Metronomic dosing enhances the anti-angiogenic effect of epothilone B.

BACKGROUND: High doses (10 nM) of epothilone B, a microtubule stabilizer, will inhibit the development of human tumor-derived angiogenesis following short (14 d) drug exposure times. Metronomic dosing regimes use lower drug doses and prolonged drug exposure times in an attempt to decrease toxicity compared with standard dosing schedules. We hypothesized that epothilone B would be an effective anti-angiogenic agent when administered at very low doses over an extended period of time. METHODS: Fragments of four fresh human tumors were cultured in a fibrin-thrombin matrix and maintained in nutrient media plus 20% fetal bovine serum (FBS) for 56 d. Tumor fragments (n=40-60 per group) were exposed to weekly doses of epothilone B at concentrations of 10, 5, 1, 0.5, or 0.1 nM. All of these concentrations are clinically achievable. Tumor angiogenesis was assessed weekly on d 14-56 using a validated visual grading system. This system rates neovessel growth, density, and length on a 0-16 scale [angiogenic index, (AI)]. The average change in AI between d 14 and 56 was calculated for all samples and used to evaluate the metronomic response. RESULTS: Epothilone B produced a dose-dependent anti-angiogenic response in all tumors. Two of the four tumors demonstrated a clear and significant metronomic anti-angiogenic effect over time. CONCLUSIONS: Epothilone B, when dosed by a metronomic schedule may have a significant anti-angiogenic effect on human solid tumors. This study provides evidence for the potential use of epothilone B on a metronomic dosing schedule.

Diagnostic Yield and Bleeding Complications Associated With Bronchoscopic Biopsy of Endobronchial Carcinoid Tumors.

BACKGROUND: Bronchial carcinoid often appears hypervascular on bronchoscopic visualization and may be associated with hemoptysis. The diagnostic yield and bleeding complications associated with bronchoscopic biopsy of bronchial carcinoid tumors remain unclear. MATERIALS AND METHODS: Patients with bronchial carcinoid tumors that were bronchoscopically visualized and biopsied at our tertiary referral medical center, over an 8-year period from 2010 to 2017, were retrospectively identified and reviewed to assess diagnostic yield and bleeding complications. Correlations with patient characteristics and carcinoid tumor features were analyzed. RESULTS: Forty-nine patients were included (57% female). Tumors were predominantly (71%) located in proximal airways (mainstem and lobar bronchi). Bronchoscopic biopsy was diagnostic in 45 patients (92%). Thirteen patients (27%) experienced moderate (n=12, 25%) or severe (n=1, 2%) bleeding. Among these, 6 tumors (46%) had a vascular appearance and 4 patients (31%) had experienced recent hemoptysis. However, neither vascularity nor hemoptysis was associated with bleeding at biopsy (P=0.68 and 0.73, respectively). Carcinoid tumors were classified as typical in 79% and atypical in 21% with no difference in diagnostic yield or bleeding risk (P=0.28 and 0.92, respectively). Tumor size was also not associated with increased diagnostic yield or bleeding risk (P=0.54 and 0.39, respectively). CONCLUSION: Bronchoscopic biopsy of endobronchial carcinoid is associated with a high diagnostic yield and severe bleeding is rarely encountered. Diagnostic yield and bleeding seemed independent of vascular tumor appearance or history of recent hemoptysis.

Angiogenesis in endocrine tumors.

