A cell-delivered and cell-activated SN38-dextran prodrug increases survival in a murine disseminated pancreatic cancer model

Irinotecan-Induced Toxicity: A Pharmacogenetic Study Beyond UGT1A1

BACKGROUND AND OBJECTIVE

Side effects of irinotecan treatment can be dose limiting and may impair quality of life. In this study, we investigated the correlation between single nucleotide polymorphisms (SNPs) in genes encoding enzymes involved in the irinotecan metabolism and transport, outside UGT1A1, and irinotecan-related toxicity. We focused on carboxylesterases, which are involved in formation of the active metabolite SN-38 and on drug transporters.

METHODS

Patients who provided written informed consent at the Erasmus Medical Center Cancer Institute to the Code Geno study (local protocol: MEC02-1002) or the IRI28-study (NTR-6612) were enrolled in the study and were genotyped for 15 SNPs in the genes CES1, CES2, SLCO1B1, ABCB1, ABCC2, and ABCG2.

RESULTS

From 299 evaluable patients, 86 patients (28.8%) developed severe irinotecan-related toxicity. A significantly higher risk of toxicity was seen in ABCG2 c.421C>A variant allele carriers (P = 0.030, OR 1.88, 95% CI 1.06-3.34). Higher age was associated with all grade diarrhea (P = 0.041, OR 1.03, 95% CI 1.00-1.06). In addition, CES1 c.1165-41C>T and CES1 n.95346T>C variant allele carriers had a lower risk of all-grade thrombocytopenia (P = 0.024, OR 0.42, 95% CI 0.20-0.90 and P = 0.018, OR 0.23, 95% CI 0.08-0.79, respectively).

CONCLUSION

Our study indicates that ABCG2 and CES1 SNPs might be used as predictive markers for irinotecan-induced toxicity.

Macrophage-based delivery of anti-fibrotic proteins alleviates bleomycin-induced pulmonary fibrosis in mice

Idiopathic pulmonary fibrosis (IPF) is a fatal interstitial lung disease characterized by chronic, progressive, and fibrotic lung injury. Although remarkable progress has been made toward understanding the pathogenesis of PF, finding more effective treatments for this fatal disease remains a challenge. In this study, we describe an innovative macrophage-based approach to deliver anti-fibrotic protein to the lung and inhibit PF in a mouse model of bleomycin (BLM)-induced lung injury. We engineered macrophages to continuously secrete three types of proteins: interleukin-10, which prevents inflammation; TGFRcFc, a soluble truncated TGF-βR2 that blocks TGF-β; and CD147, which induces matrix metalloproteinases (MMPs) and causes collagen degradation. Infusing these engineered macrophages into the lungs of BLM-induced PF mouse models in an optimal pattern significantly ameliorated PF in mice. Specifically, the most effective therapeutic outcome was achieved by infusing IL-10-secreting macrophages on day 1, followed by TGFRcFc-secreting macrophages on day 7 and CD147-secreting macrophages on day 14 into the same mice after BLM treatment. Our data suggest that macrophage-based delivery of anti-fibrotic proteins to the lungs is a promising therapy for fibrotic lung disorders.

Advances in nuclei targeted delivery of nanoparticles for the management of cancer

A carrier is inserted into the appropriate organelles (nucleus) in successful medication transport, crucial to achieving very effective illness treatment. Cell-membrane targeting is the major focus of using nuclei to localize delivery. It has been demonstrated that high quantities of anticancer drugs can be injected directly into the nuclei of cancer cells, causing the cancer cells to die and increasing the effectiveness of chemotherapy. There are several effective ways to functionalize Nanoparticles (NPs), including changing their chemical makeup or attaching functional groups to their surface to increase their ability to target organelles. To cause tumor cells to apoptosis, released medicines must engage with molecular targets on particular organelles when their concentration is high enough. Targeted medication delivery studies will increasingly focus on organelle-specific delivery.

