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ABSTRACT: Hepatocellular carcinoma (HCC) has a poor prognosis and systemic chemotherapies have disappointing results. The increasing knowledge of the molecular biology of HCC has resulted in novel targets, with the vascular endothelial growth factor and epidermal growth factor receptor (EGFR)-related pathways being of special interest. New blood vessel formation (angiogenesis) is essential for the growth of solid tumors. Anti-angiogenic strategies have become an important therapeutic modality for solid tumors. Several agents targeting angiogenesis-related pathways have entered clinical trials or have been already approved for the treatment of solid tumors. These include monoclonal antibodies, receptor tyrosine kinase inhibitors and immunomodulatory drugs. HCC is a highly vascular tumor, and angiogenesis is believed to play an important role in its development and progression. This review summarizes recent advances in the basic understanding of the role of angiogenesis in HCC as well as clinical trials with novel therapeutic approaches targeting angiogenesis and EGFR-related pathways.
World journal of hepatology. 02/2011; 3(2):38-44.
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ABSTRACT: Tumor angiogenesis has been identified to play a critical role in tumor growth and tumor progression, and is regulated by a balance of angiogenic and anti-angiogenic cytokines. Among them VEGF (vascular endothelial growth factor) and its signaling through its receptors are of crucial relevance. Inhibition of VEGF signaling by monoclonal antibodies or small molecules (kinase inhibitors) has already been successfully established for the treatment of different cancer entities and multiple new drugs are being tested in clinical trials. However not all patients are likely to respond to these therapies, but to date there are no reliable biomarkers available to predict therapy response. Many studies integrated biomarker programs in their study protocols, thus several potential biomarkers have been identified which are currently under clinical investigation in prospective randomized studies. This review intends to give an overview of the described potential biomarkers as well as different imaging techniques such as ultrasound and magnetic resonance imaging that can indicate benefit, resistance and toxicity to anti-angiogenic therapies.
International Journal of Molecular Sciences 01/2011; 12(10):7077-99. · 2.60 Impact Factor
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Joachim Drevs,
Michael Medinger,
Klaus Mross,
Stefan Fuxius,
Juergen Hennig,
Martin Buechert,
Anne Thomas,
Clemens Unger,
Bee-Lian Chen,
David Lebwohl,
Dirk Laurent
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ABSTRACT: PTK787/ZK 222584 (PTK/ZK) offers a novel approach to inhibit tumour angiogenesis.
This study characterized the safety, tolerability, biological activity and pharmacokinetic profile of PTK/ZK, while determining the optimum dose. Seventy-one patients with advanced cancer were enrolled to receive once daily dosing. Pharmacokinetic, dynamic contrast enhanced magnetic resonance imaging and safety assessments were performed, along with measurement of soluble markers. Patients were treated until they had unacceptable toxicity and/or disease progression.
Twenty-nine patients were assessable for maximum tolerated dose (MTD) determination, but no MTD was established; only two patients experienced dose limiting toxicities. PTK/ZK was well tolerated with only nine patients experiencing serious adverse events suspected to be PTK/ZK related, but no objective tumour response was observed; 34% had stable disease and 48% had progressive disease. In addition, PTK/ZK was rapidly absorbed with a maximum concentration occurring 2 hours post-dosing. Vascular endothelial growth factor and basic fibroblastic growth factor were good predictors of best tumour response, as was the MRI bidirectional transfer constant on day 2 of treatment.
An MTD was not reached in this study but, based on these data and findings from other studies, 1200 mg was found to be the optimum dose of PTK/ZK for patients with advanced cancer.