Angiogenesis is the process of new blood vessel development from preexisting vasculature. Although vascular endothelium is usually quiescent in the adult, active angiogenesis has been shown to be an important process for new vessel formation, tumor growth, progression, and spread. The angiogenic phenotype depends on the balance of proangiogenic growth factors such as vascular endothelial growth factor (VEGF) and inhibitors, as well as interactions with the extracellular matrix, allowing for endothelial migration. Endocrine glands are typically vascular organs, and their blood supply is essential for normal function and tight control of hormone feedback loops. In addition to metabolic factors such as hypoxia, the process of angiogenesis is also regulated by hormonal changes such as increased estrogen, IGF-I, and TSH levels. By measuring microvascular density, differences in angiogenesis have been related to differences in tumor behavior, and similar techniques have been applied to both benign and malignant endocrine tumors with the aim of identification of tumors that subsequently behave in an aggressive fashion. In contrast to other tumor types, pituitary tumors are less vascular than normal pituitary tissue, although the mechanism for this observation is not known. A relationship between angiogenesis and tumor size, tumor invasiveness, and aggressiveness has been shown in some pituitary tumor types, but not in others. There are few reports on the role of microvascular density or angiogenic factors in adrenal tumors. The mechanism of the vascular tumors, which include adrenomedullary tumors, found in patients with Von Hippel Lindau disease has been well characterized, and clinical trials of antiangiogenic therapy are currently being performed in patients with Von Hippel Lindau disease. Thyroid tumors are more vascular than normal thyroid tissue, and there is a clear correlation between increased VEGF expression and more aggressive thyroid tumor behavior and metastasis. Although parathyroid tissue induces angiogenesis when autotransplanted and PTH regulates both VEGF and MMP expression, there are few studies of angiogenesis and angiogenic factors in parathyroid tumors. An understanding of the balance of angiogenesis in these vascular tumors and mechanisms of vascular control may assist in therapeutic decisions and allow appropriately targeted treatment.

New insights into hypoxia-related mechanisms involved in different microvascular patterns of bronchopulmonary carcinoids and poorly differentiated neuroendocrine carcinomas. Role of ribonuclease T2 (RNASET2) and HIF-1α.

Ribonuclease T2 (RNASET2) is a pleiotropic and polyfunctional protein, which exerts several different activities in neoplastic cells since the early steps of tumor development. Besides having an antitumorigenic activity, RNASET2 inhibits both bFGF-induced and VEGF-induced angiogenesis and has a role as a stress-response, alarmin-like, protein. In this study, we investigated RNASET2 expression in well-differentiated and poorly differentiated neuroendocrine neoplasms of the lung (Lu-NENs), which are known to show clear-cut differences in morphology, biology and clinical behavior. In addition, we explored possible relationships between RNASET2 expression and a series of immunohistochemical markers related to hypoxic stress, apoptosis, proliferation and angiogenesis. Our results showed a significantly higher expression of RNASET2, HIF-1α, and its target CA IX in poorly differentiated than in well-differentiated Lu-NENs, the former also showing higher proliferation and apoptotic rates, as well as a lower microvessel density (MVD) than the latter. Moreover, we were able to demonstrate in vitro an overexpression of RNASET2 in consequence of the activation of HIF-1α. In conclusion, we suggest that in poorly differentiated Lu-NENs, RNASET2 expression may be induced by HIF-1α, behaving as an alarmin-like molecule. In this aggressive group of cancers, which have highly deregulated proliferation pathways, RNASET2 fails to exert the growth-inhibiting effects described in other types of neoplasms. Its increased expression, however, may contribute to the typical phenotypic alterations seen in poorly differentiated Lu-NENs, such as the high apoptotic rate and the extensive necrosis, and may also enhance the low MVD observed in these neoplasms.

Florid angiogenesis in mucosa surrounding an ileal carcinoid tumor expressing transforming growth factor-alpha.

Carcinoid tumors of the gastrointestinal tract are known to be associated with fibrosis and vascular elastosis, either within the tumor or at distant sites. The current report describes prominent vascular proliferation in the villi extending 38 cm proximal and 15 cm distal to an ileal carcinoid tumor. These villi were expanded by vessels, producing a segmental carpet of multiple small polypoid protrusions around the tumor. Immunohistochemical analysis suggested that the major stromal components were of endothelial and myofibroblastic cell origin. The stroma of the tumor itself had minimal fibrosis and vascularity. To our knowledge, this is the first description of vascular proliferation in the vicinity but distinct from a carcinoid tumor. The demonstration of transforming growth factor-alpha (TGF-alpha) synthesis by tumor cells supports the possibility of a field effect by angiogenic factor(s) secreted by the tumor.

