Early prediction of response to sunitinib after imatinib failure by 18F-fluorodeoxyglucose positron emission tomography in patients with gastrointestinal stromal tumor

Developing biomarker-specific end points in lung cancer clinical trials

In cancer-drug development, a number of different end points have been used to establish efficacy and support regulatory approval, such as overall survival, progression-free survival (PFS), and radiographic response rate. However, these traditional end points have important limitations. For example, in lung cancer clinical trials, evaluating overall survival end points is a protracted process and these end points are most reliable when crossover to the investigational therapy is not permitted. Furthermore, although radiographic surrogate end points, such as PFS and response rate, generally correlate with clinical benefit in the setting of cytotoxic chemotherapy and molecular targeted therapies, novel immunotherapies might have atypical response kinetics, which confounds radiographic interpretation. In this Review, we discuss the need to develop alternative or surrogate end points for lung cancer clinical trials, and focus on several new biomarkers that could serve as surrogate end points, including functional imaging biomarkers, circulating factors (tumour proteins, DNA, and cells), and pharmacodynamic tumour markers. By enabling the size, duration, and complexity of cancer trials to be reduced, biomarker end points hold the promise to accelerate drug development and improve patient outcomes.

Efficacy of sorafenib and impact on cardiac function in patients with thyroid cancer: a retrospective analysis

PURPOSE

Sorafenib has recently been recognized as an important standard option for the management of patients with differentiated thyroid cancer. Although data concerning cardiac safety are available in pan-tumor studies, no data are available on its use in everyday clinical practice in patients with thyroid cancer.

METHODS

In the off-label program of our institution, we enrolled 14 patients with different histological types of thyroid cancer suitable for treatment with sorafenib. Our aims were to evaluate cardiac safety factors-LVEF (left ventricular ejection fraction), heart rate and blood pressure-the cardiac markers NT-proBNP and troponin I, radiological response evaluated by CT and (18)FDG-PET (according to RECIST 1.1 criteria) and biomarker reduction (Eastern Cooperative Oncology Group Performance Status: ECOG PS) 0-2.

RESULTS

Patients with ECOG PS 2 accounted for 36%. After starting sorafenib, many patients displayed reduced or stabilized metabolic activity in target lesions (clinical benefit = 44%), radiologic reduction or stabilization (74%) and decreased cancer markers (90%). Lung metastases displayed the largest reductions in size. Median overall survival (OS) was 7 months and median progression-free survival (PFS) was 3 months. No sign of cardiotoxicity was observed in almost all patients. LVEF was altered in two patients and proved symptomatic in one.

CONCLUSIONS

Sorafenib seems to be effective in reducing disease progression in the early stages of treatment (3-6 months). Responses varied considerably according to the criteria investigated. Cardiac toxicities did not raise concerns and were in line with data reported in other malignancies. However, cardiac monitoring is recommended.

[18F]Fluorodeoxyglucose PET/Computed Tomography in Gastrointestinal Malignancies

This article discusses the current state-of-the-art application of 2-deoxy-2-[(18)F]fluoro-d-glucose (FDG)-PET and FDG-PET/computed tomography (CT) in the management of patients with gastrointestinal malignancies. Gastrointestinal malignancies include many different cell types, several common malignancies of which may be imaged by FDG-PET/CT. This review focuses on gastric carcinoma, pancreatic carcinoma, hepatocellular carcinoma, cholangiocarcinoma, colorectal carcinoma, and stroma cell tumors. The role of FDG-PET/CT in staging these malignancies is discussed, in addition to (re)staging, detection of recurrent disease, patient selection/prognostication, and response assessment, using the currently available literature.

Phase II study of cediranib in patients with advanced gastrointestinal stromal tumors or soft-tissue sarcoma

PURPOSE

Cediranib is a potent VEGF signaling inhibitor with activity against all three VEGF receptors and KIT. This phase II study evaluated the antitumor activity of cediranib in patients with metastatic gastrointestinal stromal tumor (GIST) resistant/intolerant to imatinib, or metastatic soft-tissue sarcomas (STS; ClinicalTrials.gov, NCT00385203).

EXPERIMENTAL DESIGN

Patients received cediranib 45 mg/day. Primary objective was to determine the antitumor activity of cediranib according to changes in 2[18F]fluoro-2-deoxy-D-glucose positron emission tomography ((18)FDG-PET) tumor uptake in patients with GIST using maximum standardized uptake values (SUVmax). Secondary objectives included objective tumor response and tolerability in patients with GIST/STS.

RESULTS

Thirty-four of 36 enrolled patients were treated (GIST n = 24; STS n = 10). At day 29, five patients had confirmed decreases in SUVmax (≥10% from day 8) and two had confirmed partial metabolic responses (≥25% decrease), but arithmetic mean percentage changes in SUVmax, averaged across the cohort, were not significant at day 8 [6.8%; 95% confidence interval (CI), 19.95-33.54) or day 29 (4.6%; 95% CI, 8.05-17.34). Eleven patients with GIST achieved a best objective tumor response of stable disease; eight achieved stable disease ≥16 weeks. In patients with STS, four of six with alveolar soft-part sarcoma (ASPS) achieved confirmed and durable partial responses. The commonest adverse events were diarrhea (85%), fatigue (74%), and hypertension (68%).

CONCLUSIONS

In patients progressing on imatinib/sunitinib, cediranib 45 mg/day demonstrated evidence of activity by (18)FDG-PET, but did not reduce average SUVmax. Evidence of antitumor activity was seen in ASPS.

Phase II study of dovitinib in patients with metastatic and/or unresectable gastrointestinal stromal tumours after failure of imatinib and sunitinib

Background:

This prospective, phase II trial evaluated the efficacy and safety of dovitinib in patients with metastatic and/or unresectable gastrointestinal stromal tumours (GISTs) after failure of at least imatinib and sunitinib.

Methods:

Patients received oral dovitinib, 500 mg once daily, for 5 consecutive days, followed by a 2-day rest, every 28 days. The primary endpoint was disease control rate (DCR; objective response+stable disease (SD)) at 24 weeks, assessed by computed tomography (CT) scan according to RECIST v1.0. Metabolic response was evaluated by positron emission tomography (PET)–CT scans performed at baseline and after 4 weeks of treatment.

Results:

Between September 2011 and April 2012, 30 patients were enroled. DCR at 24 weeks by RECIST v1.0 was 13% and one patient (3%) had a partial response. Based on the European Organization for Research and Treatment of Cancer PET response criteria, four patients (13%) had a metabolic partial response after 4 weeks of treatment. At a median follow-up of 8.3 months (range, 6.3–12.2 months), median progression-free survival (PFS) was 3.6 months (95% confidence interval (CI), 3.5–3.7 months) and median overall survival was 9.7 months (95% CI, 6.0–13.4 months). Metabolic progressive disease at Week 4 was significantly associated with shorter PFS (P=0.03). Grade 3/4 adverse events included asthenia (20%), neutropenia (13%), thrombocytopenia (10%), and hypertriglyceridaemia (10%). Most toxicities were manageable by dose modification.

