A novel combination of TRAIL and doxorubicin enhances antitumor effect based on passive tumor-targeting of liposomes.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a novel anticancer agent for non-small cell lung cancer (NSCLC). However, approximately half of NSCLC cell lines are highly resistant to TRAIL. Doxorubicin (DOX) can sensitize NSCLC cells to TRAIL-induced apoptosis, indicating the possibility of combination therapy. Unfortunately, the therapeutic effect of a DOX and TRAIL combination is limited by multiple factors including the short serum half-life of TRAIL, poor compliance and application difficulty in the clinic, chronic DOX-induced cardiac toxicity, and the multidrug resistance (MDR) property of NSCLC cells. To solve such problems, we developed the combination of TRAIL liposomes (TRAIL-LP) and DOX liposomes (DOX-LP). An in vitro cytotoxicity study indicated that DOX-LP sensitized the NSCLC cell line A-549 to TRAIL-LP-induced apoptosis. Furthermore, this combination therapy of TRAIL-LP and DOX-LP displayed a stronger antitumor effect on NSCLC in xenografted mice when compared with free drugs or liposomal drugs alone. Therefore, the TRAIL-LP and DOX-LP combination therapy has excellent potential to become a new therapeutic approach for patients with advanced NSCLC.

Liposome-bound APO2L/TRAIL is an effective treatment in a rabbit model of rheumatoid arthritis.

OBJECTIVE: We previously observed that T lymphocytes present in synovial fluid (SF) from patients with rheumatoid arthritis (RA) were sensitive to APO2L/TRAIL. In addition, there was a drastic decrease in the amount of bioactive APO2L/TRAIL associated with exosomes in SF from RA patients. This study was undertaken to evaluate the effectiveness of bioactive APO2L/TRAIL conjugated with artificial lipid vesicles resembling natural exosomes as a treatment in a rabbit model of antigen-induced arthritis (AIA). METHODS: We used a novel Ni(2+)-(N-5-amino-1-carboxypentyl)-iminodiacetic acid)-containing liposomal system. APO2L/TRAIL bound to liposomes was intraarticularly injected into the knees of animals with AIA. One week after treatment, rabbits were killed, and arthritic synovial tissue was analyzed. RESULTS: Tethering APO2L/TRAIL to the liposome membrane increased its bioactivity and resulted in more effective treatment of AIA compared with soluble, unconjugated APO2L/TRAIL, with substantially reduced synovial hyperplasia and inflammation in rabbit knee joints. The results of biophysical studies suggested that the increased bioactivity of APO2L/TRAIL associated with liposomes was due to the increase in the local concentration of the recombinant protein, augmenting its receptor crosslinking potential, and not to conformational changes in the protein. In spite of this increase in bioactivity, the treatment lacked systemic toxicity and was not hepatotoxic. CONCLUSION: Our findings indicate that binding APO2L/TRAIL to the liposome membrane increases its bioactivity and results in effective treatment of AIA.

The combination of ADI-PEG20 and TRAIL effectively increases cell death in melanoma cell lines.

Current treatment for advanced, metastatic melanoma is not very effective, and new modalities are needed. ADI-PEG20 is a drug that specifically targets ASS-negative malignant melanomas while sparing the ASS-expressing normal cells. Although laboratory research and clinical trials showed promising results, there are some ASS-negative cell lines and patients that can develop resistance to this drug. In this report, we combined ADI-PEG20 with another antitumor drug TRAIL to increase the killing of malignant melanoma cells. This combination can greatly inhibit cell growth (to over 80%) and also enhanced cell death (to over 60%) in four melanoma cell lines tested compared with control. We found that ADI-PEG20 could increase the cell surface receptors DR4/5 for TRAIL and that caspase activity correlated with the increased cell death. These two drugs could also increase the level of Noxa while decrease that of survivin. We propose that these two drugs can complement each other by activating the intrinsic and extrinsic apoptosis pathways, thus enhance the killing of melanoma cells.