A Membrane-Embedded Macromolecular Catalyst with Substrate Selectivity in Live Cells

Substrate selectivity is one of the most attractive features of natural enzymes from their "bind-to-catalyze" working flow and is thus a goal for the development of synthetic enzyme mimics that mediate abiotic transformations. However, despite the recent success in the preparation of substrate-selective enzyme mimics based on single-chain nanoparticles, examples extending such selectivity into living systems have been absent. In this article, we report the in cellulo substrate selectivity of an enzyme-mimicking macromolecular catalyst based on a cationic dense-shell nanoparticle (DSNP) scaffold. With a systematic study on DSNP's structure-activity relationship, we demonstrate that the DSNP has excellent membrane affinity that is governed by several contributing factors, namely, charge density, type of charge, and particle size, and the best-performing phosphonium-rich DSNP can be used as a membrane-embedded catalyst (MEC) for efficient on-membrane synthesis. Importantly, the DSNP catalyst retains its selectivity toward lipophilic and anionic substrates when working as an MEC for on-membrane ligation. The usefulness of such substrate selectivity and on-membrane catalysis strategy was exemplified with several molecules of interest with low cell permeability and anionic nature, which were successfully transported into eukaryotic cells by after their formation directly on the cell membrane.

Targeted Cellular Micropharmacies: Cells Engineered for Localized Drug Delivery

The recent emergence of engineered cellular therapies, such as Chimeric antigen receptor (CAR) CAR T and T cell receptor (TCR) engineered T cells, has shown great promise in the treatment of various cancers. These agents aggregate and expand exponentially at the tumor site, resulting in potent immune activation and tumor clearance. Moreover, the ability to elaborate these cells with therapeutic agents, such as antibodies, enzymes, and immunostimulatory molecules, presents an unprecedented opportunity to specifically modulate the tumor microenvironment through cell-mediated drug delivery. This unique pharmacology, combined with significant advances in synthetic biology and cell engineering, has established a new paradigm for cells as vectors for drug delivery. Targeted cellular micropharmacies (TCMs) are a revolutionary new class of living drugs, which we envision will play an important role in cancer medicine and beyond. Here, we review important advances and considerations underway in developing this promising advancement in biological therapeutics.

How to use macrophages to realise the treatment of tumour

Macrophages (Mø) are immune cells with natural phagocytic ability and play an important role in tumorigenesis, development and metastasis. Mø play a dual role of tumour inhibition and tumour promotion in tumour development due to their two different phenotypes. Mø in the tumour microenvironment have long been referred to as tumour-associated Mø (TAMs). Mø are mainly involved in tumour resistance, cancer metastasis and mediating immunosuppression. Nowadays, Mø and Mø membranes have been widely used in drug delivery systems (DDSs) because of their good biocompatibility, natural phagocytosis and their important role in tumour development. In this review, from the perspective of Mø's role in tumour development, we present strategies and drugs of Mø targeting and focusing on the several types of biomimetic nanoparticles constructed by Mø and Mø membranes in tumour therapy, and discuss the problem of this delivery system in present research and future directions.

A Bird's-Eye View of Cell Sources for Cell-Based Therapies in Blood Cancers

: Hematological malignancies comprise over a hundred different types of cancers and account for around 6.5% of all cancers. Despite the significant improvements in diagnosis and treatment, many of those cancers remain incurable. In recent years, cancer cell-based therapy has become a promising approach to treat those incurable hematological malignancies with striking results in different clinical trials. The most investigated, and the one that has advanced the most, is the cell-based therapy with T lymphocytes modified with chimeric antigen receptors. Those promising initial results prepared the ground to explore other cell-based therapies to treat patients with blood cancer. In this review, we want to provide an overview of the different types of cell-based therapies in blood cancer, describing them according to the cell source.

Individualization of Irinotecan Treatment: A Review of Pharmacokinetics, Pharmacodynamics, and Pharmacogenetics