Conclusion:

Dovitinib showed modest antitumour activity with manageable toxicities in heavily pretreated patients with advanced GISTs.

Dynamic observation of the radiosensitive effect of irisquinone on rabbit VX2 lung transplant tumors by using fluorine-18-deoxyglucose positron emission tomography/computed tomography

OBJECTIVE

We studied the radiosensitizing effect of irisquinone on a VX2 lung transplant tumor model during three-dimensional radiotherapy using fluorine-18-deoxyglucose ((18)F-FDG) PET/computed tomography (PET/CT).

MATERIALS AND METHODS

Thirty VX2 tumor-bearing rabbits were randomized into three groups: the radiotherapy group, the irisquinone+radiotherapy group, and the control group, each comprising 10 rabbits. (18)F-FDG PET/CT images were obtained to monitor the tumor/muscle (T/M) ratio of F-FDG uptake and the retention index (RI) before treatment, when the radiation dose reached 6, 12, and 18 Gy, and 1 week after radiotherapy. Tumor volume changes were also assessed. The management of the control group followed the same procedure.

RESULTS

At all treatment time points, the tumor volume was significantly smaller in the treatment groups than in the control group. The 1 and 2 h T/M ratios and RIs decreased gradually when the radiation dose reached 12 or 18 Gy in the treatment groups, whereas these values increased continuously in the control group. One week after treatment, the 1 and 2 h T/M ratios increased in the treatment groups, although these values remained lower than those in the control group. The RIs of the radiotherapy and irisquinone+radiotherapy groups were 0.329±0.133 and 0.137±0.036, respectively. Histological evaluation revealed that tumor F-FDG uptake was strongly related to tumor cell density.

CONCLUSION

F-FDG PET/CT was sensitive and noninvasive and could be used to monitor the radiosensitizing effects of irisquinone and the therapeutic efficacy of radiotherapy.

A gist of gastrointestinal stromal tumors: A review

Gastrointestinal stromal tumors (GISTs) have been recognized as a biologically distinctive tumor type, different from smooth muscle and neural tumors of the gastrointestinal tract (GIT). They constitute the majority of gastrointestinal mesenchymal tumors of the GIT and are known to be refractory to conventional chemotherapy or radiation. They are defined and diagnosed by the expression of a proto-oncogene protein detected by immunohistochemistry which serves as a crucial diagnostic and therapeutic target. The identification of these mutations has resulted in a better understanding of their oncogenic mechanisms. The remarkable antitumor effects of the molecular inhibitor imatinib have necessitated accurate diagnosis of GIST and their distinction from other gastrointestinal mesenchymal tumors. Both traditional and minimally invasive surgery are used to remove these tumors with minimal morbidity and excellent perioperative outcomes. The revolutionary use of specific, molecularly-targeted therapies, such as imatinib mesylate, reduces the frequency of disease recurrence when used as an adjuvant following complete resection. Neoadjuvant treatment with these agents appears to stabilize disease in the majority of patients and may reduce the extent of surgical resection required for subsequent complete tumor removal. The important interplay between the molecular genetics of GIST and responses to targeted therapeutics serves as a model for the study of targeted therapies in other solid tumors. This review summarizes our current knowledge and recent advances regarding the histogenesis, pathology, molecular biology, the basis for the novel targeted cancer therapy and current evidence based management of these unique tumors.

Liver surgery in the multidisciplinary management of gastrointestinal stromal tumour

INTRODUCTION

After the introduction of tyrosine kinase inhibitors (TKIs), the role of surgical resection in treating liver metastasis from gastrointestinal stromal tumour (GIST) is unclear. In this study, we evaluated the outcome of patients treated with TKIs followed by surgery for metastatic GIST.

METHODS

Eleven patients underwent liver resection after downsizing TKIs therapy for metastatic GIST from 2006 until 2010 were reviewed.

RESULTS

One and two-year overall survival rates were 80.8 and 70.7%. All patients with an initially resectable tumour were still alive without recurrence. Patients operated on clinical response had a better outcome (1- and 2-year overall survival (OS) rate 100%) than those operated on disease progression (1- and 2-year OS rates 60 and 40%; P = 0.043). No deaths were observed among patients who achieved an R0 resection (R0 versus R1/R2, P = 0.001).

DISCUSSION

R0 resection and clinical response to TKI are predictor of survival. Surgical resection should be performed as soon as feasible in responding patients. In poor responders, surgery may not add any survival benefit, except in localized progressive disease. In resectable metastatic liver disease, preoperative TKIs or upfront surgery followed by adjuvant therapy could be considered. Larger studies are needed to determine the optimum approach in patients with metastatic GIST.

Sorafenib in advanced iodine-refractory differentiated thyroid cancer: efficacy, safety and exploratory analysis of role of serum thyroglobulin and FDG-PET

CONTEXT

Radioactive iodine is a crucial tool for treatment of differentiated thyroid cancer (DTC). In 5% of cases, DTCs lose I-131 avidity and assume an aggressive behaviour. Treatment options for iodine-refractory DTC are limited. We report the experience of off-label use of the tyrosine kinase inhibitor sorafenib for treatment of advanced iodine-refractory DTC.

DESIGN

Patients with progressive DTC refractory to radioactive iodine were treated with sorafenib used off-label independently from their performance status. Primary study end-points were radiological response, progression-free survival (PFS) and safety. Secondary end-points were site-specific radiological response and overall survival (OS). An exploratory analysis of the role of serum thyroglobulin (Tg) and fluorodeoxyglucose (FDG) positron emission tomography (PET) was performed.

RESULTS

A total of 17 patients were included in the study. Median follow-up was 15·5 months. Clinical benefit was obtained in 71% of subjects (30% partial response and 41% stable disease). Sorafenib was mostly well tolerated, but a high incidence of fatal events was reported (three patients died from severe bleeding events and two from cardiac arrest). Median PFS was 9 months. Median OS was 10 months. The best responses were observed in lymph nodes and lung. Baseline Tg levels and the Tg response to treatment were correlated to both radiological response and PFS. Baseline FDG-PET assessment and early FDG-PET response were correlated to radiological response.

CONCLUSIONS

Sorafenib allows morphological disease control in the majority of patients with iodine-refractory DTC. Progression-free survival and overall survival were lower than in previous studies as a consequence of the worse clinical condition of our patients. Sorafenib is mostly well tolerated but could have been responsible for the reported fatal events. Baseline Tg and the Tg response to treatment could be useful for predicting morphological response and clinical outcome. Early FDG-PET response could be helpful for the timely identification of nonresponding patients.

