomes that are currently undergoing (or are about to undergo) clinical evaluation.

New drugs for patients with pancreatic cancer

This past year has proved to be a relatively disappointing one for the development of agents that could improve the survival rates of patients with advanced pancreatic cancer. A well designed randomized trial of treatment of patients with gemcitabine with or without a farnesyl transferase inhibitor (tried because pancreatic cancers have a high incidence of K- abnormalities) showed no improvement in survival rates. A definitive randomized controlled trial with a histone deacetylase inhibitor also proved negative. There are some signs of hope in that in early nonrandomized studies there are some new agents that appear to have some activity against the disease. These agents include the thymidylate synthase inhibitor capecitabine (which is possibly activated at the tumor site), the antigastrin immunogen G17DT (which is an immunization designed to neutralize the pancreatic growth factor gastrin), and the topoisomerase I inhibitor 9-nitrocamptothecin. In addition, the combination of the new agent oxaliplatin to high-dose 5FU plus leucovorin, which gave a median survival rate of 12.5 months, is also worthy of further study. Supportive care findings of interest for the patient with advanced pancreatic cancer of note include: the study in which eicosapentaenoic acid (fish oil) caused a modest weight gain (median of 1 kg), and the finding that ofloxacin plus ursodeoxycholic acid was not superior to ursodeoxycholic acid alone for the prevention or occlusion of biliary stents.