Dynamic contrast-enhanced magnetic resonance imaging pharmacodynamic biomarker study of sorafenib in metastatic renal carcinoma

Tumor Vascularity in Renal Masses: Correlation of Arterial Spin-Labeled and Dynamic Contrast-Enhanced Magnetic Resonance Imaging Assessments

Arterial spin-labeled (ASL) and dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) have been proposed to quantitatively assess vascularity in renal cell carcinoma (RCC). However, there are intrinsic differences between these 2 imaging methods, such as the relative contribution of vascular permeability and blood flow to signal intensity for DCE MRI. We found a correlation between ASL perfusion and the DCE-derived volume transfer constant and rate constant parameters in renal masses > 2 cm in size and these measures correlated with microvessel density in clear cell RCC.

BACKGROUND

The objective of this study was to investigate potential correlations between perfusion using arterial spin-labeled (ASL) magnetic resonance imaging (MRI) and dynamic contrast-enhanced (DCE) MRI-derived quantitative measures of vascularity in renal masses > 2 cm and to correlate these with microvessel density (MVD) in clear cell renal cell carcinoma (ccRCC).

PATIENTS AND METHODS

Informed written consent was obtained from all patients before imaging in this Health Insurance Portability and Accountability Act-compliant, institutional review board-approved, prospective study. Thirty-six consecutive patients scheduled for surgery of a known renal mass > 2 cm underwent 3T ASL and DCE MRI. ASL perfusion measures (PASL) of mean, peak, and low perfusion areas within the mass were correlated to DCE-derived volume transfer constant (K(trans)), rate constant (Kep), and fractional volume of the extravascular extracellular space (Ve) in the same locations using a region of interest analysis. MRI data were correlated to MVD measures in the same tumor regions in ccRCC. Spearman correlation was used to evaluate the correlation between PASL and DCE-derived measurements, and MVD. P < .05 was considered statistically significant.

RESULTS

Histopathologic diagnosis was obtained in 36 patients (25 men; mean age 58 ± 12 years). PASL correlated with K(trans) (ρ = 0.48 and P = .0091 for the entire tumor and ρ = 0.43 and P = .03 for the high flow area, respectively) and Kep (ρ = 0.46 and P = .01 for the entire tumor and ρ = 0.52 and P = .008 for the high flow area, respectively). PASL (ρ = 0.66; P = .0002), K(trans) (ρ = 0.61; P = .001), and Kep (ρ = 0.64; P = .0006) also correlated with MVD in high and low perfusion areas in ccRCC.

CONCLUSION

PASL correlated with the DCE-derived measures of vascular permeability and flow, K(trans) and Kep, in renal masses > 2 cm in size. Both measures correlated to MVD in clear cell histology.

Assessment of Tumor Angiogenesis: Dynamic Contrast-enhanced MR Imaging and Beyond

Dynamic contrast-enhanced (DCE) MR imaging is used increasingly often to evaluate tumor angiogenesis and the efficacy of antiangiogenic drugs. In clinical practice DCE-MR imaging applications are largely centered on lesion detection, characterization, and localization. In research, DCE-MR imaging helps inform decision making in early-phase clinical trials by showing efficacy and by selecting dose and schedule. However, the role of these techniques in patient selection is uncertain. Future research is required to optimize existing DCE-MR imaging methods and to fully validate these biomarkers for wider use in patient care and in drug development.

Arterial blood supply of hepatocellular carcinoma is associated with efficacy of sorafenib therapy

BACKGROUND

To explore the efficacy of sorafenib in treating hepatocellular carcinoma (HCC) and its relationship with the computed tomography (CT) and magnetic resonance imaging (MRI) features of HCC, analyze the prognostic factors of HCC patients treated with sorafenib, and investigate the relationship between imaging findings and outcomes.

METHODS

A total of 38 HCC patients who were treated with sorafenib from April 2009 to December 2010 were included in this study. HCCs were classified as good arterial supply and poor arterial supply according to the intensity enhancement on CT scan or MRI. Clinical data were collected and the survival time was calculated by Kaplan-Meier method.

RESULTS

Among these 38 patients [35 (92.1%) were males] treated with sorafenib, the median age was (53.3±11.1) years. Tumors in 17 patients had good arterial supply while those in the remained 21 patients had poor arterial supply. The median survival time (MST) was 10.7 months (95% CI, 8.7-12.7) and the 1-year overall survival (OS) was 41.0%. The MST and 1-year OS in patients with tumors with good arterial supply were 12 months (range, 4-20 months) and 52.9%, respectively, compared with those of 7 months (range, 1-16 months) and 23.8% in patients with tumors with poor arterial supply (P=0.002). Patients with BCLC stage B tumors had longer MST and higher OS than those with BCLC stage C tumors, although the differences were not statistically significant. Multivariate analysis showed that arterial supply of tumors remained statistically predictive for OS (HR =0.22; 95% CI, 0.07-0.67; P=0.008).

CONCLUSIONS

Arterial blood supply is an independent predictor for survival in HCC patients treated with sorafenib, and patients with tumors with good arterial supply benefit more than those with tumors with poor arterial supply.

[Functional magnetic resonance imaging of the kidneys]

Interest in functional renal magnetic resonance imaging (MRI) has significantly increased in recent years. This review article provides an overview of the most important functional imaging techniques and their potential clinical applications for assessment of native and transplanted kidneys, with special emphasis on the clarification of renal tumors.

Magnetic Resonance Imaging as a Biomarker for Renal Cell Carcinoma

As the most common neoplasm arising from the kidney, renal cell carcinoma (RCC) continues to have a significant impact on global health. Conventional cross-sectional imaging has always served an important role in the staging of RCC. However, with recent advances in imaging techniques and postprocessing analysis, magnetic resonance imaging (MRI) now has the capability to function as a diagnostic, therapeutic, and prognostic biomarker for RCC. For this narrative literature review, a PubMed search was conducted to collect the most relevant and impactful studies from our perspectives as urologic oncologists, radiologists, and computational imaging specialists. We seek to cover advanced MR imaging and image analysis techniques that may improve the management of patients with small renal mass or metastatic renal cell carcinoma.

Assessment of esophageal carcinoma undergoing concurrent chemoradiotherapy with quantitative dynamic contrast-enhanced magnetic resonance imaging

The aim of the present study was to investigate whether quantitative dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) can predict an early response in primary esophageal carcinoma patients undergoing concurrent chemoradiotherapy. A total of 25 patients with who were pathologically confirmed stage II-III esophageal carcinoma underwent quantitative DCE-MRI prior to chemoradiotherapy, and at 3 weeks post-treatment, the quantitative parameters [K^trans (volume transfer constant; the rate at which contrast agent distributes from the plasma to the EES), K_ep (rate contrast; the rate at which the contrast agent that has diffused to the EES returns to the plasma) and V_e (the contrast agent percentage in the space of the extracellular fluid)] were analyzed respectively. The 25 cases were categorized as a complete response (CR) or a partial response (PR). An independent samples Mann-Whitney U test was used to compare the quantitative parameters between CR and PR. A receiver operating characteristic curve (ROC) was used to determine the best predictor. In total, 17 patients were in the CR group and 8 patients were in the PR group. Pretreatment Ktrans, K_ep and V_e values were 0.54±0.17/min, 1.12±0.46/min and 0.37±0.14, respectively, in the CR group, and 0.40±0.21/min, 1.07±0.37/min and 0.40±0.22, respectively, in the PR group. There was a significant difference between the two groups for K^trans, but there were no significant differences between the two groups for K_ep and V_e. The K^trans, K_ep and V_e values at 3 weeks post-treatment were 0.33±0.11/min, 0.86±0.31/min and 0.66±0.05, respectively, in the CR group, and 0.62±0.22/min, 1.19±0.39/min and 0.45±0.19, respectively, in the PR group. The corresponding U values were -3.319, -1.719 and -2.628, respectively, and the P-values were 0.006, 0.119 and 0.021, respectively. The areas under the ROC curve of K^trans prior to chemoradiotherapy, and of K^trans and K_ep at 3 weeks post-treatment were 0.648, 0.741 and 0.796, respectively. In conclusion, DCE-MRI can predict an early response in primary esophageal carcinoma following 3 weeks of concurrent chemoradiotherapy. K^trans prior to chemoradiotherapy, and K^trans and K_ep at 3 weeks post-treatment are sensitive prediction parameters.