Mechanisms of resistance to anti-angiogenesis therapies

Angiogenesis, the formation of new blood vessels from preexisting ones, provides oxygen and nutrients to actively proliferating tumor cells. Hence, it represents a critical aspect of tumor progression and metastasis. Because inhibition of angiogenesis represents a major approach to cancer treatment, the development of inhibitors of angiogenesis is a major challenge. The first FDA approved anti-angiogenic drug bevacizumab, a humanized monoclonal antibody directed against the Vascular Endothelial Growth Factor (VEGF), has been approved for the treatment of metastatic colorectal, lung, breast, and kidney cancers. The encouraging results have lead to the development, in the past few years, of other agents targeting angiogenic pathways as potent anti-cancer drugs and a number of them have been approved for metastatic breast, lung, kidney, and central nervous system cancers. Despite a statistically significant increase in progression free survival, which has accelerated FDA approval, no major benefit to overall survival was described and patients inevitably relapsed due to acquired resistance. However, while progression free survival was increased by only a few months for the majority of the patients, some clearly benefited from the treatment with a real increase in life span. The objective of this review is to present an overview of the different treatments targeting angiogenesis, their efficacy and the mechanisms of resistance that have been identified in different cancer types. It is essential to understand how resistance (primary or acquired over time) develops and how it may be overcome.

First-in-human phase I trial of two schedules of OSI-930, a novel multikinase inhibitor, incorporating translational proof-of-mechanism studies

PURPOSE

OSI-930 is a novel, potent, oral small-molecule receptor tyrosine kinase inhibitor, predominantly against VEGF receptors (VEGFR), c-Kit, and platelet-derived growth factor receptors. A phase I trial was undertaken to determine safety, maximum-tolerated dose (MTD), pharmacokinetics, pharmacodynamics, and antitumor activity of OSI-930 in patients with advanced solid tumors.

EXPERIMENTAL DESIGN

OSI-930 was administered once or twice a day using a modified accelerated titration design. Pharmacokinetics and plasma soluble VEGFR2 (sVEGFR2) studies were undertaken. Dynamic contrast-enhanced MRI (DCE-MRI) and 2[18F]fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET) MTD expansion cohorts were conducted.

RESULTS

Fifty-eight patients received OSI-930 in 2 schedules; once a day schedule: 12 patients at doses up to 1,600 mg without reaching MTD; twice a day schedule: 46 patients at 400 mg (n = 7), 500 mg (n = 31), and 600 mg (n = 8). Dose-limiting toxicities were observed at 600 mg twice a day (n = 3): G3 rash (n = 2) and G4 γ-glutamyltransferase, establishing the MTD at 500 mg twice a day. Common G1-2 toxicities included fatigue, diarrhea, nausea, and rash. Antitumor responses were seen in 2 patients with advanced ovarian cancer [Response Evaluation Criteria in Solid Tumors (RECIST) partial response (PR) (n = 1); GCIG CA125 response (n = 1)]. Eleven of 19 heavily pretreated imatinib-resistant patients with gastrointestinal stromal tumors achieved RECIST stable disease (median duration: 126 days), with FDG-PET scans showing PRs in 4 of 9 patients. OSI-930 exposure increased with dose; substantial decreases in sVEGFR levels were observed with OSI-930 twice a day doses ≥400 mg, while DCE-MRI responses were shown in 4 of 6 patients.

CONCLUSIONS

OSI-930 is safe and well tolerated, with pharmacokinetic-pharmacodynamic data supporting proof-of-mechanism with clinically relevant antitumor activity.

Modeling NSCLC progression: recent advances and opportunities available

Non-small cell lung cancer (NSCLC) is one of the leading causes of death around the world with an estimated 5-year relative survival rate of 16% at diagnosis. Development of drugs treating NSCLC is not easy, and the success rate for an anticancer treatment to pass through the whole clinical development process is as low as 5%. Modeling and simulation lend themselves as tools which can potentially streamline drug development. A critical component of the models developed is a description of how the disease progresses over time and how a treatment would affect its trajectory. Our aim was to review the literature to present the models and growth functions which have been used for describing NSCLC dynamics, and how anticancer treatments can affect such dynamics, both in animals and in humans. Only a limited set of models were identified for such a purpose. Most of the models which have been used were descriptive of tumor growth, yet there were attempts to account for the underlying processes, especially in animals where it is more feasible to collect data needed for developing such models. Moreover, we discuss how modeling and simulation can aid in decision making across the different stages of drug development. Based on some encouraging results from trials of other cancer types where modeling tumor dynamics has played an important role, we propose further exploration of NSCLC using model-based techniques and further use of these techniques in designing and evaluating NSCLC trials.

Incongruity of imaging using fluorescent 2-DG conjugates compared to 18F-FDG in preclinical cancer models

PURPOSE

We compared the use of near-infrared conjugates of 2-deoxyglucose (NIR 2-DG) to 2-deoxy-2-[18F]fluoro-d-glucose (18F-FDG) for the purposes of imaging tumors, as well as response to therapy.

PROCEDURES

Uptake of both 18F-FDG and NIR 2-DG within gastrointestinal stromal tumor xenografts were imaged before and after nilotinib treatment. Confocal microscopy was performed to determine NIR 2-DG distribution in tumors.

RESULTS

Treatment with nilotinib resulted in a rapid reduction in 18F-FDG uptake and reduced tumor cell viability which was predictive of long-term antitumor efficacy. In contrast, optical imaging with NIR 2-DG probes was unable to differentiate control from niltonib-treated animals, and microscopic analysis revealed no change in probe distribution as a result of treatment.

CONCLUSIONS

These results suggest that conjugation of large bulky fluorophores to 2-DG disrupts the facilitated transport and retention of these probes in cells. Therefore, optical imaging of NIR 2-DG probes cannot substitute for 18F-FDG positron emission tomography imaging as a biomarker of tumor cell viability and metabolism.

