Automated radiosynthesis of [68 Ga]Ga-PSMA-11 and [177 Lu]Lu-PSMA-617 on the iPHASE MultiSyn module for clinical applications.

Prostate-specific membrane antigen (PSMA)-targeted imaging and therapy of prostate cancer using theranostic pairs is rapidly changing clinical practice. To facilitate clinical trials, fully automated procedures for the radiosyntheses of [68 Ga]Ga-PSMA-11 and [177 Lu]Lu-PSMA-617 were developed from commercially available precursors using the cassette based iPHASE MultiSyn module. Formulated and sterile radiopharmaceuticals were obtained in 76 ± 3% (n = 20) and 91 ± 4% (n = 15) radiochemical yields after 17 and 20 min, respectively. Radiochemical purity was always >95% and molar activities exceeded 792 ± 100 and 88 ± 6 GBq/µmol, respectively. Quality control showed conformity with all relevant release criteria and radiopharmaceuticals were used in the clinic.

Spatial and quantitative mapping of glycolysis and hypoxia in glioblastoma as a predictor of radiotherapy response and sites of relapse.

INTRODUCTION: Tumor hypoxia is a centerpiece of disease progression mechanisms such as neoangiogenesis or aggressive hypoxia-resistant malignant cells selection that impacts on radiotherapy strategies. Early identification of regions at risk for recurrence and prognostic-based classification of patients is a necessity to devise tailored therapeutic strategies. We developed an image-based algorithm to spatially map areas of aerobic and anaerobic glycolysis (Glyoxia). METHODS: 18F-FDG and 18F-FMISO PET studies were used in the algorithm to produce DICOM-co-registered representations and maximum intensity projections combined with quantitative analysis of hypoxic volume (HV), hypoxic glycolytic volume (HGV), and anaerobic glycolytic volume (AGV) with CT/MRI co-registration. This was applied to a prospective clinical trial of 10 glioblastoma patients with post-operative, pre-radiotherapy, and early post-radiotherapy 18F-FDG and 18F-FMISO PET and MRI studies. RESULTS: In the 10 glioblastoma patients (5M:5F; age range 51-69 years), 14/18 18F-FMISO PET studies showed detectable hypoxia. Seven patients survived to complete post-radiotherapy studies. The patient with the longest overall survival showed non-detectable hypoxia in both pre-radiotherapy and post-radiotherapy 18F-FMISO PET. The three patients with increased HV, HGV, and AGV volumes after radiotherapy showed 2.8 months mean progression-free interval vs. 5.9 months for the other 4 patients. These parameters correlated at that time point with progression-free interval. Parameters combining hypoxia and glycolytic information (i.e., HGV and AGV) showed more prominent variation than hypoxia-based information alone (HV). Glyoxia-generated images were consistent with disease relapse topology; in particular, one patient had distant relapse anticipated by HV, HGV, and AGV maps. CONCLUSION: Spatial mapping of aerobic and anaerobic glycolysis allows unique information on tumor metabolism and hypoxia to be evaluated with PET, providing a greater understanding of tumor biology and potential response to therapy.

Complexes of gastrin with In3+, Ru3+ or Ga3+ ions are not recognised by the cholecystokinin 2 receptor.

The peptide hormone gastrin (Gamide) binds trivalent metal ions, including indium (In), ruthenium (Ru) and gallium (Ga), with high affinity. Complexes of gastrin with chelated isotopes of In and Ga have previously been used for the location of tumours expressing the cholecystokinin 2 receptor (CCK2R). The aim of the present study was to purify the complexes of Gamide with radioactive isotopes of In, Ru or Ga and to investigate their ability to bind to the CCK2R. The radioactive Gamide complexes were purified on Sep-Pak C18 cartridges or by anion exchange HPLC. Binding to the CCK2R was assessed with a stably transfected clone of the gastric carcinoma cell line AGS. The 106Ru-Gamide complex could be eluted from the C18 cartridge; the 111In-Gamide and 68Ga-Gamide complexes bound irreversibly. All three complexes were successfully purified by anion exchange HPLC. The failure to detect binding of the 111In-Gamide, 106Ru-Gamide and 68Ga-Gamide complexes to the CCK2R suggests that formation of these complexes will not be useful for the detection of tumours expressing this receptor, but may instead provide alternative ways to block the actions of Gamide as a growth factor or a stimulant of gastric acid secretion. The complexes between the hormone gastrin and radioactive 111In, 106Ru or 68Ga ions were purified by anion exchange HPLC using a NaCl gradient. The failure to detect binding of the complexes to the cholecystokinin 2 receptor suggests that metal ion treatment may provide novel approaches to block the biological actions of gastrin.

