Peptide Receptor Radionuclide Therapy with 67Cu-CuSarTATE Is Highly Efficacious Against a Somatostatin-Positive Neuroendocrine Tumor Model.

Peptide receptor radionuclide therapy (PRRT) using radiolabeled octreotate is an effective treatment for somatostatin receptor 2-expressing neuroendocrine tumors. The diagnostic and therapeutic potential of 64Cu and 67Cu, respectively, offers the possibility of using a single somatostatin receptor-targeted peptide conjugate as a theranostic agent. A sarcophagine cage amine ligand, MeCOSar (5-(8-methyl-3,6,10,13,16,19-hexaaza-bicyclo[6.6.6]icosan-1-ylamino)-5-oxopentanoic acid), conjugated to (Tyr3)-octreotate, called 64Cu-CuSarTATE, was demonstrated to be an imaging agent and potential prospective dosimetry tool in 10 patients with neuroendocrine tumors. This study aimed to explore the antitumor efficacy of 67Cu-CuSarTATE in a preclinical model of neuroendocrine tumors and compare it with the standard PRRT agent, 177Lu-LuDOTA-Tyr3-octreotate (177Lu-LuTATE). Methods: The antitumor efficacy of various doses of 67Cu-CuSarTATE in AR42J (rat pancreatic exocrine) tumor-bearing mice was compared with 177Lu-LuTATE. Results: Seven days after a single administration of 67Cu-CuSarTATE (5 MBq), tumor growth was inhibited by 75% compared with vehicle control. Administration of 177Lu-LuTATE (5 MBq) inhibited tumor growth by 89%. Survival was extended from 12 d in the control group to 21 d after treatment with both 67Cu-CuSarTATE and 177Lu-LuTATE. In a second study, the efficacy of fractionated delivery of PRRT was assessed, comparing the efficacy of 30 MBq of 67Cu-CuSarTATE or 177Lu-LuTATE, either as a single intravenous injection or as two 15-MBq fractions 2 wk apart. Treatment of tumors with 2 fractions significantly improved survival over delivery as a single fraction (67Cu-CuSarTATE: 47 vs. 36 d [P = 0.036]; 177Lu-LuTATE: 46 vs. 29 d [P = 0.040]). Conclusion: This study demonstrates that 67Cu-CuSarTATE is well tolerated in BALB/c nude mice and highly efficacious against AR42J tumors in vivo. Administration of 67Cu-CuSarTATE and 177Lu-LuTATE divided into 2 fractions over 2 wk was more efficacious than administration of a single fraction. The antitumor activity of 67Cu-CuSarTATE in the AR42J tumor model demonstrated the suitability of this novel agent for clinical assessment in the treatment of somatostatin receptor 2-expressing neuroendocrine tumors.

Automated preparation of clinical grade [68Ga]Ga-DOTA-CP04, a cholecystokinin-2 receptor agonist, using iPHASE MultiSyn synthesis platform.

BACKGROUND: Gallium-68 ([68Ga]Ga) labelled radiopharmaceuticals have become a valuable tool in clinical practice using Positron Emission Tomography (PET). These agents are typically produced on-site owing to the short half-life of [68Ga]Ga (68 min), which hinders distant transportation and often cannot comply with Good Manufacturing Practice (GMP) in hospital environments due to limited resources or infrastructure constraints. Moreover, full blown GMP production of radiopharmaceuticals under development can be prohibitively expensive. [68Ga]Ga-DOTA-CP04 is a promising peptide for imaging neuroendocrine tumors overexpressing the cholecyctokinin-2 receptor. Automation is an integral process in ensuring the radiopharmaceuticals produced under non-GMP conditions are of a uniform quality for routine clinical use. Herein, we describe the development of an automation platform, the iPHASE MultiSyn radiosynthesizer, to produce 68Ga-labelled DOTA-CP04 for routine clinical provision. RESULTS: The use of the MultiSyn module for 68Ga-labelling of DOTA-CP04 was investigated. [68Ga]Ga-DOTA-CP04, was reproducibly prepared in high (> 70%) decay-corrected yields. [68Ga]Ga-DOTA-CP04 passed all predetermined acceptance criteria for human injection. CONCLUSIONS: [68Ga]Ga-DOTA-CP04 was produced effectively using the MultiSyn module in a consistent and reproducible manner suitable for human injection.

Modification of Biodistribution and Brain Uptake of Copper Bis(thiosemicarbazonato) Complexes by the Incorporation of Amine and Polyamine Functional Groups.

The synthesis of new bis(thiosemicarbazonato)copper(II) complexes featuring polyamine substituents via selective transamination reactions is presented. Polyamines of different lengths, with different ionizable substituent groups, were used to modify and adjust the hydrophilic/lipophilic balance of the copper complexes. The new analogues were radiolabeled with copper-64 and their lipophilicities estimated using distribution coefficients. The cell uptake of the new polyamine complexes was investigated with preliminary in vitro biological studies using a neuroblastoma cancer cell line. The in vivo biodistribution of three of the new analogues was investigated in vivo in mice using positron-emission tomography imaging, and one of the new complexes was compared to [64Cu]Cu(atsm) in an A431 squamous cell carcinoma xenograft model. Modification of the copper complexes with various amine-containing functional groups alters the biodistribution of the complexes in mice. One complex, with a pendent ( N, N-dimethylamino)ethane functional group, displayed tumor uptake similar to that of [64Cu]Cu(atsm) but higher brain uptake, suggesting that this compound has the potential to be of use in the diagnostic brain imaging of tumors and neurodegenerative diseases.