A comparative evaluation of ultrasound molecular imaging, perfusion imaging, and volume measurements in evaluating response to therapy in patient-derived xenografts

Most pre-clinical therapy studies use the change in tumor volume as a measure for disease response. However, tumor size measurements alone may not reflect early changes in tumor physiology that occur as a response to treatment. Ultrasonic molecular imaging (USMI) and Dynamic Contrast Enhanced-Perfusion Imaging (DCE-PI) with ultrasound are two attractive alternatives to tumor volume measurements. Since these techniques can provide information prior to the appearance of gross phenotypic changes, it has been proposed that USMI and DCE-PI could be used to characterize response to treatment earlier than traditional methods. This study evaluated the ability of tumor volume measurements, DCE-PI, and USMI to characterize response to therapy in two different types of patient-derived xenografts (known responders and known non-responders). For both responders and non-responders, 7 animals received a dose of 30 mg/kg of MLN8237, an investigational aurora-A kinase inhibitor, for 14 days or a vehicle control. Volumetric USMI (target integrin:α av β3) and DCE-PI were performed on day 0, day 2, day 7, and day 14 in the same animals. For USMI, day 2 was the earliest point at which there was a statistical difference between the untreated and treated populations in the responder cohort (Untreated: 1.20 ± 0.53 vs. Treated: 0.49 ± 0.40; p < 0.05). In contrast, statistically significant differences between the untreated and treated populations as detected using DCE-PI were not observed until day 14 (Untreated: 0.94 ± 0.23 vs. Treated: 1.31 ± 0.22; p < 0.05). Volume measurements alone suggested no statistical differences between treated and untreated populations at any readpoint. Monitoring volumetric changes is the "gold standard" for evaluating treatment in pre-clinical studies, however, our data suggests that volumetric USMI and DCE-PI may be used to earlier classify and robustly characterize tumor response.

Molecular imaging in oncology

The major application for PET imaging in clinical practice is represented by cancer imaging and (18)F-FDG is the most widely employed positron emitter compound. However, some diseases cannot be properly evaluated with this tracer and thus there is the necessity to develop more specific compounds. The last decades were a continuous factory for new radiopharmaceuticals leading to an endless list of PET tracers; however, just some of them guard diagnostic relevance in routine medical practice. This chapter describes a selected list of non-FDG PET tracers, basing on their introduction into and impact on clinical practice.

Efficacy of PET-CT for predicting the malignant potential of gastrointestinal stromal tumors

PURPOSES

Gastrointestinal stromal tumor (GIST) is the most common sarcoma of the intestinal tract. The risk category is usually determined by tumor size and mitotic count, but accurate preoperative diagnosis of GIST is very difficult. The purpose of this study is to evaluate the efficacy of positron emission tomography (PET)-CT for predicting the malignant potential of gastrointestinal stromal tumors.

METHODS

Ten patients with GIST who underwent a preoperative PET-CT examination were divided into two groups by risk category, and various factors were compared between the two groups. The relationships between the maximum standardized uptake value (SUVmax) and GIST parameters were examined.

RESULTS

Patients were classified into two groups by their risk category: (low/intermediate-risk or high-risk). The SUVmax was significantly higher in the high-risk group (11.0 ± 3.04) than in the low/intermediate-risk group (2.1 ± 1.5). The Ki67 labeling index was also significantly higher in the high-risk group (8.63 ± 6.2) than in the low/intermediate-risk group (1.75 ± 0.52). There was a significant correlation between the Ki67 labeling index and the SUVmax (p = 0.028) and between the mitotic index and the SUVmax (p = 0.029).

CONCLUSIONS

PET-CT can predict malignant potential. Cases with a SUVmax of over 5 may have malignant potential.

Current and emerging strategies for the management of imatinib-refractory advanced gastrointestinal stromal tumors

Since its approval by the US Food and Drug Administration in February 2002, the tyrosine kinase inhibitor, imatinib, has become the standard of care for patients with metastatic or unresectable KIT-positive gastrointestinal stromal tumors (GISTs). Imatinib functions by blocking the adenosine triphosphate binding site of the constitutively activated mutant KIT or platelet-derived growth factor receptor α, effectively shutting down the oncogenic signal that drives up to 90% of these tumors. In doing so, it has transformed the management of a condition previously refractory to systemic treatments and established GIST as a model for the use of targeted therapies and oncogene addiction in solid tumors. However, while more than 80% of patients will receive clinical benefit from imatinib monotherapy, more than half will develop progressive disease by 2 years. In this article we review the mechanism and patterns of imatinib resistance in GIST; attempt to offer a practical schema for managing imatinib-refractory patients; and lastly, offer some insight as to future directions and emerging therapeutics for the management of this highly interesting and challenging disease.

Early prediction of survival following induction chemotherapy with DCF (docetaxel, cisplatin, 5-fluorouracil) using FDG PET/CT imaging in patients with locally advanced head and neck squamous cell carcinoma

PURPOSE

Locally advanced head and neck squamous cell carcinoma (HNSCC) has a high rate of recurrence. Induction chemotherapy with DCF (docetaxel, cisplatin, 5-fluorouracil) before chemoradiotherapy could lead to the best disease control of inoperable stage III/IV HNSCC but with an increased risk of acute toxicity. Early assessment of therapeutic efficacy is a key issue in considering the benefit of escalation in a poor prognosis population.

METHODS

Patients with stage III/IV HNSCC, in whom DCF induction chemotherapy followed by concurrent chemoradiotherapy had been validated by a multidisciplinary team, were prospectively included in the study. FDG PET/CT scans were performed in all patients before and after two of the three cycles of DCF. EORTC99 criteria were used to evaluate PET responses as follows: group 1 (metabolic responders) showing a complete response (CR) or partial response (PR), and subgroup 0 (metabolic nonresponders) showing stable disease (SD) or progressive disease (PD). The primary endpoint for monitoring patients was event-free survival (EFS). EFS probabilities between the two groups were estimated by the Kaplan-Meier method and statistically compared using the log-rank test.

RESULTS

Fifteen consecutive patients (14 men, 1 woman; age 57.5 ± 6.2 years, mean ± SD) were analysed. Therapeutic assessment by PET/CT demonstrated CR in four patients, PR in six, SD in four and PD in one. Among the ten patients with a metabolic response (group 1), none had relapsed at the time of this report, while four of five patients with no metabolic response (group 0) showed recurrence within an average of 9.0 ± 1.6 months. Median EFS was, respectively, 18.9 months (3.8-25.3 months) and 10.2 months (7.5-12.7 months) in group 1 and group 0. The corresponding 1-year EFS rates were 100 % and 20 %, respectively. The difference in EFS between the two groups was statistically significant (p = 0.0014).

CONCLUSION

Early therapeutic response demonstrated on FDG PET/CT after two cycles of induction chemotherapy with DCF in patients with inoperable stage III/IV HNSCC seems to be a predictive factor for EFS.

Challenges and opportunities of metabolomics

The metabolome is a data-rich source of information concerning all the low-molecular-weight metabolites in a biofluid, which can indicate early biological changes to the host due to perturbations in metabolic pathways. Major changes can be seen after minor stimuli, which make it a valuable target for analysis. Due to the diverse and sensitive nature of the metabolome, studies must be designed in a manner to maintain consistency, reduce variation between subjects, and optimize information recovery. Technological advancements in experimental design, mouse models and instrumentation have aided in this effort. Metabolomics has the ultimate potential to be valuable in a clinical setting where it could be used for early diagnosis of a disease and as a predictor of treatment response and survival. During drug treatment, the metabolic status of an individual could be monitored and used to indicate possible toxic effects. Metabolomics therefore has great potential for improving diagnosis, treatment and aftercare of disease.

