Neoadjuvant Pazopanib Treatment in High-Risk Soft Tissue Sarcoma: A Quantitative Dynamic 18F-FDG PET/CT Study of the German Interdisciplinary Sarcoma Group

The outcome of high-risk soft tissue sarcoma (STS) is poor with radical surgery being the only potentially curative modality. Pazopanib is a multikinase inhibitor approved for the treatment of metastatic STS. Herein, in terms of the German Interdisciplinary Sarcoma Group (GISG-04/NOPASS) trial, we evaluate the potential role of kinetic analysis of fludeoxyglucose F-18 (¹⁸F-FDG) data derived from the application of dynamic positron emission tomography/computed tomography (PET/CT) in response assessment to pazopanib of STS patients scheduled for surgical resection. Sixteen STS patients treated with pazopanib as neoadjuvant therapy before surgery were enrolled in the analysis. All patients underwent dynamic PET/CT prior to and after pazopanib treatment. Data analysis consisted of visual (qualitative) analysis of the PET/CT scans, semi-quantitative evaluation based on standardized uptake value (SUV) calculations, and quantitative analysis of the dynamic ¹⁸F-FDG PET data, based on two-tissue compartment modeling. Resection specimens were histopathologically assessed and the percentage of regression grade was recorded in 14/16 patients. Time to tumor relapse/progression was also calculated. In the follow-up, 12/16 patients (75%) were alive without relapse, while four patients (25%) relapsed, among them one patient died. Median histopathological regression was 20% (mean 26%, range 5–70%). The studied population was dichotomized using a histopathological regression grade of 20% as cut-off. Based on this threshold, 10/14 patients (71%) showed partial remission (PR), while stable disease (SD) was seen in the rest 4 evaluable patients (29%). Semi-quantitative evaluation showed no statistically significant change in the widely used PET parameters, SUV_average and SUV_max. On the other hand, ¹⁸F-FDG kinetic analysis revealed a significant decrease in the perfusion-related parameter K₁, which reflects the carrier-mediated transport of ¹⁸F-FDG from plasma to tumor. This decrease can be considered as a marker in response to pazopanib in STS and could be due to the anti-angiogenic effect of the therapeutic agent.

Preoperative therapy with pazopanib in high-risk soft tissue sarcoma: a phase II window-of-opportunity study by the German Interdisciplinary Sarcoma Group (GISG-04/NOPASS)

INTRODUCTION

For resectable soft tissue sarcoma (STS), radical surgery, usually combined with radiotherapy, is the mainstay of treatment and the only potentially curative modality. Since surgery is often complicated by large tumour size and extensive tumour vasculature, preoperative treatment strategies with the aim of devitalising the tumour are being explored. One option is treatment with antiangiogenic drugs. The multikinase inhibitor pazopanib, which possesses pronounced antiangiogenic effects, has shown activity in metastatic and unresectable STS, but has so far not been tested in the preoperative setting.

METHODS AND ANALYSIS

This open-label, multicentre phase II window-of-opportunity trial assesses pazopanib as preoperative treatment of resectable STS. Participants receive a 21-day course of pazopanib 800 mg daily during wait time for surgery. Major eligibility criteria are resectable, high-risk adult STS of any location, or metachronous solitary STS metastasis for which resection is planned, and adequate organ function and performance status. The trial uses an exact single-stage design. The primary end point is metabolic response rate (MRR), that is, the proportion of patients with >50% reduction of the mean standardised uptake value (SUVmean) in post-treatment compared to pre-treatment fluorodeoxyglucose positron emission tomography CT. The MRR below which the treatment is considered ineffective is 0.2. The MRR above which the treatment warrants further exploration is 0.4. With a type I error of 5% and a power of 80%, the sample size is 35 evaluable patients, with 12 or more responders as threshold. Main secondary end points are histopathological and MRI response, resectability, toxicity, recurrence-free and overall survival. In a translational substudy, endothelial progenitor cells and vascular epithelial growth factor receptor are analysed as potential prognostic and predictive markers.

ETHICS AND DISSEMINATION

Approval by the ethics committee II, University of Heidelberg, Germany (2012-019F-MA), German Federal Institute for Drugs and Medical Devices (61-3910-4038155) and German Federal Institute for Radiation Protection (Z5-22463/2-2012-007).

