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Results for “Targeted delivery”

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At least 145 records · Page 8Linked to original sources

PubMed2007

Efficient gene delivery targeted to the brain using a transferrin-conjugated polyethyleneglycol-modified polyamidoamine dendrimer.

The blood-brain barrier (BBB) poses great difficulties for gene delivery to the brain. To circumvent the BBB, we investigated a novel brain-targeting gene vector based on the nanoscopic high-branching dendrimer, polyamidoamine (PAMAM), in vitro and in vivo. Transferrin (Tf) was selected as a brain-targeting ligand conjugated to PAMAM via bifunctional polyethyleneglycol (PEG), yielding PAMAM-PEG-Tf. UV and nuclear magnetic resonance (NMR) spectroscopy were used to evaluate the synthesis of vectors. The characteristics and biodistribution of gene vectors were evaluated by fluorescent microscopy, flow cytometry, and a radiolabeling method. The transfection efficiency of vector/DNA complexes in brain capillary endothelial cells (BCECs) was evaluated by fluorescent microscopy and determination of luciferase activity. The potency of vector/DNA complexes was evaluated by using frozen sections and measuring tissue luciferase activity in Balb/c mice after i.v. administration. UV and NMR results demonstrated the successful synthesis of PAMAM-PEG-Tf. This vector showed a concentration-dependent manner in cellular uptake study and a 2.25-fold brain uptake compared with PAMAM and PAMAM-PEG in vivo. Transfection efficiency of PAMAM-PEG-Tf/DNA complex was much higher than PAMAM/DNA and PAMAM-PEG/DNA complexes in BCECs. Results of tissue expression experiments indicated the widespread expression of an exogenous gene in mouse brain after i.v. administration. With a PAMAM/DNA weight ratio of 10:1, the brain gene expression of the PAMAM-PEG-Tf/DNA complex was approximately 2-fold higher than that of the PAMAM/DNA and PAMAM-PEG/DNA complexes. These results suggested that PAMAM-PEG-Tf can be exploited as a potential nonviral gene vector targeting to brain via noninvasive administration.

Animals↗

PubMed1997

Polypeptide growth factors: targeted delivery systems.

Growth factors are becoming extremely valuable tools in our attempts to understand the mechanisms that modulate cellular activities. Their targeting to appropriate cells and maintaining adequate pharmacological levels becomes essential, particularly in view of the different effects that these compounds have on various cells and the dose dependence of their response. Within this context, this review focuses primarily on the delivery of growth factors involved in the processes of wound healing and tissue repair.

Animals↗

PubMed2006

The hair follicle and its stem cells as drug delivery targets.

The hair follicle is a skin appendage with a complex structure containing many cell types that produce highly specialised proteins. The hair follicle is in a continuous cycle: anagen is the hair growth phase, catagen the involution phase and telogen is the resting phase. The follicle offers many potential therapeutic targets. Hoffman and colleagues have pioneered hair-follicle-specific targeting using liposomes to deliver small and large molecules, including genes. They have also pioneered ex vivo hair-follicle targeting with continued expression of the introduced gene following transplantation. Recently, it has been discovered that hair follicle stem cells are highly pluripotent and can form neurons, glial cells and other cell types, and this has suggested that hair follicle stem cells may serve as gene therapy targets for regenerative medicine.

Animals↗

PubMed2006

Development and in vitro validation of a targeted delivery vehicle for DNA vaccines.

Usage of DNA vaccination has been limited by inefficient cellular expression of plasmid constructs used in DNA vaccines. We describe a novel system for enhancing delivery of DNA vaccine plasmids into cells and their nuclei. This delivery system uses recombinant reovirus type 3 sigma1 attachment protein genetically modified with a nuclear localization sequence (sigma1-NLS) as a targeting ligand. Purified sigma1-NLS was covalently conjugated to the polycation polyethyleneimine (PEI) using a carboxyl-reactive cross-linking agent and complexed with plasmid DNA. The benefit of the NLS in enhancement of protein delivery into the nucleus was demonstrated by liposome-mediated loading of cells with sigma1 or sigma1-NLS. In L929 fibroblasts loaded with sigma1-NLS, 69% of the internalized protein was recovered in the nuclear fraction after 6 h compared to just 10% when using unmodified sigma1. Transfection of L929 cells with sigma1-NLS-conjugated PEI complexed with a luciferase expression plasmid resulted in a mean 16-fold increase in luciferase activity over complexes made with unmodified PEI, compared to a mean 3-fold boost obtained using sigma1-conjugated PEI. These results suggest that sigma1-NLS is a useful bifunctional targeting ligand suitable for enhancing DNA delivery and subsequent gene expression for both DNA vaccine applications and nonviral gene therapy.