Glutathione-Specific and Intracellularly Labile Polymeric Nanocarrier for Efficient and Safe Cancer Gene Delivery.

Cationic polymers condense nucleic acids into nanosized complexes (polyplexes) that are widely explored for nonviral gene delivery, but their strong electrostatic binding with DNA causes inefficient intracellular gene release and translation and thereby unsatisfactory gene transfection efficiencies. Facilitated intracellular dissociation of polyplexes by making the polymer undergo positive-to-negative/neutral charge reversal can effectively solve these problems, but they must be sufficiently stable during the delivery. Herein, we report the first glutathione (GSH)-specific intracellular labile polyplexes for cancer-targeted gene delivery. The polymers are made from p-(2,4-dinitrophenyloxybenzyl)-ammonium cationic moieties, whose p-2,4-dinitrophenyl ether is cleaved specifically by GSH, rather than other biological thiols, triggering the conversion of the ammonium cation into the carboxylate anion and thus the fast intracellular DNA release of the polyplexes. Furthermore, the polyplexes coated with PEG-functionalized lipids are stable in biological fluids to gain long blood circulation for tumor accumulation. Thus, the efficient tumor accumulation and cell transfection of the polyplexes loaded with the tumor suicide gene tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) give rise to potent antitumor activity similar to that of the first-line chemotherapy drug paclitaxel but with much less adverse effects.

TRAIL encapsulated to polypeptide-crosslinked nanogel exhibits increased anti-inflammatory activities in Klebsiella pneumoniae-induced sepsis treatment.

Bacterial infections are often treated inadequately. Sepsis, being one of its most severe forms, is a multi-layered, life-threatening syndrome induced by rampant immune responses, like cytokine storms, that leads to high morbidity and death of infected patients. Particularly, the current increment in resistant bacterial strains and the lack of creative antibiotics to counter such menace are central reasons to the worsening of the situation. To avoid the said crisis, the antimicrobial peptides (AMPs) were used to target cell wall components, such as lipopolysaccharides (LPS), seems to have the most promise. These combine the ability of broad-spectrum bactericidal activity with low potential for induction of resistance. Inhibition of cytokine storms induced by activated immune cells has been considered a feasible treatment for in sepsis. One of the therapeutic approaches widely utilized in inducing apoptosis in inflammatory cells is the use of tumor necrosis factor (TNF)-related apoptosis-inducing ligands (TRAIL), which trigger an extrinsic apoptotic pathway via death receptors. Herein, we report TRAIL encapsulated in a bactericidal polypeptide-crosslinked nanogel that suppressed Klebsiella pneumoniae infection and overactive macrophages. Of interest, nanogel and TRAIL-nanogel treatments were more toxic towards LPS-activated cells than to naïve cells in cell viability assays. Treatment with TRAIL-nanogel significantly prolonged survival in septic mice and reduced bacterial numbers in circulation. As such, TRAIL-nanogel may be promising as a therapeutic agent for treating bacteria-infected diseases.

Facile synthesis of semi-library of low charge density cationic polyesters from poly(alkylene maleate)s for efficient local gene delivery.

Cationic polymers are one of the main non-viral vectors for gene therapy, but their applications are hindered by the toxicity and inefficient transfection, particularly in the presence of serum or other biological fluids. While rational design based on the current understanding of gene delivery process has produced various cationic polymers with improved overall transfection, high-throughput parallel synthesis of libraries of cationic polymers seems a more effective strategy to screen out efficacious polymers. Herein, we demonstrate a novel platform for parallel synthesis of low cationic charge-density polyesters for efficient gene delivery. Unsaturated polyester poly(alkylene maleate) (PAM) readily underwent Michael-addition reactions with various mercaptamines to produce polyester backbones with pendant amine groups, poly(alkylene maleate mercaptamine)s (PAMAs). Variations of the alkylenes in the backbone and the mercaptamines on the side chain produced PAMAs with tunable hydrophobicity and DNA-condensation ability, the key parameters dominating transfection efficiency of the resulting polymer/DNA complexes (polyplexes). A semi-library of such PAMAs was exampled from 7 alkylenes and 18 mercaptamines, from which a lead PAMA, G-1, synthesized from poly(1,4-phenylene bis(methylene) maleate) and N,N-dimethylcysteamine, showed remarkable transfection efficiency even in the presence of serum, owing to its efficient lysosome-circumventing cellular uptake. Furthermore, G-1 polyplexes efficiently delivered the suicide gene pTRAIL to intraperitoneal tumors and elicited effective anticancer activity.

