Ecust004 Suppresses Breast Cancer Cell Growth, Invasion, and Migration via EMT Regulation.

PURPOSE: Erianin is a small chemical compound extracted from Dendrobium chrysotoxum and has excellent antineoplastic effects against a variety of cancers. Combretastatin A-4 (CA4) is the most effective member of natural phenolic stilbene compounds isolated from the African willow tree Combretum caffrum. Ecust004 (Chemical Formula: C18H21NO7S) is a drug candidate optimized from structure-activity relationship studies of the sulfamate derivatives of Erianin and CA4, which has better bioavailability and pharmacokinetic profiles than Erianin and CA4. METHODS: To investigate the antitumor activity of Ecust004 in different types of breast cancer cells, MDA-MB-231 and MCF7 cells were treated with Ecust004. MTT and CCK8 were used to determine the effects of Ecust004 on cell proliferation. Wound-healing and Transwell assays were used to evaluate the migration and invasion level of cells treated with Ecust004. The expression of genes and proteins associated with epithelial-mesenchymal transition was detected by RT-PCR and Western blotting. In vivo studies further clarified the functional effects of Ecust004. RESULTS: Ecust004 treatment decreased the growth and proliferation of MDA-MB-231 and MCF7 cells at a lower dosage than Erianin. In addition, compared to Erianin and CA4, Ecust004 can better inhibit the invasion and migration of MDA-MB-231 and MCF7 cells. Accordingly, the expression of genes associated with epithelial-mesenchymal transition, such as E-cadherin and vinculin, was increased. Finally, compared with Erianin and CA4, Ecust004 exhibited a better anti-tumor activity in vivo. CONCLUSION: Ecust004 inhibits the proliferation, invasion, and migration of breast cancer cells, and therefore represents a potential agent for development as an antitumor drug.

Synergistic cytotoxicity of erianin, a bisbenzyl in the dietetic Chinese herb Dendrobium against breast cancer cells.

Erianin (ER), a dietary compound extracted from Dendrobium, a traditional Chinese medicinal edible herb, is well recognized for its potential anti-cancer activity. Nevertheless, its limitations, regarding its complex isolation procedure, low yield and low water solubility, limit large scale application. Combinatorial therapeutic regimen that combines several drugs to target different pathways in a characteristically synergistic manner at lower doses of drugs proved effective in several diseases treatment. Besides, new knowledge aimed at improving drug delivery into the intracellular environment is essential. In this study, ER was assessed for its cytotoxic effect in combination with doxorubicin hydrochloride (DOX·HCl) against breast cancer cells. Drug synergy was calculated by using combination index (CI) index and we discovered that they had positive effects. To ensure uniform delivery of both drugs to cells for a desired synergistic action, a dual drug loaded liposomes was developed using thin-film dispersion, and coated by a layer of folate-chitosan. Cytotoxicity and cell proliferation based assays revealed the increase of cell inhibition rate by more than 30% compared with free drugs. Fluorescence imaging revealed that liposomes can aid faster drugs accumulate in cancer cells. The study presented a novel strategy for the treatment of breast cancer.

Multifunctional Molecular Therapeutic Agent for Targeted and Controlled Dual Chemo- and Photodynamic Therapy.

A novel molecular therapeutic agent was designed and synthesized, which contains three functional components, namely, a zinc(II) phthalocyanine substituted with a 2,4-dinitrobenzenesulfonate (DNBS) group as a glutathione (GSH)-activated photosensitizer, a chemo-prodrug based on combretastatin A-4 (CA4) with a singlet oxygen-cleavable aminoacrylate linker, and a biotin moiety as a tumor-targeting ligand. The conjugate showed preferential uptake toward the biotin-receptor-positive HepG2 cells compared with the low biotin-receptor-expressed HCT-116 cells used as the negative control, resulting in the restoration of the fluorescence emission and singlet oxygen generation upon removal of the DNBS group by intracellular GSH. The singlet oxygen produced not only induced a significant photodynamic effect against HepG2 cells but also triggered the cascaded release of the chemocytotoxic CA4, leading to synergistic cytotoxicity as shown by the less-than-unity combination index.