Animals↗

PubMed2004

Secretory phospholipase A2 as a tumor-specific trigger for targeted delivery of a novel class of liposomal prodrug anticancer etherlipids.

The use of many common clinically relevant chemotherapeutics is often limited due to insufficient delivery to the tumor and dose-limiting systemic toxicities. Therefore, therapeutics that specifically target tumor cells and are nontoxic to normal cells are required. Here, we report the development of a novel class of liposomes composed of lipid prodrugs, which use the increased secretory phospholipase A2 type IIA (sPLA2) activity of the tumor microenvironment as a trigger for the release of anticancer etherlipids (AEL). Treatment of sPLA2-secreting tumor cells in vitro with liposomes consisting of proAELs resulted in growth inhibition comparable with addition of the AELs alone. Using a specific sPLA2 inhibitor, we showed the low cytotoxicity of the nonhydrolyzed proAEL liposomes and have proven the sPLA2 dependency of the activation of proAELs to cytotoxic AELs. In addition, we showed that our proAEL liposomes circumvent the inherent hemolytic toxicities associated with the use of etherlipids, thereby allowing i.v. administration of such therapeutics as nontoxic prodrug liposomes. Furthermore, using a sPLA2-secreting human colon cancer xenograft model, we showed that the proAEL liposomes are capable of inducing a tumor growth delay in vivo. Taken together, these data support the validity of this novel tumor-selective liposomal prodrug delivery strategy. This new approach also provides a promising system for tumor-selective delivery and release of conventional chemotherapeutics encapsulated in the sPLA2-degradable prodrug liposomes.

Animals↗

PubMed2001

Targeted delivery and triggered release of liposomal doxorubicin enhances cytotoxicity against human B lymphoma cells.

Dioleoylphosphatidylethanolamine (DOPE)-containing liposomes that demonstrated pH-dependent release of their contents were stabilized in the bilayer form through the addition of a cleavable lipid derivative of polyethylene glycol (PEG) in which the PEG was attached to a lipid anchor via a disulfide linkage (mPEG-S-S-DSPE). Liposomes stabilized with either a non-cleavable PEG (mPEG-DSPE) or mPEG-S-S-DSPE retained an encapsulated dye at pH 5.5, but treatment at pH 5.5 of liposomes stabilized with mPEG-S-S-DSPE with either dithiothreitol or cell-free extracts caused contents release due to cleavage of the PEG chains and concomitant destabilization of the DOPE liposomes. While formulations loaded with doxorubicin (DXR) were stable in culture media, DXR was rapidly released in human plasma. pH-Sensitive liposomes, targeted to the CD19 epitope on B-lymphoma cells, showed enhanced DXR delivery into the nuclei of the target cells and increased cytotoxicity compared to non-pH-sensitive liposomes. Pharmacokinetic studies suggested that mPEG-S-S-DSPE was rapidly cleaved in circulation. In a murine model of B-cell lymphoma, the therapeutic efficacy of an anti-CD19-targeted pH-sensitive formulation was superior to that of a stable long-circulating formulation of targeted liposomes despite the more rapid drug release and clearance of the pH-sensitive formulation. These results suggest that targeted pH-sensitive formulations of drugs may be able to increase the therapeutic efficacy of entrapped drugs.

Animals↗

PubMed2006

The development of folate-PAMAM dendrimer conjugates for targeted delivery of anti-arthritic drugs and their pharmacokinetics and biodistribution in arthritic rats.

The aim of this study was to synthesize folate-dendrimer conjugates as suitable vehicle for site specific delivery of anti-arthritic drug (indomethacin) to inflammatory regions and to determine its targeting efficiency, biodistribution in adjuvant induced arthritic rats. Folic acid was coupled to the surface amino groups of G4-PAMAM dendrimer (G4D) via a carbodiimide reaction and loaded with indomethacin. The conjugates were characterized by (1)H-NMR and IR spectroscopy. The drug content and percent encapsulation efficiency increased with increasing folate content for the dendrimer conjugates. The in vitro release rate was decreased for the folate conjugates when compared with unconjugated dendrimer (DNI). The plasma concentration profile showed a biphasic curve indicating rapid distribution followed by slow elimination. The AUC(0-infinity), half-life and residence time of indomethacin in inflamed paw was higher for folate-dendrimer conjugates. The time-averaged relative drug exposure (r(e)) of the drug in paw and overall drug targeting efficiency (T(e)) were higher for folate conjugate with 21 folate moieties (4.1 and 2.78, respectively) when compared with DNI (1.91 and 1.88, respectively). This study demonstrated the superiority of active targeting over dendrimer mediated passive targeting and also for the first time, folate-mediated targeting of an anti-arthritic drug to the inflammatory tissues.