Polymeric mechanical amplifiers of immune cytokine-mediated apoptosis.

Physical forces affect tumour growth, progression and metastasis. Here, we develop polymeric mechanical amplifiers that exploit in vitro and in vivo physical forces to increase immune cytokine-mediated tumour cell apoptosis. Mechanical amplifiers, consisting of biodegradable polymeric particles tethered to the tumour cell surface via polyethylene glycol linkers, increase the apoptotic effect of an immune cytokine on tumour cells under fluid shear exposure by as much as 50% compared with treatment under static conditions. We show that targeted polymeric particles delivered to tumour cells in vivo amplify the apoptotic effect of a subsequent treatment of immune cytokine, reduce circulating tumour cells in blood and overall tumour cell burden by over 90% and reduce solid tumour growth in combination with the antioxidant resveratrol. The work introduces a potentially new application for a broad range of micro- and nanoparticles to maximize receptor-mediated signalling and function in the presence of physical forces.

PEGylated TRAIL ameliorates experimental inflammatory arthritis by regulation of Th17 cells and regulatory T cells.

TNF-related apoptosis-inducing ligand (TRAIL) is a death ligand that can induce apoptosis in cells expressing its cognate death receptors (DRs). Previously, we demonstrated the therapeutic potential of recombinant human TRAIL in experimental rheumatoid arthritis (RA) models. However, the mechanisms of how DR-mediated apoptosis elicits these actions is not known. Here, we show that systemically administering a potent, long-acting PEGylated TRAIL (TRAILPEG) is profoundly anti-rheumatic against two complementary experimental RA mouse models, collagen-induced arthritis (CIA) and collagen antibody-induced arthritis (CAIA), via targeting IL-17 secreting Th17 cells and regulatory T cells (Treg). Systemic administration of TRAILPEG after disease onset ameliorated the severity of inflammatory arthritis including arthritis indices, paw thickness, cartilage damage and neutrophil infiltration in both CIA and CAIA models. Additionally, the levels of inflammatory molecules (p-p65, ICAM-1, Cox-2, MMP3, and iNOS), pro-inflammatory cytokines (TNF-α, IL-1ß, IFN-γ, IL-6, IL-17) and accumulation of activated macrophages were significantly reduced after the TRAILPEG treatment. Importantly, TRAILPEG decreased the number of pro-inflammatory Th17 cells in inflamed arthritic joints through TRAIL-induced apoptosis while increasing anti-inflammatory Treg population in vivo. These results suggest that TRAILPEG ameliorates autoimmunity by targeting the Th 17-Tregs axis, making it a promising candidate drug for the treatment of RA.

Quinacrine Mediated Sensitization of Glioblastoma (GBM) Cells to TRAIL through MMP-Sensitive PEG Hydrogel Carriers.