Cold Kit for Prostate-Specific Membrane Antigen (PSMA) PET Imaging: Phase 1 Study of 68Ga-Tris(Hydroxypyridinone)-PSMA PET/CT in Patients with Prostate Cancer.

68Ga-labeled urea-based inhibitors of the prostate-specific membrane antigen (PSMA), such as 68Ga-labeled N,N'-bis(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid (HBED)-PSMA-11, are promising small molecules for targeting prostate cancer. A new radiopharmaceutical, 68Ga-labeled tris(hydroxypyridinone) (THP)-PSMA, has a simplified design for single-step kit-based radiolabeling. It features the THP ligand, which forms complexes with 68Ga3+ rapidly at a low concentration, at room temperature, and over a wide pH range, enabling direct elution from a 68Ge/68Ga generator into a lyophilized radiopharmaceutical kit in 1 step without manipulation. The aim of this phase 1 study was to assess the safety and biodistribution of 68Ga-THP-PSMA. Methods: Cohort A comprised 8 patients who had proven prostate cancer and were scheduled to undergo prostatectomy; they had Gleason scores of 7-10 and a mean prostate-specific antigen level of 7.8 µg/L (range, 5.4-10.6 µg/L). They underwent PET/CT after the administration of 68Ga-THP-PSMA. All patients proceeded to prostatectomy (7 with pelvic nodal dissection). Dosimetry from multi-time-point PET imaging was performed with OLINDA/EXM. Cohort B comprised 6 patients who had positive 68Ga-HBED-PSMA-11 PET/CT scanning results and underwent comparative 68Ga-THP-PSMA scanning. All patients were monitored for adverse events. Results: No adverse events occurred. In cohort A, 6 of 8 patients had focal uptake in the prostate (at 2 h: average SUVmax, 5.1; range, 2.4-9.2) and correlative 3+ staining of prostatectomy specimens on PSMA immunohistochemistry. The 2 68Ga-THP-PSMA scans with negative results had only 1+/2+ staining. The mean effective dose was 2.07E-02 mSv/MBq. In cohort B, 68Ga-THP-PSMA had lower physiologic background uptake than 68Ga-HBED-PSMA-11 (in the parotid glands, the mean SUVmax for 68Ga-THP-PSMA was 3.6 [compared with 19.2 for 68Ga-HBED-PSMA-11]; the respective corresponding values in the liver were 2.7 and 6.3, and those in the spleen were 2.7 and 10.5; P < 0.001 for all). In 5 of 6 patients, there was concordance in the number of metastases identified with 68Ga-HBED-PSMA-11 and 68Ga-THP-PSMA. Thirteen of 15 nodal abnormalities were subcentimeter. In 22 malignant lesions, the tumor-to-liver contrast with 68Ga-THP-PSMA was similar to that with 68Ga-HBED-PSMA (4.7 and 5.4, respectively; P = 0.15), despite a higher SUVmax for 68Ga-HBED-PSMA than for 68Ga-THP-PSMA (30.3 and 10.7, respectively; P < 0.01). Conclusion:68Ga-THP-PSMA is safe and has a favorable biodistribution for clinical imaging. Observed focal uptake in the prostate was localized to PSMA-expressing malignant tissue on histopathology. Metastatic PSMA-avid foci were also visualized with 68Ga-THP-PSMA PET. Single-step production from a Good Manufacturing Practice cold kit may enable rapid adoption.

EORTC PET response criteria are more influenced by reconstruction inconsistencies than PERCIST but both benefit from the EARL harmonization program.

BACKGROUND: This study evaluates the consistency of PET evaluation response criteria in solid tumours (PERCIST) and European Organisation for Research and Treatment of Cancer (EORTC) classification across different reconstruction algorithms and whether aligning standardized uptake values (SUVs) to the European Association of Nuclear Medicine acquisition (EANM)/EARL standards provides more consistent response classification. MATERIALS AND METHODS: Baseline (PET1) and response assessment (PET2) scans in 61 patients with non-small cell lung cancer were acquired in protocols compliant with the EANM guidelines and were reconstructed with point-spread function (PSF) or PSF + time-of-flight (TOF) reconstruction for optimal tumour detection and with a standardized ordered subset expectation maximization (OSEM) reconstruction known to fulfil EANM harmonizing standards. Patients were recruited in three centres. Following reconstruction, EQ.PET, a proprietary software solution was applied to the PSF ± TOF data (PSF ± TOF.EQ) to harmonize SUVs to the EANM standards. The impact of differing reconstructions on PERCIST and EORTC classification was evaluated using standardized uptake values corrected for lean body mass (SUL). RESULTS: Using OSEMPET1/OSEMPET2 (standard scenario), responders displayed a reduction of -57.5% ± 23.4 and -63.9% ± 22.4 for SULmax and SULpeak, respectively, while progressing tumours had an increase of +63.4% ± 26.5 and +60.7% ± 19.6 for SULmax and SULpeak respectively. The use of PSF ± TOF reconstruction impacted the classification of tumour response. For example, taking the OSEMPET1/PSF ± TOFPET2 scenario reduced the apparent reduction in SUL in responding tumours (-39.7% ± 31.3 and -55.5% ± 26.3 for SULmax and SULpeak, respectively) but increased the apparent increase in SUL in progressing tumours (+130.0% ± 50.7 and +91.1% ± 39.6 for SULmax and SULpeak, respectively). Consequently, variation in reconstruction methodology (PSF ± TOFPET1/OSEMPET2 or OSEM PET1/PSF ± TOFPET2) led, respectively, to 11/61 (18.0%) and 10/61 (16.4%) PERCIST classification discordances and to 17/61 (28.9%) and 19/61 (31.1%) EORTC classification discordances. An agreement was better for these scenarios with application of the propriety filter, with kappa values of 1.00 and 0.95 compared to 0.75 and 0.77 for PERCIST and kappa values of 0.93 and 0.95 compared to 0.61 and 0.55 for EORTC, respectively. CONCLUSION: PERCIST classification is less sensitive to reconstruction algorithm-dependent variability than EORTC classification but harmonizing SULs within the EARL program is equally effective with either.

