Combretastatin A4 phosphate treatment induces vasculogenic mimicry formation of W256 breast carcinoma tumor in vitro and in vivo.

The purpose of this study was to investigate the effect of combretastatin A4 phosphate (CA4P) on vasculogenic mimicry (VM) channel formation in vitro and in vivo after a single-dose treatment and the underlying mechanism involved in supporting VM. In vitro model of three-dimensional cultures was used to test the effect of CA4P on the tube formation of Walker 256 cells. Western blot analysis was conducted to assess the expression of hypoxia-inducible factor (HIF)-1α and VM-associated markers. W256 tumor-bearing rat model was established to demonstrate the effect of CA4P on VM formation and tumor hypoxia by double staining and a hypoxic marker pimonidazole. Anti-tumor efficacy of CA4P treatment was evaluated by tumor growth curve. Under hypoxic conditions for 48 h in vitro, W256 cells formed VM network associated with increased expression of VM markers. Pretreatment with CA4P did not influence the amount of VM in 3-D culture as well as the expression of these key molecules. In vivo, W256 tumors showed marked intratumoral hypoxia after CA4P treatment, accompanied by increased VM formation. CA4P exhibited only a delay in tumor growth within 2 days but rapid tumor regrowth afterward. VM density was positively related to tumor volume and tumor weight at day 8. CA4P causes hypoxia which induces VM formation in W256 tumors through HIF-1α/EphA2/PI3K/matrix metalloproteinase (MMP) signaling pathway, resulting in the consequent regrowth of the damaged tumor.

MALDI-MSI and label-free LC-ESI-MS/MS shotgun proteomics to investigate protein induction in a murine fibrosarcoma model following treatment with a vascular disrupting agent.

Tumour vasculature is notoriously sinusoidal and leaky, and is hence susceptible to vascular disruption. Microtubule destabilising drugs such as the combretastatins form the largest group of tumour vascular disrupting agents and cause selective shutdown of tumour blood flow within minutes to hours, leading to secondary tumour cell death. Targeting the tumour vasculature is a proven anticancer strategy but early treatment response biomarkers are required for personalising treatment planning. Protein induction following treatment with combretastatin A4-phosphate was examined in a mouse fibrosarcoma model (fs188), where tumour cells express only the matrix-bound isoform of vascular endothelial growth factor A (VEGF188). These tumours are relatively resistant to vascular disruption by combretastatin A4-phosphate and hence a study of protein induction following treatment could yield insights into resistance mechanisms. The distribution of a number of proteins induced following treatment were visualised by MALDI-mass spectrometry imaging. Responses identified were validated by LC-ESI-MS/MS and immunohistochemical staining. Significant changes in proteins connected with necrosis, cell structure, cell survival and stress-induced molecular chaperones were identified. Protein-protein interactions were identified using STRING 9.0 proteomic network software. These relationship pathways provided an insight into the activity of the active tumour milieu and a means of linking the identified proteins to their functional partners.

Synthesis and antiproliferative activity of conformationally restricted 1,2,3-triazole analogues of combretastatins in the sea urchin embryo model and against human cancer cell lines.

A series of 1,5-diaryl- and 4,5-diaryl-1,2,3-triazole derivatives of combretastatin A4 were synthesized and evaluated as antimitotic microtubule destabilizing agents using the sea urchin embryo model. Structure-activity relationship studies identified compounds substituted with 3,4,5-trimethoxyphenyl and 3,4-methylenedioxy-5-methoxyphenyl ring A and 4-methoxyphenyl ring B as potent antiproliferative agents with high cytotoxicity against a panel of human cancer cell lines including multi-drug resistant cells. 4,5-Diaryl-1,2,3-triazoles (C-C geometry) were found to be considerably more active than the respective 1,5-diaryl-1,2,3-triazoles (N-C geometry). Compound 10ad' induced G2/M cell cycle arrest and apoptosis in human T-leukemia Jurkat cells via caspase 2/3/9 activation and downregulation of the antiapoptotic protein XIAP. A mitotic catastrophe has been evaluated as another possible cell death mode.

Targeting vascular disrupting agent-treated tumor microenvironment with tissue-penetrating nanotherapy.