Dihydro-stilbene gigantol relieves CCl4-induced hepatic oxidative stress and inflammation in mice via inhibiting C5b-9 formation in the liver.

In general, anti-inflammatory treatment is considered for multiple liver diseases despite the etiology. But current drugs for alleviating liver inflammation have defects, making it necessary to develop more potent and safer drugs for liver injury. In this study, we screened a series of (dihydro-)stilbene or (dihydro-)phenanthrene derivatives extracted from Pholidota chinensis for their potential biological activities. Among 31 compounds, the dihydro-stilbene gigantol exerted most potent protective effects on human hepatocytes against lithocholic acid toxicity, and exhibited solid antioxidative and anti-inflammatory effect in vitro. In mice with CCl4-induced acute liver injury, pre-administration of gigantol (10, 20, 40 mg· kg-1· d-1, po, for 7 days) dose-dependently decreased serum transaminase levels and improved pathological changes in liver tissues. The elevated lipid peroxidation and inflammatory responses in the livers were also significantly alleviated by gigantol. The pharmacokinetic studies showed that gigantol was highly concentrated in the mouse livers, which consisted with its efficacy in preventing liver injury. Using a label-free quantitative proteomic analysis we revealed that gigantol mainly regulated the immune system process in liver tissues of CCl4-treated mice, and the complement and coagulation cascades was the predominant pathway; gigantol markedly inhibited the expression of complement component C9, which was a key component for the formation of terminal complement complex (TCC) C5b-9. These results were validated by immunohistochemistry (IHC) or real time-PCR. Confocal microscopy analysis showed that gigantol significantly inhibited the vascular deposition of TCC in the liver. In conclusion, we demonstrate for the first time that oral administration of gigantol potently relieves liver oxidative stress and inflammation, possibly via a novel mechanism of inhibiting the C5b-9 formation in the liver.

Local application of doxorubicin- loaded Iron oxid nanoparticles and the vascular disrupting agent via the hepatic artery: chemoembolization-photothermal ablation treatment of hepatocellular carcinoma in rats.

OBJECTIVES: This study investigates the effectiveness of local application of doxorubicin(Dox)-loaded, polydopamine (PDA)- coated single crystal hematite (α- Fe2O3) nanocubes (Fe2O3-PDA-Dox) and combretastatin A-4 phosphate disodium(CA4P)in treating hepatocellular carcinoma (HCC) in rats. METHODS: The magnetic characteristics and photothermal effects of the nanoparticles were determined in vitro. Tumor-bearing Sprague-Dawley rats were divided into 3 groups of 8 according to treatment: controls, transarterial chemoembolization-photothermal ablation (pTACE) (Lipidol+Fe2O3-PDA-Dox + NIR), and CA4P + pTACE (CA4P+ Lipidol+Fe2O3-PDA-Dox + NIR). Drugs were administered through the hepatic artery, and the tumors exposed to 808-nm near-infrared radiation. The Fe content of tumors was assessed using neutron activation analysis. Treatment effectiveness was assessed using heating curves, magnetic resonance imaging, pathology results, and immunohistochemical analysis. RESULTS: The mean tumor Fe content was greater in rats treated with CA4P + pTACE (1 h, 23.72 ± 12.45 µg/g; 24 h, 14.61 ± 8.23 µg/g) than in those treated with pTACE alone (1 h, 5.66 ± 4.29 µg/g; 24 h, 2.76 ± 1.33 µg/g). The tumor T2 imaging signal was lower in rats treated with CA4P + pTACE. Following laser irradiation, the tumor temperature increased, with higher temperatures reached in the CA4P + pTACE group (62 °C vs 55 °C). Tumor cells exhibited necrosis, apoptosis, and proliferation inhibition, with greater effects in the CA4P + pTACE group. Transient liver and kidney toxicity were observed on day 3, with more severe effects after CA4P + pTACE. CONCLUSIONS: Fe2O3-PDA-Dox nanoparticles are effective for TACE-PTA. Pretreatment with CA4P increases nanoparticle uptake by tumors, increasing the treatment effectiveness without increasing hepatorenal toxicity.