ß -[18F]Fluoro Azomycin Arabinoside (ß -[18F]FAZA): Synthesis, Radiofluorination and Preliminary PET Imaging of Murine A431 Tumors.

BACKGROUND: 1-α-D-(5-Deoxy-5-[18F]fluoroarabinofuranosyl)-2-nitroimidazole([18F] FAZA) is a PET radiotracer that demonstrates excellent potential in imaging regional hypoxia, and is clinically used in diagnosing a wide range of solid tumors in cancer patients. [18F]FAZA, however, is radiofluorinated in only moderate recovered radiochemical yield (rRCY, ~12%). It is postulated that the relative stability of the C1' ß-anomeric bond at C5' will make 1-ß-D-(5-fluoro-5-deoxyarabinofuranosyl)-2-nitroimidazole (ß-FAZA), the ß-conformer of FAZA, an attractive candidate for clinical hypoxia imaging. OBJECTIVES: The principle goals were to synthesize ß-FAZA and ß-Ac2TsAZA, the radiofluorination precursor, to establish the radiofluorination chemistry leading to ß-[18F]FAZA, and to investigate the biodistribution of ß-[18F]FAZA in an animal tumor-bearing model using PET imaging. METHODS: The appropriately-protected furanose sugar was coupled with 2-nitroimidazole to afford 1-ß-D-(2,3-di-O-acetylarabinofuranosyl)-2-nitroimidazole (ß-Ac2AZA). Fluorination of ß-Ac2AZA with DAST, followed by alkaline hydrolysis, afforded ß-FAZA (21%). The radiolabeling synthon, 1-ß-D-(5-O-toluenesulfonyl-2,3-di-O-acetylarabinofuranosyl)-2-nitroimidazole (ß-Ac2TsAZA), on radiofluorination using the 18F/K222 complex under various reaction conditions, followed by base-catalyzed deacetylation, afforded ß-[18F]FAZA. ß-[18F]FAZA was radiochemically stable for at least 8 h when stored in aqueous ethanol (8%) at 22 °C. A preliminary PET imaging-based biodistribution study of ß-[18F]FAZA was performed in A431 tumor-bearing nude mice. RESULTS: ß-FAZA and ß-Ac2TsAZA were synthesized in satisfactory yield. Radiochemistry of [18F]FAZA was established. PET images showed strong uptake in hypoxic regions of the tumor. CONCLUSION: The synthesis of ß-FAZA and ß-[18F]FAZA are reported. Radiofluorination of ß-Ac2TsAZA and the deprotection of ß-Ac2[18F]FAZA were facile, but led to a more complex mixture of radiofluorinated by-products than observed with the corresponding precursor of α-[18F]FAZA. PET images were indicative of hypoxia-selective accumulation of ß-[18F]FAZA in tumor.

Does PET SUV Harmonization Affect PERCIST Response Classification?