Overcoming drug resistance is a major challenge for cancer therapy. Tumor necrosis factor α-related apoptosis-inducing ligand (TRAIL) is a potent therapeutic as an activator of apoptosis, particularly in tumor but not in healthy cells. However, its efficacy is limited by the resistance of tumor cell populations to the therapeutic substance. Here, we have addressed this limitation through the development of a controlled release system, matrix-metalloproteinase (MMP)-sensitive and arg-gly-asp-ser (RGDS) peptide functionalized poly (ethylene-glycol) (PEG) particles which are synthesized via visible-light-induced water-in-water emulsion polymerization. Quinacrine (QC), a recently discovered TRAIL sensitizer drug, is loaded into the hydrogel carriers and the influence of this system on the apoptosis of a malignant type of brain cancer, glioblastoma multiforme (GBM), has been investigated in detail. The results suggest that MMP-sensitive particles are cytocompatible and superior to promote TRAIL-induced apoptosis in GBM cells when loaded with QC. Compared to QC and TRAIL alone, combination of QC-loaded PEG hydrogel and TRAIL demonstrates synergistic apoptotic inducing behavior. Furthermore, QC-loaded particles, but not QC or PEG-hydrogels alone, enhance apoptosis as is measured through expression of apoptosis-related genes. This system is promising to significantly improve the efficacy of chemotherapeutic drugs and suggests a combination treatment for GBM therapy.

TRAIL-coated leukocytes that prevent the bloodborne metastasis of prostate cancer.

Prostate cancer, once it has progressed from its local to metastatic form, is a disease with poor prognosis and limited treatment options. Here we demonstrate an approach using nanoscale liposomes conjugated with E-selectin adhesion protein and Apo2L/TRAIL (TNF-related apoptosis-inducing ligand) apoptosis ligand that attach to the surface of leukocytes and rapidly clear viable cancer cells from circulating blood in the living mouse. For the first time, it is shown that such an approach can be used to prevent the spontaneous formation and growth of metastatic tumors in an orthotopic xenograft model of prostate cancer, by greatly reducing the number of circulating tumor cells. We conclude that the use of circulating leukocytes as a carrier for the anti-cancer protein TRAIL could be an effective tool to directly target circulating tumor cells for the prevention of prostate cancer metastasis, and potentially other cancers that spread through the bloodstream.

In situ facile-forming PEG cross-linked albumin hydrogels loaded with an apoptotic TRAIL protein.

The key to making a practicable hydrogel for pharmaceutical or medical purposes is to endow it with relevant properties, i.e., facile fabrication, gelation time-controllability, and in situ injectability given a firm basis for safety/biocompatibility. Here, the authors describe an in situ gelling, injectable, albumin-cross-linked polyethylene glycol (PEG) hydrogel that was produced using a thiol-maleimide reaction. This hydrogel consists of two biocompatible components, namely, thiolated human serum albumin and 4-arm PEG20k-maleimide, and can be easily fabricated and gelled in situ within 60s by simply mixing its two components. In addition, the gelation time of this system is controllable in the range 15s to 5min. This hydrogel hardly interacted with an apoptotic TRAIL protein, ensuring suitable release profiles that maximize therapeutic efficacy. Specifically, tumors (volume: 278.8mm(3)) in Mia Paca-2 cell-xenografted BALB/c nu/nu mice treated with the TRAIL-loaded HSA-PEG hydrogel were markedly smaller than mice treated with the hydrogel prepared via an amine-N-hydroxysuccinimide reaction or non-treated mice (1275.5mm(3) and 1816.5mm(3), respectively). We believe that this hydrogel would be a new prototype of locally injectable sustained-release type anti-cancer agents, and furthermore offers practical convenience for a doctor and universal applicability for a variety of therapeutic proteins.

Combination of arginine deprivation with TRAIL treatment as a targeted-therapy for mesothelioma.

UNLABELLED: In the present study we present data to show that certain tumor cells including malignant pleural mesothelioma (MPM) cells do not express argininosuccinate synthetase (ASS), and thus are unable to synthesize arginine from citrulline. Exposure of these ASS-negative cells to the arginine degrading enzyme, arginine deiminase (ADI-PEG20), for 72 h results in significant increases in cleaved caspase-3. Importantly, this apoptotic signal is further strengthened by the addition of TNF-related apoptosis-inducing ligand (TRAIL). Using flow cytometry, we showed that the combination treatment (ADI-PEG20 at 50 ng/ml and TRAIL at 10 ng/ml) for 24 h resulted in profound cell death with 67% of cells positive for caspase-3 activity, while ADI-PEG20 alone or TRAIL alone resulted in only 10-15% cell death. This positive amplification loop is mediated through the cleavage of proapototic protein "BID". CONCLUSION: Our work represents a new strategy for treating patients with malignant pleural mesothelioma using targeted molecular therapeutics based on selected tumor markers, thus avoiding the use of potentially cytotoxic chemotherapy.

sTRAIL coupled to liposomes improves its pharmacokinetic profile and overcomes neuroblastoma tumour resistance in combination with Bortezomib.

