Validation of a New Method for Quantifying In Vivo Murine Tumor Necrosis by Sonography

Contrast-Enhanced Ultrasound of Spermatic Cord and Retroperitoneal Liposarcoma

Liposarcoma is the most common paratesticular scrotal malignancy. Ultrasound is the conventional imaging modality for evaluating scrotal masses. Contrast-enhanced ultrasound (CEUS) can provide complementary information by identifying distinct enhancement patterns. We present CEUS findings of 2 concurrent soft tissue masses in 1 patient: a spermatic cord well-differentiated liposarcoma and a retroperitoneal dedifferentiated liposarcoma. We review the Doppler ultrasound, computed tomography, and histopathologic appearances of low- versus high-grade liposarcomas in addition to the utility of CEUS with quantitative analysis in potentially grading liposarcomas.

A single dose of intravenous combretastatin A4-phosphate is reasonably well tolerated and significantly reduces tumour vascularization in canine spontaneous cancers

Combretastatin A4-phosphate (CA4P) is an anti-tumour vascular targeting agent which selectively blocks tumour blood flow. Research on CA4P in rodent tumour models is extensive; however, knowledge of its effect on spontaneous cancer is scarce. This study was conducted in canine patients with spontaneous solid tumours. The goal was to assess the toxicity and efficacy of CA4P in various spontaneous tumour types. Eight dogs with spontaneous tumours were enrolled and treated with a single dose of 75 mg m^-2 intravenous CA4P. The dogs were screened and monitored before and after injection. Pre- and post-treatment tumour blood flow was analysed in vivo by power Doppler ultrasound (PDUS) and contrast-enhanced ultrasound (CEUS). Vessel destruction and tumour necrosis were evaluated by histopathology. Clinically relevant toxicity was limited to one case of temporary tetraparesis; other adverse events were mild. Significant cardiovascular changes were mostly confined to changes in heart rate and cTnI levels. Macroscopic tumour size reduction was evident in 2 dogs. Based on PDUS and CEUS, CA4P induced a significant decrease in vascular index and tumour blood flow. Post-treatment, histopathology revealed a significant increase of necrotic tumoural tissue and a significant reduction in microvessel density in tumoural tissue. Anti-vascular and necrotizing effects of CA4P were documented in a variety of canine spontaneous cancers with only minimal side effects. This is the first study reporting the administration of CA4P to canine cancer patients with in vivo and ex vivo assessment, and a first step toward implementing CA4P in combination therapies in veterinary oncology patients. The use of CA4P in canine patients was approved and registered by the Belgian Federal Agency for Medicines and Health Products (FAMHP) (approval number 0002588, registration number 6518 ID 2F12).

Computer aided prognosis for cell death categorization and prediction in vivo using quantitative ultrasound and machine learning techniques

PURPOSE

At present, a one-size-fits-all approach is typically used for cancer therapy in patients. This is mainly because there is no current imaging-based clinical standard for the early assessment and monitoring of cancer treatment response. Here, the authors have developed, for the first time, a complete computer-aided-prognosis (CAP) system based on multiparametric quantitative ultrasound (QUS) spectroscopy methods in association with texture descriptors and advanced machine learning techniques. This system was used to noninvasively categorize and predict cell death levels in fibrosarcoma mouse tumors treated using ultrasound-stimulated microbubbles as novel endothelial-cell radiosensitizers.

METHODS

Sarcoma xenograft tumor-bearing mice were treated using ultrasound-stimulated microbubbles, alone or in combination with x-ray radiation therapy, as a new antivascular treatment. Therapy effects were assessed at 2-3, 24, and 72 h after treatment using a high-frequency ultrasound. Two-dimensional spectral parametric maps were generated using the power spectra of the raw radiofrequency echo signal. Subsequently, the distances between "pretreatment" and "post-treatment" scans were computed as an indication of treatment efficacy, using a kernel-based metric on textural features extracted from 2D parametric maps. A supervised learning paradigm was used to either categorize cell death levels as low, medium, or high using a classifier, or to "continuously" predict the levels of cell death using a regressor.

