semaxinib and Prostatic-Neoplasms

The institution of combined modality therapy for unresected solid tumors has resulted in significant improvements in tumor control and survival benefit compared with radiotherapy (RT) alone. A number of chemotherapy agents that can enhance the effectiveness of RT, such as cisplatin and 5-fluorouracil, are now considered standard treatment for patients with a number of cancer types. There is growing interest in a number of additional agents that have also been found to have radiosensitizing ability. These include paclitaxel, docetaxel, irinotecan, gemcitabine, and vinorelbine, as well as biologic agents. Other agents may be of value because they act to counter dose-limiting toxicities associated with RT. This article provides an update of some important, recently completed and ongoing clinical trials evaluating novel chemoradiation protocols, with examples taken primarily from studies conducted by the Radiation Therapy Oncology Group (RTOG). Theoretical approaches to the development of new agents and combined modality regimens are also discussed.

Topics: Alkyl and Aryl Transferases; Angiogenesis Inhibitors; Angiostatins; Antineoplastic Agents; Carcinoma, Non-Small-Cell Lung; Chemotherapy, Adjuvant; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Dose Fractionation, Radiation; Drugs, Investigational; Endothelial Growth Factors; Enzyme Inhibitors; Esophageal Neoplasms; Farnesyltranstransferase; Female; Head and Neck Neoplasms; Humans; Indoles; Intercellular Signaling Peptides and Proteins; Isoenzymes; Laryngeal Neoplasms; Lung Neoplasms; Lymphokines; Male; Membrane Proteins; Neoplasms; Peptide Fragments; Plasminogen; Prostaglandin-Endoperoxide Synthases; Prostatic Neoplasms; Pyrroles; Radiotherapy, Adjuvant; Randomized Controlled Trials as Topic; Treatment Outcome; Uterine Cervical Neoplasms; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factors

To assess the activity of the antiangiogenic agent and VEGFR2 inhibitor SU5416 in hormone-refractory prostate cancer.. Thirty-six chemotherapy naïve patients were randomized to treatment with SU5416 (145 mg/m(2)) and dexamethasone premedication or dexamethasone alone. Patients in the control arm could cross over to experimental therapy after progression. Prostate-specific antigen (PSA) was measured every 2 weeks, and radiological evaluation was performed every 8 weeks. In vitro assessment of SU5416 on PSA secretion was assessed in the LNCaP cell line. Baseline serum basic fibroblast growth factor and plasma vascular endothelial growth factor (VEGF) were explored as prognostic factors.. VEGF receptor-2 expression is detectable in prostate cancer cell lines, and SU5416 inhibited in vitro PSA secretion. No effect of SU5416 on PSA secretion or time to progression is detectable in patients. VEGF and basic fibroblast growth factor were not prognostic. Headache and fatigue were the most common SU5416 toxicities, but hyperglycemia, hyponatremia, lymphopenia, infection, and adrenal suppression, all attributable to steroids and the required central line, were common.. No disease modifying effects of SU5416 were detectable in this small study. Modest toxicity, an inconvenient administration schedule, and availability of other VEGFR-targeted agents support the decision to halt further evaluation of SU5416 in prostate cancer.

Topics: Aged; Aged, 80 and over; Angiogenesis Inhibitors; Biomarkers, Tumor; Cell Line, Tumor; Dexamethasone; Dose-Response Relationship, Drug; Fibroblast Growth Factors; Humans; Indoles; Male; Middle Aged; Prognosis; Prostate-Specific Antigen; Prostatic Neoplasms; Pyrroles; Time Factors; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factor Receptor-2

Aging is considered one of the main predisposing factors for the development of prostate malignancies. Angiogenesis is fundamental for tumor growth and its inhibition represents a promising therapeutic approach in cancer treatment. Thus, we sought to determine angiogenic responses and the effects of antiangiogenic therapy in the mouse prostate during late life, comparing these findings with the prostatic microenvironment in the Transgenic Adenocarcinoma of Mouse Prostate (TRAMP) model.. Male mice (52 week-old FVB) were submitted to treatments with SU5416 (6 mg/kg; i.p.) and/or TNP-470 (15 mg/kg; s.c.). Finasteride was administered (20 mg/kg; s.c.), alone or in association to both inhibitors. The dorsolateral prostate was collected for VEGF, HIF-1α, FGF-2 and endostatin immunohistochemical and Western Blotting analyses and for microvessel density (MVD) count.. Senescence led to increased MVD and VEGF, HIF-1α and FGF-2 protein levels in the prostatic microenvironment, similarly to what was observed in TRAMP mice prostate. The angiogenic process was impaired in all the treated groups, demonstrating significantly decreased MVD. Antiangiogenic and/or finasteride treatments resulted in decreased VEGF and HIF-1α levels, especially following TNP-470 administration, either alone or associated to SU5416. The combination of these agents resulted in increased endostatin levels, regardless of the presence of finasteride.. Prostatic angiogenesis stimulation during senescence favored the development of neoplastic lesions, considering the pro-angiogenic microenvironment as a common aspect also observed during cancer progression in TRAMP mice. The combined antiangiogenic therapy was more efficient, leading to enhanced imbalance towards angiogenic inhibition in the organ. Finally, finasteride administration might secondarily upregulate the expression of pro-angiogenic factors, pointing to the harmful effects of this therapy.