C12, a combretastatin-A4 analog, exerts anticancer activity by targeting microtubules.

Combretastatin A4 and its analogs are undergoing various clinical trials for the treatment of different cancers. This study illustrated the molecular mechanism and antitumor activity of C12, (5-Quinolin-3-yl and 4-(3,4,5-trimethoxyphenyl) substituted imidazol-2-amine), a synthetic analog of CA-4. C12 reduced the tumor volume of MCF-7 xenograft in NOD-SCID mice without affecting the bodyweight of the mice. Further, C12 inhibited the proliferation of several types of cancer cells more efficiently than their noncancerous counterparts. Using GFP-EB1 imaging, the effects of C12 on the interphase microtubule dynamics were determined in live HeLa cells. C12 (10 nM, half-maximal proliferation inhibitory concentration) reduced the growth rate of microtubules by 52% and increased the pause time of microtubules by 68%. In addition, fluorescence recovery after photobleaching analysis demonstrated that 10 nM C12 strongly suppressed spindle microtubule dynamics in HeLa cells. C12 treatment reduced the interpolar distance between the two spindle poles, increased the chromosome congression index, inhibited chromosome movement, and increased the level of mitotic checkpoint complex proteins BubR1 and Mad2. The evidence presented here indicated that C12 could induce different modes of cell death, depending on the extent of microtubule depolymerization. Since C12 targets both the mitotic and non-mitotic cells and showed a stronger activity against cancerous cells than non-cancerous cells, it may have an advantage in cancer chemotherapy. The results significantly enhance our understanding of the antitumor mechanism of the microtubule-depolymerizing agents.

Resveratrol, lunularin and dihydroresveratrol do not act as caloric restriction mimetics when administered intraperitoneally in mice.

Resveratrol as well as caloric restriction were shown to extend lifespan in some model organisms and may possibly delay onset of ageing-related diseases in humans. Yet, resveratrol supplementation does not always extend lifespan of animal models or improve health status of humans. Because of interindividual differences in human microbiota, resveratrol metabolite production in the gut differs. While some individuals produce lunularin and dihydroresveratrol in their gut, others produce dihydroresveratrol only. Therefore, we addressed the question whether these metabolites differ in their biological impact on ageing and intraperitoneally injected 13-month-old C57BL/6JRj mice on an ad-libitum (AL) HFD with resveratrol, dihydroresveratrol or lunularin (24 mg/kg bodyweight; 3 times/week). Compared to mice injected with vehicle (AL-control), resveratrol and dihydroresveratrol did not change bodyweight and had no impact on insulin or glucose levels while lunularin slightly reduced feed intake and bodyweight gain. CR-mice showed lowered cholesterol, insulin and leptin levels, elevated adiponectin and phosphorylated AMPK levels in liver as well as increased transcription of Pck1 and Pgc1α when compared to the AL-control. In contrast, injections with the test substances did not change these parameters. We therefore conclude that in our model, resveratrol, lunularin and dihydroresveratrol did not act as CR mimetics.

Combretastatin A4-phosphate and its potential in veterinary oncology: a review.