Neuroblastoma (NB), the most common and deadly extracranial solid tumour of childhood, represents a challenging in paediatric oncology. Soluble tumour necrosis factor (TNF)-related apoptosis-inducing ligand (sTRAIL) is a cancer cell-specific molecule exerting remarkable anti-tumour activities against paediatric malignancies both in vitro and in preclinical settings. However, due to its too fast elimination and to the undesired related side effects, the improvement of sTRAIL in vivo bioavailability and the specific delivery to the tumour is mandatory for increasing its therapeutic efficacy. In this manuscript, we developed an innovative pegylated liposomal formulation carrying the sTRAIL at the outer surface (sTRAIL-SL) with the intent to improve its serum half-life and increase its efficacy in vivo, while reducing side effects. Furthermore, the possibility to combine sTRAIL-SL with the proteasome inhibitor Bortezomib (BTZ) was investigated, being BTZ able to sensitize tumour cells toward TRAIL-induced apoptosis. We demonstrated that sTRAIL preserved and improved its anti-tumour activity when coupled to nanocarriers. Moreover, sTRAIL-SL ameliorated its PK profile in blood allowing sTRAIL to exert a more potent anti-tumour activity, which led, upon BTZ priming, to a statistically significant enhanced life spans in two models of sTRAIL-resistant NB-bearing mice. Finally, mechanistic studies indicated that the combination of sTRAIL with BTZ sensitized sTRAIL-resistant NB tumour cells to sTRAIL-induced cell death, both in vitro and in vivo, through the Akt/GSK3/ß-catenin axis-dependent mechanism. In conclusion, our results suggest that sTRAIL-SL might be an efficient vehicle for sTRAIL delivery and that its use in clinic, in combination with BTZ, might represent an adjuvant strategy for the treatment of stage IV, sTRAIL-resistant, NB patients.

Doxorubicin-loaded porous PLGA microparticles with surface attached TRAIL for the inhalation treatment of metastatic lung cancer.

Inhalable highly porous large PLGA microparticles with incorporated doxorubicin and surface-attached with TRAIL (TRAIL/Dox PLGA MP) were fabricated using a w/o/w double emulsification method using ammonium bicarbonate as a gas-foaming agent for the treatment of lung cancer. The TRAIL/Dox PLGA MP produced were highly porous and 11.5 ± 0.4 µm in diameter, and the loading efficiencies of Dox and TRAIL were 86.5 ± 6.5% and 91.8 ± 2.4%, respectively. TRAIL and doxorubicin were gradually released by TRAIL/Dox PLGA over 7 days, and pulmonary administration resulted in the deposition of TRAIL/Dox PLGA MP in mouse lungs, and they remained in situ for up to a week. The anti-tumor efficacy of pulmonary administered TRAIL/Dox PLGA MP was evaluated in a BALB/c nu/nu mice mouse model of H226 cell metastasis. Tumors in H226-implanted mice treated with TRAIL/Dox PLGA MP were markedly smaller and fewer in number than mice treated with TRAIL or Dox PLGA MP alone. Furthermore, this improved performance was found to be due to the synergistic apoptotic effects of the two drugs. We believe that TRAIL/Dox PLGA MP offer a promise of a sustained-release, long-acting, inhalable anti-lung cancer agent. Furthermore, the synergism observed between TRAIL and doxorubicin suggests that the doxorubicin dosage could be substantially reduced and its side effects minimized.

A sulfate polysaccharide/TNF-related apoptosis-inducing ligand (TRAIL) complex for the long-term delivery of TRAIL in poly(lactic-co-glycolic acid) (PLGA) microspheres.