Since its clinical introduction in 1998, the topoisomerase I inhibitor irinotecan has been widely used in the treatment of solid tumors, including colorectal, pancreatic, and lung cancer. Irinotecan therapy is characterized by several dose-limiting toxicities and large interindividual pharmacokinetic variability. Irinotecan has a highly complex metabolism, including hydrolyzation by carboxylesterases to its active metabolite SN-38, which is 100- to 1000-fold more active compared with irinotecan itself. Several phase I and II enzymes, including cytochrome P450 (CYP) 3A4 and uridine diphosphate glucuronosyltransferase (UGT) 1A, are involved in the formation of inactive metabolites, making its metabolism prone to environmental and genetic influences. Genetic variants in the DNA of these enzymes and transporters could predict a part of the drug-related toxicity and efficacy of treatment, which has been shown in retrospective and prospective trials and meta-analyses. Patient characteristics, lifestyle and comedication also influence irinotecan pharmacokinetics. Other factors, including dietary restriction, are currently being studied. Meanwhile, a more tailored approach to prevent excessive toxicity and optimize efficacy is warranted. This review provides an updated overview on today’s literature on irinotecan pharmacokinetics, pharmacodynamics, and pharmacogenetics.

Macrophages as delivery vehicles for anticancer agents

The delivery of anticancer agents via passive approaches such as the enhanced permeability and retention effect is unlikely to achieve sufficient concentrations throughout the tumor volume for effective treatment. Cell-based delivery approaches using tumor tropic cells have the potential to overcome the limitations of passive approaches. Specifically, this review focuses on the use of monocytes/macrophages for the delivery of a variety of anticancer agents, including nanoparticles, chemotherapeutics and gene constructs. The efficacy of this delivery approach, both as monotherapy and in combination with light-based phototherapy modalities, has been demonstrated in numerous in vitro and animal studies, however, its clinical potential remains to be determined.

Vascular endothelial growth factor-modified macrophages accelerate reendothelialization and attenuate neointima formation after arterial injury in atherosclerosis-prone mice

Vascular endothelial growth factor (VEGF) is a promising molecule for cardiovascular diseases therapy. But lack of a targeted delivery system limits its translation into clinical application. This study aimed to develop stably overexpressing VEGF macrophages for targeted VEGF delivery to injured arteries and determine their potential for repairing of the damaged endothelium. Wire-induced carotid artery injury model was established in atherosclerosis-prone mice. It was observed that the VEGF-modified macrophages were recruited to the site of vascular injury and incorporated into new endothelium formation. VEGF-modified macrophages therapy accelerated reendothelialization and attenuated neointima formation. The VEGF protein level in tissues of injured arteries treated with VEGF-modified macrophages was increased. The upregulated C-C chemokine receptor type 5 (CCR5) and unaltered CCR2 protein levels were verified in VEGF-modified macrophages in vitro. Moreover, enhanced nitric oxide (NO) production in the culture medium of VEGF-modified macrophages was demonstrated. Our results indicated that VEGF-modified macrophages acted as vectors of VEGF targeting injured arteries, promoting the repairing directly by incorporating into new endothelium formation and indirectly by secreting sustainable VEGF and producing NO locally. This study represents a novel therapeutic application of targeted cell therapy with VEGF-modified macrophages for cardiovascular diseases.

Hydrophobized SN38 to redox-hypersensitive nanorods for cancer therapy

Redox-hypersensitive hydrophobized SN38 self-assembled into rod-shaped nanoaggregates with uncompromised in vitro cytotoxicity and potent in vivo antitumor effects.

SN38-loaded <100 nm targeted liposomes for improving poor solubility and minimizing burst release and toxicity: in vitro and in vivo study

Background

SN38 (7-ethyl-10-hydroxycamptothecin) is a camptothecin derivative acts against various tumors. However, SN38 is hydrolyzed in the physiological environment (pH 7.4), and this instability interferes with its potential therapeutic effect. Our objective was to investigate SN38-loaded liposomes to overcome the poor solubility of SN38 and its biodistribution, which further diminish its toxicity.

Materials and methods

The sub-100 nm targeted liposomes was employed to deliver SN-38 and evaluate the characterization, release behaviors, cytotoxicity, in vivo pharmacokinetics and biochemical assay.