Reproducibility of Dynamic Contrast-Enhanced MRI in Renal Cell Carcinoma: A Prospective Analysis on Intra- and Interobserver and Scan-Rescan Performance of Pharmacokinetic Parameters

The objective of this study was to investigate the intra- and interobserver as well as scan-rescan reproducibility of quantitative parameters of renal cell carcinomas (RCCs) with dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). A total of 21 patients with clear cell RCCs (17 men, 4 woman; age 37-69 years, mean age 54.6 years, mean size, 5.0 ± 2.2 cm) were prospectively recruited from September 2012 to November 2012. Patients underwent paired DCE-MRI studies on a 3.0 T MR system with an interval of 48 to 72 hours. The extended-Tofts model and population-based arterial input function were used to calculate kinetic parameters. Three observers defined the 2-dimensional whole-tumor region of interest at the slice with the maximum diameter of the RCC. Intraobserver and scan-rescan differences were assessed using paired t tests, whereas interobserver differences using two-way analysis of variance. Intra- and interobserver reproducibility and scan-rescan reproducibility were evaluated using within-subject coefficient of variation (wCoV) and intraclass correlation coefficient (ICC). There were no significant intra-, interobserver, or scan-rescan differences in parameters (all P > 0.05). All ICCs for intra- and interobserver agreements were >0.75 (P < 0.05), whereas the scan-rescan agreement was moderate to good; V(e) (0.764, 95% confidence interval [CI]: 0.378-0.925) and K(ep) (0.906, 95% CI: 0.710-0.972) had higher ICC than K(trans) (0.686; 95% CI: 0.212-0.898) and V(p) (0.657; 95% CI: 0.164-0.888). In intra- and interobserver variability analyses, all parameters except V(p) had low wCoV values. K(trans) and V(e) had slightly lower intraobserver wCoV (1.2% and 0.9%) compared with K(ep) (3.7%), whereas all 3 of these parameters had similar interobserver wCoV values (2.5%, 3.1%, and 2.9%, respectively). Regarding scan-rescan variability, K(trans) and K(ep) showed slightly higher variation (15.6% and 15.4%) than V(e) (10.1%). V(p) had the largest wCoV in all variability analyses (all >30%). DCE-MRI demonstrated good intra- and interobserver reproducibility and moderate to good scan-rescan performance in the assessment of RCC using K(trans), K(ep), and V(e) as parameters under noncontinuous scanning mode. V(p) showed poor reproducibility, and thus may not be suitable for this scanning protocol.

Assessing Treatment Response Through Generalized Pharmacokinetic Modeling of DCE-MRI Data

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) enables the quantification of contrast leakage from the vascular tissue by using pharmacokinetic (PK) models. Such quantitative analysis of DCE-MRI data provides physiological parameters that are able to provide information of tumor pathophysiology and therapeutic outcome. Several assumptive PK models have been proposed to characterize microcirculation in the tumoral tissue. In this paper, we present a comparative study between the well-known extended Tofts model (ETM) and the more recent gamma capillary transit time (GCTT) model, with the latter showing initial promising results in the literature. To enhance the GCTT imaging biomarkers, we introduce a novel method for segmenting the tumor area into subregions according to their vascular heterogeneity characteristics. A cohort of 11 patients diagnosed with glioblastoma multiforme with known therapeutic outcome was used to assess the predictive value of both models in terms of correctly classifying responders and nonresponders based on only one DCE-MRI examination. The results indicate that GCTT model's PK parameters perform better than those of ETM, while the segmentation of the tumor regions of interest based on vascular heterogeneity further enhances the discriminatory power of the GCTT model.

Optimization of arterial spin labeling MRI for quantitative tumor perfusion in a mouse xenograft model

Perfusion is an important biomarker of tissue function and has been associated with tumor pathophysiology such as angiogenesis and hypoxia. Arterial spin labeling (ASL) MRI allows noninvasive and quantitative imaging of perfusion; however, the application in mouse xenograft tumor models has been challenging due to the low sensitivity and high perfusion heterogeneity. In this study, flow-sensitive alternating inversion recovery (FAIR) ASL was optimized for a mouse xenograft tumor. To assess the sensitivity and reliability for measuring low perfusion, the lumbar muscle was used as a reference region. By optimizing the number of averages and inversion times, muscle perfusion as low as 32.4 ± 4.8 (mean ± standard deviation) ml/100 g/min could be measured in 20 min at 7 T with a quantification error of 14.4 ± 9.1%. Applying the optimized protocol, heterogeneous perfusion ranging from 49.5 to 211.2 ml/100 g/min in a renal carcinoma was observed. To understand the relationship with tumor pathology, global and regional tumor perfusion was compared with histological staining of blood vessels (CD34), hypoxia (CAIX) and apoptosis (TUNEL). No correlation was observed when the global tumor perfusion was compared with these pathological parameters. Regional analysis shows that areas of high perfusion had low microvessel density, which was due to larger vessel area compared with areas of low perfusion. Nonetheless, these were not correlated with hypoxia or apoptosis. The results suggest that tumor perfusion may reflect certain aspect of angiogenesis, but its relationship with other pathologies needs further investigation.

Monitoring Vascular Disrupting Therapy in a Rabbit Liver Tumor Model: Relationship between Tumor Perfusion Parameters at IVIM Diffusion-weighted MR Imaging and Those at Dynamic Contrast-enhanced MR Imaging

PURPOSE

To investigate whether perfusion-related intravoxel incoherent motion (IVIM) diffusion-weighted (DW) magnetic resonance (MR) imaging parameters correlate with dynamic contrast material-enhanced MR imaging parameters in between-subject and/or within-subject longitudinal settings for monitoring the therapeutic effects of a vascular disrupting agent (VDA) (CKD-516) in rabbit VX2 liver tumors.

MATERIALS AND METHODS

With institutional Animal Care and Use Committee approval, 21 VX2 liver tumor-bearing rabbits (treated, n = 15; control, n = 6) underwent IVIM DW imaging with 12 b values (0-800 sec/mm(2)) and dynamic contrast-enhanced MR imaging performed before (baseline) CKD-516 administration and 4 hours, 24 hours, and 7 days after administration. Perfusion-related IVIM DW imaging parameters of the tumors, including the pseudodiffusion coefficient (D*) and perfusion fraction (f), as well as dynamic contrast-enhanced MR imaging parameters, including the volume transfer coefficient (K(trans)) and initial area under the gadolinium concentration-time curve until 60 seconds (iAUC), were measured. IVIM DW imaging parameters were correlated with dynamic contrast-enhanced MR imaging parameters by using Pearson correlation analysis between subjects at each given time and by using a linear mixed model for within-subject longitudinal data.