Definition of hepatic tumor microcirculation by single photon emission computerized tomography (SPECT).

Single photon emission computerized tomography coupled with Tc-99m MAA hepatic-arterial perfusion scintigraphy has been used to examine the density of the functional microcirculation of hepatic tumors relative to normal liver in 24 patients. In both colorectal and carcinoid tumors we have demonstrated an average three-fold greater arteriolar-capillary density in areas of tumor proliferation. The depth of the evoked tumor hypervascularity was found to extend about 4 cm. Tumors greater than 8-9 cm in diameter were uniformly found to have a central hypovascular core. These observations are of importance in the design of selective strategies utilizing therapeutic microspheres directed against the hypervascular proliferating regions of human tumors.

Clinical significance of angiogenesis in rectal carcinoid tumors.

This study was designed to examine angiogenesis in rectal carcinoid tumors in relation to the clinicopathologic features. Seventy-seven rectal carcinoid tumors were studied clinicopathologically and experimentally. Cellular proliferation and microvessel density (MVD) were examined immunohistochemically. We used the antibodies MIB-1 for Ki-67, DO7 for p53, and NU-4A1 for CD34 expression in this study. Ki-67 labeling index (LI) of all lesions was below 3%, and the median Ki-67 LI of all lesions was 0.68+/-0.70% (mean +/- SD). A correlation was recognized between tumor size, metastasis and Ki-67 LI (p<0.05). Median MVD of all lesions was 25.9+/-13.1 (mean +/- SD). MVD was correlated with the tumor size (p<0.01), presence of depression (p<0.01), lymphatic (p<0.01) or venous (p<0.05) invasion, and existence of metastasis (p<0.01). But there was no significant relationship between MVD and Ki-67 LI. p53 protein was detected sporadically in only 1 case (1.3%) demonstrating both liver and lymph node metastases. Rectal carcinoid tumors are slow-growing tumors with a lower proliferative activity. Angiogenesis plays an important role in progression of rectal carcinoid tumors independent of the cellular proliferative activity.

Levels of angiogenic peptides in sera from patients with carcinoid tumours during alpha-interferon treatment.

BACKGROUND: Alpha-interferon, a known inhibitor of angiogenesis and cell proliferation, is used in the standard treatment of patients with carcinoid tumors. We studied the levels of two angiogenic peptides (bFGF and VEGF) in sera from patients with carcinoid tumours before and during treatment with alpha-interferon. The aim was to investigate if the antitumoral effect of alpha-interferon in these patients could be at least in part explained by a reduction in the measured angiogenetic peptides. PATIENTS AND METHODS: Sera from 29 patients with carcinoid tumours were collected before and during alpha-interferon treatment and analyzed using commercially available ELISA-kits. RESULTS: Interferon alpha treatment did not cause reduction of bFGF and VEGF levels in serum from patients with carcinoid tumours. In fact there was no correlation between changes in bFGF or VEGF levels and treatment effect. CONCLUSION: The action of alpha-interferon does not seem to be mediated by bFGF or VEGF in patients with carcinoid tumours. If alpha-interferon has an anti-angiogenic effect in this patient group, it is probably mediated by angiogenic peptides other than bFGF and VEGF.

Blood flow patterns in focal liver lesions at microbubble-enhanced US.

Noninvasive diagnosis of liver lesions is usually performed with contrast material-enhanced computed tomography (CT) and magnetic resonance (MR) imaging and is based on enhancement features of the arterial and portal venous phases. Ultrasonography (US) is often limited in characterizing liver lesions because color and spectral Doppler US provide limited vascular information in large patients and in small or deep lesions. However, microbubble contrast agents, together with specialized US techniques, now allow diagnosis of liver lesions based on morphologic evaluation of lesion vascularity and visualization of specific enhancement features. Microbubble contrast agents are purely intravascular, easy to administer, and well tolerated and allow sensitive real-time evaluation of blood flow in hepatic lesions. During the portal venous phase, benign lesions (eg, hemangioma, focal nodular hyperplasia) typically enhance more than the liver, whereas malignant lesions (eg, hepatocellular carcinoma, metastases) enhance less. Microbubble-enhanced US allows characterization of very small lesions that may not be accurately characterized with CT or MR imaging. Findings from initial studies suggest that microbubble-enhanced US of the liver provides enhancement information comparable to that provided by contrast-enhanced CT and MR imaging, along with real-time morphologic evaluation of lesion vascularity.