Hypoxia-targeted radiotherapy dose painting for head and neck cancer using (18)F-FMISO PET: a biological modeling study.

BACKGROUND: This study investigates the use of (18)F-fluoromisonidazole (FMISO) PET-guided radiotherapy dose painting for potentially overcoming the radioresistant effects of hypoxia in head and neck squamous cell carcinoma (HNSCC). MATERIAL AND METHODS: The study cohort consisted of eight patients with HNSCC who were planned for definitive radiotherapy. Hypoxic subvolumes were automatically generated on pre-radiotherapy FMISO PET scans. Three radiotherapy plans were generated for each patient: a standard (STD) radiotherapy plan to a dose of 70 Gy, a uniform dose escalation (UDE) plan to the standard target volumes to a dose of 84 Gy, and a hypoxia dose-painted (HDP) plan with dose escalation only to the hypoxic subvolume to 84 Gy. Plans were compared based on tumor control probability (TCP), normal tissue complication probability (NTCP), and uncomplicated tumor control probability (UTCP). RESULTS: The mean TCP increased from 73% with STD plans to 95% with the use of UDE plans (p < 0.001) and to 93% with HDP plans (p < 0.001). The mean parotid NTCP increased from 26% to 44% with the use of UDE plans (p = 0.003), and the mean mandible NTCP increased from 2% to 27% with the use of UDE plans (p = 0.001). There were no statistically significant differences between any of the NTCPs between the STD plans and HDP plans. The mean UTCP increased from 48% with STD plans to 66% with HDP plans (p = 0.016) and dropped to 37% with UDE plans (p = 0.138). CONCLUSION: Hypoxia-targeted radiotherapy dose painting for head and neck cancer using FMISO PET is technically feasible, increases the TCP without increasing the NTCP, and increases the UTCP. This approach is superior to uniform dose escalation.

Evaluation of 18F-FMISO PET and 18F-FDG PET Scans in Assessing the Therapeutic Response of Patients With Metastatic Colorectal Cancer Treated With Anti-Angiogenic Therapy.

INTRODUCTION: Tumor hypoxia and angiogenesis are implicated in tumor growth and metastases, and anti-angiogenic therapies have an important role in treating patients with metastatic colorectal cancer. However, the prevalence of hypoxia has not been fully evaluated in colorectal liver metastases, and hypoxic response to anti-angiogenic therapy has not been clearly established. The aims of the study were to evaluate the changes seen on 18F-FMISO and 18F-FDG PET scans in patients treated with anti-angiogenic therapy, and to correlate these measures of hypoxia and metabolism with clinical outcomes, and blood biomarkers of angiogenesis. METHODS: Patients with metastatic colorectal carcinoma planned for treatment with bevacizumab and chemotherapy received routine staging investigations prior to any treatment, including a FDG PET scan. A FMISO PET scan was performed within 4 weeks of staging tests, with blood specimens collected at that time for serum VEGF and osteopontin measurement. Follow-up FDG and FMISO scans were performed after 1 cycle of treatment. Results were compared to response (RECIST), progression free survival (PFS), and overall survival (OS). RESULTS: A total of 15 patients were recruited into this prospective trial, of which 13 patients were evaluable for assessment of treatment follow-up. Baseline FDG uptake was higher than FMISO uptake, and there was a significant decrease in FDG uptake (SUVmax and TGV) but not FMISO uptake (SUVmax and TNR) after treatment. There was a positive correlation between FDG and FMISO SUVmax on both baseline and post-treatment PET scans. Blood biomarkers of serum VEGF and osteopontin were significantly correlated with the FDG and FMISO PET parameters. CONCLUSIONS: This study shows that hypoxia in metastatic colorectal cancer, assessed by FMISO PET, shows minor changes following initial treatment with anti-angiogenic therapy, but is associated with therapeutic response. FDG PET uptake changes (SUVmax, TLG) are also associated with response to anti-angiogenic therapy. These findings demonstrate the interplay between tumor metabolism and hypoxic regulation following anti-angiogenic treatment of metastatic colorectal cancer.