Anticancer research 06/2010; 30(6):2335-9. · 1.73 Impact Factor
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ABSTRACT: Auron-Misheil-Therapy (AMT) is a defined but unique combination of approved pharmaceuticals. It consists of insulin, chlorpheniramine and an aqueous camomile extract, and it has been successfully applied clinically in late-stage cancer patients. The purpose of this study was to elucidate the anti-tumor efficacy of AMT in a validated murine renal cell carcinoma animal model (RENCA). There were two independent studies; each animal group consisted of 16 mice. During a 6-week pretreatment period, vehicle (group A) and AMT (1.6 mg/kg/d) (group B) were administered once daily in a 5 days/week schedule either intramuscularly or subcutaneously. Tumor challenge at day 0 was followed by a 3-week treatment period (either vehicle or AMT once daily intramuscularly for 21 days consecutively). In study 2 the AMT dosage was increased up to 4-fold by doubling individual doses and switching to a twice daily schedule. The injections were all intramuscular. With the exception of group D, a six-week pretreatment period preceded the tumor challenge at day 0. Tumor challenge was followed by a 3-week treatment period (vehicle, AMT at either 3.2 mg/kg/d) (group A) or 6.4 mg/kg/d (group B), or AMT0, an AMT preparation which does not stimulate IL-6 secretion (6.4 mg/kg/d, group C) continuously for 21 days. AMT administration for group D (6.4 mg/kg/d) was limited to the treatment period from day 1 to 21. All mice were sacrificed 21 days after tumour transplantation. AMT administration was safe and well tolerated, and significantly reduced primary tumor volume in pretreated animals. The effective route of application was intramuscular, with dose escalation resulting in an improved anti-tumor effect. This is the first demonstration of a significant anti-tumorigenic effect of AMT in a validated tumor model.
Oncology Reports 01/2010; 23(1):205-10. · 1.84 Impact Factor
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ABSTRACT: Cediranib is a highly potent and selective vascular endothelial growth factor (VEGF) signaling inhibitor with activity against all three VEGF receptors (VEGFRs) that inhibits angiogenesis and growth of human tumor xenografts in vivo. The present study evaluated the antitumor and antiangiogenic activity of cediranib in the clinically relevant, murine renal cell carcinoma (RENCA) model and its biological response using VEGF and sVEGFR-2 as biomarkers. Mice were treated with cediranib (5 mg/kg/d p.o.) or vehicle for 2, 8 or 12 days and tumor volumes, microvessel density (MVD) and VEGF and sVEGFR-2 plasma concentrations were determined. Cediranib treatment (8 and 12 days) led to a significant reduction in tumor size (42-50%) and a highly significant reduction in MVD (30-55%) versus controls. After 12 days' treatment, VEGF plasma concentration increased significantly in both cediranib-treated and control animals and this increase correlated with tumor size; the cediranib group showed a more pronounced increase in VEGF but a reduced tumor volume compared with control animals. Plasma concentrations of VEGF reached a plateau in the cediranib group after 17-21 days' treatment. sVEGFR-2 concentrations significantly decreased over 12 days in controls, whereas they remained stable in cediranib-treated mice. sVEGFR-2 did not correlate with tumor volume in controls; mice treated with cediranib had lower relative VEGFR-2 plasma concentrations and tumor burdens. In conclusion, cediranib showed potent antitumor and antiangiogenic efficacy in the RENCA model. sVEGFR-2 plasma concentrations can act as a surrogate marker for antitumor activity of VEGFR signaling inhibitors.