RESULTS

The developed CAP system performed at a high level for the classification of cell death levels. The area under curve of the receiver operating characteristic was 0.87 for the classification of cell death levels to both low/medium and medium/high levels. Moreover, the prediction of cell death levels using the proposed CAP system achieved a good correlation (r = 0.68,  p < 0.001) with histological cell death levels as the ground truth. A statistical test of significance between individual treatment groups with the corresponding control group demonstrated that the predicted levels indicated the same significant changes in cell death as those indicated by the ground-truth levels.

CONCLUSIONS

The technology developed in this study addresses a gap in the current standard of care by introducing a quality control step that generates potentially actionable metrics needed to enhance treatment decision-making. The study establishes a noninvasive framework for quantifying levels of cancer treatment response developed preclinically in tumors using QUS imaging in conjunction with machine learning techniques. The framework can potentially facilitate the detection of refractory responses in patients to a certain cancer treatment early on in the course of therapy to enable switching to more efficacious treatments.

Sunitinib in metastatic renal cell carcinoma (mRCC): a developing country experience. Do our patients behave differently than the Western patients?

BACKGROUND

Metastatic renal cell carcinoma (mRCC) has historically been refractory to cytotoxic and hormonal agents. IL-2 and IFN-α provide response in a minority of patients. Small molecule tyrosine kinase inhibitors and monoclonal antibodies have established a role in the setting of mRCC. However, there is a lack of data from the Indian subcontinent. The aim of this study was to look whether our patients behave similarly as reported in the Western data to targeted agents, especially sunitinib.

METHODS

The study was a prospective observational study conducted for a period of 5 years from 2011 to 2016. Sixty-three patients received targeted agents and were recruited in the study. Five patients were excluded for various reasons, and three were lost to follow-up. Fifty-five patients were properly studied and followed up. Fifty patients received sunitinib, four patients received sorafenib, and one patient received parenteral temsirolimus. Patients were followed for AEs and survival.

RESULTS

The most common AEs in patients taking sunitinib were fatigue (70 %), hand-foot syndrome (62 %), skin rash (58 %), mucosal inflammation (58 %), anorexia (42 %), skin discoloration (42 %), followed by dry mouth, dysgeusia, dyspepsia, dry skin, dry mouth, hair color changes, hypothyroidism, alopecia, oral pain/stomatitis, hypertension, decreased weight, photosensitivity, peripheral edema, erythema, and others. The median overall survival in our patients was 13.2 (95 % CI 10.1-16.5), progression-free survival was 8.1 months (95 % CI 6.4-10.5), and objective response was seen in 36 %.

CONCLUSION

Non-Western patients behave differently with sunitinib therapy compared to Western patients. Our patients have more mucocutaneous side effects and lesser overall survival.

Computer Aided Theragnosis Using Quantitative Ultrasound Spectroscopy and Maximum Mean Discrepancy in Locally Advanced Breast Cancer

A noninvasive computer-aided-theragnosis (CAT) system was developed for the early therapeutic cancer response assessment in patients with locally advanced breast cancer (LABC) treated with neoadjuvant chemotherapy. The proposed CAT system was based on multi-parametric quantitative ultrasound (QUS) spectroscopic methods in conjunction with advanced machine learning techniques. Specifically, a kernel-based metric named maximum mean discrepancy (MMD), a technique for learning from imbalanced data based on random undersampling, and supervised learning were investigated with response-monitoring data from LABC patients. The CAT system was tested on 56 patients using statistical significance tests and leave-one-subject-out classification techniques. Textural features using state-of-the-art local binary patterns (LBP), and gray-scale intensity features were extracted from the spectral parametric maps in the proposed CAT system. The system indicated significant differences in changes between the responding and non-responding patient populations as well as high accuracy, sensitivity, and specificity in discriminating between the two patient groups early after the start of treatment, i.e., on weeks 1 and 4 of several months of treatment. The proposed CAT system achieved an accuracy of 85%, 87%, and 90% on weeks 1, 4 and 8, respectively. The sensitivity and specificity of developed CAT system for the same times was 85%, 95%, 90% and 85%, 85%, 91%, respectively. The proposed CAT system thus establishes a noninvasive framework for monitoring cancer treatment response in tumors using clinical ultrasound imaging in conjunction with machine learning techniques. Such a framework can potentially facilitate the detection of refractory responses in patients to treatment early on during a course of therapy to enable possibly switching to more efficacious treatments.

