<Superscript>18</Superscript>F-Labeled Galacto and PEGylated RGD Dimers for PET Imaging of α<Subscript>v</Subscript>β<Subscript>3</Subscript> Integrin Expression

Purpose

In vivo imaging of α_vβ₃ has important diagnostic and therapeutic applications. ¹⁸F-Galacto-arginine–glycine–aspartic acid (RGD) has been developed for positron emission tomography (PET) imaging of integrin α_vβ₃ expression and is now being tested on humans. Dimerization and multimerization of cyclic RGD peptides have been reported to improve the integrin α_vβ₃-binding affinity due to the polyvalency effect. Here, we compared a number of new dimeric RGD peptide tracers with the clinically used ¹⁸F-galacto-RGD.

Procedures

RGD monomers and dimers were coupled with galacto or PEG₃ linkers, and labeled with ¹⁸F using 4-nitrophenyl 2-¹⁸F-fluoropropionate (¹⁸F-NFP) or N-succinimidyl 4-¹⁸F-fluorobenzoate as a prosthetic group. The newly developed tracers were evaluated by cell-based receptor-binding assay, biodistribution, and small-animal PET studies in a subcutaneous U87MG glioblastoma xenograft model.

Results

Starting with ¹⁸F-F^?, the total reaction time for ¹⁸F-FP-SRGD2 and ¹⁸F-FP-PRGD2 is about 120 min. The decay-corrected radiochemical yields for ¹⁸F-FP-SRGD2 and ¹⁸F-FP-PRGD2 are 52?±?9% and 80?±?7% calculated from ¹⁸F-NFP. Noninvasive small-animal PET and direct tissue sampling experiments demonstrated that the dimeric RGD peptides had significantly higher tumor uptake as compared to ¹⁸F-galacto-RGD.

Conclusion

Dimeric RGD peptide tracers with relatively high tumor integrin-specific accumulation and favorable in vivo kinetics may have the potential to be translated into clinic for integrin α_vβ₃ imaging.

     

Blood Clearance Kinetics,Biodistribution, and Radiation Dosimetry of a Kit-Formulated Integrin α<Subscript>v</Subscript>β<Subscript>3</Subscript>-Selective Radiotracer <Superscript>99m</Superscript>Tc-3PRGD<Subscript>2</Subscript> in Non-Human Primates

Purpose  

^99mTc-3PRGD₂ is a ^99mTc-labeled dimeric cyclic RGD peptide with increased receptor binding affinity and improved kinetics for in vivo imaging of integrin α_vβ₃ expression in nude mouse model. To accelerate its clinical translation, we reported here the evaluation of the kit-formulated ^99mTc-3PRGD₂ in healthy cynomolgus primates for its blood clearance kinetics, biodistribution, and radiation dosimetry.     

Comparison of [<Superscript>99m</Superscript>Tc]3PRGD<Subscript>2</Subscript> Imaging and [<Superscript>18</Superscript>F]FDG PET/CT in Breast Cancer and Expression of Integrin α<Subscript>v</Subscript>β<Subscript>3</Subscript> in Breast Cancer Vascular Endothelial Cells

Purpose

This study aimed to investigate the value of ^99mtechnetium-three polyethylene glycol spacers-arginine-glycine-aspartic acid ([^99mTc]3PRGD₂) imaging in diagnosis and staging of breast cancer compared with 2-deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG) imaging, and to explore the expression of integrin α_vβ₃ in tumor vascular endothelial cells.

Procedures

Forty-two women with suspected breast cancer underwent both [^99mTc]3PRGD₂ imaging and [¹⁸F]FDG imaging. Visual analysis was used to assess primary breast lesion, axillary lymph node, and distant metastasis. The tumor-blood (T/B) ratios from [^99mTc]3PRGD₂ imaging and the maximum standardized uptake value (SUVmax) from [¹⁸F]FDG imaging were analyzed for breast lesions. Integrin α_vβ₃ was analyzed through immunohistochemistry.