Correlation of hypoxic cell fraction and angiogenesis with glucose metabolic rate in gliomas using 18F-fluoromisonidazole, 18F-FDG PET, and immunohistochemical studies.

UNLABELLED: PET offers a noninvasive means to assess neoplasms, in view of its sensitivity and accuracy in staging tumors and potentially in monitoring treatment response. The aim of this study was to evaluate newly diagnosed primary brain tumors for the presence of hypoxia, as indicated by the uptake of 18F-fluoromisonidazole (18F-FMISO) and to examine the relationship of hypoxia to the uptake of 18F-FDG and molecular markers of hypoxia. METHODS: Seventeen patients with suspected primary glioma were enrolled prospectively in this study. Sixteen patients had histology, with 2 having metastatic disease. All patients had PET studies with 18F-FMISO and 18F-FDG and MRI studies. Immunohistochemistry was undertaken with tumor markers of angiogenesis and hypoxia. Patients were monitored for disease progression and statistical analysis of data was performed. RESULTS: Of the 14 patients with histology, 8 died with a median time of 16 mo (range, 2-30 mo) until death. Of those who died, 7 had positive and 1 had negative 18F-FMISO uptake. 18F-FMISO uptake was observed in all high-grade gliomas but not in low-grade gliomas. A significant relationship was found between 18F-FDG or 18F-FMISO uptake and expression of VEGF-R1 and Ki67 expression. Other immunohistochemical markers demonstrated a trend toward increased uptake but none was significant. CONCLUSION: 18F-FMISO PET provides a noninvasive assessment of hypoxia in glioma and was prognostic for treatment outcomes in the majority of patients. 18F-FMISO PET may have a role not only in directing patients toward targeted hypoxic therapies but also in monitoring response to such therapies.

Lack of correlation of hypoxic cell fraction and angiogenesis with glucose metabolic rate in non-small cell lung cancer assessed by 18F-Fluoromisonidazole and 18F-FDG PET.

UNLABELLED: PET offers a noninvasive means to assess neoplasms, in view of its sensitivity and accuracy in staging tumors and potentially in monitoring treatment response. The aim of this study was to evaluate newly diagnosed non-small cell lung cancer (NSCLC) for the presence of hypoxia, as indicated by the uptake of (18)F-Fluoromisonidazole ((18)F-FMISO), and to examine the relationship of hypoxia to the uptake of (18)F-FDG, microvessel density, and other molecular markers of hypoxia. METHODS: Twenty-one patients with suspected or biopsy-proven NSCLC were enrolled prospectively in this study. All patients had PET studies with (18)F-FMISO and (18)F-FDG. Seventeen patients subsequently underwent surgery, with analysis performed for tumor markers of angiogenesis and hypoxia. RESULTS: In the 17 patients with resectable NSCLC (13 men, 4 women; age range, 51-77 y), the mean (18)F-FMISO uptake in tumor was significantly lower than that of (18)F-FDG uptake (P < 0.0001) and showed no correlation with (18)F-FDG uptake (r = 0.26). The mean (95% confidence interval [CI]) (18)F-FMISO SUV(max) (maximum standardized uptake value) was 1.20 [0.95-1.45] compared with the mean [95% CI] (18)F-FDG SUV(max) of 5.99 [4.62-7.35]. The correlation between (18)F-FMISO uptake, (18)F-FDG uptake, and tumor markers of hypoxia and angiogenesis was poor. A weakly positive correlation between (18)F-FMISO and (18)F-FDG uptake and Ki67 was found. CONCLUSION: The hypoxic cell fraction of primary NSCLC is consistently low, and there is no significant correlation in NSCLC between hypoxia and glucose metabolism in NSCLC assessed by (18)F-FDG. These findings have direct implications in understanding the role of angiogenesis and hypoxia in NSCLC biology.

Synthesis, 11C labeling and biological properties of derivatives of the tyrphostin AG957.