TRIAL REGISTRATION NUMBER

NCT01543802, EudraCT: 2011-003745-18; Pre-results.

Additional Prognostic Value of SUVmax Measured by F-18 FDG PET/CT over Biological Marker Expressions in Surgically Resected Cervical Cancer Patients

PURPOSE

We compared the prognostic ability of the maximum standardized uptake value (SUVmax) and various biological marker expressions to predict recurrence in patients with surgically resected cervical cancer.

METHODS

A retrospective review identified 60 patients with cervical cancer who received [18F]fluorodeoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT) at the time of the diagnosis of cancer. The SUVmax, expressions of carbonic anhydrase-IX (CA-IX), glucose transporter 1 (GLUT-1), and vascular endothelial growth factor (VEGF), and known prognostic factors were investigated.

RESULTS

The median follow-up time was 22.2 months (range 3.4-43.1 months). Using univariate analyses, the stage (stage II, p = 0.0066), SUVmax (> 6, p = 0.027), parametrial involvement (p < 0.0001), and positivity for CA-IX (p = 0.0191) were associated with recurrences of cervical cancer. With the Cox proportional hazard regression model, the SUVmax was a potent predictor for disease-free survival (DFS).

CONCLUSION

Although CA-IX expression was related to DFS in the current study, the potent predictor for DFS was SUVmax. Therefore, SUVmax is of greater prognostic value than biological marker expression in patients with surgically resected cervical cancer.

Prognostic relevance of ¹⁸F-FDG PET uptake in patients with locally advanced, extremity soft tissue sarcomas undergoing neoadjuvant isolated limb perfusion with TNF-α and melphalan

PURPOSE

The objective of this study was to determine whether (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) can adequately assess the risk of systemic disease progression in patients with primary, localized, high-grade soft tissue sarcomas of the extremities undergoing neoadjuvant isolated limb perfusion (ILP) with tumour necrosis factor and melphalan.

METHODS

This was a retrospective analysis of the files of 35 patients who underwent a PET or PET/CT scan prior to and after ILP followed by surgical resection with curative intent between 2006 and 2012. SUVmax₁ was defined as the maximum standardized uptake value (SUV) at diagnosis, SUVmax₂ as the maximum SUV after ILP and ΔSUVmax as the percentage difference between SUVmax1 and SUVmax₂.

RESULTS

The median follow-up was 40 months for all patients. The median SUVmax1 amounted to 7.6, while the median SUVmax₂ was 4.7. The median ΔSUVmax was -44%. Overall survival (OS) probability at 2 and 5 years amounted to 78 and 70%, respectively, while metastasis-free survival (MFS) probability at 2 and 5 years was 67 and 64%, respectively. Receiver-operating characteristic (ROC) curve analysis showed that both SUVmax2 and ΔSUVmax could predict systemic disease progression, while SUVmax1 could not adequately identify patients who went on to develop metastatic disease. The optimal cut-off value was 6.9 for SUVmax2 and -31 % for ΔSUVmax. Patients with an SUVmax2 <6.9 had a 2-year MFS of 80%, compared to 31 % for patients with an SUVmax2 ≥ 6.9 (p < 0.001). Patients with a ΔSUVmax < -31 %, i.e. patients with a higher metabolic response, had an MFS of 76% at 2 years, compared to 42% for patients with a ΔSUVmax ≥ -31% (p = 0.050).

CONCLUSION

SUVmax after ILP for primary, locally advanced, non-metastatic high-grade soft tissue sarcomas of the extremities appears to be significantly correlated with prognosis. Whether patients with a high SUVmax after ILP will benefit from standard or experimental adjuvant systemic treatment options should be evaluated in future studies.

Quantitative dynamic ¹⁸FDG-PET and tracer kinetic analysis of soft tissue sarcomas

PURPOSE

To study soft tissue sarcomas using dynamic positron emission tomography (PET) with the glucose analog tracer [(18)F]fluoro-2-deoxy-D-glucose ((18)FDG), to investigate correlations between derived PET image parameters and clinical characteristics, and to discuss implications of dynamic PET acquisition (D-PET).