Animals↗

PubMedDate not supplied

Folate receptor targeted delivery of liposomal daunorubicin into tumor cells.

BACKGROUND: The folate receptor (FR) is amplified in a wide variety of human tumors. Thus, targeting cytotoxic therapies to FR is a promising strategy for chemotherapy. MATERIALS AND METHODS: FR-targeted liposomal daunorubicin (f-L-DNR) was compared to non-targeted liposomal DNR (L-DNR) for cellular uptake and cytotoxicity in FR-expressing cells. Liposomal DNR retention was evaluated for liposomes loaded with either sodium citrate or ammonium sulfate as the trapping agent. The cellular uptake of liposomal DNR was determined by flow cytometry and fluorometry measurements while cytotoxicity was determined by the 3-(4,5dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. RESULTS: Liposomal DNR retention was superior for liposomes prepared using ammonium sulfate. Cellular uptake of f-L-DNR in KB oral carcinoma cells, Chinese hamster ovary (CHO-FR-beta), and KG-1 human acute myelogenous leukemia cells were 9.4, 40, and 4,6-fold higher than non-targeted L-DNR, respectively. The cytotoxicity of f-L-DNR in KB and CHO-FR-beta cells was 18 times and 49 times higher than L-DNR, respectively. Both cellular uptake and cytotoxicity of f-L-DNR could be inhibited by 1 mM folic acid. CONCLUSION: FR-mediated delivery of liposomal DNR to FR-expressing cells increases DNR cellular uptake and cytotoxicity. Therefore, therapeutic evaluation in relevant animal models is warranted.

Antibiotics, Antineoplastic↗

PubMed2000

Targeted delivery of plasmid DNA to myogenic cells via transferrin-conjugated peptide nucleic acid.

We describe a novel approach to conjugate a targeting ligand to plasmid DNA without affecting either its supercoiled conformation or its ability to be efficiently transcribed. A 14-mer peptide nucleic acid (PNA) containing lysine and cysteine on each end was designed to target to a unique sequence located at the antibiotic resistance gene of the plasmid. The binding of PNA to the plasmid was found to be dose-dependent and sequence-specific and not to change the conformation of the plasmid. Transferrin (Tf) was conjugated with PNA via a reversible disulfide bond using N-succinimidyl-3-(2-pyridyldithio)propionate. Tf-PNA retained the ability to the plasmid in a sequence-specific manner. The efficiency of this bioconjugate for delivering plasmid was examined in cultured myoblasts and myotubes. Naked DNA and Tf-PNA/DNA showed no transfection activity in either myoblasts or myotubes. Polyethyleneimine (PEI) is required for significant increase of the transfection efficiency. At N:P ratio of 5, Tf-PNA enhanced gene transfection about fourfold over that of the DNA/PEI complex in both myoblasts and myotubes. This enhancement could be inhibited by excess free Tf, indicating that the enhancement of transfection was through Tf-mediated endocytosis. These findings suggest that this targeting system may have the potential for gene transfer to myogenic cells in vivo.

Cell Line↗

PubMed2005

Selective apoptotic killing of malignant hemopoietic cells by antibody-targeted delivery of an amphipathic peptide.

The alpha-helical amphipathic peptide D-(KLAKLAK)2 is toxic to eukaryotic cells if internalized by a suitable targeting mechanism. We have targeted this peptide to malignant hemopoietic cells via conjugation to monoclonal antibodies, which recognize lineage-specific cell surface molecules. An anti-CD19/peptide conjugate efficiently killed 3/3 B lymphoid lines. However, an anti-CD33/peptide conjugate was cytotoxic to only one of three CD33-positive myeloid leukemia lines. The IC50 towards susceptible lines were in the low nanomolar range. Conjugates were highly selective and did not kill cells that did not express the appropriate cell surface cognate of the antibody moiety. Anti-CD19/peptide conjugates efficiently killed cells from patients with chronic lymphocytic leukemia but anti-CD33/peptide reagents were less effective against fresh acute myeloid leukemia cells. We therefore suggest that amphipathic peptides may be of value as targeted therapeutic agents for the treatment of a subset of hematologic malignancies.