Anticancer research 12/2009; 29(12):5065-76. · 1.73 Impact Factor
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Marlies H G Langenberg,
Carla M L van Herpen,
Johann De Bono,
Jan H M Schellens,
Clemens Unger,
Klaas Hoekman,
Hubert E Blum,
Walter Fiedler, Joachim Drevs,
Florence Le Maulf,
Anitra Fielding,
Jane Robertson,
Emile E Voest
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ABSTRACT: PURPOSE Hypertension is a commonly reported adverse effect after administration of vascular endothelial growth factor (VEGF) inhibitors. Cediranib is a highly potent and selective VEGF signaling inhibitor of all three VEGFRs. This study prospectively investigated hypertension management to help minimize dose interruptions/reductions to maximize cediranib dose intensity. PATIENTS AND METHODS Patients (n = 126) with advanced solid tumors were randomly assigned to one of four groups: cediranib 30 or 45 mg/d with or without antihypertensive prophylaxis. All patients developing hypertension on cediranib treatment were treated with a standardized, predefined hypertension management protocol. Results Cediranib was generally well tolerated, and all groups achieved high-dose intensities in the first 12 weeks (> 74% in all groups). Antihypertensive prophylaxis did not result in fewer dose reductions or interruptions. Increases in blood pressure, including moderate and severe readings of hypertension, were seen early in treatment in all groups and successfully managed. Severe hypertension occurred in one patient receiving prophylaxis versus 18 in the nonprophylaxis groups. Overall, there were nine partial responses, and 38 patients experienced stable disease >/= 8 weeks. CONCLUSION To our knowledge, this is the first prospective investigation of hypertension management during administration of a VEGF signaling inhibitor. All four regimens were well tolerated with high-dose intensities and no strategy was clearly superior. The current cediranib hypertension management protocol appears to be effective in managing hypertension compared with previous cediranib studies where no plan was in place, and early recognition and treatment of hypertension is likely to reduce the number of severe hypertension events. This protocol is included in all ongoing cediranib clinical studies.
Journal of Clinical Oncology 11/2009; 27(36):6152-9. · 18.37 Impact Factor
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ABSTRACT: This pilot study of Auron Misheil Therapy (AMT) in women with advanced cervical cancer was an open-label, single arm study to collect initial safety, efficacy, and quality of life data. Fifteen women with stage IIIb or IVa cervical cancer were given twice daily intramuscular injections of AMT (insulin, chlorpheniramine and camomile extract) for 3 months. Objective tumor response was evaluated using CT scans and analyzing the data according to the WHO RECIST criteria. Clinical Benefit Response (CBR) was assessed using a composite score comprising Karnovsky performance status, pain intensity and body weight. Safety and tolerability parameters were monitored. Quality of life was evaluated using the European Organization for Research and Treatment of Cancer Core Quality of Life Questionnaire (EORTC C-30). Eight out of 15 patients were rated as clinical responders (CBR) at 12 weeks. One patient had a partial response and 11 stable disease (WHO RECIST criteria). AMT was well tolerated. An initial analysis showed improvement in quality of life (EORTC C-30). Promising response rates, early indications of improved quality of life, and no significant safety issues mean that the second, randomized phase of the trial can be initiated with a longer treatment duration. Patients with advanced cervical cancer showed positive clinical responses to Auron Misheil Therapy. The treatment was well tolerated, with indications of improved quality of life.
Oncology Reports 11/2009; 22(4):877-83. · 1.84 Impact Factor
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ABSTRACT: The established role of VEGF signaling in promoting tumor angiogenesis has led to the development and clinical validation of several agents that selectively target this pathway in patients with advanced-stage malignancies. These include neutralizing anti-VEGF monoclonal antibodies, soluble VEGF receptors and small-molecule inhibitors of VEGF receptor function, administered either as monotherapy or in combination with chemotherapy. Several modes of action have been identified, such as inhibition of new vessel growth, regression of newly formed vasculature, alteration of tumor vessel function and direct effects on tumor cells. VEGF-targeting drugs currently play an important role in the treatment of cancer and their impact will probably further increase in the future.
Expert Review of Anti-infective Therapy 06/2009; 9(5):649-62. · 2.65 Impact Factor
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ABSTRACT: Auron-Misheil-Therapy (AMT) consisting of aqueous camomile extract supplemented with calcium, vitamins, the antihistamine chlorpheniramine and human insulin is under development as anti-cancer treatment. AMT was preclinically investigated in tumour cell lines and tumour xenografts to guide clinical phase I/II studies. AMT was tested against 56 human tumour cell lines, in a clonogenic assay in 98 patient-derived xenografts and in in vivo studies. AMT showed in vitro cytotoxic activity with highest susceptibility in cervical cancer, glioblastoma and colon cancers. In the clonogenic assay, anti- cancer activity of AMT was most active in cervical and uterine tumours, in colon cancer, glioblastoma, leukaemia, melanoma and pancreatic cancer. In vivo, AMT showed slight activity in tumour xenograft models of colon and mammary cancer. It also showed immune stimulatory effects by induction of IL-6- and TNF-alpha secretion in human PBMCs. The immune stimulatory potential of AMT, together with slight anti-tumour efficacy observed in the present study, indicates a role of AMT in tumour therapy.