Quantitative evaluation of cell death response in vitro and in vivo using conventional-frequency ultrasound

Previous studies using high-frequency ultrasound have suggested that radiofrequency (RF) spectral analysis can be used to quantify changes in cell morphology to detect cell death response to therapy non-invasively. The study here investigated this at conventional-frequencies, frequently used in clinical settings.

Spectral analysis was performed using ultrasound RF data collected with a clinical ultrasound platform. Acute myeloid leukemia (AML-5) cells were exposed to cisplatinum for 0–72 hours in vitro and prepared for ultrasound data collection. Preclinical in vivo experiments were also performed on AML-5 tumour-bearing mice receiving chemotherapy.

The mid-band fit (MBF) spectral parameter demonstrated an increase of 4.4 ± 1.5 dBr for in vitro samples assessed 48 hours after treatment, a statistically significant change (p < 0.05) compared to control. Further, in vitro concentration-based analysis of a mixture of apoptotic and untreated cells indicated a mean change of 10.9 ± 2.4 dBr in MBF between 0% and 40% apoptotic cell mixtures. Similar effects were reproduced in vivo with an increase of 4.6 ± 0.3 dBr in MBF compared to control, for tumours with considerable apoptotic areas within histological samples. The alterations in the size of cells and nuclei corresponded well with changes measured in the quantitative ultrasound (QUS) parameters.

Categorizing extent of tumor cell death response to cancer therapy using quantitative ultrasound spectroscopy and maximum mean discrepancy

Quantitative ultrasound (QUS) spectroscopic techniques in conjunction with maximum mean discrepancy (MMD) have been proposed to detect, and to classify noninvasively the levels of cell death in response to cancer therapy administration in tumor models. Evaluation of xenograft tumor responses to cancer treatments were carried out using conventional-frequency ultrasound at different times after chemotherapy exposure. Ultrasound data were analyzed using spectroscopic techniques and multi-parametric QUS spectral maps were generated. MMD was applied as a distance criterion, measuring alterations in each tumor in response to chemotherapy, and the extent of cell death was classified into less/more than 20% and 40% categories. Statistically significant differences were observed between "pre-" and "post-treatment" groups at different times after chemotherapy exposure, suggesting a high capability of proposed framework for detecting tumor response noninvasively. Promising results were also obtained for categorizing the extent of cell death response in each tumor using the proposed framework, with gold standard histological quantification of cell death as ground truth. The best classification results were obtained using MMD when applied on histograms of QUS parametric maps. In this case, classification accuracies of 84.7% and 88.2% were achieved for categorizing extent of tumor cell death into less/more than 20% and 40%, respectively.

Low-frequency quantitative ultrasound imaging of cell death in vivo

PURPOSE

Currently, no clinical imaging modality is used routinely to assess tumor response to cancer therapies within hours to days of the delivery of treatment. Here, the authors demonstrate the efficacy of ultrasound at a clinically relevant frequency to quantitatively detect changes in tumors in response to cancer therapies using preclinical mouse models.

METHODS

Conventional low-frequency and corresponding high-frequency ultrasound (ranging from 4 to 28 MHz) were used along with quantitative spectroscopic and signal envelope statistical analyses on data obtained from xenograft tumors treated with chemotherapy, x-ray radiation, as well as a novel vascular targeting microbubble therapy.