OBJECTIVES: The aim was to develop a long-term delivery system for Apo2 ligand/tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) without chemical modification (such as pegylation). METHODS: A nanocomplex system between the positively charged TRAIL and the negatively charged chondroitin sulfate (CS) (CS/TRAIL) was designed and applied in poly(lactide-co-glycolide) (PLGA) microspheres (MSs). KEY FINDINGS: A nanocomplex of approximately 200 nm was easily formed in a weight ratio of 2 TRAIL to CS (TC2) at pH 5.0. The cytotoxicity of CS/TRAIL against HeLa cells was similar to that of native TRAIL. The complex also had higher loading efficiency (above 95%) in PLGA MSs prepared by the multi-emulsion method than that of native TRAIL. The release behaviour of TRAIL from the PLGA MSs was monitored. Although the release of TRAIL from native TRAIL-loaded PLGA MSs (TMS0) was almost complete after 3 days, TC2-loaded PLGA MSs (TMS2) showed sustained TRAIL release without an initial burst for 10 days. The released TRAIL from TMS2 led to cytotoxicity accompanied by massive apoptosis of cancer cells. TMS2 significantly inhibited tumour growth in an in-vivo xenograft model in mice, without any loss of body weight after treatment. CONCLUSIONS: From the results, we concluded that TC-loaded PLGA MSs have the potential for long-term delivery of TRAIL without side effects.

In vivo treatment of tumors using host-guest conjugated nanoparticles functionalized with doxorubicin and therapeutic gene pTRAIL.

The combination of gene therapy and chemotherapy may increase the therapeutic efficacy in the treatment of patients. In this work, the anti-cancer drug Dox and therapeutic gene pTRAIL-loaded host-guest co-delivery system was assayed for the possibility of in vivo synergistically treating tumors. The introduced Dox could act as an auxiliary component to human tumor necrosis factor-related apoptosis-inducing ligand-encoding plasmid gene pTRAIL. Such delivery system possessed the good ability of in vivo retention of chemotherapeutic drugs, achieved good therapeutic effects in the inhibition of tumor growth and significantly prolonged the survival time of tumor-bearing mice. With the efficient ability to co-deliver drug and gene, such host-guest assembly should have great potential applications in cancer therapy.

Improved biological half-life and anti-tumor activity of TNF-related apoptosis-inducing ligand (TRAIL) using PEG-exposed nanoparticles.

TRAIL has received considerable attention as a potential anti-cancer agent due to its specific ability to target tumors. However, recombinant TRAIL has several limitations, such as, its short biological half-life, its inherent instability, and its potential hepatotoxicity. In this study, we developed a sustained release nanoparticle formulation of TRAIL and investigated its therapeutic effects in tumor-bearing mice. TRAIL-loaded nanoparticles (NPs) were prepared by mixing PEGylated heparin (PEG-HE), poly-L-lysine (PLL), and TRAIL. NPs prepared by the ionic interaction between polymer and TRAIL showed uniform spherical structures of diameter 213.3 ± 9.7 nm and a surface charge of 5.33 ± 1.2 mV. An in vitro study of the bioactivity of TRAIL in NPs showed that TRAIL-loaded PEG-HE/PLL NPs (TRAIL-PEG-NPs) were slightly less cytotoxic than TRAIL in vitro. To investigate pharmacokinetic parameters, TRAIL and TRAIL-PEG-NPs were intravenously injected into SD rats. The PEG-NP-based formulation demonstrated a 28.3 fold greater half-life than TRAIL alone. To evaluate the anti-tumor effect, TRAIL, TRAIL-loaded HE/PLL NPs (TRAIL-NPs), and TRAIL-PEG-NPs were intravenously injected into HCT-116 tumor-bearing BALB/c athymic mice. The TRAIL-PEG-NP formulation efficiently suppressed tumor growth (>70%), and histological findings confirmed that NPs induced significant tumor cell apoptosis without inducing liver toxicity. The PEG-exposed NP fabrication method applied in this study could be widely applied to protein and peptide delivery systems.