RESULTS

In the treated group, D*, f, K(trans), and iAUC significantly decreased (-40.7% to -26.3%) at 4-hour follow-up compared with these values in the control group (-6.9% to +5.9%) (P < .05). For longitudinal monitoring of CKD-516 treatment, D* and f showed significant positive correlations with K(trans) and iAUC (P = .004 and P = .02; P < .001 and P = .006, respectively), while no significant correlations were observed between IVIM DW imaging and dynamic contrast-enhanced MR imaging parameters between subjects at any given time (P > .05).

CONCLUSION

In a rabbit tumor model, perfusion parameters serially quantified with IVIM DW imaging can be used as alternatives to dynamic contrast-enhanced MR imaging parameters in reflecting the dynamic changes in tumor perfusion during the within-subject longitudinal monitoring of VDA treatment.

Assessment of early therapeutic response to sorafenib in renal cell carcinoma xenografts by dynamic contrast-enhanced and diffusion-weighted MR imaging

OBJECTIVE

To investigate the feasibility of dynamic contrast-enhanced MRI (DCE-MRI) and diffusion-weighted MRI (DWI) in monitoring early therapeutic response to sorafenib in renal cell carcinoma (RCC) xenograft models.

METHODS

Sorafenib (40 mg kg(-1)) was administered orally to BALB/c nude mice (n = 9) bearing subcutaneous tumours of human RCC ACHN xenografts. DCE-MRI and DWI were obtained 0, 1, 3 and 7 days after therapy, and DCE-MRI parameters (K(trans) and ve) and apparent diffusion coefficient (ADC) values were calculated. Tumour size and volume changes were correlated with changes in DCE-MRI parameters or ADC values after therapy.

RESULTS

Following therapy, K(trans) showed a significant decrease over time (p = 0.005), whereas ve did not demonstrate significant changes between time points (p = 0.97). ADC values showed a progressive increase over time (p = 0.004). Compared with pre-therapy, K(trans) showed a significant decrease after 3 days of therapy (p = 0.039), and ADC values increased significantly after 7 days (p = 0.039). Tumour size and volume did not show significant changes during 7 days. Tumour size and volume changes were not associated with changes in DCE-MRI parameters or ADC values.

CONCLUSION

DCE-MRI and DWI may show early physiological changes within 1 week after initiating sorafenib treatment on human RCC xenografts.

ADVANCES IN KNOWLEDGE

The quantitative parameters of DCE-MRI and DWI may offer the potential for assessing early therapeutic response to sorafenib in clinical trials.

Phase I/II Trial of Imatinib and Bevacizumab in Patients With Advanced Melanoma and Other Advanced Cancers

BACKGROUND

Vascular endothelial growth factor and platelet-derived growth factor signaling in the tumor microenvironment appear to cooperate in promoting tumor angiogenesis.

PATIENTS AND METHODS

We conducted a phase I trial combining bevacizumab (i.v. every 2 weeks) and imatinib (oral daily). Once a recommended phase II dose combination was established, a phase II trial was initiated in patients with metastatic melanoma. A Simon 2-stage design was used with 23 patients required in the first stage and 41 patients in total should the criteria to proceed be met. We required that 50% of the patients be progression-free at 16 weeks. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and power Doppler ultrasonography were performed in patients with metastatic tumors amenable to imaging with these methods at baseline and after 4 weeks.

RESULTS

A total of 17 patients were accrued to 4 dose and combination levels. Bevacizumab 10 mg/kg every 2 weeks could be safely combined with imatinib 800 mg daily. Common toxicities included fatigue, nausea, vomiting, edema, proteinuria, and anemia, but were not commonly severe. A total of 23 patients with metastatic melanoma (48% with American Joint Commission on Cancer stage M1c; median age, 63 years) were enrolled in the first stage of phase II. The 16-week progression-free survival rate was 35%, leading to termination of phase II after the first stage. In the small subset of patients who remained on study with lesions evaluable by DCE-MRI, significant decreases in tumor vascular permeability were noted, despite early disease progression using the Response Evaluation Criteria In Solid Tumors.

CONCLUSION

Bevacizumab and imatinib can be safely combined at the maximum doses used for each agent. We did not observe significant clinical activity with this regimen in melanoma patients.

Dynamic Contrast-Enhanced Magnetic Resonance Imaging with Gd-EOB-DTPA for the Evaluation of Liver Fibrosis Induced by Carbon Tetrachloride in Rats

Purpose

To investigate the utility of dynamic contrast-enhanced MRI (DCE-MRI) with Gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) for detecting liver fibrosis induced by carbon tetrachloride (CCl₄) in rats.

Methods

This study was approved by the institutional animal care and use committee. Liver fibrosis in rats was induced by intraperitoneal injection of 1 mL/kg 50% CCl₄ twice a week for 4-13 weeks. Control rats were injected with saline. Liver fibrosis was graded using the Metaviar score: no fibrosis (F0), mild fibrosis (F1-F2) and advanced fibrosis (F3-F4). DCE-MRI with Gd-EOB-DTPA was performed for all rats. K^trans, K_ep, V_e and iAUC of the liver parenchyma were measured. Relative enhancement (RE) value of the liver was calculated on T₁-weighted images at 15, 20 and 25 min after Gd-EOB-DTPA administration.

Results

Thirty-five rats were included: no fibrosis (n=13), mild fibrosis (n=11) and advanced fibrosis (n=11). K^trans and iAUC values were highest in advanced fibrosis group and lowest in no fibrosis group (P＜0.05). The area under the receiver operating characteristic curve (AUROC) for fibrosis (stages F1 and greater) were 0.773 and 0.882 for K^trans and iAUC, respectively. AUROC for advanced fibrosis were 0.835 and 0.867 for K^trans and iAUC, respectively. K_ep and RE values were not able to differentiate fibrosis stages (all P＞0.05).

Conclusion

K^trans and iAUC obtained from DCE-MRI with Gd-EOB-DTPA are useful for the detection and staging of rat liver fibrosis induced by CCl₄.

Dynamic contrast-enhanced computed tomography as a potential biomarker in patients with metastatic renal cell carcinoma: preliminary results from the Danish Renal Cancer Group Study-1

OBJECTIVES

The aim of this study was to explore the impact of dynamic contrast-enhanced (DCE) computer tomography (CT) as a biomarker in metastatic renal cell carcinoma (mRCC).

MATERIALS AND METHODS

Twelve patients with favorable or intermediate Memorial Sloan Kettering Cancer Center risk group and clear cell mRCC participating in an ongoing prospective randomized phase II trial comprising interleukin-2-based immunotherapy and bevacizumab were included in this preliminary analysis. All patients had a follow-up time of at least 2 years. Interpretation of DCE-CT (max slope method) was performed blinded to treatment group. The DCE-CT scans were performed at baseline, at weeks 5 and 10, and thereafter every third month. Blood flow (BF; mL/min/100 mL), peak enhancement (Hounsfield units), time to peak (seconds), and blood volume (BV; mL/100 g) were calculated. Parameters for DCE-CT were correlated with sum of diameters (defined by Response Evaluation Criteria in Solid Tumors 1.1), progression-free survival (PFS), and overall survival (OS) using Wilcoxon, Man-Whitney, Kaplan-Meier, and log rank statistics, as appropriate.

RESULTS

Blood flow at baseline ranged from 4.9 to 148.1 mL/min/100 mL (median, 62.2; 25th percentile, 25.8; 75th percentile, 110.0). Patients with high baseline BF (using quartiles as cutoffs) had significantly longer OS (not reached vs 5.2 months, P = 0.011) and longer PFS (not reached vs 3.9 months, P = 0.026). Blood volume at baseline ranged from 8.8 to 74.1 mL/100 g tissue (median, 21.5), and at week 5, from 4.9 to 34.7 mL/100 g (median, 17.2). Relative changes in BV between baseline and week 5 ranged from -64% to +68% (median, -16%; 25th percentile, -41%; 75th percentile, +2%) and were significantly associated with OS using quartiles as cutoffs (5.2 months vs not reached, P = 0.038) and PFS using the median as cutoff (5.3 months vs not reached, P = 0.009), with larger reductions associated with longer survival. Using medians as cutoffs, relative changes in both BF and BV between baseline and week 10 were significantly associated with OS (for both, 8.6 months vs not reached, P = 0.031).