International Journal of Oncology 06/2009; 34(5):1341-52. · 2.40 Impact Factor
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ABSTRACT: This review will provide physicians and oncologists with an overview of side effects related to targeted agents that inhibit vascular endothelial growth factor (VEGF), epidermal growth factor (EGF) and mammalian target of rapamycin (mTOR) signaling in the treatment of solid tumors. Such targeted agents can be divided into monoclonal antibodies, tyrosine kinase inhibitors, multitargeted tyrosine kinase inhibitors and serine/threonine kinase inhibitors. Molecular targeted therapies are generally well tolerated, but inhibitory effects on the biological function of the targets in healthy tissue can result in specific treatment-related side effects, particularly with multitargeted agents. We offer some guidance on how to manage adverse events in cancer patients based on the range of options currently available.
Onkologie 04/2009; 32(3):129-38. · 0.87 Impact Factor
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ABSTRACT: In a phase-III trial it was recently shown that an adjuvant renal cell carcinoma (RCC) vaccine (Reniale) reduces the risk of tumour progression following nephrectomy. This clinical trial focused on efficacy and did not investigate end-points relating to mode-of-action of the vaccine. In a murine model we investigated mode-of-action, efficacy, and safety of a homologous RENCA cell-based vaccine.
Six groups with 12 BALB/c mice per group received five vaccinations (lysate of 1x10(6)-1x10(7) RENCA cells, manufactured with or without prior IFN-gamma incubation) at 3-wk intervals before tumour transplantation and one vaccination 14 d afterwards. Controls (12 mice) received only solvent. All mice were sacrificed 21 d after tumour transplantation.
Animal welfare, tumour growth, number of metastases, and the presence of cytotoxic T-lymphocytes as determined by a (51)chromium-release assay. Adoptive immune transfer experiments (vaccination of nine mice with the RENCA vaccine or saline and transfer of serum, spleen cells, and CD4 and/or CD8 depleted spleen cells into five recipient mice each) were carried out to demonstrate involvement of different immune mechanisms.
All controls developed a renal tumour, compared to 7/72 animals (9.7%) in the vaccine groups. The mean number of lung metastases was 100 (range 3-750) in controls and 4 (range 0-196) in the vaccine groups, respectively. Tumour uptake and number of metastases were not related to the vaccine dose. The (51)chromium-release assay confirmed a significant tumour-specific cytolytic activity and marginally increased NK activity of splenocytes from vaccinated mice against RENCA cells compared to controls. Adoptive immune transfer experiments showed that the antitumoural effective immune mechanisms are cell-based.
We could demonstrate the mode-of-action, efficacy, and safety of a homologous tumour vaccine in a RENCA model. These findings support the positive results from a phase-III trial with Reniale.
European urology 07/2008; 56(1):123-31. · 7.67 Impact Factor
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ABSTRACT: Combined therapy of continuous low dose capecitabine and high dose celecoxib targeting angiogenesis was used in a phase II trial to treat advanced cancer patients. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) was used to monitor antiangiogenic effects.
37 Patients (21 men, 16 women), mean age 60 years, with advanced and progressive cancer of various tumor types were included. Therapy consisted of 2 x 500 mg oral capecitabine/ day and 2 x 400 mg oral celecoxib/day continuously until progression of disease. To monitor antiangiogenic effects, DCE-MRI measurements were performed at baseline, after 1 month, and after 3 months of therapy. Tumor assessment was performed according to RECIST criteria, toxicity was evaluated according to the CTC version 2.0 catalogue.