Four analogues of AG957, a known inhibitor of the tyrosine kinase p210(bcr-abl), have been synthesized and tested for their growth inhibitory effect against the BCR/ABL-positive FDrv210C cells as well as the epidermal growth factor (EGF) receptor-positive Baf/ERX cells. All compounds that can undergo oxidation to the corresponding quinone demonstrated inhibition of FDrv210C cells and Baf/ERX cells. Compounds that cannot become oxidized showed significantly less inhibition of BCR/ABL- or EGF receptor-mediated cell proliferation. The (11)C-labeled compounds were prepared by labeling 4-aminobenzoic acid using [(11)C]CH(3)I, which afforded the corresponding (11)C-labeled methyl ester in excellent yields. Subsequent condensation of the amino group with an appropriately substituted hydroxy benzaldehyde formed the respective Schiff base. Reduction of this compound with NaBH(3)CN gave the (11)C-labeled inhibitors in an overall radiochemical yield of 17.3+/-2.1% (n=3; not decay corrected) and an average specific radioactivity of 40 GBq/micromol (1.1 Ci/micromol) at the end of synthesis. The total synthesis time from EOB including HPLC purification and formulation was 45 min.

Imaging the ischemic penumbra with 18F-fluoromisonidazole in a rat model of ischemic stroke.

BACKGROUND AND PURPOSE: The ischemic penumbra is a major focus of stroke research. 18F-fluoromisonidazole (18F-FMISO), a positron emission tomography (PET) marker of hypoxic cells, has shown promise as a technique to image the penumbra in humans. Our aim was to delineate the pattern of 18F-FMISO binding in a rat middle cerebral artery transient thread-occlusion model, and correlate this with tissue outcome at 24 hours. We hypothesized that the pattern of 18F-FMISO binding would mimic that seen in humans. METHODS: Thirty-eight rats underwent 2 hours transient middle cerebral artery (MCA) occlusion, and then received 18F-FMISO at time points from 0.5 to 22 hours post-MCA occlusion and were killed 2 hours later. Autoradiographic assessment of 18F-FMISO binding and assessment (triphenyltetrazolium chloride) of the area of infarction were performed on tissue slices. RESULTS: Until 1 hour after MCA occlusion, 18F-FMISO binding was increased in the entire MCA territory, with little or no infarction visible. Over the next 5 hours, the pattern of binding evolved to a small rim of intensely binding tissue surrounding the infarct core, which itself showed reduced binding compared with the contralateral hemisphere. By 24 hours, there was minimal accumulation of 18F-FMISO binding and a large area of infarction. CONCLUSIONS: The pattern of 18F-FMISO binding rats reproduced the pattern seen in humans, consistent with this tracer being a marker of the ischemic penumbra in both species. This technique may have application in studying the ischemic penumbra in animal models, and correlating this with similar studies in humans.

A novel method for determining hepatic sinusoidal oxygen permeability in the isolated perfused rat liver using [15O]O2.

Measurement of hepatic sinusoidal permeability of oxygen and other substrates may help elucidate the mechanisms responsible for impaired liver function in cirrhosis. However studies of sinusoidal oxygen permeability in normal liver and various disease states have been limited due to the considerable technical difficulties involved in the use of standard techniques. We have developed a new method for measuring sinusoidal oxygen permeability in the isolated perfused rat liver that overcomes the difficulties of previous methods by using [(15)O]O(2) and an in-line fluid monitor. This method uses data obtained from impulse response curves of radiolabelled red cells, albumin and oxygen that are fitted mathematically using the axial dispersion model to yield rate constants that describe oxygen transit through the liver. We have demonstrated the utility and reproducibility of this method by comparing multiple injections and permeability determinations in the same preparation. This approach could be used in isolated perfused organs to study oxygen permeability in a range of disease states.

Imaging and quantitation of the hypoxic cell fraction of viable tumor in an animal model of intracerebral high grade glioma using [18F]fluoromisonidazole (FMISO).

We have demonstrated that FMISO uptake is significantly higher in tumor tissue in the C6 intracerebral glioma rat model compared to normal brain, and that there is persisting hypoxia in gliomas independent of tumor size. FMISO uptake was observed homogeneously throughout viable glioma tissue in tumor sizes ranging from 2mm to almost 1cm. Quantitation of uptake of FMISO showed a tumor/brain ratio of 1.9 and a tumor/blood ratio of 2.6 at 2 hours post injection.

Separation of Intrinsic and Electrostrictive Volume Effects in Redox Reaction Volumes of Metal Complexes Measured Using High-Pressure Cyclic Staircase Voltammetry.