CONCLUSIONS

Dynamic contrast-enhanced CT is a potential biomarker in patients with mRCC. High baseline BF and reductions in BF and BV during early treatment are associated with improved outcome. Large-scale studies are required.

Bevacizumab-based neoadjuvant chemotherapy for colorectal cancer liver metastases: Pitfalls and helpful tricks in a review for clinicians

Bevacizumab added to chemotherapy has shown encouraging efficacy in the neoadjuvant therapy of colorectal cancer liver metastases. In absence of biological predictor factors of efficacy to bevacizumab-based treatment, the assessment of response may be a crucial point to select patients who may benefit the most from surgery. At the same time the pathological response after liver resection could represent a guide for the next therapeutic plan. In the pre-surgical phase, conventional computed tomography and response evaluation with RECIST criteria may underestimate the response to anti-angiogenic drugs. Modified computed tomography criteria of response, morphologic changes as well as novel imaging techniques and metabolic assessment by fluorodeoxyglucose positron emission tomography seem to be promising methods for the assessment of response and for leading the clinical choices. Pathological response at the time of surgery is an important prognostic factor and a surrogate of survival for resected patients. Different classification criteria to assess pathological response have been developed, residual viable tumor, tumor regression grade (TRG), modified TRG and tumor thickness at the tumor-normal interface, but to date a superiority of one approach over the others has not been clearly established. In this review, we evaluate the available data with the aim to help the clinicians in the pre- and post-surgical care of patient with colorectal cancer liver metastases treated with bevacizumab-based neoadjuvant strategy.

Sites of disease as predictors of outcome in metastatic renal cell carcinoma patients treated with first-line sunitinib or sorafenib

BACKGROUND

This study investigated whether the effectiveness of first-line tyrosine-kinase inhibitors was associated with sites of disease in patients with metastatic renal cell carcinoma (mRCC).

METHODS

A retrospective cohort of consecutive mRCC patients receiving first-line sorafenib (SO) or sunitinib (SU) was analyzed.

RESULTS

In total, 203 patients received SO and 99 SU. In patients with liver metastasis, SU was associated with a 18% higher risk of time-to-treatment failure (TTF), and a 39% higher risk of death than SO: conversely, patients without liver metastases who received SU showed a 46% decreased risk of TTF and 62% decreased risk of death.

CONCLUSIONS

mRCC patients with liver metastases treated with first-line SO showed a better outcome compared with SU, while mRCC patients without liver metastases treated with first-line SU showed a better outcome compared with SO.

Imaging for assessment of treatment response in hepatocellular carcinoma: Current update

Morphologic methods such as the Response Evaluation Criteria in Solid Tumors (RECIST) are considered as the gold standard for response assessment in the management of cancer. However, with the increasing clinical use of antineoplastic cytostatic agents and locoregional interventional therapies in hepatocellular carcinoma (HCC), conventional morphologic methods are confronting limitations in response assessment. Thus, there is an increasing interest in new imaging methods for response assessment, which can evaluate tumor biology such as vascular physiology, fibrosis, necrosis, and metabolism. In this review, we discuss various novel imaging methods for response assessment and compare them with the conventional ones in HCC.

Perfusion computed tomography as functional biomarker in randomized run-in study of bevacizumab and everolimus in well-differentiated neuroendocrine tumors

OBJECTIVES

This study aimed to assess the antitumor activity of everolimus and bevacizumab among patients with advanced neuroendocrine tumors and to assess perfusion computed tomography (CT) as a potential functional biomarker.

METHODS

Patients with low- to intermediate-grade neuroendocrine tumors received one 3-week cycle of 15 mg/kg of bevacizumab on day 1 or 10 mg of everolimus daily. Subsequent cycles consisted of the combination of both drugs. Perfusion CTs were performed at baseline and at the end of cycles 1 and 3.

RESULTS

Therapy decreased blood flow (BF) proportional to baseline measurements. Bevacizumab was associated with a 44% decrease in BF (P < 0.0001). After the addition of everolimus, a further 29% decrease (P = 0.02) in BF was observed. Everolimus alone was associated with 13% increase in mean transit time (P = 0.02). Clinical activity was demonstrated, with a confirmed response rate of 21% and a median progression-free survival of 14.6 (95% confidence interval, 13.0-16.1) months. Pretreatment tumor permeability surface (P = 0.009), posttreatment mean transit time (P = 0.003), percent reduction in BF (P = 0.03), and percent reduction in blood volume (P = 0.002) were associated with best percent reduction in tumor diameters.

CONCLUSIONS

Bevacizumab and everolimus demonstrated antitumor activity. Perfusion CT is a promising tool for the development of antiangiogenic strategies and for the selection of patients who are likely to benefit from therapy.

Mixed-effects modeling of clinical DCE-MRI data: application to colorectal liver metastases treated with bevacizumab

PURPOSE

Most dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) data are evaluated for individual patients with cohorts analyzed to detect significant changes from baseline values, repeating the process at each posttreatment timepoint. Our study aimed to develop a statistically valid model for the complete time course of DCE-MRI data in a patient cohort.

MATERIALS AND METHODS

Data from 10 patients with colorectal cancer liver metastases were analyzed, including two baseline scans and four post-bevacizumab scans. Apparent changes in tumor median K(trans) were adjusted for changes in observed enhancing tumor fraction (EnF) by multiplying K(trans) by EnF (KEnF). A mixed-effects model (MEM) was defined to describe the KEnF time course for all patients simultaneously by assuming a three-parameter indirect response model with model parameters lognormally distributed across patients.

RESULTS

The typical cohort time course showed a KEnF reduction to 59% of baseline at 24 hours, returning to 65% of baseline values by day 12. Interpatient variability of model parameters ranged from 11% to 307%.

CONCLUSION

The MEM approach has potential for comparing responses at a group level in clinical trials with different doses, schedules, or combination regimens. Furthermore, the KEnF biomarker successfully resolved confounds in interpreting K(trans) arising from therapy induced changes in the volume of enhancing tumor.

Models and methods for analyzing DCE-MRI: a review

PURPOSE

To present a review of most commonly used techniques to analyze dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), discusses their strengths and weaknesses, and outlines recent clinical applications of findings from these approaches.

METHODS

DCE-MRI allows for noninvasive quantitative analysis of contrast agent (CA) transient in soft tissues. Thus, it is an important and well-established tool to reveal microvasculature and perfusion in various clinical applications. In the last three decades, a host of nonparametric and parametric models and methods have been developed in order to quantify the CA's perfusion into tissue and estimate perfusion-related parameters (indexes) from signal- or concentration-time curves. These indexes are widely used in various clinical applications for the detection, characterization, and therapy monitoring of different diseases.

RESULTS

Promising theoretical findings and experimental results for the reviewed models and techniques in a variety of clinical applications suggest that DCE-MRI is a clinically relevant imaging modality, which can be used for early diagnosis of different diseases, such as breast and prostate cancer, renal rejection, and liver tumors.

CONCLUSIONS

Both nonparametric and parametric approaches for DCE-MRI analysis possess the ability to quantify tissue perfusion.