Cancer treatment with vascular disrupting agents (VDAs) causes rapid and extensive necrosis in solid tumors. However, these agents fall short in eliminating all malignant cells, ultimately leading to tumor regrowth. Here, we investigated whether the molecular changes in the tumor microenvironment induced by VDA treatment sensitize the tumors for secondary nanotherapy enhanced by clinical-stage tumor penetrating peptide iRGD. Treatment of peritoneal carcinomatosis (PC) and breast cancer mice with VDA combretastatin A-4 phosphate (CA4P) resulted in upregulation of the iRGD receptors αv-integrins and NRP-1, particularly in the peripheral tumor tissue. In PC mice treated with CA4P, coadministration of iRGD resulted in an approximately threefold increase in tumor accumulation and a more homogenous distribution of intraperitoneally administered nanoparticles. Notably, treatment with a combination of CA4P, iRGD, and polymersomes loaded with a novel anthracycline Utorubicin (UTO-PS) resulted in a significant decrease in the overall tumor burden in PC-bearing mice, while avoiding overt toxicities. Our results indicate that VDA-treated tumors can be targeted therapeutically using iRGD-potentiated nanotherapy and warrant further studies on the sequential targeting of VDA-induced molecular signatures.

(4-Methoxyphenyl)(3,4,5-trimethoxyphenyl)methanone inhibits tubulin polymerization, induces G2/M arrest, and triggers apoptosis in human leukemia HL-60 cells.

(4-Methoxyphenyl)(3,4,5-trimethoxyphenyl)methanone (PHT) is a known cytotoxic compound belonging to the phenstatin family. However, the exact mechanism of action of PHT-induced cell death remains to be determined. The aim of this study was to investigate the mechanisms underlying PHT-induced cytotoxicity. We found that PHT displayed potent cytotoxicity in different tumor cell lines, showing IC50 values in the nanomolar range. Cell cycle arrest in G2/M phase along with the augmented metaphase cells was found. Cells treated with PHT also showed typical hallmarks of apoptosis such as cell shrinkage, chromatin condensation, phosphatidylserine exposure, increase of the caspase 3/7 and 8 activation, loss of mitochondrial membrane potential, and internucleosomal DNA fragmentation without affecting membrane integrity. Studies conducted with isolated tubulin and docking models confirmed that PHT binds to the colchicine site and interferes in the polymerization of microtubules. These results demonstrated that PHT inhibits tubulin polymerization, arrests cancer cells in G2/M phase of the cell cycle, and induces their apoptosis, exhibiting promising anticancer therapeutic potential.

[An injectable hydrogel/staple fiber composite for sustained release of CA4P and doxorubicin for combined chemotherapy of xenografted breast tumor in mice].

OBJECTIVE: To prepare an injectable hydrogel/staple fiber composite loaded with combretastain A-4 disodium phosphate (CA4P) and doxorubicin (DOX) and evaluate its antitumor efficacy via intratumoral injection. METHODS: DOX-loaded PELA staple fibers (FDOX) were prepared using electro-spinning and cryo-cutting, and the drug distribution on the surface of the fibers was observed using a fluorescence microscope, and the encapsulation efficiency and loading capacity of FDOX were determined with a fluorospectro photometer. The fibers were then dispersed in CA4P-loaded PLGA-PEG-PLGA tri-block polymer solution at room temperature to obtain the hydrogel/staple fiber composite (GCA4P/FDOX). The thermo-sensitivity of this composite was determined by a test tube inverting method. An ultraviolet spectrophotometer and a fluorospectrophotometer were used to detect the release profile of CA4P and DOX, respectively. We observed in vivo gel formation of the composite after subcutaneous injection in mice. The in vitro cytotoxicity of GCA4P/FDOX composite in MCF-7 and 4T1 cells was assessed using cell Counting Kit-8 (CCK-8) reagent. In a mouse model bearing breast tumor 4T1 cell xenograft, we evaluated the antitumor efficacy of the composite by monitoring tumor growth within 30 days after intratumoral injection of the composite. HE staining, immunohistochemistry for Ki67 and immunofluorescence (TUNEL) assay were used for pathological examination of the tumor tissues 21 days after the treatments. RESULTS: The average length of FDOX was 4.0±1.3 µm, and its drug loading capacity was (2.69±0.35)% with an encapsulation efficiency of (89.70±0.12)%. DOX was well distributed on the surface of the fibers. When the temperature increased to 37 ℃, the composite rapidly solidified to form a gel in vitro. Drug release behavior test showed that CA4P was completely released from the composite in 5 days and 87% of DOX was released in 30 days. After subcutaneous injection, the composite solidified rapidly without degradation at 24 h after injection. After incubation with GCA4P/FDOX for 72 h, only 30.6% of MCF-7 cells and 28.9% of 4T1 cells were viable. In the tumor-bearing mice, the tumor volume was 771.9±76.9 mm3 in GCA4P/FDOX treatment group at 30 days. Pathological examination revealed obvious necrosis of the tumor tissues and tumor cell apoptosis induced by intratumoral injection of G4A4P/FDOX. CONCLUSION: As an efficient dual drug delivery system, this hydrogel/staple fiber composite provides a new strategy for local combined chemotherapy of solid tumors.