Acute Disease↗

PubMed2006

Uptake characteristics of NGR-coupled stealth PEI/pDNA nanoparticles loaded with PLGA-PEG-PLGA tri-block copolymer for targeted delivery to human monocyte-derived dendritic cells.

We have investigated the in vitro uptake, toxicity, phenotypic consequences and transfection efficiency of a stealth NGR/PEG/PDBA-coupled-SHA-PEI/pDNA targeting polyplex loaded with PLGA-PEG-PLGA tri-block copolymer in human monocyte-derived dendritic cells (DCs). Modification with PEG effectively shielded and reduced non-specific phagocytosis by immature DCs to approximately 20%. Coupling the NGR cell-specific peptide to the PEGylated polyplex (NGR/PEG/PDBA-SHA-PEI/pDNA) however resulted in specific and enhanced phagocytosis in DCs without any observable toxicity at the optimum concentration of 0.25% of the copolymer. DNase treatment had no effect on DNA integrity in the encapsulated polyplex. Confocal microscopy confirmed intracellular localization of the targeting NGR/PEG/PDBA-SHA-PEI/pDNA microparticles, resulting in more enhanced uptake of the radiolabeled plasmid DNA and approximately 5- and 10-fold increase over the control tri-block Pluronic F68 copolymer and the non-targeting polyplex, respectively. More importantly, phagocytosis of the targeting microparticles neither altered the functionality of immature DCs nor the phenotypic expression of DC-specific cell surface molecules, CD80, CD86, CD40 and CD54 (ICAM-1), suggesting that uptake of the targeting microparticles by themselves did not induce DC maturation. Taken together, these results suggest that PLGA-PEG-PLGA encapsulation of this stealth targeting polyplex has no negative effects on key properties of immature DCs and should pave the way for targeting DCs for vaccination purposes.

Cell Survival↗

PubMed2006

Target delivery, service modernisation and system reform: reinventing planning in the English National Health Service.

PURPOSE: Aims to focus on the imperative to achieve national activity and performance targets in secondary care as set out in the NHS Plan. DESIGN/METHODOLOGY/APPROACH: The paper is in the form of "notes from the front line" that are based on the experience of the Royal Cornwall Hospitals NHS Trust (RCHT). FINDINGS: These include that planning needs to be understood as the means by which the NHS manages its future; that planning needs to become more technically and methodologically sophisticated; that planning is a process rather than a description of an organisational function; and that the NHS will only resolve the shortage of planning competencies once planning is seen as a management disciple. ORIGINALITY/VALUE: On the basis of the feedback received from drafts of this paper, it is suggested that the conclusions drawn are generally applicable across the English health service.

Delivery of Health Care↗

PubMed1998

Targeted delivery of plasmid DNA to hepatocytes in vivo: optimization of the pharmacokinetics of plasmid DNA/galactosylated poly(L-lysine) complexes by controlling their physicochemical properties.

In vivo receptor-mediated targeting of plasmid DNA to hepatocytes was achieved through optimizing the physicochemical and pharmacokinetic properties of a plasmid DNA/carrier complex. Galactosylated poly(L-lysine) (Gal-PLL) was synthesized using PLL with a molecular weight of 1,800, 13,000 or 29,000 without loss of the cationic charge. Plasmid DNA encoding chloramphenicol acetyltransferase was complexed with each Gal-PLL. A larger amount of PLL1800 is required for the complex formation than with PLL13000 and PLL29000, and increasing the number of galactose units on Gal-PLL resulted in reduced binding to plasmid DNA. The particle size and zeta-potential of the complexes varied depending on the mixing ratio and Gal-PLL used. Then, plasmid DNA/Gal-PLL complexes having diameters of 200 nm or less and a weak negative charge were prepared. After i.v. injection of [32P]plasmid DNA/Gal13-PLL13000 and [32P]plasmid DNA/Gal26-PLL29000, almost 80% of the radioactivity rapidly accumulated in the liver, preferentially in the parenchymal cells. The hepatic uptake clearances (CLliver) were much greater than any of the other tissue uptake clearances. Compared with these complexes, [32P]plasmid DNA/Gal5-PLL1800 and [32P]plasmid DNA/Gal5-PLL13000 had a smaller CLliver, suggesting that both the molecular weight of PLL and the degree of galactose modification determine the hepatic targeting of plasmid DNA. In vitro and in vivo gene expression studies revealed that plasmid DNA/Gal13-PLL13000 and plasmid DNA/Gal26-PLL29000 complexes are superior to plasmid DNA/Gal5-PLL1800 complex for introducing DNA into cells. These results demonstrated that an optimal design of a DNA/carrier complex based on physicochemical properties and a pharmacokinetic analysis of the distribution properties leads to successful in vivo gene delivery.