Pre- and posttreatment PET comparative scans should ideally be obtained with identical acquisition and processing, but this is often impractical. The degree to which differing protocols affect PERCIST classification is unclear. This study evaluates the consistency of PERCIST classification across different reconstruction algorithms and whether a proprietary software tool can harmonize SUV estimation sufficiently to provide consistent response classification. METHODS: Eighty-six patients with non-small cell lung cancer, colorectal liver metastases, or metastatic melanoma who were scanned for therapy monitoring purposes were prospectively recruited in this multicenter trial. Pre- and posttreatment PET scans were acquired in protocols compliant with the Society of Nuclear Medicine and Molecular Imaging and the European Association of Nuclear Medicine (EANM) acquisition guidelines and were reconstructed with a point spread function (PSF) or PSF + time-of-flight (TOF) for optimal tumor detection and also with standardized ordered-subset expectation maximization (OSEM) known to fulfill EANM harmonizing standards. After reconstruction, a proprietary software solution was applied to the PSF ± TOF data (PSF ± TOF.EQ) to harmonize SUVs with the OSEM values. The impact of differing reconstructions on PERCIST classification was evaluated. RESULTS: For the OSEMPET1/OSEMPET2 (OSEM reconstruction for pre- and posttherapeutic PET, respectively) scenario, which was taken as the reference standard, the change in SUL was -41% ± 25 and +56% ± 62 in the groups of tumors showing a decrease and an increase in 18F-FDG uptake, respectively. The use of PSF reconstruction affected classification of tumor response. For example, taking the PSF ± TOFPET1/OSEMPET2 scenario increased the apparent reduction in SUL in responding tumors (-48% ± 22) but reduced the apparent increase in SUL in progressing tumors (+37% ± 43), as compared with the OSEMPET1/OSEMPET2 scenario. As a result, variation in reconstruction methodology (PSF ± TOFPET1/OSEMPET2 or OSEM PET1/PSF ± TOFPET2) led to 13 of 86 (15%) and 17 of 86 (20%) PERCIST classification discordances, respectively. Agreement was better for these scenarios with application of the propriety filter, with κ values of 1 and 0.95 compared with 0.79 and 0.72, respectively. CONCLUSION: Reconstruction algorithm-dependent variability in PERCIST classification is a significant issue but can be overcome by harmonizing SULs using a proprietary software tool.

Quantitative and qualitative analysis of [(18)F]FDG and [(18)F]FAZA positron emission tomography of head and neck cancers and associations with HPV status and treatment outcome.

PURPOSE: While methods for imaging tumor hypoxia with positron emission tomography (PET) have been developed, optimal methods for interpreting and utilizing these datasets in the clinic remain unclear. In this study, we analyzed hypoxia PET images of head and neck cancer patients and compared imaging metrics with human papilloma virus (HPV) status and clinical outcome. METHODS: Forty-one patients treated as part of a phase III trial of the hypoxic cytotoxin tirapazamine (TROG 02.02) were imaged with PET using fluorodeoxyglucose (FDG) and fluoroazomycin arabinoside (FAZA). FDG and FAZA PET images were interpreted qualitatively and quantitatively, and compared with tumor T stage, HPV status, and treatment outcome using multivariate statistics. RESULTS: PET signals in the tumor and lymph nodes exhibited significant intra- and inter-patient variability. The FAZA hypoxic volume demonstrated a significant correlation with tumor T stage. PET-hypoxic tumors treated with cisplatin exhibited significantly worse treatment outcomes relative to PET-oxic tumors or PET-hypoxic tumors treated with tirapazamine. CONCLUSION: Quantitative analysis of FAZA PET yielded metrics that correlated with clinical T stage and were capable of stratifying patient outcome. These results encourage further development of this technology, with particular emphasis on establishment of robust quantitative methods.

Applying Advanced Imaging Techniques to a Murine Model of Orthotopic Osteosarcoma.

INTRODUCTION: Reliable animal models are required to evaluate novel treatments for osteosarcoma. In this study, the aim was to implement advanced imaging techniques in a murine model of orthotopic osteosarcoma to improve disease modeling and the assessment of primary and metastatic disease. MATERIALS AND METHODS: Intra-tibial injection of luciferase-tagged OPGR80 murine osteosarcoma cells was performed in Balb/c nude mice. Treatment agent [pigment epithelium-derived factor (PEDF)] was delivered to the peritoneal cavity. Primary tumors and metastases were evaluated by in vivo bioluminescent assays, micro-computed tomography, [(18)F]-Fluoride-PET and [(18)F]-FDG-PET. RESULTS: [(18)F]-Fluoride-PET was more sensitive than [(18)F]-FDG-PET for detecting early disease. Both [(18)F]-Fluoride-PET and [(18)F]-FDG-PET showed progressive disease in the model, with fourfold and twofold increases in standardized uptake value (p < 0.05) by the study endpoint, respectively. In vivo bioluminescent assay showed that systemically delivered PEDF inhibited growth of primary osteosarcoma. DISCUSSION: Application of [(18)F]-Fluoride-PET and [(18)F]-FDG-PET to an established murine model of orthotopic osteosarcoma has improved the assessment of disease. The use of targeted imaging should prove beneficial for the evaluation of new approaches to osteosarcoma therapy.

STatistically Assigned Response Criteria in Solid Tumors (STARCIST).