Evaluation of dynamic contrast-enhanced MRI derived microvascular permeability in recurrent glioblastoma treated with bevacizumab

Bevacizumab, an antibody to vascular endothelial growth factor, is commonly used in the setting of recurrent glioblastoma (rGB). The aim of the present study was to evaluate whether dynamic-contrast-enhanced MRI (DCE-MRI) derived microvascular permeability is related to bevacizumab treatment outcome in rGB. Twenty-two patients with rGB underwent DCE-MRI at a median of 2.6 weeks prior initializing bevacizumab therapy. Follow-up MRI-scans (DCE-MRI available for 19/22 patients) were obtained after a median of 9.9 weeks. The volume transfer constant (K(trans))--an estimate related to microvascular permeability--at baseline and voxel-wise-reduction (VWR) in K(trans) at first follow-up were measured from the entire contrast-enhancing tumor (CET) and correlated with progression-free and overall survival (PFS, OS) using uni- and multivariate cox-regression (significance-level p < 0.05). Baseline K(trans) ranged from 0.050 to 0.205 min(-1) (median, 0.109 min(-1)). The VWR in K(trans) ranged from 19.9 to 97.2 % (median, 89.4 %). Patients with lower baseline K(trans) and higher VWR in K(trans) showed significantly longer PFS and OS. Given the strong correlation of VWR in K(trans) and CET-volume changes (Spearman's ρ = -0.73, p < 0.01) both variables were included in a multivariate model. Thereby, neither VWR in K(trans) nor CET-volume changes retained independent significance for PFS or OS. Pre-treatment K(trans) stratifies PFS and OS in patients with bevacizumab-treated rGB. Although early pharmacodynamics changes in K(trans) were not assessed, the VWR in K(trans) at first follow-up had no additional benefit over assessment of CET-volume changes. Further prospective trials are needed to confirm these findings and to elucidate the potential role of pre-treatment K(trans) as a predictive and/or prognostic biomarker.

Targeting the hepatocyte growth factor/mesenchymal epithelial transition pathway in gastric cancer: biological rationale and clinical applications

Advanced gastric cancer (GC) is a dreadful disease with a poor prognosis and the majority of patients die within 1 year of diagnosis. In the past decade, important signaling pathways promoting tumor proliferation and aggressiveness have been evaluated; the hepatocyte growth factor/mesenchymal epithelial transition (MET) pathway is one of the most promising pathways in that regard. This pathway has been evaluated in preclinical and early clinical settings of GC. From the very early studies, MET expression has been recognized as an important poor prognostic marker in GC. However, only after the development of MET-targeting agents, it became important in terms of antitumor therapy with the clinical evaluation of several MET-targeting agents in GC. The results of the ongoing multicenter studies evaluating MET-targeting agents are eagerly awaited as they may improve our understanding of the precise role of these agents in the treatment armamentarium of advanced GC.

Predictive biomarkers in renal cell cancer: insights in drug resistance mechanisms

INTRODUCTION

VEGF-targeted therapy is currently the first line treatment for patients with metastatic clear cell renal cell carcinoma (ccRCC), but most patients either display primary (intrinsic) resistance or acquire drug resistance. In recent years multiple mechanisms of resistance to VEGF-targeted therapy emerged from preclinical research, but it is currently unknown to what extent these drug resistance modalities play a role in the clinic. Here we reviewed the current literature on biomarkers that predict treatment outcome in patients with ccRCC to gain insight in clinical drug resistance mechanisms.

METHODS

A search syntax was compiled by combining different synonyms of "biomarker" AND "renal" AND "cancer". MEDLINE was accessed through PubMed, where this syntax was entered and used to search titles and abstracts of publications. Articles were selected based on three criteria: (1) description of patients with clear cell RCC, (2) treatment with VEGF targeted therapy and (3) discussion of biomarkers that were studied for potential association with treatment response.

RESULTS

The literature search was performed on March 4th 2014 and yielded 1882 articles. After carefully reading the titles and abstracts based on the three previously mentioned criteria, 103 publications were evaluated. Backward citation screening was performed on all eligible studies and revealed another 24 articles. This search revealed that (1) High glucose uptake and low contrast enhancement on PET- and CT-imaging before start of treatment may correlate with poor response to therapy, (2) Low dose intensity due to treatment intolerance is related to shorter progression free survival. (3) Acquired resistance appears to be associated with rebound vascularization based on both longitudinal monitoring of contrast enhancement by CT and blood vessel counts in tumor tissue, and (4) Based on plasma cytokine and single nucleotide polymorphism (SNP) studies, interleukin-8, VEGFR-3, FGFR2 and HGF/MET emerged as potential clinical markers for chemoresistance.

CONCLUSION

Low dose intensity, specific tumor-imaging techniques and potential biological biomarkers may be predictive for response to VEGF-targeted therapy in ccRCC. Some of these plausible biomarkers may also provide more insight into the underlying mechanisms of resistance such as altered glucose metabolism and rapid rebound vascularization.

Functional MR imaging of the abdomen

In this article, functional magnetic resonance (MR) imaging techniques in the abdomen are discussed. Diffusion-weighted imaging (DWI) increases the confidence in detecting and characterizing focal hepatic lesions. The potential uses of DWI in kidneys, adrenal glands, bowel, and pancreas are outlined. Studies have shown potential use of quantitative dynamic contrast-enhanced MR imaging parameters, such as K(trans), in predicting outcomes in cancer therapy. MR elastography is considered to be a useful tool in staging liver fibrosis. A major issue with all functional MR imaging techniques is the lack of standardization of the protocol.

Evaluating digestive neuroendocrine tumor progression and therapeutic responses in the era of targeted therapies: state of the art

Well-differentiated neuroendocrine tumors (NETs) are a group of heterogeneous rare tumors. They are often slow-growing and patients can have very long survival, even at the metastatic stage. The evaluation of tumor progression and therapeutic responses is currently based on Response Evaluation Criteria In Solid Tumors v1.1 (RECIST) criteria. As for other malignancies, RECIST criteria are being reexamined for NETs in the era of targeted therapies because tumor response to targeted therapies is rarely associated with shrinkage, as opposed to prolonged progression-free survival. Therefore, size-based criteria no longer seem to be suitable to the assessment of NET progression and therapeutic responses, especially considering targeted therapies. New imaging criteria, combining morphological and functional techniques, have proven relevant for other malignancies treated with targeted therapies. To date, such studies have rarely been conducted on NETs. Moreover, optimizing the management of NET patients also requires considering clinical, biological, and pathological aspects of tumor evolution. Our objectives herein were to comprehensively review current knowledge on the assessment of tumor progression and early prediction of therapeutic responses and to broaden the outlook on well-differentiated NETs, in the era of targeted therapies.

[Quantitative imaging in uro-oncology]

INTRODUCTION

Imaging currently performed in uro-oncology could provide useful information. The use of all this information could help to better understand tumor growth and response to treatment. Therefore, it seems interesting to review the knowledge, to describe the main techniques currently available in many centers or in process and to clarify their results.

MATERIALS AND METHODS

A systematic literature review was conducted in the PubMed database to identify all imaging techniques performed for therapeutic evaluation in uro-oncology. The keywords used were: cancer, kidney, bladder, prostate, urology biomarkers, imaging, ultrasound, CT-scan, MRI, PET-CT, RECIST, BOLD, ASL, gold DWI Diffusion, contrast, F-miso. The first publications identified were analyzed to search unidentified studies by the selected keywords.

RESULTS

From simple to more complex morphology data from functional imaging (PET, MRI), data obtained from imaging helps to better understand tumor growth and response to treatment. Although optimizations are coming, all the techniques reported are available in many centers or going to be.

CONCLUSION

The imaging evaluation in onco-urology can bring a large amount of information. Integrating to research protocols is now essential to sustain this activity.

MRI phenotype in renal cancer: is it clinically relevant?