Nuclear and environment morphometric profile in tumor size and nodal metastasis of resected typical pulmonary carcinoid.

As the biologic behavior in lung tumors with neuroendocrine differentiation is highly dependent on cell death (apoptosis) and extracellular matrix invasion, Bcl2 and extracellular matrix density have been targeted as potentially useful tumor markers. In this study, we sought to validate the importance of Bcl2 and ECM density and to study the relationships of Bcl2 and ECM density with clinical factors and other tumor or stromal markers. We examined Bcl2 and several other markers in tumor tissues from 55 patients with surgically excised pulmonary typical carcinoid. We used histochemistry, immunohistochemistry, and morphometry to evaluate the amount of tumor staining for Bcl2 and ECM; the surrogate markers for aggressive potential for our study were tumor size and lymph node metastasis determined at diagnosis. Multivariate logistic model analysis demonstrated that after surgical excision control, tumor size was significantly related to nodal metastasis (P = 0.01), but quantitative staining of the tumor for Bcl2 and ECM added prognostic information and was as strongly prognostic as tumor size (P<0.01). Cutpoints at the median staining of 3.1% and 9.8 microm2 for Bcl2 and ECM, respectively, divided patients into two groups with distinctive risk for nodal metastasis. Those with Bcl2 > 3.1% and ECM <9.8 microm2 had high risk for nodal metastasis. We concluded that tumor staining for Bcl2 and ECM in resected PTC is strongly related to tumor size and nodal metastasis. Patients with > 3.1% and <9.8 microm2 staining in their tumors comprise a subset with a high hazard for nodal metastasis and may be an appropriate target for prospective studies of adjuvant chemotherapy after surgical resection.

Capillaries. A cytologic feature of pulmonary carcinoid tumors.

The cytologic features of pulmonary carcinoid tumors have been well described, but most reports have not mentioned capillaries as a prominent finding. Two cases are described in which abundant capillaries in endobronchial brushing and fine needle aspiration specimens were a helpful feature in making the correct diagnosis.

[Arterial lipiodol chemoembolization of a left liver metastasis through the right internal thoracic artery]. / Chimioembolisation artérielle lipiodolée d'une métastase du foie gauche via l'artère thoracique interne droite.

The purpose of this article is to illustrate the efficacy of the chemoembolization in patients with hypervascular metastases and to describe the post-embolization change in vascularization pattern. Unusual collaterals may develop following embolization. A 59-year-old woman, followed for unresectable small bowel carcinoid tumor since 1991, underwent successful chemoembolization of several liver metastases. Only one liver lesion, located in segment IV, showed interval increase in size. This lesion was supplied by the right internal mammary artery. A branch of the right internal mammary artery was catheterized using a microcatheter and embolization was performed using doxorubicine-Lipiodol (Adriblastine, Lipiodol) and gelfoam (Spongel). No complications occurred after the procedure. The right internal mammary artery should be considered as a possible source of collateral arterial supply to the liver and should be evaluated in patients with local progression of disease.

Angiography in the diagnosis of carcinoid syndrome.

The diagnosis of carcinoid syndrome has been confirmed by selective abdominal angiography in a consecutive series of 18 patients. In eight patients the primary carcinoid tumour was removed before angiography. The primary lesion was demonstrated in eight of ten cases. Metastases from the carcinoid tumours was present in all 18 patients. All cases of mesenteric metastases and 12 of 14 cases with liver metastases were visualized by angiography. All but one of the liver metastases were highly vascularized and therefore easy to recognize, making angiography a good monitor in the control of medical therapy or in planning of surgical intervention.