Combining combretastatin A4 phosphate with ginsenoside Rd synergistically inhibited hepatocellular carcinoma by reducing HIF-1α via PI3K/AKT/mTOR signalling pathway.

OBJECTIVES: Combretastatin A4 phosphate (CA4P), a vascular disrupting agent (VDA), can cause rapid tumour vessel occlusion. Subsequently, extensive necrosis is discovered in the tumour center, which induces widespread hypoxia and the rise of the α subunit of hypoxia-inducible factor-1 (HIF-1α). The aim of this study was to evaluate the inhibition of hepatocellular carcinoma growth by combining CA4P with HIF-1 α inhibitor and investigate the mechanism of this combination. METHODS: Ginsenoside Rd (Rd) was used in combination with CA4P to estimate the inhibition effect in HepG2 cells and HepG2 xenograft mouse model. The efficacy of anti-tumour was evaluated by tumour growth curve. The protein expression of HIF-1α and PI3K/AKT/mTOR signalling pathway were analysed by western blot. KEY FINDINGS: Combination of CA4P and Rd inhibited HepG2 cell proliferation and induced apoptosis in vivo and in vitro. It also increased the necrotic area of the tumour and delayed the tumour growth. Moreover, Rd down-regulated HIF-1α protein expression by inhibiting PI3K/AKT/mTOR signalling pathway. CONCLUSIONS: Combination of CA4P and Rd had synergistic anti-tumour effects. The mechanism may be related to the inhibition of HIF-1α by PI3K/AKT/mTOR signalling pathway. This strategy provides a new thought for the combinative therapy of VDAs.

Predicting Clinical Efficacy of Vascular Disrupting Agents in Rodent Models of Primary and Secondary Liver Cancers: An Overview with Imaging-Histopathology Correlation.

Vascular disrupting agents (VDAs) have entered clinical trials for over 15 years. As the leading VDA, combretastatin A4 phosphate (CA4P) has been evaluated in combination with chemotherapy and molecular targeting agents among patients with ovarian cancer, lung cancer and thyroid cancer, but still remains rarely explored in human liver cancers. To overcome tumor residues and regrowth after CA4P monotherapy, a novel dual targeting pan-anticancer theragnostic strategy, i.e., OncoCiDia, has been developed and shown promise previously in secondary liver tumor models. Animal model of primary liver cancer is time consuming to induce, but of value for more closely mimicking human liver cancers in terms of tumor angiogenesis, histopathological heterogeneity, cellular differentiation, tumor components, cancer progression and therapeutic response. Being increasingly adopted in VDA researches, multiparametric magnetic resonance imaging (MRI) provides imaging biomarkers to reflect in vivo tumor responses to drugs. In this article as a chapter of a doctoral thesis, we overview the construction and clinical relevance of primary and secondary liver cancer models in rodents. Target selection for CA4P therapy assisted by enhanced MRI using hepatobiliary contrast agents (CAs), and therapeutic efficacy evaluated by using MRI with a non-specific contrast agent, dynamic contrast enhanced (DCE) imaging, diffusion weighted imaging (DWI) are also described. We then summarize diverse responses among primary hepatocellular carcinomas (HCCs), secondary liver and pancreatic tumors to CA4P, which appeared to be related to tumor size, vascularity, and cellular differentiation. In general, imaging-histopathology correlation studies allow to conclude that CA4P tends to be more effective in secondary liver tumors and in more differentiated HCCs, but less effective in less differentiated HCCs and implanted pancreatic tumor. Notably, cirrhotic liver may be responsive to CA4P as well. All these could be instructive for future clinical trials of VDAs.

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.

Clinical trial experience with CA4P anticancer therapy: focus on efficacy, cardiovascular adverse events, and hypertension management.