RESULTS

Ultrasound-based spectroscopic biomarkers indicated significant changes in cell-death associated parameters in responsive tumors. Specifically changes in the midband fit, spectral slope, and 0-MHz intercept biomarkers were investigated for different types of treatment and demonstrated cell-death related changes. The midband fit and 0-MHz intercept biomarker derived from low-frequency data demonstrated increases ranging approximately from 0 to 6 dBr and 0 to 8 dBr, respectively, depending on treatments administrated. These data paralleled results observed for high-frequency ultrasound data. Statistical analysis of ultrasound signal envelope was performed as an alternative method to obtain histogram-based biomarkers and provided confirmatory results. Histological analysis of tumor specimens indicated up to 61% cell death present in the tumors depending on treatments administered, consistent with quantitative ultrasound findings indicating cell death. Ultrasound-based spectroscopic biomarkers demonstrated a good correlation with histological morphological findings indicative of cell death (r2=0.71, 0.82; p<0.001).

CONCLUSIONS

In summary, the results provide preclinical evidence, for the first time, that quantitative ultrasound used at a clinically relevant frequency, in addition to high-frequency ultrasound, can detect tissue changes associated with cell death in vivo in response to cancer treatments.

Sunitinib in advanced pancreatic neuroendocrine tumors: latest evidence and clinical potential

Based on preclinical data available in the RIP1-Tag2 transgenic mouse model, sunitinib is an inhibitor of angiogenesis in pancreatic neuroendocrine tumors blocking vascular endothelial growth factor receptors and platelet-derived growth factor receptors in endothelial cells and pericytes, respectively. Evidence of objective response in phase I trials justified the initiation of a large phase II/III program using sunitinib in patients with advanced/metastatic well-differentiated pancreatic neuroendocrine tumors. In the phase II study, sunitinib showed potent antitumor activity and a safe toxicity profile. In a recent double-blind placebo-controlled randomized phase III trial, sunitinib doubled the progression-free survival of patients, induced objective responses, and reduced the risk of death of patients with advanced/metastatic well-differentiated tumors. These data allowed the approval of sunitinib in several countries including Europe and the United States of America. These recent data provide hope for patients with well-differentiated pancreatic neuroendocrine tumors and will change standards of care in this disease.

Sunitinib therapy for metastatic renal cell carcinoma: recommendations for management of side effects

Sunitinib, a new vascular endothelial growth factor receptor inhibitor, has demonstrated high activity in renal cell carcinoma (RCC) and is now widely used for patients with metastatic disease. Although generally well tolerated and associated with a low incidence of common toxicity criteria grade 3 or 4 toxicities, sunitinib exhibits a distinct pattern of novel side effects that require monitoring and management. This article summarizes the most important side effects and proposes recommendations for their monitoring, prevention and treatment, based on the existing literature and on suggestions made by an expert group of Canadian oncologists. Fatigue, diarrhea, anorexia, oral changes, skin toxicity and hypertension seem to be the most clinically relevant toxicities of sunitinib. Fatigue may be partly related to the development of hypothyroidism during sunitinib therapy for which patients should be observed and, if necessary, treated. Hypertension can be treated with standard antihypertensive therapy and rarely requires treatment discontinuation. Neutropenia and thrombocytopenia usually do not require intervention, in particular no episodes of neutropenic fever have been reported to date. A decrease in left ventricular ejection fraction is a rare, but potentially life-threatening side effect. Because of its metabolism by cytochrome P450 3A4 a number of drugs can potentially interact with sunitinib. Clinical response and toxicity should be carefully observed when sunitinib is combined with either a cytochrome P450 3A4 inducer or inhibitor and doses adjusted as necessary. Knowledge about side effects, as well as the proactive assessment and consistent management of sunitinib-related side effects, is critical to ensure optimal benefit from sunitinib treatment.