Topics: 5-alpha Reductase Inhibitors; Adenocarcinoma; Angiogenesis Inhibitors; Animals; Blotting, Western; Cyclohexanes; Disease Models, Animal; Endostatins; Fibroblast Growth Factor 2; Finasteride; Hypoxia-Inducible Factor 1, alpha Subunit; Immunohistochemistry; Indoles; Male; Mice; Mice, Transgenic; Neovascularization, Pathologic; O-(Chloroacetylcarbamoyl)fumagillol; Prostatic Neoplasms; Pyrroles; Sesquiterpenes; Tumor Microenvironment; Vascular Endothelial Growth Factor A

Androgen modulation of angiogenesis in prostate cancer may be not directly mediated by androgen receptor (AR) as AR is not detected in the prostatic endothelial cells.. We examined the paracrine stimulation of cell proliferation by prostate tumor cells and its modulation by androgen and estrogens in a murine endothelial cell line (MEC) that does not express AR.. Tumor cell conditioned media (TCM) collected from LAPC-4 or LNCaP prostatic tumor cells produced a time- and concentration-dependent induction of cell growth in MECs, which was parallel to the VEGF concentration in the TCM. This TCM-induced cell growth in MECs was enhanced by the treatment of prostatic tumor cells with dihydrotestosterone (DHT). Both the TCM-stimulation and DHT-enhancement effects in MECs were completely blocked by SU5416, a specific VEGF receptor antagonist. Co-administration of 17α-estradiol or 17β-estradiol with DHT in prostatic tumor cells completely inhibited the DHT-enhancement effect while treatment with DHT, 17α-estradiol or 17β-estradiol did not produce any significant direct effect in MECs. Moreover, administration of 17α-estradiol or 17β-estradiol in xenograft animals with LAPC-4 or LNCaP prostate tumor significantly decreased the microvessel number in the tumor tissues.. Our study indicated that prostate tumor cells regulate endothelial cell growth through a paracrine mechanism, which is mainly mediated by VEGF; and DHT is able to modulate endothelial cell growth via tumor cells, which is inhibited by 17α-estradiol and 17β-estradiol. Thus, both17α-estradiol and 17β-estradiol are potential agents for anti-angiogenesis therapy in androgen-responsive prostate cancer.

Topics: Androgens; Animals; Cell Line; Cell Line, Tumor; Cell Size; Dihydrotestosterone; Endothelial Cells; Estradiol; Estrogens; Humans; Indoles; Male; Mice; Prostate; Prostatic Neoplasms; Pyrroles; Receptors, Vascular Endothelial Growth Factor

Epidermal growth factor receptor (EGFR) and vascular endothelial growth factor receptor-2 (VEGFR-2), two protein tyrosine kinases, are involved in pathological disorders and the progression of different types of carcinomas. Concomitant inhibition of both tyrosine kinase activities appears to be an attractive target for cancer chemotherapy. A series of new quinazoline derivatives substituted by amide, urea, or carbamic acid ester groups have been synthesized. The biological activities of these new compounds have been evaluated for their enzyme inhibition and antiproliferative activities.

Topics: Amides; Antineoplastic Agents; Carbamates; Cell Line, Tumor; Cell Proliferation; Drug Screening Assays, Antitumor; ErbB Receptors; Humans; Male; Prostatic Neoplasms; Protein Kinase Inhibitors; Quinazolines; Urea; Vascular Endothelial Growth Factor Receptor-2

In recent decades, radiation research has concentrated primarily on the cancer cell compartment. Much less is known about the effect of ionizing radiation on the endothelial cell compartment and the complex interaction between tumor cells and their microenvironment. Here we report that ionizing radiation is a potent antiangiogenic agent that inhibits endothelial cell survival, proliferation, tube formation and invasion. Vascular endothelial growth factor (VEGF) and basic fibroblast growth factor were able to reduce the radiosensitivity of endothelial cells. Yet, it is also found that radiation induces angiogenic factor production by tumor cells that can be abrogated by the addition of antiangiogenic agents. Receptor tyrosine kinase inhibitors of Flk-1/KDR/VEGFR2, FGFR1 and PDGFR beta, SU5416, and SU6668 enhanced the antiangiogenic effects of direct radiation of the endothelial cells. In a coculture system of PC3 prostate cancer cells and endothelial cells, isolated irradiation of the PC3 cells enhanced endothelial cell invasiveness through a Matrigel matrix, which was inhibited by SU5416 and SU6668. Furthermore, ionizing radiation up-regulated VEGF and basic fibroblast growth factor in PC3 cells and VEGFR2 in endothelial cells. Together these findings suggest a radiation-inducible protective role for tumor cells in the support of their associated vasculature that may be down-regulated by coadministration of angiogenesis inhibitors. These results rationalize concurrent administration of angiogenesis inhibitors and radiotherapy in cancer treatment.