For many years, research on anticancer therapy has focussed almost exclusively on targeting cancer cells directly, to selectively kill them or restrict their growth. But limited advances in this strategy have led researchers to shift their attention to other potential targets. Active research is now on-going on targeting tumour stroma. Vascular disrupting agents (VDAs) appear a promising class of anticancer drugs that are currently under investigation as a sole or combined therapy in human cancer patients. This article will briefly touch on the history and biology of combretastatin A4-phosphate (CA4P) as a typical example of VDAs and will concentrate on the side effects that can be expected when used in veterinary patients. Particularly, the pathogenesis of these side effects and how they may be prevented and/or treated will be discussed. The purpose of this article is to illustrate the potentials of CA4P as anticancer therapy in veterinary oncology patients.

Tunable release of chemotherapeutic and vascular disrupting agents from injectable fiber fragments potentiates combination chemotherapy.

Cancer progression and metastasis relies much on vasculature networks in tumor microenvironment, and the combination treatment with chemotherapeutic drugs and vascular disrupting agents represents apparent clinical benefits. In the current study, fiber fragments with loadings of hydroxycamptothecin (HCPT) or combretastatin A-4 (CA4) were proposed for tumor inhibition and blood vessel disruption after local administration in tumors. To address challenges in balancing the disruption of tumor vessels and intratumoral uptake of chemotherapeutic agents, this study is focus on release tuning of HCPT and CA4 from the fiber fragment mixtures. Hydroxypropyl-ß-cyclodextrin (HPCD) was blended at ratios from 0 to 10% into CA4-loaded fiber fragments (Fc) to modulate CA4 release durations from 0.5 to 24days, and HCPT-loaded fiber fragments (Fh) indicated a sustained release for over 35days. In vitro cytotoxicity tests indicated a sequential inhibition on the endothelial and tumor cell growth, and the growth inhibition of tumor cells was more significant after treatment with mixtures of Fh and Fc containing 2% HPCD (Fc2) than that of other mixtures. In an orthotopic breast tumor model, compared with those of free CA4, or Fc with a fast or slow release of CA4, Fh/Fc mixtures with CA4 release durations from 2 to 12days indicated a lower tumor growth rate, a prolonged animal survival, a lower vessel density in tumors, and a less significant tumor metastasis. In addition, the tumor cell proliferation rate, hypoxia-inducible factor-1α expression within tumors, and the number of surface metastatic nodules in lungs were significantly lower after treatment with Fh/Fc2 mixtures with a CA4 release duration of 5days than those of other mixtures. It demonstrates the advantages of fiber fragment mixtures in independently modulating the release of multiple drugs and the essential role of release tuning of chemotherapeutic drugs and vascular disrupting agents in improving the therapeutic efficacy.

Construction of a two-in-one liposomal system (TWOLips) for tumor-targeted combination therapy.

In oncology, there is a growing need for simpler, more selective methods to deliver drug therapies directly to the tumor site. For combination therapies, simultaneous targeted delivery of multiple drugs would represent a significant improvement. In contrast to previous work that took a de novo approach, we constructed a novel two-in-one liposomal system (TWOLips) from two single drug-loaded liposomes. Our results demonstrated that TWOLips could be prepared by a simple process, through silica coating of one liposome and incubation with the second liposome. TWOLips had a mean diameter of 100 nm, relatively high drug loading rates (96.8%±0.9% for doxorubicin and 78.4%±1.2% for combretastatin), and high storage stability. TWOLips modification by adding a targeting moiety, an all D-amino acid peptide derived from a natural vascular endothelial growth factor, resulted in strong, selective binding to vascular endothelial growth factor receptor 2, a tumorigenesis marker, in vitro and in vivo. TWOLips significantly inhibited tumor growth and angiogenesis and enhanced survival in mice with A375 melanoma xenografts. The TWOLips system had a low potential risk of toxicity. Since the stepwise assembly could be carried further (additional drug-loaded liposomes), TWOLips shows potential as a treatment for many cancers, especially those that require multiple drugs.

A combretastatin-mediated decrease in neutrophil concentration in peripheral blood and the impact on the anti-tumor activity of this drug in two different murine tumor models.