Combretastatin A4-phosphate (CA4P) is a vascular-disrupting agent (VDA) in clinical development for the treatment of ovarian and other cancers. In contrast to antiangiogenic agents, such as bevacizumab, which suppress the development of new tumor vasculature, VDAs target established tumor vasculature. These differing but complementary mechanisms of action are currently being explored in clinical trials combining CA4P and bevacizumab. Clinical experience to date has highlighted an important need to better understand the cardiovascular adverse events of CA4P, both alone and in combination with antiangiogenic agents, which can also be associated with cardiovascular adverse events. An acute but transient increase in blood pressure is often the most clinically relevant toxicity associated with CA4P. Increases in CA4P-related blood pressure typically occur 0.5 to 1 h after initiation of the 10-min infusion, peak by 2 h, and return to baseline 3 to 4 h after the infusion. Post-infusion increases in blood pressure are likely to recur in subsequent treatment cycles; however, the severity does not appear to increase with successive cycles. Other cardiovascular adverse events, such as transient, predominantly grade 1-2 tachycardia, bradycardia, QTc prolongation, and in rare cases myocardial ischemia, have also been observed with CA4P but at markedly lower frequencies than hypertension. The clinical trial experience with CA4P suggests that cardiovascular assessment of patients prior to CA4P treatment and careful management of blood pressure during CA4P treatment can largely mitigate the risk of cardiovascular adverse events. Accordingly, we have developed a blood pressure management algorithm for use in the ongoing phase II/III FOCUS study of the triple combination of CA4P with physician's choice chemotherapy and bevacizumab.

The vascular disrupting agent combretastatin A-4 phosphate causes prolonged elevation of proteins involved in heme flux and function in resistant tumor cells.

Vascular disrupting agents (VDAs) represent a promising class of anti-cancer drugs for solid tumor treatment. Here, we aim to better understand the mechanisms underlying tumor reccurrence and treatment resistance following the administration of a VDA, combretastatin A-4 phosphate (CA4P). Firstly, we used photoacoustic tomography to noninvasively map the effect of CA4P on blood oxygen levels throughout subcutaneous non-small cell lung cancer (NSCLC) tumors in mice. We found that the oxygenation of peripheral tumor vessels was significantly decreased at 1 and 3 hours post-CA4P treatment. The oxygenation of the tumor core reduced significantly at 1 and 3 hours, and reached anoxia after 24 hours. Secondly, we examined the effect of CA4P on the levels of proteins involved in heme flux and function, which are elevated in lung tumors. Using immunohistochemistry, we found that CA4P substantially enhanced the levels of enzymes involved in heme biosynthesis, uptake, and degradation, as well as oxygen-utilizing hemoproteins. Furthermore, measurements of markers of mitochondrial function suggest that CA4P did not diminish mitochondrial function in resistant tumor cells. These results suggest that elevated levels of heme flux and function contribute to tumor regrowth and treatment resistance post-VDA administration.

Enhancing Nanoparticle Accumulation and Retention in Desmoplastic Tumors via Vascular Disruption for Internal Radiation Therapy.

Aggressive, desmoplastic tumors are notoriously difficult to treat because of their extensive stroma, high interstitial pressure, and resistant tumor microenvironment. We have developed a combination therapy that can significantly slow the growth of large, stroma-rich tumors by causing massive apoptosis in the tumor center while simultaneously increasing nanoparticle uptake through a treatment-induced increase in the accumulation and retention of nanoparticles in the tumor. The vascular disrupting agent Combretastatin A-4 Phosphate (CA4P) is able to increase the accumulation of radiation-containing nanoparticles for internal radiation therapy, and the retention of these delivered radioisotopes is maintained over several days. We use ultrasound to measure the effect of CA4P in live tumor-bearing mice, and we encapsulate the radio-theranostic isotope 177Lutetium as a therapeutic agent as well as a means to measure nanoparticle accumulation and retention in the tumor. This combination therapy induces prolonged apoptosis in the tumor, decreasing both the fibroblast and total cell density and allowing further tumor growth inhibition using a cisplatin-containing nanoparticle.

A randomized Phase II trial of the tumor vascular disrupting agent CA4P (fosbretabulin tromethamine) with carboplatin, paclitaxel, and bevacizumab in advanced nonsquamous non-small-cell lung cancer.