Therapy was well tolerated without grade 3 and 4 toxicities. The mean number of treatment cycles was 4 (range: 1-15+). Disease stabilization after 3 cycles was seen in 11 patients. 6 patients were stable over long periods. The mean number of treatment cycles in this group was 10 (range: 7-15+). DCE-MRI demonstrated a reduction of tumor vessel permeability and blood flow in patients who reached stable disease or some minor regression.
Continuous dosing of the combination of capecitabine and celecoxib was well tolerated, produced antiangiogenic effects, and has antitumor activity. Patients with rapid progression did not benefit.
Onkologie 01/2008; 30(12):629-35. · 0.87 Impact Factor
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ABSTRACT: The (6-maleimidocaproyl)hydrazone derivative of doxorubicin (DOXO-EMCH) is an albumin-binding prodrug of doxorubicin with acid-sensitive properties that shows superior antitumor efficacy in murine tumor models and a favorable toxicity profile in mice, rats, and dogs compared with doxorubicin. The purpose of the phase I study was to characterize the toxicity profile of DOXO-EMCH, establish a recommended dose for phase II studies, and assess potential anticancer activity.
A starting dose of 20 mg/m2 doxorubicin equivalents was chosen. Forty-one patients with advanced cancer disease were treated with an i.v. infusion of DOXO-EMCH once every 3 weeks at a dose level of 20 to 340 mg/m2 doxorubicin equivalents.
Treatment with DOXO-EMCH was well tolerated up to 200 mg/m2 without manifestation of drug-related side effects. Myelosuppression (grade 1-2) and mucositis (grade 1-2) were the predominant adverse effects at dose levels of 260 mg/m2 and myelosuppression (grade 1-3) as well as mucositis (grade 1-3) were dose limiting at 340 mg/m2. No cardiac toxicity was observed. Of 30 of 41 evaluable patients, 12 patients (40%) had progressive disease, 15 patients (57%) had stable disease, and 3 patients (10%) had a partial remission.
DOXO-EMCH showed a good safety profile and was able to induce tumor regressions in tumor types known to be anthracycline-sensitive tumors, such as breast cancer, small cell lung cancer, and sarcoma. The recommended doxorubicin equivalent dose for phase II studies is 260 mg/m2.
Clinical Cancer Research 09/2007; 13(16):4858-66. · 7.74 Impact Factor
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Joachim Drevs,
Patrizia Siegert,
Michael Medinger,
Klaus Mross,
Ralph Strecker,
Ute Zirrgiebel,
Jan Harder,
Hubert Blum,
Jane Robertson,
Juliane M Jürgensmeier,
Thomas A Puchalski,
Helen Young,
Owain Saunders,
Clemens Unger
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ABSTRACT: AZD2171 is a highly potent oral selective inhibitor of vascular endothelial growth factor (VEGF) signaling. This phase I study was designed to evaluate the safety and tolerability of increasing doses of AZD2171, with additional assessments of pharmacokinetics, pharmacodynamics, and efficacy.
In part A, 36 patients with solid tumors and liver metastases refractory to standard therapies received once-daily oral AZD2171 (0.5 to 60 mg). Doses were escalated in successive cohorts until the maximum-tolerated dose was identified. In part B, patients with (n = 36) or without (n = 11) liver metastases were randomly assigned to receive once-daily AZD2171 (20, 30, or 45 mg). In both parts, treatment continued until tumor progression or dose-limiting toxicity (DLT) was observed.