MATERIAL AND METHODS

D-PET images of 11 patients with soft tissue sarcomas were analyzed voxel-by-voxel using a compartment tracer kinetic model providing estimates of transfer rates between the vascular, non-metabolized, and metabolized compartments. Furthermore, standard uptake values (SUVs) in the early (2 min p.i.; SUVE) and late (45 min p.i.; SUVL) phases of the PET acquisition were obtained. The derived transfer rates K1, k2 and k3, along with the metabolic rate of (18)FDG (MRFDG) and the vascular fraction νp, was fused with the computed tomography (CT) images for visual interpretation. Correlations between D-PET imaging parameters and clinical parameters, i.e. tumor size, grade and clinical status, were calculated with a significance level of 0.05.

RESULTS

The temporal uptake pattern of (18)FDG in the tumor varied considerably from patient to patient. SUVE peak was higher than SUVL peak for four patients. The images of the rate constants showed a systematic pattern, often with elevated intensity in the tumors compared to surrounding tissue. Significant correlations were found between SUVE/L and some of the rate parameters.

CONCLUSIONS

Dynamic (18)FDG-PET may provide additional valuable information on soft tissue sarcomas not obtainable from conventional (18)FDG-PET. The prognostic role of dynamic imaging should be investigated.

Correlation between biological marker expression and F-fluorodeoxyglucose uptake in cervical cancer measured by positron emission tomography

BACKGROUND

This study aimed to determine whether several biologic markers were associated with (18)fluorine-fluorodeoxyglucose ((18)F-FDG) uptake in patients with carcinoma of the cervix.

PATIENTS AND METHODS

60 patients with International Federation of Gynecology and Obstetrics (FIGO) stages IA2 to IIB cervical cancer, who underwent (18)FDG positron emission tomography/computed tomography (PET/CT), were included in the current study. All patients underwent radical hysterectomy. Tumor sections were stained by immunohistochemistry for glucose transporter 1 (GLUT1), carbonic anhydrase-IX (CA-IX), vascular endothelial growth factor (VEGF), hexokinase type I (HK-I), hexokinase type II (HK-II), and cytoplasmic and nuclear hypoxia-inducible factor (HIF) 1α.

RESULTS

The expression of GLUT1 (p = 0.005), VEGF (p = 0.021), HK-II (p = 0.009), and cytoplasmic HIF1α (p = 0.024) was significantly associated with a higher median standardized uptake value (SUVmax). There was a positive correlation between (18)F-FDG uptake and GLUT1 (p = 0.008), CA-IX (p = 0.030), HK-II (p < 0.001) as well as cytoplasmic HIF1α (p = 0.016), whereas this relationship was not observed among the VEGF, HK-I and nuclear HIF1α.

CONCLUSION

The data presented in this study indicate that (18)F-FDG uptake is associated with the presence of GLUT1, VEGF, nuclear HK-II, and cytoplasmic HIF1α. There was also a significant correlation among the rate of expression of GLUT1, HK-II, cytoplasmic HIF1α, and CAIX in carcinomas of the cervix.

Positron emission tomography as a surrogate marker for evaluation of treatment response in patients with desmoid tumors under therapy with imatinib

We used 2-deoxy-2-[(18)F] fluoro-D-glucose (FDG) positron emission tomography (PET) to evaluate patients with desmoid tumors undergoing therapy with imatinib. The study included 22 patients with progressive disease (PD) of a biopsy proven desmoid tumor treated orally with imatinib 800 mg daily. Patients were examined using PET prior to onset of therapy and during treatment. Restaging was performed in parallel using computed tomography (CT) and/or magnetic resonance imaging (MRI). Outcome of 22 evaluable patients was as follows: five patients with partial response (PR); twelve patients with stable disease (SD) accounting for 77% with non-progressive disease; five patients showed PD. A 30% decrease of the mean average standardized uptake value (SUV) of sequential PET examinations could be demonstrated; no patient demonstrated a substantial increase in SUV. Patients with PR/SD were matched to a group of nonprogressive disease and tested versus PD. The initial average SUV and SUVmax seem to be candidates for a response prediction with an approximate P-value of 0.06553 and 0.07785, respectively. This is the first larger series of desmoid patients monitored using PET showing that early SUV changes may help to discriminate responders from nonresponders and, thus, to decide whether imatinib therapy should be continued.