BACKGROUND: Several reproducibility studies have established good test-retest reliability of FDG-PET in various oncology settings. However, these studies are based on relatively short inter-scan periods of 1-3 days while, in contrast, response assessments based on FDG-PET in early phase drug trials are typically made over an interval of 2-3 weeks during the first treatment cycle. With focus on longer, on-treatment scan intervals, we develop a data-driven approach to calculate baseline-specific cutoff values to determine patient-level changes in glucose uptake that are unlikely to be explained by random variability. Our method takes into account the statistical nature of natural fluctuations in SUV as well as potential bias effects. METHODS: To assess variability in SUV over clinically relevant scan intervals for clinical trials, we analyzed baseline and follow-up FDG-PET scans with a median scan interval of 21 days from 53 advanced stage cancer patients enrolled in a Phase 1 trial. The 53 patients received a sub-pharmacologic drug dose and the trial data is treated as a 'test-retest' data set. A simulation-based tool is presented which takes as input baseline lesion SUVmax values, the variance of spurious changes in SUVmax between scans, the desired Type I error rate, and outputs lesion and patient based cut-off values. Bias corrections are included to account for variations in tracer uptake time. RESULTS: In the training data, changes in SUVmax follow an approximately zero-mean Gaussian distribution with constant variance across levels of the baseline measurements. Because of constant variance, the coefficient of variation is a decreasing function of the magnitude of baseline SUVmax. This finding is consistent with published results, but our data shows greater variability. Application of our method to NSCLC patients treated with erlotinib produces results distinct from those based on the EORTC criteria. Based on data presented here as well as previous repeatability studies, the proposed method has greater statistical power to detect a significant %-decrease on SUVmax compared to published criteria relying on symmetric thresholds. CONCLUSIONS: Defining patient-specific, baseline dependent cut-off values based on the (null) distribution of naturally occurring fluctuations in glucose uptake enable identification of statistically significant changes in SUVmax. For lower baseline values, the produced cutoff values are notably asymmetric with relatively large changes (e.g. >50 %) required for statistical significance. For use with prospectively defined endpoints, the developed method enables the use of one-armed trials to detect pharmacodynamic drug effects based on FDG-PET. The clinical importance of changes in SUVmax is likely to remain dependent on both tumor biology and the type of treatment.

Harmonizing FDG PET quantification while maintaining optimal lesion detection: prospective multicentre validation in 517 oncology patients.

PURPOSE: Point-spread function (PSF) or PSF + time-of-flight (TOF) reconstruction may improve lesion detection in oncologic PET, but can alter quantitation resulting in variable standardized uptake values (SUVs) between different PET systems. This study aims to validate a proprietary software tool (EQ.PET) to harmonize SUVs across different PET systems independent of the reconstruction algorithm used. METHODS: NEMA NU2 phantom data were used to calculate the appropriate filter for each PSF or PSF+TOF reconstruction from three different PET systems, in order to obtain EANM compliant recovery coefficients. PET data from 517 oncology patients were reconstructed with a PSF or PSF+TOF reconstruction for optimal tumour detection and an ordered subset expectation maximization (OSEM3D) reconstruction known to fulfil EANM guidelines. Post-reconstruction, the proprietary filter was applied to the PSF or PSF+TOF data (PSFEQ or PSF+TOFEQ). SUVs for PSF or PSF+TOF and PSFEQ or PSF+TOFEQ were compared to SUVs for the OSEM3D reconstruction. The impact of potential confounders on the EQ.PET methodology including lesion and patient characteristics was studied, as was the adherence to imaging guidelines. RESULTS: For the 1380 tumour lesions studied, Bland-Altman analysis showed a mean ratio between PSF or PSF+TOF and OSEM3D of 1.46 (95%CI: 0.86-2.06) and 1.23 (95%CI: 0.95-1.51) for SUVmax and SUVpeak, respectively. Application of the proprietary filter improved these ratios to 1.02 (95%CI: 0.88-1.16) and 1.04 (95%CI: 0.92-1.17) for SUVmax and SUVpeak, respectively. The influence of the different confounding factors studied (lesion size, location, radial offset and patient's BMI) was less than 5%. Adherence to the European Association of Nuclear Medicine (EANM) guidelines for tumour imaging was good. CONCLUSION: These data indicate that it is not necessary to sacrifice the superior lesion detection and image quality achieved by newer reconstruction techniques in the quest for harmonizing quantitative comparability between PET systems.

68Ga-EDTA PET/CT imaging and plasma clearance for glomerular filtration rate quantification: comparison to conventional 51Cr-EDTA.

UNLABELLED: Glomerular filtration rate (GFR) can accurately be determined using (51)Cr-ethylenediaminetetraacetic acid (EDTA) plasma clearance counting but is time-consuming and requires technical skills and equipment not always available in imaging departments. (68)Ga-EDTA can be readily available using an onsite generator, and PET/CT enables both imaging of renal function and accurate camera-based quantitation of clearance of activity from blood and its appearance in the urine. This study aimed to assess agreement between (68)Ga-EDTA GFR ((68)Ga-GFR) and (51)Cr-EDTA GFR ((51)Cr-GFR), using serial plasma sampling and PET imaging. METHODS: (68)Ga-EDTA and (51)Cr-EDTA were injected concurrently in 31 patients. Dynamic PET/CT encompassing the kidneys was acquired for 10 min followed by 3 sequential 3-min multibed step acquisitions from kidneys to bladder. PET quantification was performed using renal activity at 1-2 min (PETinitial), renal excretion at 2-10 min (PETearly), and, subsequently, urinary excretion into the collecting system and bladder (PETlate). Plasma sampling at 2, 3, and 4 h was performed, with (68)Ga followed by (51)Cr counting after positron decay. The level of agreement for GFR determination was calculated using a Bland-Altman plot and Pearson correlation coefficient (PCC). RESULTS: (51)Cr-GFR ranged from 10 to 220 mL/min (mean, 85 mL/min). There was good agreement between (68)Ga-GFR and (51)Cr-GFR using serial plasma sampling, with a Bland-Altman bias of -14 ± 20 mL/min and a PCC of 0.94 (95% confidence interval, 0.88-0.97). Of the 3 methods used for camera-based quantification, the strongest correlation was for plasma sampling-derived GFR with PETlate (PCC of 0.90; 95% confidence interval, 0.80-0.95). CONCLUSION: (68)Ga-GFR agreed well with (51)Cr-GFR for estimation of GFR using serial plasma counting. PET dynamic imaging provides a method to estimate GFR without plasma sampling, with the additional advantage of enabling renal imaging in a single study. Additional validation in a larger cohort is warranted to further assess utility.