Redox reaction volumes, obtained by high-pressure cyclic voltammetry, are reported for a selection tris(diimine), tris(diamine), hexaammine, and hexaaqua couples of Fe(III/II), Cr(III/II), Ru(III/II), and Co(III/II). Separation of the intrinsic and electrostrictive volume contributions for these couples has been achieved, some in both aqueous and acetonitrile solutions. For the Co(phen)(3)(3+/2+) system, the intrinsic volume change is estimated to be +15.3 +/- 2.1 cm(3) mol(-)(1) (based on measurements in water) and +16.5 +/- 2.0 cm(3) mol(-)(1) (in acetonitrile). For the Co(bipy)(3)(3+/2+) system, values are +12.7 +/- 1.4 cm(3) mol(-)(1) (in water) and +15.5 +/- 2.5 cm(3) mol(-)(1) (in acetonitrile). Using these experimentally determined intrinsic contributions, a simple structural model suggests that the intrinsic volume change for these reactions can be described using the change in effective volume of a sphere with radius close to that of the coordinating-atom-metal bond length. Electrostrictive volume changes for the 3+/2+ complex-ion couples are a function of solute size and coordinated ligands. For Ru(H(2)O)(6)(3+) and Fe(H(2)O)(6)(3+) reduction, volume behavior is significantly different from that of the other systems studied and can be rationalized in terms of possible H-bonding interactions with surrounding solvent which affect the electrostrictive volume changes but which are not available for the ammine and other complexes studied.

In vivo imaging of cellular proliferation in renal cell carcinoma using 18F-fluorothymidine PET.

OBJECTIVES: The ability to measure cellular proliferation non-invasively in renal cell carcinoma may allow prediction of tumour aggressiveness and response to therapy. The aim of this study was to evaluate the uptake of 18F-fluorothymidine (FLT) PET in renal cell carcinoma (RCC), and to compare this to 18F-fluorodeoxyglucose (FDG), and to an immunohistochemical measure of cellular proliferation (Ki-67). METHODS: Twenty seven patients (16 male, 11 females; age 42-77) with newly diagnosed renal cell carcinoma suitable for resection were prospectively enrolled. All patients had preoperative FLT and FDG PET scans. Visual identification of tumour using FLT PET compared to normal kidney was facilitated by the use of a pre-operative contrast enhanced CT scan. After surgery tumour was taken for histologic analysis and immunohistochemical staining by Ki-67. RESULTS: The SUVmax (maximum standardized uptake value) mean±SD for FLT in tumour was 2.59±1.27, compared to normal kidney (2.47±0.34). The mean SUVmax for FDG in tumour was similar to FLT (2.60±1.08). There was a significant correlation between FLT uptake and the immunohistochemical marker Ki-67 (r=0.72, P<0.0001) in RCC. Ki-67 proliferative index was mean ± SD of 13.3%±9.2 (range 2.2% - 36.3%). CONCLUSION: There is detectable uptake of FLT in primary renal cell carcinoma, which correlates with cellular proliferation as assessed by Ki-67 labelling index. This finding has relevance to the use of FLT PET in molecular imaging studies of renal cell carcinoma biology.

The resistance to ischemia of white and gray matter after stroke.

A contributing factor to the failure of trials of neuroprotectants in acute ischemic stroke may be the differing vulnerability to ischemia of white compared with gray matter. To address this issue, we determined to establish the existence of potentially viable tissue in white matter and its evolution to infarction or salvage in both gray and white matter compartments in patients with ischemic stroke. Twenty-seven patients (mean age, 73.4 years) at a median of 16.5 hours after symptom onset were studied using the hypoxic marker 18F-misonidazole with positron emission tomography (PET). Tissue was segmented using an magnetic resonance probabilistic map. Although there was a greater volume of initially "at-risk tissue" in gray matter (58.3 cm3, 29.9-93.0 cm3 than white matter (42.0 cm3, 15.8-74.0 cm3; p <0.001) at the time of PET imaging, a higher proportion of this was still potentially viable in white matter (41.4%, 4.6-74.5%) than in gray matter (23.6%, 3.2-61.1%; p <0.05). However, a similar proportion in each compartment spontaneously survived. These data provide evidence for the existence of potentially salvageable tissue in human white matter and is consistent with it having a similar or even greater resistance to ischemia than gray matter. For the latter possibility, alternative therapeutic strategies may be required for its salvage.