Renal cell carcinoma (RCC) is most commonly diagnosed as an incidental finding on cross-sectional imaging and represents a significant clinical challenge. Although most patients have a surgically curable lesion at the time of diagnosis, the variability in the biologic behavior of the different histologic subtypes and tumor grade of RCC, together with the increasing array of management options, creates uncertainty for the optimal clinical approach to individual patients. State-of-the-art magnetic resonance imaging (MRI) provides a comprehensive assessment of renal lesions that includes multiple forms of tissue contrast as well as functional parameters, which in turn provides information that helps to address this dilemma. In this article, we review this evolving and increasingly comprehensive role of MRI in the detection, characterization, perioperative evaluation, and assessment of the treatment response of renal neoplasms. We emphasize the ability of the imaging "phenotype" of renal masses on MRI to help predict the histologic subtype, grade, and clinical behavior of RCC.

New approaches for precise response evaluation in hepatocellular carcinoma

With the increasing clinical use of cytostatic and novel biologic targeted agents, conventional morphologic tumor burden assessments, including World Health Organization criteria and Response Evaluation Criteria in Solid Tumors, are confronting limitations because of their difficulties in distinguishing viable tumor from necrotic or fibrotic tissue. Therefore, the investigation for reliable quantitative biomarkers of therapeutic response such as metabolic imaging or functional imaging has been desired. In this review, we will discuss the conventional and new approaches to assess tumor burden. Since targeted therapy or locoregional therapies can induce biological changes much earlier than morphological changes, these functional tumor burden analyses are very promising. However, some of them have not gone thorough all steps for standardization and validation. Nevertheless, these new techniques and criteria will play an important role in the cancer management, and provide each patient more tailored therapy.

Dynamic contrast-enhanced magnetic resonance imaging in prostate cancer clinical trials: potential roles and possible pitfalls

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) evaluates the tissue microvasculature and may have a role in assessing and predicting therapeutic response in prostate cancer (PCa). In this review, we review principles of DCE-MRI and present the potential quantitative information that can be obtained. We discuss how it may be used as a biomarker for treatment with antiangiogenic and antivascular agents and potentially identify patients with PCa who may benefit from this form of therapy. Likewise, DCE-MRI may play a role in assessing response to combined androgen deprivation therapy and radiation therapy and theoretically could be a prognostic biomarker in evaluating second-generation hormone therapies. We also address the challenges of using DCE-MRI in PCa clinical trials and discuss the difficulties with standardization of this methodology to allow for biomarker validation, with particular reference to PCa.

Anti-angiogenic therapy for cancer: current progress, unresolved questions and future directions

Tumours require a vascular supply to grow and can achieve this via the expression of pro-angiogenic growth factors, including members of the vascular endothelial growth factor (VEGF) family of ligands. Since one or more of the VEGF ligand family is overexpressed in most solid cancers, there was great optimism that inhibition of the VEGF pathway would represent an effective anti-angiogenic therapy for most tumour types. Encouragingly, VEGF pathway targeted drugs such as bevacizumab, sunitinib and aflibercept have shown activity in certain settings. However, inhibition of VEGF signalling is not effective in all cancers, prompting the need to further understand how the vasculature can be effectively targeted in tumours. Here we present a succinct review of the progress with VEGF-targeted therapy and the unresolved questions that exist in the field: including its use in different disease stages (metastatic, adjuvant, neoadjuvant), interactions with chemotherapy, duration and scheduling of therapy, potential predictive biomarkers and proposed mechanisms of resistance, including paradoxical effects such as enhanced tumour aggressiveness. In terms of future directions, we discuss the need to delineate further the complexities of tumour vascularisation if we are to develop more effective and personalised anti-angiogenic therapies.

Associations between tumor vascularization assessed by in vivo DCE-MRI and the presence of disseminated tumor cells in bone marrow in breast cancer patients at the time of diagnosis

PURPOSE

To explore possible associations between in vivo pharmacokinetic dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) parameters and the presence of disseminated tumor cells (DTCs) in bone marrow in breast cancer patients at the time of diagnosis.

MATERIALS AND METHODS

Thirty-seven women with breast cancer (stage T2-4N0-1M0) were included. Patients were classified as DTC+ if one or more DTCs were detected by immunocytochemistry. DCE-MRI was acquired with a radial 3D T1 -weighted spoiled gradient echo sequence with k-space weighted image contrast. K(trans), kep, and ve were calculated using the extended Tofts model and a population-derived arterial input function. The nonparametric Mann-Whitney U-test was used to compare the histogram distributions of the pharmacokinetic parameters for the DTC+ and the DTC- patients.

RESULTS

DTCs were detected in 7 of the 37 patients (19%). In DTC+ patients, the distribution of tumor K(trans) and kep were significantly (P < 0.01) more shifted towards lower values than in DTC- patients.

CONCLUSION

An association between vascular dependent pharmacokinetic DCE-MRI parameters and the presence of DTCs were found. Compared to DTC- patients, DTC+ patients had poorer perfusion and permeability, indicative of hypoxia. Thus, pharmacokinetic parameters might be surrogate biomarkers of metastatic potential and future relapse.

Diffusion-weighted and multiphase contrast-enhanced MRI as surrogate markers of response to neoadjuvant sunitinib in metastatic renal cell carcinoma

BACKGROUND

Current imaging criteria for categorising disease response in metastatic renal cell carcinoma (mRCC) correlate poorly with overall survival (OS) in patients on anti-angiogenic therapies. We prospectively assess diffusion-weighted and multiphase contrast-enhanced (MCE) MR imaging (MRI) as markers of outcome.

METHODS

Treatment-naive mRCC patients on a phase II trial using sunitinib completed an MRI substudy. Whole-tumour apparent diffusion coefficient (ADC) maps and histograms were generated, and mean ADC and AUC(low) (proportion of the tumour with ADC values lying below the 25th percentile of the ADC histogram) recorded. On MCE-MRI, regions of interest were drawn around the most avidly enhancing components to analyse enhancement parameters. Baseline (n=26) and treatment-related changes in surviving patients (n=20) were correlated with OS. Imaged metastases were also analysed.

RESULTS

Forty-seven per cent of the patients showed significant changes in whole-tumour mean ADC following therapy, but there was no correlation with outcome. Patients with a high baseline AUC(low) and greater-than-median AUC(low) increase had reduced OS (HR=3.67 (95% confidence interval (CI)=1.23-10.9), P=0.012 and HR=3.72 (95% CI=0.98-14.21), P=0.038, respectively). There was no correlation between MCE-MRI parameters and OS. Twenty-eight metastases were analysed and showed positive correlation with primary tumour mean ADC for individual patients (r=0.607; P<0.001).

CONCLUSION

Primary RCC ADC histogram analysis shows dynamic changes with sunitinib. Patients in whom the tumour ADC histogram demonstrated high baseline AUC(low) or a greater-than-median increase in AUC(low) with treatment had reduced OS.

Recommendations for the clinical and radiological evaluation of response to treatment in metastatic renal cell cancer

The evaluation of response to treatment is a critical step for determining the effectiveness of oncology drugs. Targeted therapies such as tyrosine kinase inhibitors and mammalian target of rapamycin inhibitors are active drugs in patients with metastatic renal cell carcinoma (mRCC). However, treatment with this type of drugs may not result in significant reductions in tumor size, so standard evaluation criteria based on tumor size, such as Response Evaluation Criteria in Solid Tumors (RECIST), may be inappropriate for evaluating response to treatment in patients with mRCC. In fact, targeted therapies apparently yield low response rates that do not reflect increased disease control they may cause and, consequently, the benefit in terms of time to progression. To improve the clinical and radiological evaluation of response to treatment in patients with mRCC treated with targeted drugs, a group of 32 experts in this field have reviewed different aspects related to this issue and have put together a series of recommendations with the intention of providing guidance to clinicians on this matter.