Results

Forty-five breast lesions were found (malignant, n?=?38; benign, n?=?7). The sensitivity, specificity, and accuracy of [^99mTc]3PRGD₂ and [¹⁸F]FDG imaging in visual analysis for the breast lesion were 97.4, 87.5, and 95.6 % and 97.4, 71.4, and 93.3 %, respectively (P?>?0.05). For semi-quantitative analysis, no significant difference of the area under the curves (AUC) was found in the imaging using the two radiopharmaceuticals (0.880 and 0.955; Z?=?0.88, P?>?0.05). The sensitivity, specificity, and accuracy for axillary lymph node metastasis with [^99mTc]3PRGD₂ and [¹⁸F]FDG were 78.05, 99.36, and 94.92 % and 85.37, 98.72, and 95.64 %, respectively (P?>?0.05). Nine patients with distant metastases were all detected with the two radiopharmaceuticals. The expression of integrin α_vβ₃ was correlated with [^99mTc]3PRGD₂ uptake (r?=?0.582, P?=?0.001), which were significantly higher in the HER2-positive and stage III–IV patients (P?<?0.05).

Conclusions

The prospective study demonstrated that [^99mTc]3PRGD₂ imaging seems to be valuable for diagnosis of breast cancer and its staging. It may be less sensitive for detecting small lymph node metastatic lesions when compared with [¹⁸F]FDG imaging. Integrin α_vβ₃ in tumor microvessels was associated with the breast cancer subtype and its staging.

     

Imaging VEGF Receptors and α<Subscript>v</Subscript>β<Subscript>3</Subscript> Integrins in a Mouse Hindlimb Ischemia Model of Peripheral Arterial Disease

Purpose

To compare targeted imaging of vascular endothelial growth factor (VEGF) receptors vs. α_vβ₃ integrins in a mouse hindlimb ischemia model of peripheral artery disease.

Procedures

Male wild-type (WT) C57BL/6 mice (8- to 10-week old) (n?=?24) underwent left femoral artery ligation. The right leg served as control. Five days later, mice were injected with either VEGF receptor targeting [^99mTc]DOTA-PEG-scVEGF ([^99mTc]scV) (n?=?8) or with α_vβ₃-targeting tracer [^99mTc]HYNIC-cycloRGD ([^99mTc]RGD) (n?=?8) and underwent single photon emission computed tomography (SPECT) x-ray computed tomography imaging. To assess non-specific [^99mTc]scV uptake, six additional mice received a mixture of [^99mTc]scV and 30-fold excess of targeting protein, scVEGF. Tracer uptake as %ID was measured using volumetric regions encompassing the hindlimb muscles and as %ID/g from harvested limb muscles. Double and triple immunofluorescent analysis on tissue sections established localization of α_vβ₃, VEGFR-1, VEGFR-2, as well as certain cell lineage markers.

Results

Tracer uptake, as %ID/g, was higher in ligated limbs of mice injected with [^99mTc]scV compared to ligated hindlimbs in mice injected with [^99mTc]RGD (p?=?0.02). The ratio of tracer uptake for ligated/control hindlimb was borderline higher for [^99mTc]scV than for [^99mTc]RGD (p?=?0.06). Immunofluorescent analysis showed higher prevalence of VEGFR-1, VEGFR-2, and α_vβ₃, in damaged vs. undamaged hindlimb tissue, but with little co-localization of these markers. Double immunofluorescent staining showed partial co-localization of VEGFR-1, VEGFR-2, and α_vβ_3, with endothelial cell marker FVIII, but not with CD31. Immunostaining for VEGFR-1 and VEGFR-2 additionally co-localized with lineage markers for endothelial progenitor cell and monocytes/macrophages, with a more diverse pattern of co-localization for VEGFR-2.

Conclusion

In a mouse hindlimb ischemia model of peripheral artery disease, [^99mTc]scV SPECT tracer-targeting VEGF receptors showed a more robust signal than [^99mTc]RGD tracer-targeting α_vβ₃. Immunofluorescent analysis suggests that uptake of [^99mTc]scV and [^99mTc]RGD in damaged tissue is due to non-overlapping cell populations and reflects different dynamic processes and that enhanced uptake of [^99mTc]scV may be due to the presence of VEGF receptors on additional cell types.

     

Binding of α<Subscript>v</Subscript>β<Subscript>3</Subscript> Integrin-Specific Radiotracers Is Modulated by Both Integrin Expression Level and Activation Status

Purpose

Molecular imaging of α_vβ₃ integrin has exhibited real potential to guide the appropriate use of anti-angiogenic therapies. However, an incomplete understanding of the factors that influence binding of α_vβ₃ integrin-specific radiotracers currently limits their use for assessing response to therapy in cancer patients. This study identifies two fundamental factors that modulate uptake of these radiotracers.ProceduresExperiments were performed in prostate cancer (PC3) and glioblastoma (U87MG) cells, which differentially express α_vβ₃ integrin. α_vβ₃ integrin-specific radiotracers were used to investigate the effect of manipulating α_vβ₃ integrin expression or activation in cellular binding assays. β₃ integrin and α_vβ₃ integrin expression were measured by western blotting and flow cytometry, respectively. The effect of select pharmacological inhibitors on α_vβ₃ integrin activation and expression was also determined.