INTRODUCTION: Combretastatin A4-phosphate, fosbretabulin tromethamine (CA4P) is a vascular disrupting agent that targets tumor vasculature. This study evaluated the safety of CA4P when combined with carboplatin, paclitaxel, and bevacizumab in chemotherapy-naïve subjects with advanced nonsquamous, non-small-cell lung cancer. METHODS: Adult subjects with confirmed American Joint Committee on Cancer six stage IIIB/IV non-small-cell lung cancer and an Eastern Cooperative Oncology Group performance score of 0 or 1 were randomized to receive six cycles (treatment phase) of paclitaxel (200 mg/m2), carboplatin (area under the concentration versus time curve 6), and bevacizumab (15 mg/kg) on day 1 and repeated every 21 days, or this regimen plus CA4P (60 mg/m2) on days 7, 14, and 21 of each cycle. Subjects could then receive additional maintenance treatment (excluding carboplatin and paclitaxel) for up to 1 year. RESULTS: Sixty-three subjects were randomized, 31 to control and 32 to CA4P, and 19 (61.3%) and 17 (53.1%), respectively, completed the treatment phase. Exposure to study treatment and dose modifications were comparable between the randomized groups. The overall incidence of treatment-emergent adverse events was similar between groups, with increased neutropenia, leukopenia, and hypertension in the CA4P group. Deaths, serious adverse events, and early discontinuations from treatment were comparable between the randomized treatment groups. The overall tumor response rate with CA4P was 50% versus 32% in controls. Overall and progression-free survival rates were comparable between the groups. CONCLUSION: CA4P plus carboplatin, paclitaxel, and bevacizumab appears to be a tolerable regimen with an acceptable toxicity profile in subjects with advanced non-small-cell lung cancer.

Combretastatins: In vitro structure-activity relationship, mode of action and current clinical status.

For the first time combretastatins were isolated from African willow tree Combretum Caffrum. Subsequent studies have shown the impact of combretastatin A4 phosphate, a water-soluble prodrug, on endothelial cells in tumor vascular system. The same effect was not observed in the vascular system. This selectivity is associated with combretastatins mechanism of action: binding to colchicine domain of microtubules, which affects the cytoskeleton functionality of immature endothelial cells. At the same time, combretastatins directly induce cell death via apoptosis and/or mitotic catastrophe pathways. The combination of both elements makes combretastatin an anticancer compound of high efficiency. The cis-configuration is crucial for its biological activity. To date, many derivatives were synthesized. The attempts to resolve spontaneous isomerization to less active trans-stilbene derivative are still in progress. This issue seems to be overcome by incorporation of the ethene bridge with heterocyclic moiety in combretastatins structure. This modification retains the cis-configuration and prevents isomerization. Nevertheless, combretastatin A4 phosphate disodium is still the most potent compound of this group. The combination therapy, which is the most effective treatment, includes combretastatin A4 phosphate (CA4P) and conventional chemotherapeutics and/or radiotherapy. CA4P is relatively well tolerated giving adverse events of moderate severity, which includes: nausea, vomiting, headache, and tumor pain. The aforementioned effects subside on the day of drug administration or on the following day.

Dynamic bioluminescence and fluorescence imaging of the effects of the antivascular agent Combretastatin-A4P (CA4P) on brain tumor xenografts.

Combretastatin A-4 (CA4) is a natural product isolated from Combretum caffrum that inhibits tubulin polymerization by binding to the colchicine-binding site. A corresponding water soluble pro-drug (referred to as CA4P), has undergone extensive clinical trials and has been evaluated in pre-clinical studies using multiple modalities. We previously reported a novel assay based on dynamic bioluminescent imaging to assess tumor vascular disruption and now present its application to assessing multiple tumors simultaneously. The current study evaluated the vascular-disrupting activity of CA4P on subcutaneous 9L rat brain tumor xenografts in mice using dynamic bioluminescence imaging. A single dose of CA4P (120 mg/kg, intraperitoneally) induced rapid, temporary tumor vascular shutdown revealed by a rapid and reproducible decrease of light emission from luciferase-expressing 9L tumors following administration of luciferin as a substrate. A time-dependent reduction of tumor perfusion after CA4P treatment was confirmed by immunohistological assessment of the perfusion marker Hoechst 33342 and the tumor vasculature marker CD31. The vasculature showed distinct recovery within 24 h post therapy. Multiple tumors behaved similarly, although a size dependent vascular inhibition was observed. In conclusion, CA4P caused rapid, temporary tumor vascular shutdown and led to reduction of tumor perfusion in rat brain tumor xenografts and the multiple tumor approach should lead to more efficient studies requiring fewer animals and greater consistency.

Evaluation of tumor ischemia in response to an indole-based vascular disrupting agent using BLI and (19)F MRI.