Diffusion and perfusion MRI prediction of progression-free survival in patients with hepatocellular carcinoma treated with concurrent chemoradiotherapy

PURPOSE

To assess whether MR perfusion and diffusion parameters taken before concurrent chemoradiotherapy (CCRT) are useful imaging biomarkers for predicting progression-free survival (PFS) in patients with hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Twenty patients with locally advanced HCC who had no treatment before CCRT underwent dynamic contrast-enhanced (DCE) and diffusion-weighted MRI. Mean values of the volume transfer constant (K(trans) ), reflex constant (Kep ), extravascular extracellular volume fraction (Ve ) and the apparent diffusion coefficient (ADC) were estimated on a region of interest. The best cutoff value for each factor was assessed to differentiate between patients who had PFS shorter or longer than the median PFS. Patients were dichotomized in terms of the cutoff value. The survival outcome of the two groups and the predictive ability of each factor on PFS were evaluated.

RESULTS

Median time to PFS was 179 days. The best cutoff values for ADC, K(trans) , Kep , and Ve was 1.008 × 10(-3) mm(2) s(-1) , 0.108 min(-1) , 0.570 min(-1) , and 0.298%. Patients with higher ADC had significantly longer PFS than those with lower ADC(P < 0.0001).

CONCLUSION

The ADC of HCC acquired before CCRT correlated with PFS and was valuable in the prediction of the clinical outcome of HCC treated with CCRT.

[Pharmacological therapy of urogenital cancer: rational routine diagnostic imaging]

BACKGROUND

Imaging studies are an integral and important diagnostic modality to stage, monitor, and follow-up patients with metastatic urogenital cancer. The currently available guidelines on diagnosis and treatment of urogenital cancer do not provide the clinician with evidence-based recommendations for daily routine. It is the aim of the current manuscript to develop scientifically valid recommendations with regard to the most appropriate imaging technique and the most useful time interval in metastatic urogenital cancer patients undergoing systemic therapy.

RESULTS

Therapeutic response of soft tissue metastases is evaluated with the use of the RECIST criteria. In skeletal metastases, bone scans with validated algorithms must be performed to assess response. In patients with testicular germ cell tumors, computed tomography (CT) of the chest, the retroperitoneum, and the abdomen represents the standard imaging technique of choice usually performed prior to and at the end of systemic chemotherapy. Only in seminomas with residual tumors > 3 cm in diameter should FDG-PET/CT be performed about 6 weeks after chemotherapy. Metastatic renal cell carcinomas treated with molecular targeted therapies are routinely evaluated by CT scans at 3 month intervals. In specific cases, FDG-PET/CT is able to predict responses as early as 8 weeks after initiation of treatment. In patients with metastatic urothelial carcinomas, imaging studies should be performed after every second cycle of cytotoxic therapy. In patients with metastatic prostate cancer, the modality and the frequency of imaging studies depends on the type of the treatment. In men undergoing androgen deprivation therapy, no routine imaging studies are recommended except for patients with new onset symptoms or significant PSA progression prior to change of treatment. In men with metastatic castration-resistant PCA who are treated with cytotoxic regimes, routine imaging studies in the presence of decreasing or stable PSA serum concentrations are not indicated. In men treated with lyase inhibitor or inhibitors of the androgen receptor signaling cascade, imaging studies should be performed at 3 month intervals due to the low correlation of PSA serum concentrations with clinical response.

CONCLUSIONS

Imaging studies to assess therapeutic response to systemic treatment in metastatic cancers of the urogenital tract must be chosen depending on the treatment regime, primary organ, and potential consequences of the findings. Routine imaging studies without specific clinical or therapeutic relevance are not justified.

[Modern imaging of kidney tumors]

If a renal mass is suspected on clinical examination or ultrasound the finding has to be confirmed by cross-sectional imaging. Methods that are used include multidetector-row computed tomography (MDCT) and magnetic resonance imaging (MRI). Also contrast-enhanced ultrasound has been successfully implemented in renal imaging and now plays a major role in the differentiation of benign from malignant renal masses. In expert hands it can be used to show very faint vascularization and subtle enhancement. The MDCT technique benefits from the recently introduced dual energy technology that allows superior characterization of renal masses in a single-phase examination, thereby greatly reducing radiation exposure. For young patients and persons allergic to iodine MRI should be used and it provides excellent soft tissue contrast and visualizes contrast enhancement kinetics in multiphase examinations.This article aims at giving a comprehensive overview of these different imaging modalities, their clinical indications and contraindications, as well as a description of imaging findings of various renal masses.

Safety, pharmacokinetics, pharmacodynamics, and antitumor activity of dalantercept, an activin receptor-like kinase-1 ligand trap, in patients with advanced cancer

PURPOSE

The angiogenesis inhibitor dalantercept (formerly ACE-041) is a soluble form of activin receptor-like kinase-1 (ALK1) that prevents activation of endogenous ALK1 by bone morphogenetic protein-9 (BMP9) and BMP10 and exhibits antitumor activity in preclinical models. This first-in-human study of dalantercept evaluated its safety, tolerability, pharmacokinetics, pharmacodynamics, and antitumor activity in adults with advanced solid tumors.

EXPERIMENTAL DESIGN

Patients in dose-escalating cohorts received dalantercept subcutaneously at one of seven dose levels (0.1-4.8 mg/kg) every 3 weeks until disease progression. Patients in an expansion cohort received dalantercept at 0.8 or 1.6 mg/kg every 3 weeks until disease progression.

RESULTS

In 37 patients receiving dalantercept, the most common treatment-related adverse events were peripheral edema, fatigue, and anemia. Edema and fluid retention were dose-limiting toxicities and responded to diuretic therapy. No clinically significant, treatment-related hypertension, proteinuria, gross hemorrhage, or gastrointestinal perforations were observed. One patient with refractory squamous cell cancer of the head and neck had a partial response, and 13 patients had stable disease according to RECISTv1.1, eight of whom had prolonged periods (≥12 weeks) of stable disease. Correlative pharmacodynamic markers included tumor metabolic activity and tumor blood flow, which decreased from baseline in 63% and 82% of evaluable patients, respectively, and telangiectasia in eight patients.

CONCLUSION

Dalantercept was well-tolerated at doses up to 1.6 mg/kg, with a safety profile distinct from inhibitors of the VEGF pathway. Dalantercept displayed promising antitumor activity in patients with advanced refractory cancer, and multiple phase II studies are underway.

Predictive markers in advanced renal cell carcinoma

Predictive markers of response to therapy are increasingly important in advanced renal cell carcinoma (RCC) due to the proliferation of treatment options in recent years. Different types of potential predictive markers may include clinical, toxicity-based, serum, tissue, and radiologic biomarkers. Clinical factors are commonly used in overall prognostic models of RCC but have limited utility in predicting response to therapy. Correlation between development of particular toxicities and response to therapy has been noted, such as the correlation between hypertension and response to angiogenesis-targeted therapy. Serum and tissue biomarkers will be covered in detail elsewhere, but factors such as serum lactate dehydrogenase (LDH) and circulating cytokines show promise in this regard. Finally, baseline or early treatment radiology studies may have predictive ability for longer term efficacy, with most studies to date focusing on functional imaging modalities such as positron emission tomography (PET) scans, dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI), and DCE ultrasound (US). The ultimate goal of developing predictive biomarkers is to enable rational and personalized treatment strategies for patients with advanced RCC.

