Vascular targeting by EndoTAG-1 enhances therapeutic efficacy of conventional chemotherapy in lung and pancreatic cancer.

Cationic lipid complexed paclitaxel (EndoTAG-1) is a novel vascular targeting agent for the treatment of cancer. Here, the aim was to investigate intratumoral drug distribution after EndoTAG-1 therapy and analyze the impact of EndoTAG-1 scheduling on antitumoral efficacy. The therapeutic effect of EndoTAG-1 in combination with conventional gemcitabine or cisplatin therapy was evaluated in L3.6pl orthotopic pancreatic cancer and a subcutaneous Lewis lung (LLC-1) carcinoma model. Oregon Green paclitaxel encapsulated in cationic liposomes in combination with intravital fluorescence microscopy clearly exhibited delivery of the drug by EndoTAG-1 to the tumor endothelium, whereas Oregon Green paclitaxel dissolved in cremophor displayed an interstitial distribution pattern. The therapeutic efficacy of EndoTAG-1 was critically dependent on the application schedule with best therapeutic results using a metronomic rather than a maximum tolerated dose application sequence. The combination of EndoTAG-1 therapy and cytotoxic chemotherapy significantly enhanced antitumoral efficacy in both tumor models. Interestingly, only EndoTAG-1 in combination with gemcitabine was able to inhibit the incidence of metastasis in pancreatic cancer. In conclusion, vascular targeting tumor therapy by EndoTAG-1 combined with standard small molecular chemotherapy results in markedly enhanced antitumoral efficacy. Therefore, this combination represents a promising novel strategy for clinical cancer therapy.

Interrupted or continuous slowly absorbable sutures for closure of primary elective midline abdominal incisions: a multicenter randomized trial (INSECT: ISRCTN24023541).

OBJECTIVE: In patients undergoing midline incisions, the abdominal fascia can be closed with a continuous or interrupted suture using various materials. The aim of this study is to compare: (1) interrupted technique with rapidly absorbable sutures and (2) continuous techniques with different slowly absorbable sutures, focusing on the incidence of incisional hernias within 1 year. SUMMARY OF BACKGROUND DATA: A meta-analysis suggested that the incidence of incisional hernias can be more effectively reduced with slowly absorbable continuous sutures. METHODS: Multicenter randomized surgical trial with 3 parallel groups. Patients were scheduled for primary elective midline incisions. All surgeons were trained (4:1 suture wound length in continuous groups) and monitored. Primary end point, measured within 1 year after surgery, was the frequency of incisional hernias diagnosed by clinical examination and confirmed by ultrasound. Complications and safety were used as secondary end points. This study has been registered with the ISRCTN Register (INSECT: ISRCTN24023541). RESULTS: Conducted on 625 randomized patients (210 interrupted Vicryl, 205 continuous polydioxanone suture (PDS), 210 continuous Monoplus), the primary analysis showed an incidence of 28 incisional hernias (15.9%) versus 15 (8.4%) versus 22 (12.5%) for the 3 closure techniques, respectively (P = 0.09). No significant difference was observed between the 3 groups with regard to burst abdomen (4 [2.0%] vs. 6 [3.0%] vs. 8 [4.0%], P = 0.46), wound infection (26 [12.7%] vs. 39 [19.4%] vs. 33 [16.3%], P = 0.19), pulmonary infections (9 [4.4%] vs. 5 [2.5%] vs. 5 [2.5%], P = 0.46), serious adverse events (63 [30.0%] vs. 57 [27.8%] vs. 61 [29.1%], P = 0.89), and 1-year mortality (16 [7.9%] vs. 11 [5.5%] vs. 16 [7.9%], P = 0.54). CONCLUSIONS: The incidence of incisional hernias and the frequency of wound infection was higher than expected in all groups. New concepts need to be developed and studied to substantially reduce the frequency of incisional hernias.

Effect of Src kinase inhibition on metastasis and tumor angiogenesis in human pancreatic cancer.

Tumor angiogenesis is a process that requires migration, proliferation, and differentiation of endothelial cells. We hypothesized that decrease in pancreatic tumor growth due to inhibition of Src activity is associated with the inability of Src kinase to trigger a network of such signaling processes, which finally leads to endothelial cell death and angiogenesis-restricted tumor dormancy. The therapeutic efficacy of Src kinase inhibitor AZM475271 was tested in nude mice orthotopically xenografted with L3.6pl pancreatic carcinoma cells. No liver metastases and peritoneal carcinosis were detected and a significant effect on the average pancreatic tumor burden was observed following treatment with AZM475271, which in turn correlated with a decrease in cell proliferation and an increase in apoptotic endothelial cells. AZM475271 was shown to significantly inhibit migration of human umbilical vein endothelial cells in an in vitro Boyden Chamber cell migration assay. In a rat aortic ring assay we could demonstrate as well inhibition of endothelial cell migration and sprouting following therapy with Src kinase inhibitor at similar doses. The most conclusive anti-angiogenic activity of AZM475271 was demonstrated in vivo (mouse corneal micropocket assay) by showing a marked inhibition of basic fibroblast growth factor-induced neovascularization in response to systemic administration of AZM475271. Furthermore, we could show reduced proliferation of HUVECs determined with the TACS MTT Cell Viability Assay Kit. The blockade of Src kinase significantly reduced the level of VEGF in L3.6pl medium, the effect which was found also in the cell culture supernate from HUVECs. Inhibition of Src kinase by AZM475271 also showed prevention of survival signaling from VEGF and EGF receptors. Treatment with AZM475271 resulted in VEGF - dependent inhibition of tyrosine phosphorylation of FAK. HUVECs were also examined using propidium iodide staining for cell cycle analysis by FACS. Inhibition of Src kinase promoted HUVEC apoptosis in a dose-dependent manner. Taken together, our results suggest that the Src kinase inhibitor AZM475271, in addition to its effects on tumor cells, suppresses tumor growth and metastasis in vitro and in vivo potentially also by anti-angiogenic mechanisms.