The vascular disrupting agent combretastatin A-4 disodium phosphate (CA4P) induces fluctuations in peripheral blood neutrophil concentration. Because neutrophils have the potential to induce both vascular damage and angiogenesis we analyzed neutrophil involvement in the anti-tumoral effects of CA4P in C3H mammary carcinomas in CDF1 mice and in SCCVII squamous cell carcinomas in C3H/HeN mice. Flow cytometry analyses of peripheral blood before and up to 144 h after CA4P administration (25 and 250 mg/kg) revealed a decrease 1 h after treatment, followed by an early (3-6 h) and a late (>72 h) increase in the granulocyte concentration. We suggest that the early increase (3-6 h) in granulocyte concentration was caused by the initial decrease at 1 h and found that the late increase was associated with tumor size, and hence independent of CA4P. No alterations in neutrophil infiltration into the C3H tumor after CA4P treatment (25 and 250 mg/kg) were found. Correspondingly, neutrophil depletion in vivo, using an anti-neutrophil antibody, followed by CA4P treatment (25 mg/kg) did not increase the necrotic fraction in C3H tumors significantly. However, by increasing the CA4P dose to 250 mg/kg we found a significant increase of 359% in necrotic fraction when compared to neutrophil-depleted mice; in mice with no neutrophil depletion CA4P induced an 89% change indicating that the presence of neutrophils reduced the effect of CA4P. In contrast, neither CA4P nor 1A8 affected the necrotic fraction in the SCCVII tumors significantly. Hence, we suggest that the initial decrease in granulocyte concentration was caused by non-tumor-specific recruitment of neutrophils and that neutrophils may attenuate CA4P-mediated anti-tumor effect in some tumor models.

In vivo assessment of the vascular disrupting effect of M410 by DCE-MRI biomarker in a rabbit model of liver tumor.

The present study aimed to prospectively monitor the vascular disrupting effect of M410 by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in rabbits with VX2 liver tumors. Twenty-eight rabbits bearing VX2 tumors in the left lobe of the liver were established and randomly divided into treatment and control groups, intravenously injected with 25 mg/kg M410 or sterile saline, respectively. Conventional and DCE-MRI data were acquired on a 3.0-T MR unit at pretreatment, 4 h, 1, 4, 7 and 14 days post-treatment. Histopathological examinations [hematoxylin and eosin (H&E) and CD34 immunohistochemisty staining] were performed at each time point. The dynamic changes in tumor volume, kinetic DCE-MRI parameter [volume transfer constant (Ktrans)] and histological data were evaluated. Tumors grew slower in the M410 group 4-14 days following treatment, compared with rapidly growing tumors in the control group (P<0.05). At 4 h, 1 and 4 days, Ktrans significantly decreased in the M410 group compared with that in the control group (P<0.05). However, Ktrans values were similar in the two groups for the other time points studied. The changes in DCE-MRI parameters were consistent with the results obtained from H&E and CD34 staining of the tumor tissues. DCE-MRI parameter Ktrans may be used as a non-invasive imaging biomarker to monitor the dynamic histological changes in tumors following treatment with the vascular targeting agent M410.

Tumor environment changed by combretastatin derivative (Cderiv) pretreatment that leads to effective tumor targeting, MRI studies, and antitumor activity of polymeric micelle carrier systems.