Advanced MR techniques in multicenter clinical trials

MRI has had a place in the clinical trials process for more than 20 years. However, for much of that time MRI has been used primarily for subjective interpretation and relatively straightforward structural measurements. More advanced MR techniques have been considered too difficult to implement consistently across multiple sites in a single trial--this despite the fact that these techniques often provide the best window into the direct effects of targeted therapeutics. As an example, numerous compounds are currently under development whose principle effect is to temporarily or permanently alter tumor microvasculature. Changes induced by these compounds typically manifest as reductions in blood flow and vascular permeability within tumors. These changes can be measured directly using dynamic contrast-enhanced MRI. Early studies using this technique were limited to single centers, limiting both the overall size of the studies and the rate at which they were able to accrue patients. Recent efforts, however, have demonstrated that with sufficient attention to protocol design, imaging site selection and training, and analysis standardization, it is possible to obtain consistent and high quality results using even relatively complex acquisition protocols. This article will briefly review both the benefits and the drawbacks of including advanced MR techniques in clinical trial protocols. It will then review in detail the challenges presented by the need to deploy these techniques both to large research institutions and to community imaging centers which may have little or no familiarity with them at the outset of the trial.

The interaction between prognostic and pharmacodynamic biomarkers

Background:

Interactions between prognostic and pharmacodynamic (PD) biomarkers have received little attention.

Methods:

Prognostic and PD utilities were assessed with linear mixed-effects models using published data on repeated measurements of circulating caspase-cleaved (ctCK18) and total (tCK18) cytokeratin 18, in 57 patients with metastatic colorectal cancer undergoing chemotherapy.

Results:

The model for tCK18 (but not cCK18) separated the prognostic/PD interaction from the pure prognostic effect, illustrating the principle of dual prognostic and PD characteristics for a given biomarker.

Conclusion:

These models provide the framework for the analysis and interpretation of longitudinal data to detect prognostic/PD biomarker interactions.

Metastatic renal cell cancer

Targeted therapy is the treatment of choice in patients with metastatic renal cell cancer (mRCC) at most institutions although a combination of cytokine therapy and targeted therapy still is being investigated. Morphological size-based criteria (RECIST) has failed in monitoring the effect of targeted therapy in patients with mRCC, as successful therapy often does not result in a decrease in tumour size. Modifications of size-based criteria and criteria based on computed tomography (CT) contrast enhancement has been introduced. Different imaging modalities that rely on characteristics other than size such as dynamic contrast-enhanced (DCE) ultrasonography, DCE CT, DCE magnetic resonance imaging (MRI), diffusion-weighted MRI, positron emission tomography and texture analysis seem to contribute with prognostic information, even at baseline scans, and can predict tumour response early after initiating therapy. No new standard for the imaging follow-up of targeted therapy in mRCC has been established.

A phase 1 trial of imatinib, bevacizumab, and metronomic cyclophosphamide in advanced colorectal cancer

Background:

This phase 1 clinical trial was conducted to determine the safety, maximum-tolerated dose (MTD), and pharmacokinetics of imatinib, bevacizumab, and metronomic cyclophosphamide in patients with advanced colorectal cancer (CRC).

Methods:

Patients with refractory stage IV CRC were treated with bevacizumab 5 mg kg⁻¹ i.v. every 2 weeks (fixed dose) plus oral cyclophosphamide q.d. and imatinib q.d. or b.i.d. in 28-day cycles with 3+3 dose escalation. Response was assessed every two cycles. Pharmacokinetics of imatinib and cyclophosphamide and circulating tumour, endothelial, and immune cell subsets were measured.

Results:

Thirty-five patients were enrolled. Maximum-tolerated doses were cyclophosphamide 50 mg q.d., imatinib 400 mg q.d., and bevacizumab 5 mg kg⁻¹ i.v. every 2 weeks. Dose-limiting toxicities (DLTs) included nausea/vomiting, neutropaenia, hyponatraemia, fistula, and haematuria. The DLT window required expansion to 42 days (1.5 cycles) to capture delayed toxicities. Imatinib exposure increased insignificantly after adding cyclophosphamide. Seven patients (20%) experienced stable disease for >6 months. Circulating tumour, endothelial, or immune cells were not associated with progression-free survival.

Conclusion:

The combination of metronomic cyclophosphamide, imatinib, and bevacizumab is safe and tolerable without significant drug interactions. A subset of patients experienced prolonged stable disease independent of dose level.

Changes in tumour vessel density upon treatment with anti-angiogenic agents: relationship with response and resistance to therapy

Background:

We examine how changes in a surrogate marker of tumour vessel density correlate with response and resistance to anti-angiogenic therapy.

Methods:

In metastatic renal cancer patients treated with anti-angiogenic tyrosine kinase inhibitors, arterial phase contrast-enhanced computed tomography was used to simultaneously measure changes in: (a) tumour size, and (b) tumour enhancement (a surrogate marker of tumour vessel density) within individual lesions.

Results:

No correlation between baseline tumour enhancement and lesion shrinkage was observed, but a reduction in tumour enhancement on treatment was strongly correlated with reduction in lesion size (r=0.654, P<0.0001). However, close examination of individual metastases revealed different types of response: (1) good vascular response with significant tumour shrinkage, (2) good vascular response with stabilisation of disease, (3) poor vascular response with stabilisation of disease and (4) poor vascular response with progression. Moreover, contrasting responses between different lesions within the same patient were observed. We also assessed rebound vascularisation in tumours that acquired resistance to treatment. The amplitude of rebound vascularisation was greater in lesions that had a better initial response to therapy (P=0.008).

Interpretation:

Changes in a surrogate marker of tumour vessel density correlate with response and resistance to anti-angiogenic therapy. The data provide insight into the mechanisms that underlie response and resistance to this class of agent.

Phase I pharmacokinetic and pharmacodynamic study of pazopanib in children with soft tissue sarcoma and other refractory solid tumors: a children's oncology group phase I consortium report

PURPOSE

Pazopanib, an oral multikinase angiogenesis inhibitor, prolongs progression-free survival in adults with soft tissue sarcoma (STS). A phase I pharmacokinetic and pharmacodynamic study of two formulations of pazopanib was performed in children with STS or other refractory solid tumors.

PATIENTS AND METHODS

Pazopanib (tablet formulation) was administered once daily in 28-day cycles at four dose levels (275 to 600 mg/m(2)) using the rolling-six design. Dose determination for a powder suspension was initiated at 50% of the maximum-tolerated dose (MTD) for the intact tablet. Ten patients with STS underwent dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) scanning at baseline and 15 ± 2 days after initiation of pazopanib at the tablet MTD.

RESULTS

Fifty-three patients were enrolled; 51 were eligible (26 males; median age, 12.9 years; range, 3.8 to 23.9 years). Hematologic and nonhematologic toxicities were generally mild, with dose-limiting lipase, amylase, and ALT elevation, proteinuria, and hypertension. One patient with occult brain metastasis had grade 4 intracranial hemorrhage. The MTD was 450 mg/m(2) for tablet and 160 mg/m(2) for suspension. Steady-state trough concentrations were reached by day 15 and did not seem to be dose dependent. One patient each with hepatoblastoma or desmoplastic small round cell tumor achieved a partial response; eight patients had stable disease for ≥ six cycles, seven of whom had sarcoma. All patients with evaluable DCE-MRI (n = 8) experienced decreases in tumor blood volume and permeability (P < .01). Placental growth factor increased, whereas endoglin and soluble vascular endothelial growth factor receptor-2 decreased (P < .01; n = 41).

CONCLUSION

Pazopanib is well tolerated in children, with evidence of antiangiogenic effect and potential clinical benefit in pediatric sarcoma.