(18)F-fluorodeoxyglucose positron emission tomography/computed tomography and magnetic resonance imaging in patients with liver metastases from uveal melanoma: results from a pilot study

PURPOSE

(18)F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) and MRI are used for detecting liver metastases from uveal melanoma. The introduction of new treatment options in clinical trials might benefit from early response assessment. Here, we determine the value of FDG-PET/CT with respect to MRI at diagnosis and its potential for monitoring therapy.

MATERIAL AND METHODS

Ten patients with biopsy-proven liver metastases of uveal melanoma enrolled in a randomized phase III trial (NCT00110123) underwent both FDG-PET coupled with unenhanced CT and gadolinium-diethylene triamine pentaacetic acid-enhanced liver MRI within 4 weeks. FDG-PET and MRI were evaluated blindly and then compared using the ratio of lesion to normal liver parenchyma PET-derived standardized uptake value (SUV). The influence of lesion size and response to chemotherapy were studied.

RESULTS

Overall, 108 liver lesions were seen: 34 (31%) on both modalities (1-18 lesions/patient), four (4%) by PET/CT only, and 70 (65%) by MRI only. SUV correlated with MRI lesion size (r=0.81, P<0.0001). PET/CT detected 26 of 33 (79%) MRI lesions of more than or equal to 1.2 cm, whereas it detected only eight of 71 (11%) lesions of less than 1.2 cm (P<0.0001). MRI lesions without PET correspondence were small (0.6±0.2 vs. 2.1±1.1 cm, P<0.0001). During follow-up (six patients, 30 lesions), the ratio lesion-to-normal-liver SUV diminished in size-stable lesions (1.90±0.64-1.46±0.50, P<0.0001), whereas it increased in enlarging lesions (1.56±0.40-1.99±0.56, P=0.032).

CONCLUSION

MRI outweighs PET/CT for detecting small liver metastases. However, PET/CT detected at least one liver metastasis per patient and changes in FDG uptake not related to size change, suggesting a role in assessing early therapy response.

Consensus report on the radiological management of patients with gastrointestinal stromal tumours (GIST): recommendations of the German GIST Imaging Working Group

The aim was to reach consensus in imaging for staging and follow-up as well as for therapy response assessment in patients with gastrointestinal stromal tumours (GIST). The German GIST Imaging Working Group was formed by 9 radiologists engaged in assessing patients with GIST treated with targeted therapy. The following topics were discussed: indication and optimal acquisition techniques of computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET)/CT; tumour response assessment considering response criteria and measurement techniques on CT, MRI and PET/CT; result interpretation; staging interval and pitfalls. Contrast-enhanced CT is the standard method for GIST imaging. MRI is the method of choice in case of liver-specific questions or contraindications to CT. PET/CT should be used for early response assessment or inconclusive results on morphologic imaging. All imaging techniques should be standardized allowing a reliable response assessment. Response has to be assessed with respect to lesion size, lesion density and appearance of new lesions. A critical issue is pseudoprogression due to myxoid degeneration or intratumoural haemorrhage. The management of patients with GIST receiving a targeted therapy requires a standardized algorithm for imaging and an appropriate response assessment with respect to changes in lesion size and density.

Predictive value of early and late residual 18F-fluorodeoxyglucose and 18F-fluorothymidine uptake using different SUV measurements in patients with non-small-cell lung cancer treated with erlotinib

PURPOSE

To evaluate the predictive value of early and late residual (18)F-fluorodeoxyglucose (FDG) and (18)F-fluorothymidine (FLT) uptake using different SUV measurements in PET in patients with advanced non-small-cell lung cancer (NSCLC) treated with erlotinib.

METHODS

We retrospectively reviewed data from 30 patients with untreated stage IV NSCLC who had undergone a combined FDG PET and FLT PET scan at 1 week (early) and 6 weeks (late) after the start of erlotinib treatment. Early and late residual FDG and FLT uptake were measured in up to five lesions per scan with different quantitative standardized uptake values (SUV(max), SUV(2Dpeak), SUV(3Dpeak), SUV(50), SUV(A50), SUV(A41)) and compared with short-term outcome (progression vs. nonprogression after 6 weeks of erlotinib treatment). Receiver-operating characteristics (ROC) curve analysis was used to determine the optimal cut-off value for detecting nonprogression after 6 weeks. Kaplan-Meier analysis and the log-rank test were used to evaluate the association between residual uptake and progression-free survival (PFS).

RESULTS

Nonprogression after 6 weeks was associated with a significantly lower early and late residual FDG uptake, measured with different quantitative parameters. In contrast, nonprogression after 6 weeks was not associated with early and late residual FLT uptake. Furthermore, patients with a lower early residual FDG uptake measured in terms of SUV(max) and SUV(2Dpeak) had a significantly prolonged PFS (282 days vs. 118 days; p = 0.022) than patients with higher values. Similarly, lower late residual FDG uptake and early residual FLT uptake measured in terms of SUV(3Dpeak), SUV(A50) and SUV(A41), and late FLT uptake measured in terms of SUV(3Dpeak) and SUV(A50) was associated with an improved PFS.

CONCLUSION

Early and late residual FDG uptake, measured using different quantitative SUV parameters, are predictive factors for short-term outcome in patients with advanced NSCLC treated with erlotinib. Additionally, low residual FDG and FLT uptake early and late in the course of erlotinib treatment is associated with improved PFS.

Repeatability of 18F-FDG uptake measurements in tumors: a metaanalysis

PET with the glucose analog (18)F-FDG is increasingly used to monitor tumor response to therapy. To use quantitative measurements of tumor (18)F-FDG uptake for assessment of tumor response, the repeatability of this quantitative metabolic imaging method needs to be established. Therefore, we determined the repeatability of different standardized uptake value (SUV) measurements using the available data.

METHODS

A systematic literature search was performed to identify studies addressing (18)F-FDG repeatability in malignant tumors. The level of agreement between test and retest values of 2 PET uptake measures, maximum SUV (SUV(max)) and mean SUV (SUV(mean)), was assessed with the coefficient of repeatability using generalized linear mixed-effects models. In addition, the influence of tumor volume on repeatability was assessed. Principal component transformation was used to compare the reproducibility of the 2 different uptake measures.

RESULTS

Five cohorts were identified for this metaanalysis. For SUV(max) and SUV(mean), datasets of 86 and 102 patients, respectively, were available. Percentage repeatability is a function of the level of uptake. SUV(mean) had the best repeatability characteristics; for serial PET scans, a threshold of a combination of 20% as well as 1.2 SUV(mean) units was most appropriate. After adjusting for uptake rate, tumor volume had minimal influence on repeatability.