Bifunctional (64)Cu-labelled macrobicyclic cage amine isothiocyanates for immuno-positron emission tomography.

New macrobicyclic cage amine or "sarcophagine" (sar) bifunctional chelators have been synthesised that form copper complexes of exceptional in vivo stability and incorporate isothiocyanate (-NCS) functional groups for conjugation to an antibody. The chelators were synthesised from the methyl-capped complex [Mg(II)(CH3)(NH2)sar](2+). Coordination of Mg(II) within the cavity of the cage amine ligand protects the secondary amine atoms from reacting with the -NCS functional groups. Two different [Mg(II)(NCS-sar)](2+) derivatives were conjugated to the HER2/neu-targeting antibody trastuzumab and the progress of the reaction monitored by electrospray mass spectrometry. The Mg(II) ion was removed from the immunoconjugates under mild conditions (0.1 M citrate buffer, pH 6). Labelling of the (CH3)(p-NCS-Ph)sar-trastuzumab conjugate with (64)Cu(II), a radioisotope suitable for positron emission tomography (PET), was fast (∼5 min) and easily performed at room temperature with high radiochemical purity (>95%). Biodistribution and PET imaging studies in vivo showed that (64)Cu-labelled (CH3)(p-NCS-Ph)sar-trastuzumab maintained high stability under physiological conditions with high and selective uptake in a HER2-positive cancer cell line. The stability of the copper complex and the 12.7 h half-life of the radioisotope allows clear visualisation of tumours out to 48 h.

Differential (18)F-FDG and (18)F-FLT Uptake on Serial PET/CT Imaging Before and During Definitive Chemoradiation for Non-Small Cell Lung Cancer.

UNLABELLED: We aimed to prospectively observe cellular metabolism and proliferation in patients with non-small-cell lung cancer (NSCLC) during radical chemoradiation therapy using serial PET/CT with (18)F-FDG and 3'-deoxy-3'-(18)F-fluorothymidine ((18)F-FLT). METHODS: Twenty patients with stage I-III NSCLC and candidates for radical chemoradiation therapy (60 Gy in 30 fractions over 6 wk) were recruited. (18)F-FDG and (18)F-FLT PET/CT were performed at baseline and during therapy (weeks 2 and 4). Tumor response was assessed semiquantitatively and using visual response criteria. RESULTS: The median and range for primary tumor volume (cm(3)) at baseline on (18)F-FDG were 28 and 2-241, respectively, and on (18)F-FLT 31 and 2-184, respectively. At week 2, (18)F-FDG was 26 (range, 2-164), and (18)F-FLT was 11 (range, 0-111). At week 4, (18)F-FDG was 19 (1-147), and (18)F-FLT was 7 (0-48). The median and range of maximum standardized uptake value (SUVmax) at baseline on (18)F-FDG were 14 and 4-31, respectively, and on (18)F-FLT 6 and 2-12, respectively. Week 2 (18)F-FDG median SUVmax was 10 (2-31), and (18)F-FLT median SUVmax was 3 (1-15); week 4 (18)F-FDG median SUVmax was 10 (2-15), and (18)F-FLT median SUVmax was 2 (2-9). There was fair agreement between visual tumor response on (18)F-FDG and (18)F-FLT during therapy (Cohen's unweighted κ statistic, 0.27 at week 2 and 0.355 at week 4). Cerebral metastases were detected on 1 baseline (18)F-FLT scan, resulting in palliative management. Progressive disease was detected on week 2 scans in 3 patients, resulting in changes to radiation therapy (2 patients) and treatment intent (1 patient). CONCLUSION: This study demonstrates that (18)F-FLT PET/CT is a more sensitive tracer of early treatment response than (18)F-FDG PET/CT. The ability of these tracers to detect distinct biologic processes may lead to their use as biomarkers for personalized radiation therapy and prognosis in the future.

Correlation of p16 status, hypoxic imaging using [18F]-misonidazole positron emission tomography and outcome in patients with loco-regionally advanced head and neck cancer.