Relationship between biological marker expression and fluorine-18 fluorodeoxyglucose uptake in incidentally detected thyroid cancer

The aim of this study was to investigate the underlying mechanisms associated with fluorine-18 fluorodeoxyglucose (F-18 FDG) uptake in an incidentally detected thyroid cancer during nonthyroid cancer evaluation. Among 92 patients (10 men and 82 women; mean age, 56.2 +/- 10.9 years; age range, 26-78 years) with focal thyroid FDG uptake during nonthyroid cancer evaluation, 14 patients with cytologically confirmed papillary thyroid cancer were included. For semiquantitative analysis, the maximal standardized uptake value was calculated. Immunohistochemical studies were performed for hypoxia inducible factor 1 alpha (HIF1alpha), HIF2alpha, glucose transporter 1 (GLUT1), GLUT3, carbonic anhydrase IX (CA-IX), hexokinase type II (HK II), and vascular endothelial growth factor (VEGF). The significant findings of this study were as follows: (1) a lack of HIF1alpha and HIF2alpha expression; (2) low-degree expression of GLUT1 (1 patient), GLUT3 (5 of 14 patients), HK II (3 of 14 patients), and CA-IX (1 patient); and (3) high degree expression of VEGF (all 14 patients). The data presented in this study indicate that F-18 FDG uptake in incidentally detected thyroid cancer was not related to hypoxia-induced upregulation of GLUT1, GLUT3, CA-IX, and HK II. Ki-67 expression was not associated with F-18 FDG uptake. However, all incidentally detected thyroid cancers showed a high degree of expression of VEGF.

[Combined functional and morphological imaging of sarcomas: significance for diagnostics and therapy monitoring]

(18)F-fluorodeoxyglucose positron-emission tomography (FDG-PET) and especially hybrid FDG-PET/CT is becoming more and more accepted for the clinical management of adult and pediatric patients with sarcomas. By integrating the CT component the specificity in particular but also the sensitivity of the modality are improved further. With PET/CT a complete staging including the detection of lung metastases is feasible in a single examination. For patients with primary bone and soft tissue sarcomas FDG-PET/CT is utilized for diagnosis, staging and restaging, metabolic tumor grading, guidance of biopsies, detection of tumor recurrence and therapy monitoring. Furthermore, it has been demonstrated that FDG uptake of the tumor prior to treatment and changes of FDG uptake after therapy significantly correlate with histopathologic response and survival of patients. Therefore, PET and PET/CT have a prognostic value. In the future new perspectives of hybrid PET/CT imaging will arise by introducing novel radiotracers and combined functional imaging of tumor metabolism and perfusion. High resolution MRI is essential for local evaluation of the primary tumor and preoperative planning with assessment of possible infiltration of vascular or neural structures. Contrast-enhanced MRI remains a key tool in the diagnosis of recurrent disease, especially in tumors which are not hypermetabolic. Dynamic contrast-enhanced MR sequences can significantly contribute to therapy monitoring. More research is necessary to prospectively compare dynamic contrast-enhanced MRI and FDG-PET/CT for evaluation of local and recurrent diseases.

Prediction of residual disease of spine infection using F-18 FDG PET/CT

STUDY DESIGN

Prospective study.

OBJECTIVE

To determine whether F-18 fluoro-deoxy-glucose positron emission tomography/computed tomography (F-18 FDG PET/CT) follow-up imaging after treatment in patients with spinal infection (SI) could provide useful prognostic information and determine the residual SI.

SUMMARY OF BACKGROUND DATA

There are seldom data on the capability of follow-up imaging methods to predict residual disease and treatment efficacy in patients with SI.

METHODS

Thirty patients with SI underwent F-18 FDG PET/CT at initial and during follow-up. From F-18 FDG PET/CT, quantitative indexes were obtained. The residual SI was determined by the presence of preoperative symptoms, hematological infection marker, and radiologic findings.