CONCLUSION

SUV(mean) had better repeatability performance than SUV(max). Both measures showed poor repeatability for lesions with low (18)F-FDG uptake. We recommend the evaluation of biologic effects in PET by reporting a combination of minimal relative and absolute changes to account for test-retest variability.

FDG-PET as a pharmacodynamic biomarker for early assessment of treatment response to linifanib (ABT-869) in a non-small cell lung cancer xenograft model

Linifanib (ABT-869) is a multitargeted receptor tyrosine kinase inhibitor. This work aims to evaluate F-fluorodeoxyglucose-positron emission tomography (FDG-PET) as a pharmacodynamic (PD) biomarker for linifanib treatment utilizing the Calu-6 model of human non-small cell lung (NSCLC) cancer in SCID-beige mice. Animals received either vehicle or 12.5 mg/kg linifanib orally twice a day for the duration of the study. Imaging was performed at -1, 1, 3, and 7 days after beginning treatment (n = 12-14 per group). Linifanib inhibited tumor growth and suppressed tumor metabolic activity. Changes in tumor FDG uptake were observed as early as 1 day after beginning linifanib treatment and were sustained for the duration of the study. This study confirms that linifanib is efficacious in this xenograft model of human NSCLC and confirms FDG-PET is a potential PD biomarker strategy for linifanib therapy.

Better late than early: FDG-PET imaging in metastatic renal cell carcinoma

Sunitinib treatment benefits patients with metastatic renal cell carcinoma (mRCC), but response duration can vary widely and resistance is not predicted by standard measures. [¹⁸F]fluoro-2-deoxy-2-D-glucose positron emission tomography (FDG-PET) uptake is variable in mRCC, but changes in FDG-PET uptake may be useful in monitoring disease progression. Further work is needed to personalize treatment for patients with mRCC.

Quantitative analysis of response to treatment with erlotinib in advanced non-small cell lung cancer using 18F-FDG and 3'-deoxy-3'-18F-fluorothymidine PET

The purpose of this study was to evaluate the relevance for the prediction of clinical benefit of first-line treatment with erlotinib using different quantitative parameters for PET with both (18)F-FDG and 3'-deoxy-3'-(18)F-fluorothymidine ((18)F-FLT) in patients with advanced non-small cell lung cancer.

METHODS

Data were used from a prospective trial involving patients with untreated stage IV non-small cell lung cancer. (18)F-FDG PET and (18)F-FLT PET were performed before and 1 (early) and 6 (late) weeks after erlotinib treatment. Several quantitative standardized uptake values (SUVs) using different definitions of volumes of interest with varying isocontours (maximum SUV [SUV(max)], 2-dimensional peak SUV [SUV(2Dpeak)], 3-dimensional [3D] peak SUV [SUV(3Dpeak)], 3D isocontour at 50% of the maximum pixel value [SUV(50)], 3D isocontour at 50% adapted for background [SUV(A50)], 3D isocontour at 41% of the maximum pixel value adapted for background [SUV(A41)], 3D isocontour at 70% of the maximum pixel value [SUV(70)], 3D isocontour at 70% adapted for background [SUV(A70)], and relative SUV threshold level [SUV(RTL)]) and metabolically active volume measurements were obtained in the hottest single tumor lesion and in the sum of up to 5 lesions per scan in 30 patients. Metabolic response was defined as a minimum reduction of 30% in each of the different SUVs and as a minimum reduction of 45% in metabolically active volume. Progression-free survival (PFS) was compared between patients with and without metabolic response measured with each of the different parameters, using Kaplan-Meier statistics and a log-rank test.

RESULTS

Patients with a metabolic response on early (18)F-FDG PET and (18)F-FLT PET in the hottest single tumor lesion as well as in the sum of up to 5 lesions per scan had a significantly longer PFS, regardless of the method used to calculate SUV. However, the highest significance was obtained for SUV(max), SUV(50), SUV(A50), and SUV(A41.) Patients with a metabolic response measured by SUV(max) and SUV(3Dpeak) on late (18)F-FDG PET in the hottest single tumor lesion had a significantly longer PFS. Furthermore, Kaplan-Meier analyses showed a strong association between PFS and response seen by metabolically active volume, measured either in early (18)F-FLT or in late (18)F-FDG.

CONCLUSION

Early (18)F-FDG PET and (18)F-FLT PET can predict PFS regardless of the method used for SUV calculation. However, SUV(max), SUV(50), SUV(A50), and SUV(A41) measured with (18)F-FDG might be the best robust SUV to use for early response prediction. Metabolically active volume measurement in early (18)F-FLT PET and late (18)F-FDG PET may have an additional predictive value in monitoring response in patients with advanced non-small cell lung cancer treated with erlotinib.

Early [18F]fluorodeoxyglucose positron emission tomography at two days of gefitinib treatment predicts clinical outcome in patients with adenocarcinoma of the lung

PURPOSE

Positron emission tomography (PET) with [(18)F]fluorodeoxyglucose (FDG) is increasingly used in early assessment of tumor response after chemotherapy. We investigated whether a change in [(18)F]FDG uptake at 2 days of gefitinib treatment predicts outcome in patients with lung adenocarcinoma.

EXPERIMENTAL DESIGN

Twenty patients were enrolled. [(18)F]FDG-PET/computed tomographic (CT) scan was carried out before and 2 days after gefitinib treatment. Maximum standardized uptake values (SUV) were measured, and post-gefitinib percentage changes in SUV were calculated. Early metabolic response (SUV decline < -25%) was compared with morphologic response evaluated by CT scan and with progression-free survival (PFS).

RESULTS

At 2 days of gefitinib treatment, 10 patients (50%) showed metabolic response, 8 had metabolic stable disease, and 2 had progressive metabolic disease. Percentage changes of SUV at 2 days were correlated with those of tumor size in CT at 1 month (R(2) = 0.496; P = 0.0008). EGFR gene was assessable in 15 patients, and of 12 patients with EGFR mutations, 8 showed metabolic response at 2 days and 6 showed morphologic response at 1 month. None of 3 patients with wild-type EGFR showed metabolic or morphologic response. Metabolic response at 2 days was not statistically associated with PFS (P = 0.095), but when a cutoff value of -20% in SUV decline was used, metabolic responders had longer PFS (P < 0.0001).

CONCLUSION

Early assessment of [(18)F]FDG tumor uptake with PET at 2 days of gefitinib treatment could be useful to predict clinical outcome earlier than conventional CT evaluation in patients with lung adenocarcinoma.

