Characterization of the effects of antiangiogenic agents on tumor pathophysiology

Bilateral Aural Adenocarcinoma in a Congo African Grey Parrot ( Psittacus erithacus erithacus)

A 28-year-old female Congo African grey parrot ( Psittacus erithacus erithacus) was evaluated because of a mass in the left external auditory meatus. Results of a computed tomography scan revealed an osteolytic left hemimandibular mass with irregular bone production and a soft tissue mass in the left external auditory meatus. Results of cytologic examination of fine needle aspirates of the hemimandible were interpreted as adenocarcinoma with reactive osteoblasts. The owner chose palliative treatment, and a debulking procedure was performed on the left external auditory meatus mass 52 days after initial presentation to control self-trauma. Euthanasia was elected 67 days after initial presentation because of poor prognosis associated with the development of bilateral masses of the external auditory meatus and lateral deviation of the mandible, findings that were confirmed by postmortem examination. Histopathologic results confirmed the diagnosis of bilateral aural adenocarcinoma with invasion of both temporal bones and hemimandibles.

Quantitative contrast enhanced ultrasound of the liver for time intensity curves-Reliability and potential sources of errors

INTRODUCTION

Time intensity curves for real-time contrast enhanced low MI ultrasound is a promising technique since it adds objective data to the more subjective conventional contrast enhanced technique. Current developments showed that the amount of uptake in modern targeted therapy strategies correlates with therapy response. Nevertheless no basic research has been done concerning the reliability and validity of the method.

PATIENTS AND METHODS

Videos sequences of 31 consecutive patients for at least 60s were recorded. Parameters analysed: area under the curve, maximum intensity, mean transit time, perfusion index, time to peak, rise time. The influence of depth, lateral shift as well as size and shape of the region of interest was analysed.

RESULTS

The parameters time to peak and rise time showed a good stability in different depths. Overall there was a variation >50% for all other parameters. Mean transit time, time to peak and rise time were stable from 3 to 10cm depths, whereas all other parameters showed only satisfying results at 4-6cm. Time to peak and rise time were stable as well against lateral shifting whereas all other parameters had again variations over 50%. Size and shape of the region of interest did not influence the results.

DISCUSSION

(1) It is important to compare regions of interest, e.g. in a tumour vs. representative parenchyma in the same depths. (2) Time intensity curves should not be analysed in a depth of less than 4cm. (3) The parameters area under the curve, perfusion index and maximum intensity should not be analysed in a depth more than 6cm. (4) Size and shape of a region of interest in liver parenchyma do not affect time intensity curves.

Phase I/II study of selective cyclooxygenase-2 inhibitor celecoxib as a radiation sensitizer in patients with unresectable brain metastases

PURPOSE

The primary goal of this phase I/II study was to evaluate the feasibility, safety and efficacy of celecoxib administered concomitant to radiotherapy to treat unresectable BM.

PATIENTS AND METHODS

Patients with measurable BM by CT or MRI, unresectability criteria by a neurosurgeon and RPA-RTOG class II were eligible. Celecoxib was administered at 400 mg/day during the entire course of radiotherapy. All patients were irradiated with 60Co beams to whole-brain dose of 32 Gy (20 fractions of 1.6 Gy each two times a day with a 6 h interval between treatments) followed by a 22.4 Gy boost (same fractionation schedule) over evident lesions.

RESULTS

Twenty-seven patients were treated. The concurrent regimen was well tolerated with 15 cases of mild dyspepsia. Alopecia (NCI grades 1-2) was the most important side effect. Three patients presented rash/desquamation of moderate intensity. Radiological responses occurred in 18 of 25 valuable patients (72), with five complete responses (CR). Symptomatic responses were reported in 25 of 27 patients (92.6), with 20 CR. The overall response rate (considering complete plus partial responses) was 66.7. Percentile 50 for time-to-progression, time-to-neurological-progression and functional-independence-time were 3, 6.25 and 6.7 months, respectively. Median survival time was 8.7 months.