RESULTS

The SUVmax were significantly declined after treatment in both of residual (2.85 +/- 1.17 vs. 2.06 +/- 1.03; P < 0.0001) and nonresidual SI (4.31 +/- 2.07 vs. 1.44 +/- 0.46; P < 0.0001). The SUVmean were also decreased after treatment in both of residual (1.45 +/- 0.45 vs. 1.04 +/- 0.29; P = 0.0014) and nonresidual SI (2.09 +/- 1.03 vs. 0.81 +/- 0.25; P < 0.0001). By lesion-based analysis, when < or =43.01% of %deltaSUVmax was used as threshold value, the area under curve (AUC) was 0.879 (P = 0.0001). The sensitivity and specificity were 85.7% and 82.6%, respectively. When < or =44.12% of %deltaSUVmean was used as threshold value, AUC was 0.828 (P = 0.0001). The sensitivity and specificity were 85.7% and 68%, respectively. In patient-based analysis, when < or =46.14% of %deltaSUVmax was used as threshold value, AUC was 0.904 (P = 0.0001). The sensitivity and specificity were 100% and 76.9%, respectively. When < or =41.78% of %deltaSUVmean was used as threshold value, AUC was 0.923 (P = 0.0001). The sensitivity and specificity were 100%, 76.9%, respectively.

CONCLUSION

F-18 FDG PET/CT is useful for discrimination of residual and nonresidual SI after treatment. Among the various quantitative indexes, %deltaSUVmax is a potent predictor of residual SI in the current study.

The use of positron emission tomography in soft tissue sarcoma patients under therapy with trabectedin

Background

We used 2-deoxy-2-[¹⁸F] fluoro-D-glucose (FDG) positron emission tomography (PET) to evaluate the FDG uptake in patients with advanced and/or metastatic soft tissue sarcoma (STS) undergoing therapy with Ecteinascidin-743 (ET-743, Trabectedin, Yondelis™).

Patients and Methods

The pilot study included nine patients with metastatic STS receiving a minimum of one cycle of treatment with trabectedin. Patients were examined using PET prior to onset of therapy and after completion of one or three cycles of trabectedin. Restaging according to Response Evaluation Criteria in Solid Tumours (RECIST) was performed in parallel using computed tomography (CT) and/or magnetic resonance imaging (MRI) and served for reference.

Results

Clinical outcome of nine evaluable patients was as follows: one patient with partial remission (PR), three patients with stable disease (SD), and five patients with progressive disease (PD). A more than 40% decrease of the standardized uptake value (SUV) of sequential PET examination could be demonstrated for the responding patient (PR), whereas patients with SD or PD showed a stable SUV, but no increase in SUV.

Conclusion

To our knowledge, this is the first small series of patients being treated with trabectedin and monitored using sequential PET imaging demonstrating SUV stabilization in nearly all monitored patients.

Utilization of positron emission tomography in the management of patients with sarcoma

PURPOSE OF REVIEW

18F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET) is being used with increased frequency in the care of patients with sarcoma. In this review, the recent literature covering all aspects of PET imaging in the management of patients with soft tissue and bone sarcomas will be discussed.

RECENT FINDINGS

In a prospective multicenter study, PET imaging accurately detected primary tumors as well as lymph node and bone metastases in patients with sarcoma. Limitations in detecting lung metastasis can be overcome by using a hybrid PET/CT scanner. In patients with neurofibromatosis, 18F-FDG-PET demonstrated its application to detect and monitor for the malignant transformation of neurofibromas. Changes in tumor 18F-FDG uptake correlate significantly with histopathologic response and survival in patients with sarcoma.

SUMMARY

PET imaging is emerging as an important imaging modality in the management of patients with sarcoma. Its applications include tumor grading, staging, therapeutic monitoring, and prognostication in adult and pediatric populations.

Promises and challenges of positron emission tomography for assessment of sarcoma in daily clinical practice

A correct histological diagnosis, careful staging and detection of tumour response to treatment are all crucial in the management of sarcomas. Imaging is important in all of these stages. Sarcomas have distinct biological and treatment-related features posing challenges for imaging. For example, size measurements may not adequately reflect response rates. Techniques which can measure tissue function rather than generate merely anatomical data such as positron emission tomography (PET) are rapidly gaining interest. We discuss the importance of imaging in different stages of patient management, emphasising the unique characteristics of sarcoma. Furthermore, we discuss the potential of PET for the various indications, focussing on therapy evaluation.