Results

The SN38-loaded targeted liposomes consisted of small (100.49 nm) spherical nanoparticles with negative charge (−37.93 mV) and high entrapment efficiency (92.47%). The release behavior of the SN38-loaded targeted liposomes was fitted with Higuchi kinetics (R²=0.9860). Free SN38 presented initial burst release. The IC₅₀ for the SN38-loaded targeted liposomes (0.11 μM) was significantly lower than for the SN38 solution (0.37 μM) in the MCF7 cell line (P<0.01). Confocal laser scanning microscopy also confirmed highly efficient accumulation in the MCF7 cells. Pharmacokinetics demonstrated that the SN38-loaded targeted liposomes had a slightly increased half-life and mean residence time and decreased area under the concentration–time curve and maximum concentration. The results suggested that retention was achieved while the exposure of SN38 was significantly decreased. A noninvasive in vivo imaging system also showed that the targeted liposomes selectively targeted MCF7 tumors. In vivo toxicity data demonstrated that the decrease in platelets was significantly improved by SN38-loaded targeted liposomes, and diarrhea was not observed in BALB/c mice.

Conclusion

In summary, SN38-loaded targeted liposomes could be a good candidate for application in human breast cancer.

Peptide nanosponges designed for rapid uptake by leukocytes and neural stem cells

The structure of novel binary nanosponges consisting of (cholesterol-(K/D)_nDEVDGC)₃-trimaleimide units possessing a trigonal maleimide linker, to which either lysine (K)₂₀ or aspartic acid (D)₂₀ are tethered, has been elucidated by means of TEM. A high degree of agreement between these findings and structure predictions through explicit solvent and then coarse-grained molecular dynamics (MD) simulations has been found. Based on the nanosponges' structure and dynamics, caspase-6 mediated release of the model drug 5(6)-carboxyfluorescein has been demonstrated. Furthermore, the binary (DK20) nanosponges have been found to be virtually non-toxic in cultures of neural progenitor cells. It is of a special importance for the future development of cell-based therapies that DK20 nanosponges were taken up efficiently by leucocytes (WBC) in peripheral blood within 3 h of exposure. The percentage of live cells among the WBC was not significantly decreased by the DK20 nanosponges. In contrast to stem cell or leucocyte cell cultures, which have to be matched to the patient, autologous cells are optimal for cell-mediated therapy. Therefore, the nanosponges hold great promise for effective cell-based tumor targeting.

Nanosponges for drug delivery.

Dual 7-ethyl-10-hydroxycamptothecin conjugated phospholipid prodrug assembled liposomes with in vitro anticancer effects

7-Ethyl-10-hydroxycamptothecin (SN38), as a highly active topoisomerase I inhibitor, is 200-2000-fold more cytotoxic than irinotecan (CPT-11) commercially available as Camptosar®. However, poor solubility and low stability extensively restricted its clinical utility. In this report, dual SN38 phospholipid conjugate (Di-SN38-PC) prodrug based liposomes were developed in order to compact these drawbacks. Di-SN38-PC prodrug was first synthesized by inhomogeneous conjugation of two SN38-20-O-succinic acid molecules with L-α-glycerophosphorylcholine (GPC). The assembly of the prodrug was carried out without any excipient by using thin film method. Dynamic light scattering (DLS), transmission electron microscope (TEM) and cryogenic transmission electron microscopy (cyro-TEM) characterization indicated that Di-SN38-PC can form spherical liposomes with narrow particle size (<200nm) and negatively charged surface (-21.6±3.5mV). The loading efficiency of SN38 is 65.2 wt.% after a simple calculation. In vitro release test was further performed in detail. The results demonstrated that Di-SN38-PC liposomes were stable in neutral environment but degraded in a weakly acidic condition thereby released parent drug SN38 effectively. Cellular uptake studies reflected that the liposomes could be internalized into cells more significantly than SN38. In vitro antitumor activities were finally evaluated by MTT assay, colony formation assay, flow cytometry, RT-PCR analysis and Western Blot. The results showed that Di-SN38-PC liposomes had a comparable cytotoxicity with SN38 against MCF-7 and HBL-100, and a selective promotion of apoptosis of tumor cells. Furthermore, a pharmacokinetics test showed that Di-SN38-PC liposomes had a longer circulating time in blood compared with the parent drug. All the results indicate that Di-SN38-PC liposomes are an effective delivery system of SN38.