Eighty-three patients received AZD2171, which was generally well tolerated at doses of 45 mg/d or less; the most frequently reported dose-related adverse events were diarrhea, dysphonia, and hypertension. The most common DLT was hypertension (n = 7), which occurred at AZD2171 doses of 20 mg and higher. After a single dose, maximum plasma (peak) drug concentration after single-dose administration (Cmax) was achieved 1 to 8 hours postdosing with an arithmetic mean half-life associated with terminal slope of a semilogarithmic concentration-time curve (t1/2 lamda(z)) of 22 hours. Pharmacodynamic assessments demonstrated time-, dose-, and exposure-related decreases in initial area under the curve, defined over 60 seconds post-contrast arrival in the tissue (iAUC60) using dynamic contrast-enhanced magnetic resonance imaging, as well as dose- and time-dependent reductions in soluble VEGF receptor 2 levels. Preliminary evidence of efficacy included two confirmed partial responses and 22 patients with stable disease; effects on tumor size appeared to be dose related.
Once-daily oral AZD2171 at doses of 45 mg or less was generally well tolerated and was associated with encouraging antitumor activity in patients with a broad range of advanced solid tumors.
Journal of Clinical Oncology 08/2007; 25(21):3045-54. · 18.37 Impact Factor
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Lucy Lee,
Sunil Sharma,
Bruno Morgan,
Peter Allegrini,
Christian Schnell,
Josef Brueggen,
Robert Cozens,
Mark Horsfield,
Clemens Guenther,
Will P Steward, Joachim Drevs,
David Lebwohl,
Jeanette Wood,
Paul M J McSheehy
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ABSTRACT: PTK/ZK is a novel, oral angiogenesis inhibitor that specifically targets all 3 vascular endothelial growth factor (VEGF) receptor tyrosine kinases and is currently in phase III clinical trials. In early clinical trials, PTK/ZK demonstrated a dose-dependent reduction in tumor vascular parameters as measured by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and an acute increase in plasma VEGF levels. The reduction in tumor vascularity was significantly correlated with improved clinical outcome in patients with advanced colorectal cancer and liver metastases. To assess the predictive value of a mouse model of tumor metastases, comparisons were performed for the biological activity of PTK/ZK in the mouse model and in patients with liver metastases in the clinical phase I trials. An orthotopic, syngeneic mouse model was used: C57BL/6 mice injected in the ear with murine B16/BL6 melanoma cells which metastases to the cervical lymph-nodes. The primary tumor and spontaneous metastases express VEGF and VEGF receptors and respond to treatment with VEGFR tyrosine kinase inhibitors. PTK/ZK was administered orally, with assessments by DCE-MRI of the metastases and plasma VEGF taken predose and at 3 days posttreatment and efficacy determined at 7 days posttreatment. Dose-ranging studies in naive mice provided preclinical pharmacokinetic data, while two dose-escalation phase I studies provided clinical pharmacokinetic data. An exposure-response relationship was observed both for mouse metastases (measured as % tumor weight treated/control) and for human liver metastases (measured as % regression). In the B16/BL6 model, the active dose of 50 mg/kg PTK/ZK yielded 62.4 (+/- 16.0) h microM plasma exposure, which is comparable to the plasma area under the concentration time curve (AUC) achieved by the 1000 mg dose of PTK/ZK used in clinical trials. At this exposure level in clinical trials, DCE-MRI showed a reduction in the area under the enhancement curve (IAUC) to 47% of baseline. At a similar exposure in the PTK/ZK-treated mice, a reduction in IAUC to 75% of baseline was observed. Furthermore, at doses of 50 mg/kg PTK/ZK and above, an increase in plasma VEGF level 10 h after drug administration was observed in mice which was consistent with findings from the clinical trials. In conclusion, the preclinical pharmacodynamics of PTK/ZK correlate well with clinical activity in phase I trials over comparable exposures to the drug. Thus, data from this preclinical model proved to be consistent with and thus predictive of the biologic effects of PTK/ZK in phase I/II clinical trials.