Angiogenesis and immunity: a bidirectional link potentially relevant for the monitoring of antiangiogenic therapy and the development of novel therapeutic combination with immunotherapy

The immune system regulates angiogenesis in cancer with both pro- and antiangiogenic activities. The induction of angiogenesis is mediated by tumor-associated macrophages and myeloid-derived suppressor cells (MDSC) which produce proinflammatory cytokines, endothelial growth factors (VEGF, bFGF…), and protease (MMP9) implicated in neoangiogenesis. Some cytokines (IL-6, IL-17…) activated Stat3 which also led to the production of VEGF and bFGF. In contrast, other cytokines (IFN, IL-12, IL-21, and IL-27) display an antiangiogenic activity. Recently, it has been shown that some antiangiogenic molecules alleviates immunosuppression associated with cancer by decreasing immunosuppressive cells (MDSC, regulatory T cells), immunosuppressive cytokines (IL-10, TGFβ), and inhibitory molecules on T cells (PD-1). Some of these broad effects may result from the ability of some antiangiogenic molecules, especially cytokines to inhibit the Stat3 transcription factor. The association often observed between angiogenesis and immunosuppression may be related to hypoxia which induces both neoangiogenesis via activation of HIF-1 and VEGF and favors the intratumor recruitment and differentiation of regulatory T cells and MDSC. Preliminary studies suggest that modulation of immune markers (intratumoral MDSC and IL-8, peripheral regulatory T cells…) may predict clinical response to antiangiogenic therapy. In preclinical models, a synergy has been observed between antiangiogenic molecules and immunotherapy which may be explained by an improvement of immune status in tumor-bearing mice after antiangiogenic therapy. In preclinical models, antiangiogenic molecules promoted intratumor trafficking of effector cells, enhance endogenous anti-tumor response, and synergyzed with immunotherapy protocols to cure established murine tumors. All these results warrant the development of clinical trials combining antiangiogenic drugs and immunotherapy.

Sequential FDG-PET/CT as a biomarker of response to Sunitinib in metastatic clear cell renal cancer

PURPOSE

To test the hypothesis that sequential (18)F-fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) is a correlative marker in metastatic clear cell renal cancer (mRCC), patients were treated with sunitinib. Three sequential scans were conducted to determine whether the timing of the investigation was relevant.

EXPERIMENTAL DESIGN

Forty-four untreated mRCC patients were enrolled into this prospective phase II study. (18)F-FDG-PET/CT scans were conducted before (n = 44) and after 4 weeks (n = 43) and 16 weeks (n = 40) of sunitinib given at standard doses. The primary endpoint was to correlate FDG-PET/CT response (20% reduction in SUV(max)) at 4 and 16 weeks with overall survival (OS).

RESULTS

Forty-three (98%) patients had FDG-PET/CT avid lesions at diagnosis (median SUV(max) = 6.8, range: <2.5-18.4). In multivariate analysis, a high SUV(max) and an increased number of PET-positive lesions correlated with shorter OS [HR: 3.30 (95% CI: 1.36-8.45) and 3.67 (95% CI: 1.43-9.39), respectively]. After 4 weeks of sunitinib, a metabolic response occurred in 24 (57%) patients, but this did not correlate with progression-free survival (HR for responders = 0.87; 95% CI: 0.40-1.99) or OS (HR for responders = 0.80; 95% CI: 0.34-1.85). After 16 weeks of treatment, disease progression on FDG-PET/CT occurred in 28% (n = 12) patients which correlated with a decreased OS and PFS [HR = 5.96 (95% CI: 2.43-19.02) and HR = 12.13 (95% CI: 3.72-46.45), respectively].

CONCLUSIONS

Baseline FDG-PET/CT yields prognostic significant data. FDG-PET/CT responses occur in the majority of patients after 4 weeks of therapy; however, it is not until 16 weeks when the results become prognostically significant.

Clinical applications of positron emission tomography in sarcoma management

Positron emission tomography (PET) with the fluorine-18-labeled glucose analog FDG is a technique that noninvasively visualizes glucose metabolism in the human body. In oncology, the addition of FDG-PET to the conventional anatomical imaging techniques provides very useful clinical information in diagnosis, staging, treatment response monitoring and follow-up. In the heterogeneous group of patients with sarcoma, FDG-PET has been shown to be of great value in improving patient care. In this article we will discuss the current role of FDG-PET in the management of patients with sarcoma and its value in assessing tumor grade, guiding biopsy, staging, monitoring treatment response, restaging and prognostication. Our future expectation is that the value of PET will only augment owing to the implementation of FDG-PET in clinical guidelines, the increasing availability worldwide, and the development of new tracers and new hybrid imaging techniques.

F-FDG PET Imaging in the Evaluation of Treatment Response to New Chemotherapies beyond Imatinib for Patients with Gastrointestinal Stromal Tumors

Aim. (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) is a powerful tool for staging and defining "good responders" to chemotherapy in tumor setting. Gastrointestinal stromal tumors (GISTs) are sarcoma involving gastrointestinal tract and may require a chemotherapy including imatinib, a tyrosine kinase inhibitor agent. Some GIST patients become refractory to imatinib; therefore, other tyrosine kinase inhibitors or concomitant chemotherapy may be considered for treatment. The aim of this paper is to assess if (18)F-FDG PET imaging is a useful tool to evaluate treatment response to new chemotherapies beyond imatinib for GIST patients. Methods. We performed a review of the literature about the role of (18)F-FDG PET in the evaluation of treatment response to new chemotherapies beyond imatinib for GIST patients. Results and Conclusions. (18)F-FDG PET seems to be able to assess therapy response earlier than computed tomography (CT) imaging in imatinib refractory GIST patients treated with other agents. However, a dual modality PET-CT imaging is recommendable to achieve a better detection of all lesions.

Total 18F-dopa PET tumour uptake reflects metabolic endocrine tumour activity in patients with a carcinoid tumour

Purpose

Positron emission tomography (PET) using 6-[¹⁸F]fluoro-L-dihydroxyphenylalanine (¹⁸F-dopa) has an excellent sensitivity to detect carcinoid tumour lesions. ¹⁸F-dopa tumour uptake and the levels of biochemical tumour markers are mediated by tumour endocrine metabolic activity. We evaluated whether total ¹⁸F-dopa tumour uptake on PET, defined as whole-body metabolic tumour burden (WBMTB), reflects tumour load per patient, as measured with tumour markers.

Methods

Seventy-seven consecutive carcinoid patients who underwent an ¹⁸F-dopa PET scan in two previously published studies were analysed. For all tumour lesions mean standardised uptake values (SUVs) at 40% of the maximal SUV and tumour volume on ¹⁸F-dopa PET were determined and multiplied to calculate a metabolic burden per lesion. WBMTB was the sum of the metabolic burden of all individual lesions per patient. The 24-h urinary serotonin, urine and plasma 5-hydroxindoleacetic acid (5-HIAA), catecholamines (nor)epinephrine, dopamine and their metabolites, measured in urine and plasma, and serum chromogranin A served as tumour markers.