Macrophage-based cell therapies: The long and winding road

In the quest for better medicines, attention is increasingly turning to cell-based therapies. The rationale is that infused cells can provide a targeted therapy to precisely correct a complex disease phenotype. Between 1987 and 2010, autologous macrophages (MΦs) were used in clinical trials to treat a variety of human tumors; this approach provided a modest therapeutic benefit in some patients but no lasting remissions. These trials were initiated prior to an understanding of: the complexity of MΦ phenotypes, their ability to alter their phenotype in response to various cytokines and/or the environment, and the extent of survival of the re-infused MΦs. It is now known that while inflammatory MΦs can kill tumor cells, the tumor environment is able to reprogram MΦs into a tumorigenic phenotype; inducing blood vessel formation and contributing to a cancer cell growth-promoting milieu. We review how new information enables the development of large numbers of ex vivo generated MΦs, and how conditioning and gene engineering strategies are used to restrict the MΦ to an appropriate phenotype or to enable production of therapeutic proteins. We survey applications in which the MΦ is loaded with nanomedicines, such as liposomes ex vivo, so when the drug-loaded MΦs are infused into an animal, the drug is released at the disease site. Finally, we also review the current status of MΦ biodistribution and survival after transplantation into an animal. The combination of these recent advances opens the way for improved MΦ cell therapies.

Chemotherapeutic agent CPT-11 eliminates peritoneal resident macrophages by inducing apoptosis

CPT-11 (Irinotecan) is a first-line chemotherapeutic agent in clinic, but it may induce side effects including diarrhea and enteritis in patients. The underlying mechanism of CPT-11's intestinal toxicity is unclear. Peritoneal resident macrophages have been reported to be important for the maintenance of intestinal homeostasis. In this study, we evaluated the cytotoxic effects of CPT-11 on mouse peritoneal resident macrophages. CPT-11 was administered intraperitoneally to mice and their peritoneal exudate cells were isolated for evaluation. CPT-11 treatment strikingly decreased the ratio of F4/80(hi)MHCII(low) large peritoneal macrophages (LPMs), which are regarded as prenatally-originated peritoneal resident macrophages. Consistent with this, the transcription factor GATA6 specifically expressed in LPMs was barely detectable in the macrophages from CPT-11-treated mice, indicative of elimination of LPMs. Such elimination of LPMs was at least partly due to CPT-induced apoptosis in macrophages, because inhibition of apoptosis by caspase-3 inhibitor z-DEVD-fmk significantly diminished the loss of GATA6(+) LPMs. As GATA6 is a transcription factor that controls expression of multiple genes regulating peritoneal B-1 cell development and translocation, elimination of GATA6(+) LPMs led to a great reduction in B-1 cells in the peritoneal cavity after CPT-11 treatment. These results indicated that CPT-11-induced apoptosis contributed to the elimination of peritoneal resident macrophages, which might in turn impair the function of peritoneal B-1 cells in maintaining intestinal homeostasis. Our findings may at least partly explain why CPT-11 treatment in cancer patients induces diarrhea and enteritis, which may provide a novel avenue to prevent such side effects.

Challenges in SN38 drug delivery: current success and future directions

INTRODUCTION

Clinical use of SN38 is limited by its poor aqueous solubility and hydrolysis of the lactone ring at pH > 6 to inactive carboxylate form. A variety of drug delivery systems have been developed to improve the solubility and stability of SN38, and reduce its toxicity. A few noteworthy formulations with some success in initial phases of clinical trials are reported.

AREAS COVERED

This work aims to provide a comprehensive review on the various techniques and strategies employed (physical, chemical and biological methods) to improve physicochemical properties and to deliver the drug efficiently to the cancer cells. Physical methods such as nanoparticle encapsulation, cyclodextrin complexation; chemical methods such as prodrugs, polymer-, albumin- and immunoconjugates; and enzyme activated prodrug therapy are discussed.

EXPERT OPINION

The challenges in SN38 drug delivery may be overcome by two ways: ensuring multiple layers of protection against degradation and slow but sustained release of therapeutically effective drug concentrations. It may also be achieved by preparing a polymer-drug conjugate and further encapsulating the conjugate in suitable carrier system; tumor-targeted SN38 delivery by using immunoconjugates, enzyme-activated prodrug therapy and antibody-directed nanoparticle delivery. However, selection of a suitable ligand for tumor targeting and use of safe and biocompatible nanoparticle systems play an important role in realizing this goal.