Cancer Chemotherapy and Pharmacology 07/2006; 57(6):761-71. · 2.83 Impact Factor
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ABSTRACT: Prostate-specific antigen (PSA) is a serine protease that is overexpressed in prostate carcinoma and represents a molecular target for selectively releasing an anticancer agent from a prodrug formulation. In this work, we developed albumin-binding prodrugs with the structures MT-Ser-Ser-Tyr-Tyr- Ser-Gly-DOXO, MT-Asn-Ser-Ser-Tyr-Phe-Gln-DOXO (MT = maleimidotriethyleneglycol acid; DOXO = Doxorubicin) or EMC-Arg-Arg-Ser-Ser-Tyr-Tyr-Ser-Gly-DOXO (EMC = epsilon-maleimidocaproic acid; X = amino acid). The maleimide Doxorubicin derivatives bound rapidly to the cysteine-34 position of endogenous and exogenous albumin and were efficiently cleaved by PSA at the P(1)-P'(1) scissile bond, releasing a respective Doxorubicin dipeptide (Ser-Gly-DOXO or Phe-Gln-DOXO). The derivative containing arginine residues (EMC-Arg-Arg-Ser-Ser-Tyr-Tyr-Ser-Gly-DOXO) exhibited excellent water solubility for intravenous administration. Subsequent biological evaluation was focused on a PSA-negative xenograft model (PC 3) and a PSA-positive xenograft model (CWR22) in order to assess the selectivity of our therapeutic approach. EMC-Arg-Arg-Ser-Ser-Tyr-Tyr-Ser-Gly-DOXO showed no in vivo activity in the PSA-negative PC 3 model, but good activity in the CWR22 PSA-positive model that was comparable to Doxorubicin.
Archiv der Pharmazie 11/2005; 338(10):462-72. · 1.71 Impact Factor
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ABSTRACT: Retinal neovascularisation occurs under the influence of angiogenic factors that are induced by hypoxia, like vascular endothelial growth factor (VEGF), which is one of the major mediators. PTK/ZK inhibits VEGF signal transduction by blocking the tyrosine kinase of all three VEGF receptors. PTK/ZK is currently being evaluated in clinical trials for angioinhibitory therapy in tumour patients. To avoid potential systemic side effects, local application would be desirable for the treatment of ischemic retinopathies in humans. We therefore investigated the effect of intravitreally applied PTK/ZK in a mouse model for ischemia-induced retinopathy.
C57BL/6J mice were placed in 75% oxygen on postnatal day 7. On day 12, they were treated with an intravitreal injection of PTK/ZK (5 microM or 40 microM) in one eye and buffer solution in the fellow eye. Afterwards, the animals were kept in room air until intracardial perfusion with fluorescein-dextran on day 17. Retinal whole mounts were prepared and ischemic retinopathy was evaluated using a standardised retinopathy score.
A single intravitreal injection of 40 microM PTK/ZK reduced angioproliferative changes compared to the control eye of each animal (n=37). The difference in retinopathy scores was highly significant (P=0.002, Wilcoxon signed-rank test). Injection of 5 microM PTK/ZK did not show a significant antiangiogenic effect.
Tyrosine kinase inhibitors are promising substances not only in cancer therapy, but also in the treatment of ischemic retinopathies that are mediated by VEGF. We showed that in a mouse model for ischemia-induced retinopathy a single intravitreal injection of 40 microM PTK/ZK is capable of significantly reducing angioproliferative retinopathy. The local application of PTK/ZK could be a new way to treat ischemic ocular diseases such as diabetic retinopathy in humans.