Animals↗

PubMed1991

Tumor-targeted delivery of 8-hydroxyquinoline.

RIF-1 mouse tumors express high levels of beta-glucuronidase activity relative to most normal tissues. The high activity can be exploited for targeting specific drugs preferentially to tumor tissues. In this study we examined the kinetics of 8-hydroxyquinoline (8-OHQ) accumulation in tumor and in several normal tissues resulting from the in vivo deconjugation of 8-hydroxyquinolyl-glucuronide (8-OHQ-GlcA). Tumors were acidified with D-glucose and NaHCO3 prior to the administration of 8-OHQ-GlcA; subsequently the deconjugated aglycone, 8-OHQ, accumulated preferentially in tumors and reached peak levels between 30 and 60 min after the 8-OHQ-GlcA injection. Mild hyperthermia of 30 min at 43 degrees C to the tumors further increased their peak 8-OHQ levels by a factor of 2-3. Some normal tissues, mostly kidney, liver, and colon, also accumulated 8-OHQ, but the aglycone appeared early in the normal tissues (near 30 min post-injection) and was significantly reduced by 60 min when 8-OHQ remained high in the tumor. Administration of 8-OHQ-GlcA alone, without prior tumor acidification, failed to produce measurable accumulations of 8-OHQ in tumors and in normal tissues. Tissue clearance of 8-OHQ is mediated primarily by the enzymatic reconjugation of 8-OHQ via UDP-glucuronosyltransferase (UDPGT). UDPGT activity was high in liver, kidney, and bowel, but low in the RIF tumor, spleen, muscle, and brain. Hyperthermia had only a modest effects on UDPGT activity: a heat dose of 30 min at 45 degrees C reduced activity less than 60%. Thus, preferential accumulation and prolonged retention of 8-OHQ in RIF tumors may be caused by a combination of factors: a) high tumor beta-glucuronidase activity, b) selective tumor acidification during hyperglycemia, c) low tumor UDPGT activity, and d) other factors, such as tumor blood flow.

Animals↗

PubMed2000

Subcellular post-transcriptional targeting: delivery of an intracellular protein to the extracellular leaflet of the plasma membrane using a glycosyl-phosphatidylinositol (GPI) membrane anchor in neurons and polarised epithelial cells.

The effectiveness of viral vector-mediated gene transfer depends on the expression of therapeutic transgenes in the correct target cell types. So far, however, little attention has been given to targeted subcellular distribution of expressed transgenes. Targeting individual transgenes to particular subcellular compartments will provide various advantages in increasing the safety, efficacy, and specificity of viral vector-mediated gene delivery. Viruses normally hijack the cellular protein synthesis machinery for their own advantages. It is thus unknown whether cells infected with viral vectors will be able to target proteins to the correct subcellular organelles, or whether the subcellular targeting machinery would be selectively disrupted by viral infection. In this article we explored whether a herpes simplex virus type 1-derived vector could be used to deliver a transgene engineered to be targeted to the extracellular membrane of target cells. To do so we constructed a temperature-sensitive mutant HSV-1 vector, tsK-TT21 expressing a recombinant marker protein, tissue inhibitor of metalloproteinases (TIMP), linked to sequence encoding a signal for the addition of a glycosyl-phosphatidylinositol (GPI)-anchor within the endoplasmic reticulum. Our results demonstrate that HSV1-derived viral vectors can be used to target transgenes as GPI anchored proteins to the outside leaflet of plasma membranes, without disrupting the targeting machinery of host epithelial cells or neurons. This approach could then be used to target specific proteins to the cell membrane to modify cell-cell interactions, the function of specific plasma membrane proteins, or their interactions with other membrane proteins, and also to target a prodrug converting enzyme to the plasma membrane of target cells, therefore enhancing its cell killing effects.

Biotinylation↗

PubMed2004

Dead cells in melanoma tumors provide abundant antigen for targeted delivery of ionizing radiation by a mAb to melanin.