Vascular disrupting agents (VDAs) have been proposed as an effective broad spectrum approach to cancer therapy, by inducing ischemia leading to hypoxia and cell death. A novel VDA (OXi8007) was recently reported to show rapid acute selective shutdown of tumor vasculature based on color-Doppler ultrasound. We have now expanded investigations to noninvasively assess perfusion and hypoxiation of orthotopic human MDA-MB-231/luc breast tumor xenografts following the administration of OXi8007 based on dynamic bioluminescence imaging (BLI) and magnetic resonance imaging (MRI). BLI showed significantly lower signal four hours after the administration of OXi8007, which was very similar to the response to combretastatin A-4P (CA4P), but the effect lasted considerably longer, with the BLI signal remaining depressed at 72 hrs. Meanwhile, control tumors exhibited minimal change. Oximetry used (19)F MRI of the reporter molecule hexafluorobenzene and FREDOM (Fluorocarbon Relaxometry using Echo Planar Imaging for Dynamic Oxygen Mapping) to assess pO2 distributions during air and oxygen breathing. pO2 decreased significantly upon the administration of OXi8007 during oxygen breathing (from 122 ± 64 to 34 ± 20 Torr), with further decrease upon switching the gas to air (pO2 = 17 ± 9 Torr). pO2 maps indicated intra-tumor heterogeneity in response to OXi8007, though ultimately all tumor regions became hypoxic. Both BLI and FREDOM showed the efficacy of OXi8007. The pO2 changes measured by FREDOM may be crucial for future study of combined therapy.

Trapping effect on a small molecular drug with vascular-disrupting agent CA4P in rodent H22 hepatic tumor model: in vivo magnetic resonance imaging and postmortem inductively coupled plasma atomic emission spectroscopy.

The aim of the present study is to verify the trapping effect of combretastatin A-4-phosphate (CA4P) on small molecular drugs in rodent tumors. Mice with H22 hepatocarcinoma were randomized into groups A and B. Magnetic resonance imaging (MRI) of T1WI, T2WI, and DWI was performed as baseline. Mice in group A were injected with Gd-DTPA and PBS. Mice in group B were injected with Gd-DTPA and CA4P. All mice undergo CE-T1WI at 0 h, 3 h, 6 h, 12 h, and 24 h. Enhancing efficacy of the two groups on CE-T1WI was compared with the signal-to-noise ratio (SNR) calculated. Concentrations of gadolinium measured by ICP-AES in the tumor were compared between groups. On the early CE-T1WI, tumors were equally enhanced in both groups. On the delayed CE-T1WI, the enhancing effect of group A was weaker than that of group B. The SNR and the concentration of gadolinium within the tumor of group A were lower than that of group B at 6 h, 12 h, and 24 h after administration. This study indicates that CA4P could improve the retention of Gd-DTPA in the tumor and MRI allowed dynamically monitoring trapping effects of CA4P on local retention of Gd-DTPA as a small molecular drug.

Vascular disrupting effects of combretastatin A4 phosphate on murine endometriotic lesions.

OBJECTIVE: To study the effect of combretastatin A4 phosphate (CA4P) on the vascularization of endometriotic lesions. DESIGN: Intravital microscopic, histologic, and immunohistochemical study. SETTING: University institute. ANIMAL(S): BALB/c mice. INTERVENTION(S): Murine endometriotic lesions were induced by syngeneic transplantation of endometrium into dorsal skinfold chambers. After 6 days, the mice received an intraperitoneal injection of 80 mg/kg CA4P or vehicle. MAIN OUTCOME MEASURE(S): Vascularization of the lesions and the surrounding tissue was analyzed by intravital fluorescence microscopy over 8 days. Lesion morphology, vessel maturation, viability, and proliferation of endometrial glands and stroma were assessed by histology and immunohistochemistry. RESULT(S): All lesions were initially well vascularized, containing immature and mature microvessels. Injection of CA4P induced a selective vessel collapse in the lesions without affecting the surrounding microvasculature. This resulted in a decreased functional capillary density and blood perfusion of CA4P-treated lesions after 2 hours when compared with controls. However, the vascularization of the lesions progressively normalized, and their numbers of proliferating and apoptotic cells did not differ from those of controls. CONCLUSION(S): This study demonstrates a selective vascular disrupting effect of CA4P on endometriotic lesions, indicating that vascular disrupting agents may be suitable for endometriosis therapy.