Results

Radiotracer binding was proportional to α_vβ₃ integrin expression when it was decreased (β₃ knock-down cells) or increased, either using pharmacological inhibitors of cell signalling or by culturing cells for different times. Studies with both small molecule and arginine–glycine–aspartic acid (RGD)-based radiotracers revealed increased radiotracer binding after activation of α_vβ₃ integrin with Mn²⁺ or talin head domain. Moreover, inhibition of fundamental signalling pathways (mitogen-activated protein kinase kinase (MEK), Src and VEGFR2) decreased radiotracer binding, reflecting reduced α_vβ₃ integrin activity.

Conclusion

Binding of small molecule ligands and radiolabelled RGD peptides is modulated by expression and activation status of α_vβ₃ integrin. α_vβ₃ integrin-specific radiotracers can provide otherwise inaccessible information of the effect of signalling pathways on α_vβ₃ integrin. This has significant implications for assessing response to anti-angiogenic therapies in clinical studies.

     

ImmunoPET Imaging of α<Subscript>v</Subscript>β<Subscript>6</Subscript> Expression Using an Engineered Anti-α<Subscript>v</Subscript>β<Subscript>6</Subscript> Cys-diabody Site-Specifically Radiolabeled with Cu-64: Considerations for Optimal Imaging with Antibody Fragments

Purpose

Increased expression of the α_vβ₆ integrin correlates with advanced tumor grade and poor clinical outcome, identifying α_vβ₆ as a prognostic indicator and an attractive target for molecular imaging. This work investigated the ability of a disulfide-stabilized [⁶⁴Cu]NOTA-α_vβ₆ cys-diabody to image α_vβ₆ expression in vivo using a nu/nu mouse model bearing human melanoma xenografts and positron-emission tomography.

Procedures

Small-animal positron emission tomography (PET) imaging, quantitative ROI analysis, and ex vivo biodistribution were conducted to ascertain tumor uptake and organ distribution of the [⁶⁴Cu]NOTA-α_vβ₆ cys-diabody. Immunohistochemical staining of tumors and mouse organs and immunoreactivity assays were utilized to correlate in vivo and ex vivo observations.

Results

PET imaging of the [⁶⁴Cu]NOTA-α_vβ₆ cys-diabody revealed low tumor uptake at 24 h p.i. in DX3Puroβ₆ tumors (2.69 ± 0.45 %ID/g) with comparable results found in the DX3Puro tumors (2.24 ± 0.15 %ID/g). Quantitative biodistribution confirmed that DX3Puroβ₆ tumor uptake was highest at 24 h p.i. (4.63 ± 0.18 %ID/g); however, uptake was also observed in the stomach (4.84 ± 2.99 %ID/g), small intestines (4.50 ± 1.69 %ID/g), large intestines (4.73 ± 0.97 %ID/g), gallbladder (6.04 ± 1.88 %ID/g), and lungs (3.89 ± 0.69 %ID/g).

Conclusions

Small-animal PET imaging was successful in visualizing α_vβ₆-positive tumor uptake of the [⁶⁴Cu]NOTA-α_vβ₆ cys-diabody. Cys-diabody cross-reactivity was observed between human and murine α_vβ₆ and immunohistochemical staining confirmed the presence of an endogenous α_vβ₆ antigen sink, which led to suboptimal tumor contrast in this mouse model. Future investigations will focus on dose escalation studies to overcome the endogenous antigen sink while increasing DX3Puroβ₆ tumor uptake.

     

β<Subscript>3</Subscript> phosphorylation of platelet α<Subscript>IIb</Subscript>β<Subscript>3</Subscript> is crucial for stability of arterial thrombus and microparticle formation in vivo

Background

It is well accepted that functional activity of platelet integrin α_IIbβ₃ is crucial for hemostasis and thrombosis. The β₃ subunit of the complex undergoes tyrosine phosphorylation shown to be critical for outside-in integrin signaling and platelet clot retraction ex vivo. However, the role of this important signaling event in other aspects of prothrombotic platelet function is unknown.