Sunitinib in metastatic renal cell carcinoma: recommendations for management of noncardiovascular toxicities

The multitargeted tyrosine-kinase inhibitor sunitinib has emerged as one of the standards of care for good- and intermediate-risk metastatic renal cell carcinoma. Although generally associated with acceptable toxicity, sunitinib exhibits a novel and distinct toxicity profile that requires monitoring and management. Fatigue, diarrhea, anorexia, oral changes, hand-foot syndrome and other skin toxicity, thyroid dysfunction, myelotoxicity, and hypertension seem to be the most common and clinically relevant toxicities of sunitinib. Drug dosing and treatment duration are correlated with response to treatment and survival. Treatment recommendations for hypertension have been published but, currently, no standard guidelines exist for the management of noncardiovascular side effects. To discuss the optimal management of noncardiovascular side effects, an international, interdisciplinary panel of experts gathered in November 2009. Existing literature on incidence, severity, and underlying mechanisms of side effects as well as on potential treatment options were carefully reviewed and discussed. On the basis of these proceedings and the thorough review of the existing literature, recommendations were made for the monitoring, prevention, and treatment of the most common noncardiovascular side effects and are summarized in this review. The proactive assessment and consistent and timely management of sunitinib-related side effects are critical to ensure optimal treatment benefit by allowing appropriate drug dosing and prolonged treatment periods.

Perfusion CT and US of colorectal cancer liver metastases: a correlative study of two dynamic imaging modalities

The purpose of this study was to evaluate the correlation between dynamic-contrast-enhanced computed tomography (DCE-CT) and first-pass dynamic-contrast-enhanced ultrasound (DCE-US) of normal appearing liver parenchyma and of colorectal cancer liver metastases. Thirty patients with hepatic metastases from colorectal cancer underwent DCE-CT and DCE-US. To obtain DCE-US reproducibility measurements, double contrast-passages (2 × 2.4 mL SonoVue intravenous) were acquired. From several DCE-US-derived perfusion indices, the slope-value scored best with a reproducibility concordance correlation coefficient ranging from 0.75-0.93 and overall highest correlation to DCE-CT-derived variables (r = 0.52 to 0.73). The DCE-US-based tumor-to-liver perfusion gradient also showed a low test-retest variability and moderately correlated to DCE-CT (concordance correlation coefficient 0.87-0.92; r = 0.57 to 0.59). To conclude, DCE-US-based slope-value and tumor-to-liver perfusion gradient correlate best with DCE-CT perfusion values. However, both techniques cannot be used interchangeably. DCE-US should be restricted for studies in which a considerable change in perfusion is expected and for patients with a relatively high tumor blood flow at baseline.

Targeted therapies in renal cell cancer: recent developments in imaging

Targeted therapy has significantly improved the perspectives of patients with metastatic renal cell cancer (mRCC). Frequently, these new molecules cause disease stabilization rather than substantial tumor regression. As treatment options expand with the growing number of targeted agents, there is an increasing need for surrogate markers to early assess tumor response. Here, we review the currently available imaging techniques and response evaluation criteria for the assessment of tumor response in mRCC patients. For computed tomography (CT), different criteria are discussed including the Response Evaluation Criteria in Solid Tumors (RECIST), the Choi criteria, the modified Choi criteria, and the size and attenuation CT (SACT) criteria. Functional imaging modalities are discussed, such as dynamic contrast-enhanced CT (DCE-CT), dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), dynamic contrast-enhanced ultrasonography (DCE-US), and positron emission tomography (PET).

Metastatic renal cell carcinoma treated with sunitinib: early evaluation of treatment response using dynamic contrast-enhanced ultrasonography

PURPOSE

To determine the utility of dynamic contrast-enhanced ultrasonography (DCE-US) as a prognostic tool for metastatic renal cell carcinoma patients receiving sunitinib and to identify DCE-US parameters that correlate with early treatment response.

EXPERIMENTAL DESIGN

Thirty-eight patients received 50 mg/d sunitinib on schedule 4/2 (4 weeks on followed by 2 weeks off treatment). After two cycles, response evaluation criteria in solid tumors were used to classify patients as responders or nonresponders. DCE-US evaluations were done before treatment and at day 15; variations between days 0 and 15 were calculated for seven DCE-US functional parameters and were compared for responders and nonresponders. The correlation between DCE-US parameters and disease-free survival (DFS) and overall survival (OS) was assessed.

RESULTS

The ratio between DCE-US examinations at baseline and day 15 significantly correlated with response in five of the seven DCE-US parameters. Two DCE-US parameters (time to peak intensity and slope of the wash-in) were significantly associated with DFS; time to peak intensity was also significantly associated with OS.