INTRODUCTION: We investigated the relationship between hypoxia, human papillomavirus (HPV) status and outcome in head and neck squamous cell carcinoma. METHODS: Patients with stage III and IV head and neck squamous cell carcinoma treated on phase I and II chemoradiation trials with 70-Gy radiation combined with tirapazamine/cisplatin or cisplatin/fluorouracil (5FU), hypoxic imaging using [18F]-misonidazole positron emission tomography and known HPV status (by p16 immunohistochemistry) were included in this sub-study. Separate analyses were conducted to consider the impact of tirapazamine on HPV-negative tumours in the phase II trial. RESULTS: Both p16-positive oropharyngeal tumours and p16-negative head and neck squamous cell carcinoma tumours had a high prevalence of tumour hypoxia; 14/19 (74%) and 35/44 (80%), respectively. The distribution of hypoxia (primary, nodal) was similar. On phase II, trial patients with p16-negative hypoxic tumours had worse loco-regional control with cisplatin and 5FU compared with tirapazamine and cisplatin (P < 0.001) and worse failure-free survival (hazard ratio = 5.18; 95% confidence interval, 1.98-13.55; P = 0.001). Only 1 out of 14 p16-positive patients on the phase II trial experienced loco-regional failure. CONCLUSION: Hypoxia, as assessed by [18F]-misonidazole positron emission tomography, is frequently present in both p16-positive and negative head and neck cancer. Further research is required to determine whether hypoxic imaging can be used to predict benefit from hypoxia-targeting therapies in patients with p16-negative tumours.

Absence of a relationship between tumor ¹8F-fluorodeoxyglucose standardized uptake value and survival in patients treated with definitive radiotherapy for non-small-cell lung cancer.

INTRODUCTION: A recent meta-analysis suggested that patients with non-small-cell lung cancer (NSCLC) whose primary tumors have a higher standardized uptake value (SUV) derived from F-fluorodeoxyglucose positron emission tomography (PET) have a worse prognosis in comparison with those with tumors with lower values. However, previous analyses have had methodological weaknesses. Furthermore, the prognostic significance over the full range of SUV values in patients treated nonsurgically remains unclear. The aim of this retrospective study was to investigate the relationship between survival and maximum SUV (SUV(max)) analyzed as a continuous variable, in patients with NSCLC, staged using PET/computed tomography (CT) and treated with radiotherapy with or without chemotherapy. METHODS: Eligible patients had a histological diagnosis of NSCLC, were treated with radical radiotherapy with or without chemotherapy as their primary treatment, and had pretreatment PET/CT scans. SUV(max), defined as the maximum pixel SUV value retrieved from the primary tumor, was analyzed primarily as a continuous variable for overall survival. RESULTS: Eighty-eight patients met eligibility criteria: stage I, 19; stage II, 10; and stage III, 59. Median SUV(max) was 15.0 (range, 2.5-56). Higher stage was associated with higher SUV(max) values (p = 0.048). In univariate analysis, there was no evidence of a prognostic effect of SUV(max) (hazard ratio per doubling = 0.83; 95% confidence interval, 0.62-1.11; p = 0.22). Analyzing SUV(max) as a dichotomous variable (median cut point = 15.0), the hazard ratio (high: low) for risk of death was 0.71, with p = 0.18 (95% confidence interval, 0.44-1.15). CONCLUSIONS: In this cohort of patients, increasing SUV(max) derived from F-fluorodeoxyglucose-PET/CT was associated with increasing tumor, node, metastasis (TNM) stage. We found no evidence of an association of increasing SUV(max) with a shorter survival. Previous reports of an association between prognosis and SUV(max) may partly be the result of methodological differences between this study and previous reports and an association between stage and SUV(max).

InterProScan 5: genome-scale protein function classification.

MOTIVATION: Robust large-scale sequence analysis is a major challenge in modern genomic science, where biologists are frequently trying to characterize many millions of sequences. Here, we describe a new Java-based architecture for the widely used protein function prediction software package InterProScan. Developments include improvements and additions to the outputs of the software and the complete reimplementation of the software framework, resulting in a flexible and stable system that is able to use both multiprocessor machines and/or conventional clusters to achieve scalable distributed data analysis. InterProScan is freely available for download from the EMBl-EBI FTP site and the open source code is hosted at Google Code.

In vivo measurement of hippocampal GABAA/cBZR density with [18F]-flumazenil PET for the study of disease progression in an animal model of temporal lobe epilepsy.

PURPOSE: Imbalance of inhibitory GABAergic neurotransmission has been proposed to play a role in the pathogenesis of temporal lobe epilepsy (TLE). This study aimed to investigate whether [(18)F]-flumazenil ([(18)F]-FMZ) PET could be used to non-invasively characterise GABAA/central benzodiazepine receptor (GABAA/cBZR) density and affinity in vivo in the post-kainic acid status epilepticus (SE) model of TLE. METHODS: Dynamic [(18)F]-FMZ -PET scans using a multi-injection protocol were acquired in four male wistar rats for validation of the partial saturation model (PSM). SE was induced in eight male Wistar rats (10 weeks of age) by i.p. injection of kainic acid (7.5-25 mg/kg), while control rats (n = 7) received saline injections. Five weeks post-SE, an anatomic MRI scan was acquired and the following week an [(18)F]-FMZ PET scan (3.6-4.6 nmol). The PET data was co-registered to the MRI and regions of interest drawn on the MRI for selected structures. A PSM was used to derive receptor density and apparent affinity from the [(18)F]-FMZ PET data. KEY FINDINGS: The PSM was found to adequately model [(18)F]-FMZ binding in vivo. There was a significant decrease in hippocampal receptor density in the SE group (p<0.01), accompanied by an increase in apparent affinity (p<0.05) compared to controls. No change in cortical receptor binding was observed. Hippocampal volume reduction and cell loss was only seen in a subset of animals. Histological assessment of hippocampal cell loss was significantly correlated with hippocampal volume measured by MRI (p<0.05), but did not correlate with [(18)F]-FMZ binding. SIGNIFICANCE: Alterations to hippocampal GABAA/cBZR density and affinity in the post-kainic acid SE model of TLE are detectable in vivo with [(18)F]-FMZ PET and a PSM. These changes are independent from hippocampal cell and volume loss. [(18)F]-FMZ PET is useful for investigating the role that changes GABAA/cBZR density and binding affinity play in the pathogenesis of TLE.