PURPOSE: To evaluate effect of a vascular disrupting agent, a combretastatin derivative (Cderiv), on tumor targeting for polymeric micelle carrier systems, containing either a diagnostic MRI contrast agent or a therapeutic anticancer drug. METHODS: Cderiv was pre-administered 72 h before polymeric micelle MRI contrast agent injection. Accumulation of the MRI contrast agent in colon 26 murine tumor was evaluated with or without pretreatment of Cderiv by ICP and MRI. RESULTS: Significantly higher accumulation of the MRI contrast agent was found in tumor tissues when Cderiv was administered at 72 h before MRI contrast agent injection. T(1)-weighted images of the tumor exhibited substantial signal enhancement in tumor area at 24 h after the contrast agent injection. In T(1)-weighted images, remarkable T(1)-signal enhancements were observed in part of tumor, not in whole tumor. These results indicate that Cderiv pretreatment considerably enhanced the permeability of the tumor blood vessels. Antitumor activity of adriamycin encapsulated polymeric micelles with the Cderiv pretreatment suppressed tumor growth in 44As3 human gastric scirrhous carcinoma-bearing nude mice. CONCLUSIONS: Pretreatment of Cderiv enhanced tumor permeability, resulting in higher accumulation of polymeric micelle carrier systems in solid tumors.

Quantitative model for efficient temporal targeting of tumor cells and neovasculature.

The combination of cytotoxic therapies and antiangiogenic agents is emerging as a most promising strategy in the treatment of malignant tumors. However, the timing and sequencing of these treatments seem to play essential roles in achieving a synergic outcome. Using a mathematical modeling approach that is grounded on available experimental data, we investigate the spatial and temporal targeting of tumor cells and neovasculature with a nanoscale delivery system. Our model suggests that the experimental success of the nanoscale delivery system depends crucially on the trapping of chemotherapeutic agents within the tumor tissue. The numerical results also indicate that substantial further improvements in the efficiency of the nanoscale delivery system can be achieved through an adjustment of the temporal targeting mechanism.

Application of human pancreatic carcinoid BON cells for receptor-targeted drug development.

In our previous study, we found that several tumor cell lines displayed high receptor-specific binding affinity, one of which, the human pancreatic carcinoid BON cell line, demonstrates high affinity binding of the bombesin (BN) and somatostatin (SST) receptor-specific ligands. In the present study, BON cells, as a representative model, were further applied to evaluate various peptide analogs and cytotoxic receptor-targeted peptide conjugates. We observed quick ligand-receptor internalization in BON cells as well as high binding affinity. Furthermore, BON cells have high expression of multidrug resistance-associated genes (MDR1) and show camptothecin (CPT) resistance. Various receptor-specific cytotoxic conjugates were synthesized and evaluated in the BON cell model via in vitro and in vivo studies. We found that all the tested conjugates displayed potent antitumor ability in xenografts. Especially, the CPT conjugates, CPT-SST, and CPT-BN, are most likely to increase sensitivity to CPT-resistant BON cells. Our findings suggest that appropriately defined tumor cell lines may provide physiologically relevant cell-based evaluations of novel peptide analogs and receptor-targeted chemotherapeutics.

Myocardial stunning following combined modality combretastatin-based chemotherapy: two case reports and review of the literature.

Myocardial stunning, known as stress cardiomyopathy, broken-heart syndrome, transient left ventricular apical ballooning, and Takotsubo cardiomyopathy, has been reported after many extracardiac stressors, but not following chemotherapy. We report 2 cases with characteristic electrocardiographic and echocardiographic features following combined modality therapy with combretastatin, a vascular-disrupting agent being studied for treatment of anaplastic thyroid cancer. In 1 patient, an ECG performed per protocol 18 hours after drug initiation showed deep, symmetric T-wave inversions in limb leads I and aVL and precordial leads V(2) through V(6). Echocardiography showed mildly reduced overall left ventricular systolic function with akinesis of the entire apex. The patient had mild elevations of troponin I. Coronary angiography revealed no epicardial coronary artery disease. The electrocardiographic and echocardiographic abnormalities resolved after several weeks. The patient remains stable from a cardiovascular standpoint and has not had a recurrence during follow-up. An electrocardiogram performed per protocol in a second patient showed deep, symmetric T-wave inversions throughout the precordial leads and a prolonged QT interval. Echocardiography showed mildly reduced left ventricular function with hypokinesis of the apical-septal wall. Acute coronary syndrome was ruled out, and both the electrocardiographic and echocardiographic changes resolved at follow-up. Although the patient remained pain-free without recurrence of anginal symptoms during long-term follow-up, the patient developed progressive malignancy and died.