CONCLUSIONS

DCE-US is a useful tool for predicting the early efficacy of sunitinib in metastatic renal cell carcinoma patients. Robust correlations were observed between functional parameters and classic assessments, including DFS and OS.

Methodology for quantifying interactions between perfusion evaluated by DCE-US and hypoxia throughout tumor growth

The objective was to validate a combination of two new technologies to depict tumor physiology both temporally and spatially with dynamic contrast-enhanced sonography and an oximeter. Human cancer prostate tumors xenografted onto mice were followed for three weeks using dynamic contrast-enhanced ultrasonography (DCE-US) to detect tumor perfusion. Time intensity curves in linear data were quantified on four regions-of-interest (ROI, main tumor section and its anterior, central and posterior intra-tumoral areas) to extract three indices of perfusion. An oxygen sensor was guided by sonography to obtain accurate pO(2) measurements in the three predefined areas of tumors during their development. No impact on tumor growth of subsequent pO(2) probe insertion was detected. Among the four ROIs studied, the local central tumor showed significant perfusion and oxygenation variations throughout the experiment. A correlation was observed between local central tumor perfusion and pO(2), both of them decreasing through time (p = 0.0068; r = 0.66). The methodology which we developed demonstrated the potential of combining DCE-US with direct tissue pO(2) measurements, improving the description of complex intratumoral dynamic behavior.

Gastrointestinal stromal tumors treated with imatinib: monitoring response with contrast-enhanced sonography

OBJECTIVE

The purpose of this study was to evaluate contrast-enhanced Doppler sonography with perfusion software as a predictor of early tumor response to imatinib (Glivec) in c-kit-positive gastrointestinal stromal tumors (GISTs).

SUBJECTS AND METHODS

Thirty patients (59 tumors) with metastases or a recurrence from a GIST were prospectively included in a single-center imaging trial. Contrast-enhanced Doppler sonography was performed with an Aplio scanner the day before (day-1) starting oral treatment (400 mg) and at days 1, 7, 14, 60, 90, and 6 months, 9 months, and 1 year. The percentage of contrast uptake (Levovist or Sonovue) before treatment and at the different stages of follow-up was evaluated by two radiologists. Digitized quantification was performed using Photoshop software. To define the benchmark standard, all patients were rated as responders or nonresponders at 2 and 6 months by a board consisting of oncologists and radiologists who had all clinical and imaging data at their disposal. Changes in the percentage of contrast uptake at each sonographic examination were compared statistically.

RESULTS

A total of 185 examinations were performed. Forty-four lesions in 24 patients were completely evaluated at 2 months, and 29 lesions in 15 patients were completely evaluated at 6 months. Initial contrast uptake at day 1 was predictive of the future response. A strong correlation was found between the decline in tumor contrast uptake at days 7 and 14 and tumor response (p < 10(-4)).

CONCLUSION

Contrast-enhanced Doppler sonography is a noninvasive imaging technique that allows the early prediction of tumor response in c-kit-positive GIST treated with Glivec.

To predict progression-free survival and overall survival in metastatic renal cancer treated with sorafenib: pilot study using dynamic contrast-enhanced Doppler ultrasound

INTRODUCTION

The objective of this study was to evaluate dynamic contrast-enhanced Doppler ultrasound (DCE-US) with perfusion software (Vascular Recognition Imaging) and contrast agent injection as a predictor of tumour response, progression-free survival (PFS) and overall survival (OS).

PATIENTS AND METHODS

Thirty patients with a metastatic renal cell carcinoma (RCC) already enrolled in a double-blind randomised study were evaluated. Examinations were performed at baseline, and after 3 and 6 weeks on sorafenib or a placebo in patients with tumour targets that were accessible to DCE-US.