Method

Here, we assess the role of β₃ tyrosine phosphorylation in platelet function regulation with a knock-in mouse strain, where two β₃ cytoplasmic tyrosines are mutated to phenylalanine (DiYF). We employed platelet transfusion technique and intravital microscopy for observing the cellular events involved in specific steps of thrombus growth to investigate in detail the role of β₃ tyrosine phosphorylation in arterial thrombosis in vivo.

Results

Upon injury, DiYF mice exhibited delayed arterial occlusion and unstable thrombus formation. The mean thrombus volume in DiYF mice formed on collagen was only 50% of that in WT. This effect was attributed to DiYF platelets but not to other blood cells and endothelium, which also carry these mutations. Transfusion of isolated DiYF but not WT platelets into irradiated WT mice resulted in reversal of the thrombotic phenotype and significantly prolonged blood vessel occlusion times. DiYF platelets exhibited reduced adhesion to collagen under in vitro shear conditions compared to WT platelets. Decreased platelet microparticle release after activation, both in vitro and in vivo, were observed in DiYF mice compared to WT mice.

Conclusion

β₃ tyrosine phosphorylation of platelet α_IIbβ₃ regulates both platelet pro-thrombotic activity and the formation of a stable platelet thrombus, as well as arterial microparticle release.

     

In vitro performance of prefilled CO<Subscript>2</Subscript> absorbers with the Aisys<Superscript>®</Superscript>

Low flow anesthesia increases the use of CO₂ absorbents, but independent data that compare canister life of the newest CO₂ absorbents are scarce. Seven different pre-packed CO₂ canisters were tested in vitro: Amsorb Plus, Spherasorb, LoFloSorb, Medisorb, Medisorb EF, LithoLyme, and SpiraLith. CO₂ (160 mL min^?1) flowed into the tip of a 2 L breathing bag that was ventilated with a tidal volume of 500 mL, a respiratory rate of 10/min, and an I:E ratio of 1:1 using the controlled mechanical ventilation mode of the Aisys ^® (GE, Madison, WI, USA). In part I, canister life of each brand (all of the same lot) was tested with 12 different fresh gas flows (FGF) ranging from 0.25 to 4 L min^?1. In part II, canister life of six canisters each of two different lots of each brand were tested with a 350 mL min^?1 FGF. Canister life is presented as “FCU”, fractional canister usage, the fraction of a canister used per hour, and is defined for the inspired CO₂ concentration (F_ICO₂) that denotes exhaustion. In part III, canister life per 100 g fresh granule content was calculated. FCU decreased linearly with increasing FGF. The relative position of the FCU–FGF curves of the different brands depends on the F_ICO₂ threshold because the exhaustion rate (the rate of rise once F_ICO₂ starts to increase) differs among the brands. Intra-lot variability was 18 % or less. The different prepacks can be ranked according their efficiency (least to most efficient) as follows: Amsorb Plus = Medisorb EF < LoFloSorb < Medisorb = Spherasorb = LithoLyme < SpiraLith (all for an F_ICO₂ threshold = 0.5 %). Canister life per 100 g fresh granule content is almost twice as long when LiOH is used as the primary absorbent. The most important factors that determine canister life of prepacks in a circle breathing system are the chemical composition of the canister, the absolute amount of absorbent present in the canister, and the F_ICO₂ replacement threshold. The use of the fractional canister usage allows cost comparisons among different prepacks. Results should not be extrapolated to prepacks that fit onto other anesthesia machines.     

<Superscript>68</Superscript>Ga-Chloride PET Reveals Human Pancreatic Adenocarcinoma Xenografts in Rats—Comparison with FDG

Purpose  

The aim of the study was to compare ⁶⁸Ga-chloride with 2-[¹⁸F]fluoro-2-deoxy-d-glucose (FDG) for the imaging of pancreatic xenografts.     