CONCLUSION

Our initial results suggest that radiotherapy plus celecoxib is safe and a possible active treatment for patients with BM. Further investigation in a randomized trial is warranted to validate its clinical utility.

Varied response of spontaneous tumors to antiangiogenic agents

Since conventional therapies are directly dependent on the supply of either drugs or oxygen, a key question is whether antiangiogenic agents produce detrimental effects on tumor vascular function, thus compromising combination therapies. A second question is whether experimental results based on fast-growing, transplanted tumors mimic those in slowly developing spontaneous tumors, which may be more representative of response in human primary tumors. To investigate changes in tumor pathophysiology, three antiangiogenic agents were compared: a) endostatin, b) anti-VEGFR-2 (DC101), and c) celecoxib. Total blood vessels were identified using anti-CD31, perfused vessels using DiOC7, and hypoxia by EF5 uptake. Although individual tumor growth rates varied substantially, DC101 produced the most striking inhibition. DC101 increased total and perfused vessel spacing as well as overall hypoxia, while endostatin increased total vessel spacing, and hypoxia and celecoxib had no marked effects. These results reinforce the idea that pathophysiological changes in spontaneous tumors are in general reflective of response in transplanted tumors. Furthermore, although DC101 inhibited growth in roughly half of the spontaneous tumors, the remaining tumors were unaffected. A key focus of future studies will be to investigate the underlying rationale for the widely varying antiangiogenic response among tumors that outwardly appear so similar.

Measurement of tumor interstitial volume fraction: Method and implication for drug delivery

It is important to evaluate the tumor interstitial volume fraction that is accessible for drug accumulation during the distribution phase in order to determine the potential efficacy of cancer chemotherapy. In this study, we performed simulations of magnetic resonance imaging (MRI) signal intensity using a two-compartment tissue model for quantitative analyses of absolute interstitial volume measurements while we experimentally characterized a mouse tumor model with a dual MR contrast-agent method. Previously, consecutive intravenous injections of a strictly intravascular T1 contrast agent followed by an extravasating agent were used as a strategy for the quantification of both relative blood volume (Rel_BV) and relative interstitial volume (Rel_ITST) (Weissleder et al. Eur J Cancer 1998;34:1448-1454; Bogdanov et al. Neoplasia 1991;1:438-435). In the current study, we demonstrate that this approach can be further improved, and that it enables one to accurately evaluate both relative and absolute interstitial volumes. The animal data indicated that a significant difference exists between the absolute interstitial volume fractions of subcutaneously implanted MDA PCa 2b tumor and skeletal muscle tissue (27.5 +/- 9.1% and 15.9 +/- 0.7%, respectively (P < 0.05)), while only a minor difference was found for the absolute blood volumes (Abs_BV) (Kim et al. Magn Reson Med 2002;47:1110-1120) of these tissues.

Inhibition of tumor angiogenesis by non-steroidal anti-inflammatory drugs: emerging mechanisms and therapeutic perspectives

Chronic intake of non steroidal anti-inflammatory drugs (NSAIDs) is associated with a reduced risk of developing gastrointestinal tumors, in particular colon cancer. Increasing evidence indicates that NSAID exert tumor-suppressive activity on pre-malignant lesions (polyps) in humans and on established experimental tumors in mice. Some of the tumor-suppressive effects of NSAIDs depend on the inhibition of cyclooxygenase-2 (COX-2), a key enzyme in the synthesis of prostaglandins and thromboxane, which is highly expressed in inflammation and cancer. Recent findings indicate that NSAIDs exert their anti-tumor effects by suppressing tumor angiogenesis. The availability of COX-2-specific NSAIDs opens the possibility of using this drug class as anti-angiogenic agents in combination with chemotheapy or radiotherapy for the treatment of human cancer. Here we will briefly review recent advances in the understanding of the mechanism by which NSAIDs suppress tumor angiogenesis and discuss their potential clinical application as anti-cancer agents.