Liquid chromatographic-mass spectrometry analysis and pharmacokinetic studies of erianin for intravenous injection in dogs.

The purpose of the present study was to examine the pharmacokinetic characteristics of erianin (2-methoxy-5-[2-(3,4,5-trimethoxyphenyl)-ethyl]-phenol, CAS 95041-90-0), a nature product extracted from Dendrobium chrysotoxum, having notable antitumour activity, after intravenous injection of erianin fat emulsion to beagle dogs. An HPLC-MS method was developed to analyze the erianin levels in dog plasma and validated in a pharmacokinetic study. Plasma profiles were obtained after intravenous injection of erianin fat emulsion at the doses 7.5, 15 and 30 mg/kg. The elimination half-life (t(1/2)) values for erianin were estimated to be 1.41+/- 0.31, 1.66 +/- 0.19, 1.60 0.28 h, while the mean area under concentration-time curve (AUC(0-infinity)) values were 1021.3 +/- 373.7, 2305.1 +/- 597.0 and 3952.1 +/- 378.2 ng x h/ml, respectively. In conclusion, the present observations indicated that erianin plasma concentrations were clearly dose-proportional for the dose range studied. There was no gender difference in pharmacokinetics for erianin in male and female dogs.

Combination of combretastatin A4 phosphate and doxorubicin-containing liposomes affects growth of B16-F10 tumors.

The study aimed to check the effectiveness of anticancer therapy combining a vascular-disruptive drug (combretastatin phosphate, CA4P) and a liposomal formulation of a chemotherapeutic (doxorubicin). CA4P was synthesized in our laboratory according to a previously described procedure. The antivascular drug and long-circulating doxorubicin-loaded liposomes were used to treat B16-F10 murine melanoma experimental tumors. Seventy-four hours after drug administration, a decrease in the number of tumor blood vessels was apparent and necrotic areas within tumors were visible. Combination therapy consisting of alternate administrations of CA4P and liposomal doxorubicin yielded greater inhibition of tumor growth than monotherapies alone. The best therapeutic results were obtained with the antivascular drug administered intratumorally every second day at 50 mg/kg body mass. In the case of combined therapy, the best results were obtained when the vascular-disruptive agent (CA4P) and the antineoplastic agent (liposomal doxorubicin) were administered in alternation.

Radiation-guided targeting of combretastatin encapsulated immunoliposomes to mammary tumors.

PURPOSE: Radiation upregulates expression of endothelial cell adhesion molecules providing a potential avenue for targeting drugs to irradiated tissue. Induced upregulation of E-selectin can be used to target immunoliposomes to solid tumors. The effects of targeting immunoliposomes containing the antivascular drug combretastatin disodium phosphate (CA4P) to irradiated mammary tumors were investigated in this study. METHODS: Mice bearing transplanted MCa-4 mouse mammary tumors were assigned to one of the factorial treatments permuting the administration of free CA4P, tumor irradiation, CA4P encapsulated liposomes, and CA4P encapsulated immunoliposomes (conjugated with anti-E-selectin). Single and fractionated dosing of radiation and/or CA4P was evaluated. RESULTS: For single dose treatments the group that received a single dose of radiation plus a single dose of immunoliposomes showed a significant delay in tumor growth compared to all other treatment groups. Fractionated radiation plus fractionated doses of immunoliposomes resulted in further tumor growth delay; however, it was not significantly different from other fractionated dose treatment groups that combined radiation and CA4P. CONCLUSIONS: Targeting of antivascular drugs to irradiated tumors via ligand-bearing liposomes results in significant tumor growth delay. This effect can be further potentiated using a fractionated irradiation dosing schedule combined with fractionated immunoliposome treatments.