Interferon alpha and rapamycin inhibit the growth of carcinoid and medullary thyroid cancer in vitro.

Neuroendocrine tumors (NETs) are highly vascularized neoplasms characterized by rising incidence. Moreover, the neuroendocrine cells were shown to express vascular endothelial growth factor (VEGF) and VEGF receptors. Therefore, angiomodulators could be potentially a new group of drugs enhancing still unsatisfactory effectiveness of NET therapy. The aim of this study was to assess the direct influence of angiomodulators: VEGF and five endogenous and exogenous antiangiogenic compounds (endostatin, interferon alpha [IFNα], rapamycin, JV1-36, semaxinib [SU5416]) on the growth of two NET cell lines: lung carcinoid H727 cell line and medullary thyroid cancer TT cell line in vitro. IFNα and rapamycin induced the inhibitory effect on H727 and TT cell viability and proliferation, increasing apoptosis and arresting the cell cycle. Also semaxinib (10(-5)M) inhibited proliferation of both cell lines. VEGF and endostatin did not influence the growth of H727 and TT cells. The inhibitory effect of IFNα, rapamycin and semaxinib on carcinoid and medullary thyroid cancer growth was revealed in our in vitro study, although some other antiangiogenic agents did not directly influence H727 and TT cell growth. Thus, IFNα and mTOR inhibitors as multidirectionally acting drugs with antiangiogenic effect could be potentially efficient in treatment of neuroendocrine tumors and are worth further studies.

Preoperative embolization followed by surgical excision of a giant thymic carcinoid.

We report the case of a 35-year old woman with a giant thymic carcinoid of the left hemithorax. Enhanced computed tomography showed marked vascularization of the tumour, with an enlarged drainage vein. Endovascular embolization of the major feeding arteries of the tumour was performed preoperatively with good angiographic results. A left thoracotomy was performed the following day. Minimal bleeding was observed due to prior embolization. The patient made a rapid postoperative recovery and was discharged 8 days later.

Can C-arm cone-beam CT detect a micro-embolic effect after TheraSphere radioembolization of neuroendocrine and carcinoid liver metastasis?

RATIONAL AND OBJECTIVE: Radioembolization with yttrium-90 microspheres is a therapy that is used for hepatic tumors. 20-30 µm microspheres loaded with Y90 are supposedly occluding tumor vessels at the capillary level. Then, these spheres deliver high-dose radiation to the tumor. However, this theoretical embolic effect has never been appreciated in imaging. Dual-Phase cone-beam computed tomography (DPCBCT) is a multi-phasic intra-procedural scan that uses only one contrast media injection to visualize early (feeding vessel) and delayed (capillary level) tumor enhancement. The purpose of this study was to determine whether there is a micro-embolic effect induced by TheraSpheres® (MDS Nordion, Ottawa, Ontario, Canada) at the capillary level by using DPCBCT imaging. MATERIALS AND METHODS: 14 patients with 72 carcinoid or neuroendocrine tumors were treated with radioembolization, and all underwent DPCBCT (Allura Xper, Philips Healthcare) imaging before and immediately after radioembolization with TheraSpheres®. Tumor enhancement was measured in each phase by drawing a region of interest within the tumors. RESULTS: 72 tumors were evaluated: average tumor density in the early arterial phase was 241 and 230 Hounsfield units (HU) (p<0.001) before and after radioembolization, respectively; the average density in the delayed arterial phase was 226 and 161 HU (p<0.001) before and after radioembolization, respectively. Average difference in tumor attenuation before and after radioembolization in early arterial and delayed phase was 11 HU and 64 HU (p<0.001), respectively. CONCLUSION: The significant decrease in tumor enhancement in the DPCBCT delayed phase after TheraSpheres® injection indicates that there is an appreciable microembolic effect at the tumor capillary bed level.