Melanoma is a cancer with a rising incidence, and metastatic disease is almost always lethal. We investigated the feasibility of targeting melanin, an intracellular melanocyte pigment, to deliver cytotoxic radiation to human melanoma cells in vivo by using a melanin-binding mAb (6D2). Nude mice bearing MNT1 pigmented human melanoma tumors were treated with mAb 6D2 labeled with 1.5 mCi (1 Ci = 37 GBq) of the beta-emitter 188-Rhenium (188Re) and manifested inhibition of tumor growth and prolonged survival. mAb 6D2 bound tumor melanin and demonstrated no crossreactivity with normal melanized tissues in black mice. The mechanism of melanin targeting involved Ab binding to extracellular melanin released during tumor cell turnover or to dying cells with permeable membranes. In this approach, the cytotoxic radiation emanating from labeled Ab bound to melanin is presumably delivered by "crossfire" effect to the adjacent viable tumor cells. Our results establish the feasibility of targeting melanin released from dead melanoma cells in tumors with radiolabeled Abs to achieve a therapeutic effect. In contrast to conventional tumor antigens, melanin is insoluble, resistant to degradation, and can be expected to accumulate in targeted tissues, suggesting that the efficacy of therapy could increase with each subsequent treatment cycle.

Animals↗

PubMedDate not supplied

Targeted delivery of antisense oligodeoxynucleotide and small interference RNA into lung cancer cells.

Selective gene inhibition by antisense oligodeoxynucleotide (AS-ODN) or by small interference RNA (siRNA) therapeutics promises the treatment of diseases that cannot be cured by conventional drugs. However, antisense therapy is hindered due to poor stability in physiological fluids and limited intracellular uptake. To address these problems, a ligand targeted and sterically stabilized nanoparticle formulation has been developed in our lab. Human lung cancer cells often overexpress the sigma receptor and, thus, can be targeted with a specific ligand such as anisamide. AS-ODN or siRNA against human survivin was mixed with a carrier DNA, calf thymus DNA, before complexing with protamine, a highly positively charged peptide. The resulting particles were coated with cationic liposomes consisting of DOTAP and cholesterol (1:1, molar ratio) to obtain LPD (liposome-polycation-DNA) nanoparticles. Ligand targeting and steric stabilization were then introduced by incubating preformed LPD nanoparticles with DSPE-PEG-anisamide, a PEGylated ligand lipid developed earlier in our lab, by the postinsertion method. Nontargeted nanoparticles coated with DSPE-PEG were also prepared as a control. Antisense activities of nanoparticles were determined by survivin mRNA down-regulation, survivin protein down-regulation, ability to trigger apoptosis in tumor cells, tumor cell growth inhibition, and chemosensitization of the treated tumor cells to anticancer drugs. We found that tumor cell delivery and antisense activity of PEGylated nanoparticles were sequence dependent and rely on the presence of anisamide ligand. The uptake of oligonucleotide in targeted, PEGylated nanoparticles could be competed by excess free ligand. Our results suggest that the ligand targeted and sterically stabilized nanoparticles can provide a selective delivery of AS-ODN and siRNA into lung cancer cells for therapy.

Cell Line, Tumor↗

PubMed2003

Selective targeted delivery of TNFalpha to tumor blood vessels.

We sought to enhance the selective toxicity of tumor necrosis factor alpha (TNFalpha) to permit its systemic use in cancer therapy. Because ligand-targeted therapeutics have proven successful in improving the selective toxicity of drugs, we prepared a fusion protein (L19mTNFalpha) composed of mouse TNFalpha and a high-affinity antibody fragment (L19 scFv) to the extradomain B (ED-B) domain of fibronectin, a marker of angiogenesis. L19mTNFalpha was expressed in mammalian cells, purified, and characterized. L19mTNFalpha was an immunoreactive and biologically active homotrimer. Radiolabeled L19mTNFalpha selectively targeted tumor neovasculature in tumor-bearing mice, where it accumulated selectively and persistently (tumor-to-blood ratio of the percentage of injected dose per gram [%ID/g] of 700, 48 hours from injection). L19mTNFalpha showed a greater anticancer therapeutic activity than both mTNFalpha and TN11mTNFalpha, a control fusion protein in which an antibody fragment, irrelevant in the tumor model used, substituted for L19. This activity was further dramatically enhanced by its combination with melphalan or the recently reported fusion protein L19-IL2. In conclusion, L19mTNFalpha allows concentrating therapeutically active doses of TNFalpha at the tumor level, thus opening new possibilities for the systemic use of TNFalpha in cancer therapy.

Adenocarcinoma↗