Preclinical FLT-PET and FDG-PET imaging of tumor response to the multi-targeted Aurora B kinase inhibitor, TAK-901.

INTRODUCTION: The Aurora kinases play a key role in mitosis and have recently been identified as attractive targets for therapeutic intervention in cancer. The aim of this study was therefore to investigate the utility of 3'-[(18)F]fluoro-3'-deoxythymidine (FLT) and 2-deoxy-2-[(18)F]fluoro-D-glucose (FDG) for assessment of tumor response to the multi-targeted Aurora B kinase inhibitor, TAK-901. METHODS: Balb/c nude mice bearing HCT116 colorectal xenografts were treated with up to 30mg/kg TAK 901 or vehicle intravenously twice daily for two days on a weekly cycle. Tumor growth was monitored by calliper measurements and PET imaging was performed at baseline, day 4, 8, 11 and 15. Tumors were harvested at time points corresponding to days of PET imaging for analysis of ex vivo markers of cell proliferation and metabolism together with markers of Aurora B kinase inhibition including phospho-histone H3 (pHH3) and senescence associated ß-galactosidase. RESULTS: Tumor growth was inhibited by 60% on day 12 of 30mg/kg TAK-901 therapy. FLT uptake was significantly reduced by day 4 of treatment and this corresponded with reduction in bromodeoxyuridine and pHH3 staining by immunohistochemistry. All biomarkers rebounded towards baseline levels by the commencement of the next treatment cycle, consistent with release of Aurora B kinase suppression. TAK-901 therapy had no impact on glucose metabolism as assessed by FDG uptake and GLUT1 staining by immunohistochemistry. CONCLUSIONS: FLT-PET, but not FDG-PET, is a robust non-invasive imaging biomarker of early HCT116 tumor response to the on-target effects of the multi-targeted Aurora B kinase inhibitor, TAK-901. ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE: This is the first report to demonstrate the impact of the multi-targeted Aurora B kinase inhibitor, TAK-901 on tumor FLT uptake. The findings provide a strong rationale for the evaluation of FLT-PET as an early biomarker of tumor response in the early phase clinical development of this compound.

High-resolution imaging of pulmonary ventilation and perfusion with 68Ga-VQ respiratory gated (4-D) PET/CT.

PURPOSE: Our group has previously reported on the use of (68)Ga-ventilation/perfusion (VQ) PET/CT scanning for the diagnosis of pulmonary embolism. We describe here the acquisition methodology for (68)Ga-VQ respiratory gated (4-D) PET/CT and the effects of respiratory motion on image coregistration in VQ scanning. METHODS: A prospective study was performed in 15 patients with non-small-cell lung cancer. 4-D PET and 4-D CT images were acquired using an infrared marker on the patient's abdomen as a surrogate for breathing motion following inhalation of Galligas and intravenous administration of (68)Ga-macroaggregated albumin. Images were reconstructed with phase-matched attenuation correction. The lungs were contoured on CT and PET VQ images during free-breathing (FB) and at maximum inspiration (Insp) and expiration (Exp). The similarity between PET and CT volumes was measured using the Dice coefficient (DC) comparing the following groups; (1) FB-PET/CT, (2) InspPET/InspCT, (3) ExpPET/Exp CT, and (4) FB-PET/AveCT. A repeated measures one-way ANOVA with multiple comparison Tukey tests were performed to evaluate any difference between the groups. Diaphragmatic motion in the superior-inferior direction on the 4-D CT scan was also measured. RESULTS: 4-D VQ scanning was successful in all patients without additional acquisition time compared to the nongated technique. The highest volume overlap was between ExpPET and ExpCT and between FB-PET and AveCT with a DC of 0.82 and 0.80 for ventilation and perfusion, respectively. This was significantly better than the DC comparing the other groups (0.78-0.79, p < 0.05). These values agreed with a visual inspection of the images with improved image coregistration around the lung bases. The diaphragmatic motion during the 4-D CT scan was highly variable with a range of 0.4-3.4 cm (SD 0.81 cm) in the right lung and 0-2.8 cm (SD 0.83 cm) in the left lung. Right-sided diaphragmatic nerve palsy was observed in 3 of 15 patients. CONCLUSION: (68)Ga-VQ 4-D PET/CT is feasible and the blurring caused by respiratory motion is well corrected with 4-D acquisition, which principally reduces artefact at the lung bases. The images with the highest spatial overlap were the combined expiration phase or FB PET and average CT. With higher resolution than SPECT/CT, the PET/CT technique has a broad range of potential clinical applications including diagnostic algorithms for patients with suspected pulmonary embolism, preoperative evaluation of regional lung function and improving assessment or understanding of pulmonary physiology in the vast range of pulmonary diseases.