PEGylated TNF-related apoptosis-inducing ligand (TRAIL) for effective tumor combination therapy.

Although PEGylated TNF-related apoptosis-inducing ligand (PEG-TRAIL) has good tumor cell specificity and stability, its therapeutic potential is restricted by the development of tumor cell resistance. The purpose of this study was to develop an effective combination therapy with sustained biological activity based on microspheres. Doxorubicin (DOX), PEG-TRAIL, and DOX plus PEG-TRAIL (dual agent) were microencapsulated into poly (lactic-co-glycolic acid) (PLGA) microspheres using a double-emulsion solvent extraction method. Prepared dual agent microspheres showed the encapsulation efficiency 69.4 ± 2.3 for DOX and 87.7 ± 2.9% for PEG-TRAIL. Potential anti-tumor efficacy of this system was investigated in vitro and in vivo in a human colon cancer (HCT116) and in a human prostate cancer (PC-3). DOX and PEG-TRAIL release from dual agent microspheres were biologically active and significantly inhibited the TRAIL-sensitive HCT116 and resistant PC-3 cells in vitro. Dual agent microspheres simultaneous delivery of DOX and PEG-TRAIL was superior to all other DOX or PEG-TRAIL microspheres in vivo. A single local injection of PLGA microspheres loaded with low amounts of DOX, PEG-TRAIL, or dual agent resulted in 14.8, 30.2, and 63.6% reductions in HCT116 tumor volume and 20.4, 14.2, and 67.7% reductions in PC-3 tumor volume at 35 days. Our findings show that dual agent microspheres offer a promising means of delivering DOX and PEG-TRAIL to tumor sites.

PEGylated TNF-related apoptosis-inducing ligand (TRAIL)-loaded sustained release PLGA microspheres for enhanced stability and antitumor activity.

The purpose of this work was to develop an effective PEGylated TNF-related apoptosis-inducing ligand (PEG-TRAIL) delivery system for antitumor therapy based on local injection to tumor sites that has a sustained effect without protein aggregation or an initial release burst. The authors designed poly (lactic-co-glycolic) acid (PLGA) microspheres that deliver PEG-TRAIL locally and continuously at tumor sites with sustained biological activity and compared its performance with that of TRAIL microspheres. TRAIL or PEG-TRAIL was microencapsulated into PLGA microspheres using a double-emulsion solvent extraction method. Prepared TRAIL and PEG-TRAIL microspheres showed entirely spherical, smooth surfaces. However, PEG-TRAIL microspheres exhibited a 2.07-fold higher encapsulation efficiency than TRAIL microspheres, and exhibited a tri-phasic in vitro release profile with a lower initial burst (15.8%) than TRAIL microspheres (42.7%). Furthermore, released PEG-TRAIL showed a continued ability to induce apoptosis over 14 days. In vivo pharmacokinetic studies also demonstrated that PEG-TRAIL microspheres had a sustained release profile (18 days), and that the steady-state concentration of PEG-TRAIL in rat plasma was reached at day 3 and maintained until day 15; its steady-state concentration in rat plasma changed from 1444.3 ± 338.4 to 2697.7 ± 419.7 pg/ml. However, TRAIL microspheres were released out within 2 days after administration. Finally, in vivo antitumor tests revealed that tumor growths were significantly more inhibited by a single dose of PEG-TRAIL microspheres than TRAIL microspheres when delivered at 300 µg of TRAIL/mouse. Tumors taken from mouse treated with PEG-TRAIL microspheres showed 78.3% tumor suppression at 24 days, and this was 3.02-fold higher than that observed for TRAIL microspheres (25.9% tumor inhibition). Furthermore, these improved pharmaceutical characteristics of PEG-TRAIL microspheres resulted in superior therapeutic effects without detectable side effects. These findings strongly suggest that PEG-TRAIL microspheres offer a new therapeutic strategy for the treatment of cancers.