Current Approaches for Improving Intratumoral Accumulation and Distribution of Nanomedicines

The ability of nanoparticles and macromolecules to passively accumulate in solid tumors and enhance therapeutic effects in comparison with conventional anticancer agents has resulted in the development of various multifunctional nanomedicines including liposomes, polymeric micelles, and magnetic nanoparticles. Further modifications of these nanoparticles have improved their characteristics in terms of tumor selectivity, circulation time in blood, enhanced uptake by cancer cells, and sensitivity to tumor microenvironment. These "smart" systems have enabled highly effective delivery of drugs, genes, shRNA, radioisotopes, and other therapeutic molecules. However, the resulting therapeutically relevant local concentrations of anticancer agents are often insufficient to cause tumor regression and complete elimination. Poor perfusion of inner regions of solid tumors as well as vascular barrier, high interstitial fluid pressure, and dense intercellular matrix are the main intratumoral barriers that impair drug delivery and impede uniform distribution of nanomedicines throughout a tumor. Here we review existing methods and approaches for improving tumoral uptake and distribution of nano-scaled therapeutic particles and macromolecules (i.e. nanomedicines). Briefly, these strategies include tuning physicochemical characteristics of nanomedicines, modulating physiological state of tumors with physical impacts or physiologically active agents, and active delivery of nanomedicines using cellular hitchhiking.

Macrophage mediated biomimetic delivery system for the treatment of lung metastasis of breast cancer

The biomimetic delivery system (BDS) based on special types of endogenous cells like macrophages and T cells, has been emerging as a novel strategy for cancer therapy, due to its tumor homing property and biocompatibility. However, its development is impeded by complicated construction, low drug loading or negative effect on the cell bioactivity. The present report constructed a BDS by loading doxorubicin (DOX) into a mouse macrophage-like cell line (RAW264.7). It was found that therapeutically meaningful amount of DOX could be loaded into the RAW264.7 cells by simply incubation, without significantly affecting the viability of the cells. Drug could release from the BDS and maintain its activity. RAW264.7 cells exhibited obvious tumor-tropic capacity towards 4T1 mouse breast cancer cells both in vitro and in vivo, and drug loading did not alter this tendency. Importantly, the DOX loaded macrophage system showed promising anti-cancer efficacy in terms of tumor suppression, life span prolongation and metastasis inhibition, with reduced toxicity. In conclusion, it is demonstrated that the BDS developed here seems to overcome some of the main issues related to a BDS. The DOX loaded macrophages might be a potential BDS for targeted cancer therapy.

Attenuated Toxoplasma gondii Stimulates Immunity to Pancreatic Cancer by Manipulation of Myeloid Cell Populations

Suppressive myeloid cells represent a significant barrier to the generation of productive antitumor immune responses to many solid tumors. Eliminating or reprogramming suppressive myeloid cells to abrogate tumor-associated immune suppression is a promising therapeutic approach. We asked whether treatment of established aggressive disseminated pancreatic cancer with the immunotherapeutic attenuated Toxoplasma gondii vaccine strain CPS would trigger tumor-associated myeloid cells to generate therapeutic antitumor immune responses. CPS treatment significantly decreased tumor-associated macrophages and markedly increased dendritic cell infiltration of the pancreatic tumor microenvironment. Tumor-resident macrophages and dendritic cells, particularly cells actively invaded by CPS, increased expression of costimulatory molecules CD80 and CD86 and concomitantly boosted their production of IL12. CPS treatment increased CD4(+) and CD8(+) T-cell infiltration into the tumor microenvironment, activated tumor-resident T cells, and increased IFNγ production by T-cell populations. CPS treatment provided a significant therapeutic benefit in pancreatic tumor-bearing mice. This therapeutic benefit depended on IL12 and IFNγ production, MyD88 signaling, and CD8(+) T-cell populations. Although CD4(+) T cells exhibited activated effector phenotypes and produced IFNγ, CD4(+) T cells as well as natural killer cells were not required for the therapeutic benefit. In addition, CD8(+) T cells isolated from CPS-treated tumor-bearing mice produced IFNγ after re-exposure to pancreatic tumor antigen, suggesting this immunotherapeutic treatment stimulated tumor cell antigen-specific CD8(+) T-cell responses. This work highlights the potency and immunotherapeutic efficacy of CPS treatment and demonstrates the significance of targeting tumor-associated myeloid cells as a mechanism to stimulate more effective immunity to pancreatic cancer.