RESULTS

A total of 85 examinations were performed, 30 at baseline, 28 at 3 weeks and 27 at 6 weeks. The combination of a decrease in contrast uptake exceeding 10% and stability or a decrease in tumour volume allowed us to discriminate seven good responders and 20 poor responders at 3 weeks. There was a statistically significant difference in PFS (p=10(-4)) and OS (p=10(-4)) between good and poor responders.

CONCLUSION

DCE-US is a new noninvasive imaging technique which might be an effective tool for evaluating antiangiogenic drugs in renal cancer.

Dynamic assessment of antiangiogenic therapy by monitoring both tumoral vascularization and tissue degeneration

Tumor growth is dependent both on endothelial and tumor cells. The aim of this study was to investigate dynamically whether changes in tumor vasculature implicate tumor tissue degeneration during antiangiogenic therapies. In order to quantify intra-tumor vascularization and necrosis, we have used ultrasound technology. This study has identified essential parameters needed to quantify specifically and sensitively the number of microvessels and the extent of necrosis in xenografted human carcinomas during natural tumor evolution, using contrast-enhanced high-frequency ultrasonography with (HFCDUS) or without (HFUS) color Doppler. We showed that quantification of intra-tumor microvessels between HFCDUS and immunohistochemistry is correlated using an anti-CD31 antibody. Furthermore, quantification of tumor necrosis with HFUS was confirmed by histological examination of hematoxylin-eosin-saffranin-stained sections over the observation period. Subsequently, for the assessment of novel angiogenic inhibitors, HFCDUS and HFUS were used to elucidate the underlying dynamics linking vessel inhibition and tumor eradication. We describe a novel application for HFCDUS/HFUS that constitutes an effective, convenient, and non-invasive method for clinical assessment of angiogenic inhibitors. In conclusion, we showed that tumor cells abruptly became necrotic following an antivascular therapy, whereas untreated tumors were protected from degeneration by a significant blood supply.

In vivo diffusion-weighted imaging of liver tumor necrosis in the VX2 rabbit model at 1.5 Tesla

OBJECTIVES

We sought to demonstrate the feasibility of using single-shot spin-echo echo-planar imaging for imaging liver tumor necrosis in the in vivo VX2 rabbit model at 1.5 T.

MATERIALS AND METHODS

VX2 liver tumors were grown in 4 rabbits. Diffusion-weighted images (DWIs) were acquired during breath-hold using twice refocused SE-EPI (b = 0, 700, 1400 seconds/mm). Anatomic images for tumor size measurements were acquired using T2W TSE. Rabbits were euthanized for subsequent necropsy. Viable and necrotic tumor tissue ADC measurements were performed with reference to hematoxylin and eosin pathology.

RESULTS

A total of 8 tumors were grown with diameters ranging from 1.2 to 5.3 cm. Viable and necrotic tumor compartments were clearly differentiated. Apparent diffusion coefficient in necrotic tumor cores, 1.26 +/- 0.11 x 10 mm/s, were significantly greater than those in surrounding viable tumor tissues, 0.74 +/- 0.06 x 10 mm/s (mean +/- SD, P < 0.05).

CONCLUSIONS

In vivo DWI of liver tumor necrosis in the VX2 rabbit model is feasible using a 1.5 T clinical magnetic resonance imaging scanner. DWI may permit longitudinal assessment of liver tumor therapies in both preclinical and clinical studies.

Combination of HIFU therapy with contrast-enhanced sonography for quantitative assessment of therapeutic efficiency on tumor grafted mice