The immunosuppressant FTY720 inhibits tumor angiogenesis via the sphingosine 1-phosphate receptor 1.

FTY720, a sphingosine 1-phosphate (S1P) analog, acts as an immunosuppressant through trapping of T cells in secondary lymphoid tissues. FTY720 was also shown to prevent tumor growth and to inhibit vascular permeability. The MTT proliferation assay illustrated that endothelial cells are more susceptible to the anti-proliferative effect of FTY720 than Lewis lung carcinoma (LLC1) cells. In a spheroid angiogenesis model, FTY720 potently inhibited the sprouting activity of VEGF-A-stimulated endothelial cells even at concentrations that apparently had no anti-proliferative effect. Mechanistically, the anti-angiogenic effect of the general S1P receptor agonist FTY720 was mimicked by the specific S1P1 receptor agonist SEW2871. Moreover, the anti-angiogenic effect of FTY720 was abrogated in the presence of CXCR4-neutralizing antibodies. This indicates that the effect was at least in part mediated by the S1P1 receptor and involved transactivation of the CXCR4 chemokine receptor. Additionally, we could illustrate in a coculture spheroid model, employing endothelial and smooth muscle cells (SMCs), that the latter confer a strong protective effect regarding the action of FTY720 upon the endothelial cells. In a subcutaneous LLC1 tumor model, the anti-angiogenic capacity translated into a reduced tumor size in syngeneic C57BL/6 mice. Consistently, in the Matrigel plug in vivo assay, 10 mg/kg/d FTY720 resulted in a strong inhibition of angiogenesis as demonstrated by a reduced capillary density. Thus, in organ transplant patients, FTY720 may prove efficacious in preventing graft rejection as well as tumor development.

Rapamycin induces tumor-specific thrombosis via tissue factor in the presence of VEGF.

Therapeutic strategies that target and disrupt the already-formed vessel networks of growing tumors are actively pursued. The goal of these approaches is to induce a rapid shutdown of the vascular function of the tumor so that blood flow is arrested and tumor cell death occurs. Here we show that the mammalian target of rapamycin (mTOR) inhibitor rapamycin, when administered to tumor-bearing mice, selectively induced extensive local microthrombosis of the tumor microvasculature. Importantly, rapamycin administration had no detectable effect on the peritumoral or normal tissue. Intravital microscopy analysis of tumors implanted into skinfold chambers revealed that rapamycin led to a specific shutdown of initially patent tumor vessels. In human umbilical vein endothelial cells vascular endothelial growth factor (VEGF)-induced tissue factor expression was strongly enhanced by rapamycin. We further show by Western blot analysis that rapamycin interferes with a negative feedback mechanism controlling this pathologic VEGF-mediated tissue factor expression. This thrombogenic alteration of the endothelial cells was confirmed in a one-step coagulation assay. The circumstance that VEGF is up-regulated in most tumors may explain the remarkable selectivity of tumor vessel thrombosis under rapamycin therapy. Taken together, these data suggest that rapamycin, besides its known antiangiogenic properties, has a strong tumor-specific, antivascular effect in tumors.

Magnetic resonance imaging in an orthotopic rat model: blockade of epidermal growth factor receptor with EMD72000 inhibits human pancreatic carcinoma growth.

The purpose of our research was to investigate the antiangiogenic effect of the epidermal growth factor receptor monoclonal antibody (anti-EGF-R MAB) EMD72000, in an orthotopic human pancreatic carcinoma model in rats, assessed by magnetic resonance (MR) imaging using angiogenic surrogate markers in comparison with histopathologic findings. Human pancreatic adenocarcinoma cells L3.6pl were injected orthotopically in the pancreas of 12 athymic nude rats. Through a 21-day course, groups of 6 rats were treated intraperitoneally with either EMD72000 or with saline solution for control animals. Dynamic contrast-enhanced MR imaging was performed before and after the treatment to assess microvascular permeability, estimated by the endothelial transfer coefficient (KPS) and fractional plasma volumes (fPV) of the pancreatic tumors. EMD72000-treated animals showed significantly less tumor volume progression (1,080 mm3 +/- 1,244; p = 0.012) and significantly lower values for microvascular permeability (KPS = 4.2 ml min(-1) 100 ml(-1) of tissue +/- 2.8; p = 0.015), fractional plasma volume (fPV = 0.018 ml ml(-1) of tissue +/- .015; p = 0.003) and microvessel density (MVD = 13 +/- 4 (0.159 mm2); p = 0.001) than saline-treated animals (6,544 mm3 +/- 5,202; 9.5 ml min(-1) 100 ml(-1) of tissue +/- 4.3, 0.056 ml ml(-1) of tissue +/- 0.019 and 25 +/- 5 (0.159 mm2), respectively). KPS and fPV values showed moderate positive correlation with MVD (r = 0.5, p = 0.103; r = 0.6, p = 0.065, respectively). Intraperitoneal injection of EMD72000 inhibits orthotopic human pancreatic carcinoma growth in rats. Antiangiogenic effects of anti-EGF-R MAB EMD72000 can be quantified and monitored noninvasively by dynamic MR imaging.