Topics: Angiogenesis Inhibitors; Cell Division; Cells, Cultured; Dose-Response Relationship, Radiation; Endothelial Growth Factors; Endothelium, Vascular; Fibroblast Growth Factor 2; Humans; Indoles; Intercellular Signaling Peptides and Proteins; Kinetics; Lymphokines; Male; Neoplasm Invasiveness; Neovascularization, Pathologic; Oxindoles; Particle Accelerators; Propionates; Prostatic Neoplasms; Pyrroles; Reverse Transcriptase Polymerase Chain Reaction; Tumor Cells, Cultured; Umbilical Veins; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factors; X-Rays

We have previously demonstrated the differential expression in tumor-associated blood vessels of two vascular endothelial growth factor receptors (VEGFRs), VEGFR1 and VEGFR2, during initiation and progression of prostate cancer in the genetically engineered transgenic adenocarcinoma of the mouse prostate (TRAMP) mouse model. In our "progression switch" model, expression of VEGFR1 is associated with early and more differentiated disease, whereas expression of VEGFR2 is associated with advanced and more poorly differentiated disease. To test the hypothesis that stage-specific inhibition of vascular endothelial growth factor signaling could be used as therapy for autochthonous prostate cancer, we initiated a preclinical trial with SU5416, a potent antiangiogenic small molecule inhibitor of VEGFR associated tyrosine kinase activity. In our early intervention trial, administration of SU5416 to TRAMP mice did not appear to influence angiogenesis or tumor progression between 10 and 16 weeks of age, a time corresponding to high levels of VEGFR1 expression. In our late intervention trial, however, we observed a significant decrease in tumor-associated mean vessel density, increased apoptotic index, and pronounced regions of cell death when SU5416 was administered to TRAMP mice between 16 and 22 weeks of age, a time corresponding to high levels of VEGFR2 expression. These results clearly demonstrate that therapy directed specifically against the VEGFR signaling axis can dramatically impair angiogenesis and induce apoptosis of autochthonous spontaneous and progressive prostate cancer.

Topics: Angiogenesis Inhibitors; Animals; Apoptosis; Cell Differentiation; Disease Models, Animal; Disease Progression; Drug Evaluation, Preclinical; Gene Expression Regulation, Neoplastic; Indoles; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Microcirculation; Neovascularization, Pathologic; Prostatic Neoplasms; Protein-Tyrosine Kinases; Pyrroles; Up-Regulation; Vascular Endothelial Growth Factor Receptor-1; Vascular Endothelial Growth Factor Receptor-2

The multifaceted nature of the angiogenic process in malignant neoplasms suggests that protocols that combine antiangiogenic agents may be more effective than single-agent therapies. However it is unclear which combination of agents would be most efficacious and will have the highest degree of synergistic activity while maintaining low overall toxicity. Here we investigate the concept of combining a "direct" angiogenesis inhibitor (endostatin) with an "indirect" antiangiogenic compound [SU5416, a vascular endothelial growth factor receptor 2 (VEGFR2) receptor tyrosine kinase (RTK) inhibitor]. These angiogenic agents were more effective in combination than when used alone in vitro (endothelial cell proliferation, survival, migration/invasion, and tube formation tests) and in vivo. The combination of SU5416 and low-dose endostatin further reduced tumor growth versus monotherapy in human prostate (PC3), lung (A459), and glioma (U87) xenograft models, and reduced functional microvessel density, tumor microcirculation, and blood perfusion as detected by intravital microscopy and contrast-enhanced Doppler ultrasound. One plausible explanation for the efficacious combination could be that, whereas SU5416 specifically inhibits vascular endothelial growth factor signaling, low-dose endostatin is able to inhibit a broader spectrum of diverse angiogenic pathways directly in the endothelium. The direct antiangiogenic agent might be able to suppress alternative angiogenic pathways up-regulated by the tumor in response to the indirect, specific pathway inhibition. For future clinical evaluation of the concept, a variety of agents with similar mechanistic properties could be tested.

Topics: Adenocarcinoma; Angiogenesis Inhibitors; Animals; Apoptosis; Carcinoma, Non-Small-Cell Lung; Cell Division; Cell Movement; Cell Survival; Drug Synergism; Endostatins; Endothelium, Vascular; Female; Glioblastoma; Humans; Indoles; Lung Neoplasms; Male; Mice; Mice, Inbred BALB C; Mice, Nude; Mice, SCID; Neoplasms; Neovascularization, Pathologic; Prostatic Neoplasms; Pyrroles; Ultrasonography; Vascular Endothelial Growth Factor A; Xenograft Model Antitumor Assays