Albrecht von Graæes Archiv für Ophthalmologie 07/2005; 243(6):593-600. · 2.17 Impact Factor
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Klaus Mross, Joachim Drevs,
Marianne Müller,
Michael Medinger,
Dieter Marmé,
Jürgen Hennig,
Bruno Morgan,
David Lebwohl,
Eric Masson,
Yu-Yun Ho,
Clemens Günther,
Dirk Laurent,
Clemens Unger
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ABSTRACT: The family of VEGF receptors are important mediators of angiogenesis, which is essential for tumour growth and metastasis. PTK/ZK is a multiple VEGF receptor inhibitor that blocks the activity of all known VEGF receptor tyrosine kinases. This phase I/II trial evaluated the safety, pharmacokinetics and efficacy of PTK/ZK in patients with liver metastases from solid tumours. Patients were administered oral PTK/ZK monotherapy once daily at doses of 300-1200 mg/day in 28-day cycles until unacceptable toxicity or tumour progression occurred. Twenty-seven patients were enrolled and treatment with PTK/ZK was generally well tolerated. The most frequently reported adverse events were fatigue, nausea, dizziness, and vomiting (mostly National Cancer Institute Common Toxicity Criteria grade 1 or 2). The area under the concentration-time curve (AUC) of PTK/ZK increased between 300 and 1000 mg/day with no further increase from 1000 to 1200 mg/day; the AUC decreased by 50% between day 1 and day 15. The DCE-MRI showed a statistically significant early reduction of tumour blood supply (measured as Ki) at day 2 at doses > or = 750 mg/day. Disease progression was significantly correlated with percent change from baseline Ki. Thirteen patients had stable disease for at least two cycles (56 days). Median overall survival was 11.8 months (95% CI = 6.6, 17.1 months). Long-term therapy with PTK/ZK demonstrated predictable pharmacokinetics, was safe and feasible in patients with metastatic disease, and showed promising clinical activity. The minimum biologically active dose was established at 750 mg/day whereas the recommended dose for phase III studies is 1200 mg/day.
European Journal of Cancer 07/2005; 41(9):1291-9. · 5.54 Impact Factor
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ABSTRACT: Receptor and non-receptor protein tyrosine kinases (PTKs) are essential enzymes in cellular signaling processes and signal transduction pathways that regulate cell growth, differentiation, migration and metabolism by catalyzing protein phosphorylation and dephosphorylation. In recent years, different tyrosine kinase receptors were identified as regulators of tumor or tumor vessel growth. Their inhibition by specific tyrosine kinase inhibitors and antibodies targeting growth factors and their receptors were recently shown to constitute a new modality for treating cancers. The pathognomonic role of the inhibited tyrosine kinase defines the way of action, whereas the amount of expression in tumor tissue is thought to define the indication for the tumor entity. Various compounds targeting PTKs are under clinical investigation in phase I-III trials or are already approved. This review describes new drugs targeting BCR-Abl, c-kit, EGFR (epidermal growth factor receptor), tumor angiogenesis via VEGF (vascular endothelial growth factor), HER2/neu and "multitarget" tyrosine kinase inhibitors.
Current Pharmaceutical Design 02/2005; 11(9):1139-49. · 3.87 Impact Factor
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ABSTRACT: Our aim was to correlate concentrations of circulating vascular endothelial growth factor (VEGF) and serum soluble angiopoietin receptor (sTIE-2) before and after endovascular treatment with the grading in human dural arteriovenous fistulas (DAVFs). In ten patients with DAVFs undergoing diagnostic cerebral angiography and endovascular intervention, pre-treatment and post-treatment levels of plasma VEGF and serum TIE-2 were examined in a prospective study design. A total of 32 plasma samples and 19 serum samples was collected from the cubital vein, the arterial sheath before and--if applicable--after intervention. Plasma VEGF and serum Tie-2 levels were measured by standardized ELISA protocols. In eight of ten patients with DAVF increased circulating VEGF levels (elevation of more than mean + 2 SD of published normal values) were found, whereas two patients showed increased sTIE-2 levels. Six of the seven patients treated by endovascular embolization displayed a post-interventional decrease of VEGF values. The serum TIE-2 levels decreased slightly after intervention. Pre-treatment vVEGF levels varied significantly between patients with grades I and II/III fistulas according to the Cognards classification system. Our pilot study suggests that assessment of angiogenesis parameters in patients with DAVFs might correlate with the DAVFs' grade. To support the hypothesis that a change in angiogenic indicators may serve as indicators for a response to therapy, a larger number of patients should be followed for a longer time period.
Neuroradiology 02/2005; 47(1):10-7. · 2.82 Impact Factor