“AND” logic gate regulated pH and reduction dual-responsive prodrug nanoparticles for efficient intracellular anticancer drug delivery

A copper ion-based core-cross-linking strategy is used to develop an AND logic gate regulated pH-/reduction-responsive antitumor drug delivery system.

Cells as delivery vehicles for cancer therapeutics

Cell-based therapeutics have advanced significantly over the past decade and are poised to become a major pillar of modern medicine. Three cell types in particular have been studied in detail for their ability to home to tumors and to deliver a variety of different payloads. Neural stem cells, mesenchymal stem cells and monocytes have each been shown to have great potential as future delivery systems for cancer therapy. A variety of other cell types have also been studied. These results demonstrate that the field of cell-based therapeutics will only continue to grow.

Prodrug and nanomedicine approaches for the delivery of the camptothecin analogue SN38

SN38 (7-ethyl-10-hydroxy camptothecin) is a prominent and efficacious anticancer agent. It is poorly soluble in both water and pharmaceutically approved solvents; therefore, the direct formulation of SN38 in solution form is limited. Currently, the water soluble prodrug of SN38, irinotecan (CPT-11), is formulated as a low pH solution and is approved for chemotherapy. However, CPT-11, along with most other water-soluble prodrugs shows unpredictable inter-patient conversion to SN38 in vivo, instability in the physiological environment and variable dose-related toxicities. More recently, macromolecular prodrugs (i.e. EZN-2208, IMMU-130) and nanomedicine formulations (i.e. nanoemulsions, polymeric micelles, lipid nanocapsule/nanoparticle, and liposomes) of SN38 have been investigated for improved delivery to cancer cells and tissues. Specifically, these carriers can take advantage of the EPR effect to direct drug preferentially to tumour tissues, thereby substantially improving efficacy and minimising side effects. Furthermore, oral delivery has been shown to be possible in preclinical results using nanomedicine formulations (i.e. dendrimers, lipid nanocapsules, polymeric micelles). This review summarizes the recent advances for the delivery of SN38 with a focus on macromolecular prodrugs and nanomedicines.

Magnetic-Fe/Fe(3)O(4)-nanoparticle-bound SN38 as carboxylesterase-cleavable prodrug for the delivery to tumors within monocytes/macrophages

The targeted delivery of therapeutics to the tumor site is highly desirable in cancer treatment, because it is capable of minimizing collateral damage. Herein, we report the synthesis of a nanoplatform, which is composed of a 15 ± 1 nm diameter core/shell Fe/Fe(3)O(4) magnetic nanoparticles (MNPs) and the topoisomerase I blocker SN38 bound to the surface of the MNPs via a carboxylesterase cleavable linker. This nanoplatform demonstrated high heating ability (SAR = 522 ± 40 W/g) in an AC-magnetic field. For the purpose of targeted delivery, this nanoplatform was loaded into tumor-homing double-stable RAW264.7 cells (mouse monocyte/macrophage-like cells (Mo/Ma)), which have been engineered to express intracellular carboxylesterase (InCE) upon addition of doxycycline by a Tet-On Advanced system. The nanoplatform was taken up efficiently by these tumor-homing cells. They showed low toxicity even at high nanoplatform concentration. SN38 was released successfully by switching on the Tet-On Advanced system. We have demonstrated that this nanoplatform can be potentially used for thermochemotherapy. We will be able to achieve the following goals: (1) Specifically deliver the SN38 prodrug and magnetic nanoparticles to the cancer site as the payload of tumor-homing double-stable RAW264.7 cells; (2) Release of chemotherapeutic SN38 at the cancer site by means of the self-containing Tet-On Advanced system; (3) Provide localized magnetic hyperthermia to enhance the cancer treatment, both by killing cancer cells through magnetic heating and by activating the immune system.