Results

All but 1 were evaluable for WBMTB; 74 patients had metastatic disease. ¹⁸F-dopa PET detected 979 lesions. SUV_max on ¹⁸F-dopa PET varied up to 29-fold between individual lesions within the same patients. WBMTB correlated with urinary serotonin (r = 0.51) and urinary and plasma 5-HIAA (r = 0.78 and 0.66). WBMTB also correlated with urinary norepinephrine, epinephrine, dopamine and plasma dopamine, but not with serum chromogranin A.

Conclusion

Tumour load per patient measured with ¹⁸F-dopa PET correlates with tumour markers of the serotonin and catecholamine pathway in urine and plasma in carcinoid patients, reflecting metabolic tumour activity.

Current and emerging pharmacological treatments for gastrointestinal stromal tumour

Gastrointestinal stromal tumours (GIST) are the most common mesenchymal tumours of the gastrointestinal tract, previously classified as leiomyosarcomas. Most GIST express KIT and the majority have mutations in the KIT gene. The most common KIT mutation occurs in the juxtamembrane domain of exon 11. These mutations lead to cellular proliferation and survival. GIST with exon 11 mutations respond better to tyrosine kinase inhibitors (TKIs) than those with exon 9 mutations. Most KIT-negative GIST express platelet-derived growth factor receptor (PDGFR)-α; however, a small percentage of GIST are negative for both KIT and PDGFRα. Imatinib and other TKIs have dramatically improved the outcome of patients with metastatic GIST. Newer and more advanced TKIs are under intense investigation as eventually all GIST patients develop resistant tumours. In addition, these drugs can be utilized in the preoperative setting for patients with unresectable localized tumours or those at high risk for surgical morbidity. TKIs have been given in the adjuvant setting for patients with resected tumours at high risk for recurrence. The duration of adjuvant therapy is currently under evaluation; however, it is possible that these patients would need to continue therapy indefinitely.

Assessment of Therapeutic Effect of Sunitinib by (11)C-Acetate PET Compared with FDG PET Imaging in a Patient with Metastatic Renal Cell Carcinoma

Although sunitinib shows a high response rate in patients with untreated metastatic renal cell carcinoma (mRCC), quite a few patients show no therapeutic effect. Therefore, it is crucial to distinguish the patients who respond to sunitinib from those who do not as early as possible after the administration of the therapy. We herein report a case of mRCC in which (11)C-acetate (AC) positron emission tomography (PET) showed an early therapeutic effect of sunitinib treatment 4 weeks after its administration.

Metabolic effects of signal transduction inhibition in cancer assessed by magnetic resonance spectroscopy

Despite huge efforts in development of drugs targeting oncogenic signalling, the number of such drugs entering clinical practice to date remains limited. Rational use of biomarkers for drug candidate selection and early monitoring of response to therapy may accelerate this process. Magnetic resonance spectroscopy (MRS) can be used to assess metabolic effects of drug treatment both in vivo and in vitro, and technological advances are continuously increasing the utility of this non-invasive method. In this review, we summarise the use of MRS for monitoring the effect of targeted anticancer drugs, and discuss the potential role of MRS in the context of personalised cancer treatment.

Early prediction of nonprogression in advanced non-small-cell lung cancer treated with erlotinib by using [(18)F]fluorodeoxyglucose and [(18)F]fluorothymidine positron emission tomography

PURPOSE

Positron emission tomography (PET) with both 2'-deoxy-2'-[(18)F]fluoro-D-glucose (FDG) and 3'-[(18)F]fluoro-3'-deoxy-L-thymidine (FLT) was evaluated with respect to the accuracy of early prediction of nonprogression following erlotinib therapy, independent from epidermal growth factor receptor (EGFR) mutational status, in patients with previously untreated advanced non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

Thirty-four patients with untreated stage IV NSCLC were evaluated in this phase II trial. Changes in FDG and FLT uptake after 1 (early) and 6 (late) weeks of erlotinib treatment were compared with nonprogression measured by computed tomography after 6 weeks of treatment, progression-free survival (PFS), and overall survival (OS).

RESULTS

Changes in FDG uptake after 1 week of therapy predicted nonprogression after 6 weeks of therapy with an area under the receiver operating characteristic curve of 0.75 (P = .02). Furthermore, patients with an early metabolic FDG response (cutoff value: 30% reduction in the peak standardized uptake value) had significantly longer PFS (hazard ratio [HR], 0.23; 95% CI, 0.09 to 0.59; P = .002) and OS (HR, 0.36; 95% CI, 0.13 to 0.96; P = .04). Early FLT response also predicted significantly longer PFS (HR, 0.31; 95% CI, 0.10 to 0.95; P = .04) but not OS and was not predictive for nonprogression after 6 weeks of therapy.

CONCLUSION

Early FDG-PET predicts PFS, OS, and nonprogression after 6 weeks of therapy with erlotinib in unselected, previously untreated patients with advanced NSCLC independent from EGFR mutational status.

Parametric images via dynamic 18F-fluorodeoxyglucose positron emission tomographic data acquisition in predicting midterm outcome of liver metastases secondary to gastrointestinal stromal tumours

PURPOSE

(18)F-Fluorodeoxyglucose positron emission tomography (FDG PET) may underestimate viable tumour tissue in patients with gastrointestinal stromal tumours (GIST) treated with molecular targeted agents. The aim of the present study was to investigate the value of parametric images generated after dynamic data acquisition for the detection of active liver metastases.

METHODS

The analysis included 65 dynamic FDG PET studies in 34 patients with liver metastases from GIST who were treated with imatinib or sunitinib. Parametric images of intercept and slope were calculated by dedicated software using a voxel-based linear regression of time-activity data. Intercept images represent the tracer's distribution volume and the slope its overall metabolic turnover. All images were assessed visually and semi-quantitatively. Liver disease status was established 12 months after each PET study. Dichotomous variables of visual interpretation and various quantitative parameters were entered in a statistical model of linear discriminant analysis.

RESULTS

Visual analysis of slope images was more sensitive than the standard 1-h FDG uptake evaluation (70.6 vs 51.0%, p = 0.016) in detecting cases with liver disease progression (n = 51). Specificity did not differ. Combination of all variables in the discriminant analysis model correctly classified 87.7% of cases as progressive or non-progressive disease. Sensitivity was raised to 88.2%.

CONCLUSION

Parametric images of intercept and slope add a new dimension to the interpretation of FDG PET studies, by isolating visually and quantifying the perfusion and phosphorylation-dependent part of tracer uptake. In treated GIST patients, integration of this information with the 1-h uptake data achieves better characterization of hepatic lesions with respect to disease activity.