The objective was to evaluate treatment efficiency of a new high-intensity focused ultrasound (HIFU) prototype combining a therapeutic transducer with a sonographic probe. The optimal HIFU sequence was defined on ex vivo samples before in vivo evaluation of tumor ablation was performed by perfusion quantification after contrast agent injection. The original feature of this prototype is a 9-MHz sonographic probe in a HIFU device and connected to an Aplio (Toshiba) sonograph. Acoustical power and treatment time were determined on ex vivo livers to generate 1-cm-long lesions. Lesion reproducibility was assessed for the power and treatment time selected. The gap between lesions and HIFU displacement shot procedures were optimized to ablate a 1-cm3 volume. The optimized protocol was applied to five murine tumors in vivo. Tumor ablation was quantified according to (1) contrast uptake (CU) after HIFU using perfusion software (Toshiba) in "vascular recognition imaging" mode and Sonovue (Bracco) contrast agent, and (2) the percentage of necrosis quantified on histologic slides. Ex vivo results: optimized settings, at 442 W/cm2 applied during three cycles (3 s on/5 s off) generated 10 identical elementary lesions measuring 9.78 (+/-0.66) * 2.11 (+/-0.33) mm2. A 4-mm gap between adjacent lesions and a 2-min pause between shot lines were found optimal. In vivo results: 60 % (+/-22) mean reduction in CU after HIFU and tumor necrosis histologically estimated at 58 % (+/-5.7) were quantified for the five animals. The therapeutic potential of this HIFU prototype was demonstrated in vivo through objective quantification of tumor ablation based on CU.

Safety, pharmacokinetic, and antitumor activity of SU11248, a novel oral multitarget tyrosine kinase inhibitor, in patients with cancer

PURPOSE

To establish the safety, pharmacokinetics, and recommended dose of sunitinib, a novel oral multitargeting tyrosine kinase inhibitor with antiangiogenic and antitumor properties, in patients with advanced malignancies.

PATIENTS AND METHODS

Sunitinib was given orally for 4 weeks every 6 weeks.

RESULTS

Twenty-eight patients received doses ranging from 15 to 59 mg/m2 (ranging from 50 mg every other day to 150 mg/d). Dose-limiting toxicities reported at the maximum-tolerated doses > or = 75 mg/d were reversible grade 3 fatigue, grade 3 hypertension, and grade 2 bullous skin toxicity. Therefore, the recommended dose was 50 mg/d. At this dose, the main adverse effects were sore mouth, edema, and thrombocytopenia. Hair discoloration and yellow coloration of the skin were observed at doses > or = 50 mg/d. Pharmacokinetic data indicate that potentially active target plasma concentrations > or = 50 ng/mL can be achieved with moderate interpatient variability and a long half-life compatible with a single daily dosing. Six objective responses were observed in three renal cell carcinomas, one neuroendocrine tumor, one stromal tumor, and one unknown primary adenocarcinoma patient. At higher doses (> or = 75 mg/d), tumor responses were often associated with reduced intratumoral vascularization and central tumor necrosis, eventually resulting in organ perforation or fistula.

CONCLUSION

At the dose of 50 mg/d (4 weeks on, 2 weeks off), sunitinib displays manageable toxicity. Antitumor activity supports further studies in patients with renal cell carcinoma, gastrointestinal, neuroendocrine, and stromal tumors. Future studies may consider including prospective imaging techniques such as high frequency ultrasound to monitor tumor density.

In Vitro Echogenicity Characterization of Poly[lactide-coglycolide] (PLGA) Microparticles and Preliminary In Vivo Ultrasound Enhancement Study for Ultrasound Contrast Agent Application

OBJECTIVES

This work includes (1) the characterization of a reproducible poly[lactide-coglycolide] (PLGA) microparticle preparation with an optimial mean diameter and size distribution and (2) the preliminary in vivo ultrasonographic investigation of PLGA microparticles.

METHODS

A first series of PLGA microparticle preparations (1 to 15 mum) was acoustically characterized on a hydrodynamic device to select the most appropriate for ultrasound contrast agent application. Preparations of 3-microm microparticles were selected, characterized at different doses, and then injected into 20 melanoma grafted mice for contrast-enhanced power Doppler ultrasonography evaluation.

RESULTS

The 3-microm microparticles (3.26-microm mean diameter with 0.41-microm standard deviation) led to in vitro enhancement of 18.3 dB at 0.62 mg/mL. In vivo experiments showed 47% enhancement of intratumoral vascularization detection after PLGA injection, significantly correlated (P < 0.0001) with preinjection intravascularization and tumoral volume. No toxicity was histologically observed.

CONCLUSION

The 3-microm PLGA microparticles provided significant enhancement in vitro and in vivo without any toxicity.