Evaluation of the Microstat™ sublingual PCO<Subscript>2</Subscript> monitor in ambulatory patients

Physicians often need to measure arterial PCO₂ in clinical practice. Arterial blood gas sampling is typically available only in hospitals and may be unpleasant for patients. Minimally invasive techniques for measuring PCO₂ offer the potential for overcoming these limitations. The MicroStat monitor non-invasively measures PCO₂ in the sublingual tissues, which should track arterial PCO₂ in hemodynamically stable patients. This was a prospective observational study. Patients undergoing routine cardiac catheterization were recruited. Following arterial cannulation, two sequential sublingual PCO₂ measurements were taken and a contemporaneous arterial sample was sent for blood gas analysis. For each subject we calculated the mean sublingual–arterial CO₂ gradient and the test–retest sublingual PCO₂ difference. Twenty-five patients were studied. Mean sublingual–arterial PCO₂ gradient was +6.8 mmHg (95 % limits of agreement ?3.0 to 16.6 mmHg). Test–retest difference was 3.4 mmHg (95 % limits of agreement ?1.1 to 7.9 mmHg), p = 0.11 (Wilcoxon test), repeatability was 11 mmHg. The MicroStat sublingual PCO₂ monitor over-estimates arterial PCO₂ with wide limits of agreement. Test–retest repeatability was poor. Use of sublingual PCO2 monitoring with the MicroStat monitor cannot currently replace blood gas sampling.     

Imaging α4β2 Nicotinic Acetylcholine Receptors (nAChRs) in Baboons with [<Superscript>18</Superscript>F]XTRA,a Radioligand with Improved Specific Binding in Extra-Thalamic Regions

Purpose

Currently available positron-emitting radiotracers for imaging of the α4β2 subtype of nicotinic acetylcholine receptors (nAChRs) exhibit high and moderate specific binding in the thalamus and extra-thalamic brain regions, respectively. In many neuropsychiatric disorders, α4β2-nAChRs are altered in the extra-thalamic brain regions, but not necessarily in the thalamus. The purpose of this study was to evaluate [¹⁸F]XTRA, a new α4β2-nAChR positron emission tomography (PET) radioligand with improved specific binding in extra-thalamic brain regions, in non-human primates.

Procedures

The regional distribution of [¹⁸F]XTRA in the brain of Papio anubis baboons was evaluated in baseline and blocking experiments. Various PET modeling procedures were used for determination of volume of distribution (V _T), binding potential (BP_ND), and receptor occupancy. Radiation dosimetry for [¹⁸F]XTRA was studied in male CD-1 mice and extrapolated to human dosimetry estimates using OLINDA/EXM software.

Results

[¹⁸F]XTRA was synthesized using an automated radiochemistry module with 25 % decay-corrected radiochemical yield. [¹⁸F]XTRA readily enters the baboon brain and specifically labels α4β2-nAChRs. Mathematical modeling demonstrates high binding potential values (BP_ND = 7 and 1.3 in the thalamus and frontal cortex, respectively). A PET scanning time of 90–120 min was sufficient to obtain stable V _T values in the extra-thalamic regions. The extrapolated human effective dose was 0.041 mSv/MBq (0.15 Rem/mCi).

Conclusion

[¹⁸F]XTRA exhibits improved specific binding in the baboon brain including extra-thalamic regions and it is considered radiologically acceptable for human studies. Further evaluations of [¹⁸F]XTRA in human subjects are under way.

     

Specific Targeting of Atherosclerotic Plaques in ApoE<Superscript>−/−</Superscript> Mice Using a New Camelid sdAb Binding the Vulnerable Plaque Marker LOX-1

Purpose

Molecular imaging has the potential to provide quantitative information about specific biological aspects of developing atherosclerotic lesions. This requires the generation of reliable, highly specific plaque tracers. This study reports a new camelid single-domain antibody fragment (sdAb) targeting the Lectin-like oxidized low-density lipoprotein receptor (LOX-1), a biomarker for the detection and molecular phenotyping of vulnerable atherosclerotic plaques.

Procedures

A camelid sdAb was generated and selected for high affinity binding to LOX-1. Ex vivo biodistribution and in vivo single photon emission computed tomography (SPECT)/computed tomography (CT) imaging studies were performed in wild-type mice and in fat-fed atherosclerotic apolipoprotein E-deficient mice with ^99mTc-labeled sdAbs. Gamma-counting and autoradiography analyses were performed on dissected aorta segments with different degrees of plaque burden. The specificity of the LOX-1-targeting sdAb was evaluated by blocking with unlabeled sdAb or by comparison with a nontargeting ^99mTc-labeled control sdAb.

Results

We generated a sdAb binding LOX-1 with a K_D of 280 pM?±?62 pM affinity. After ^99mTc-labeling, the tracer had radiochemical purity higher then 99 % and retained specificity in in vitro binding studies. Tracer blood clearance was fast with concomitant high kidney retention. At 3 h after injection, uptake in tissues other than plaques was low and not different than background, suggesting a restricted expression pattern of LOX-1. Conversely, uptake in aortic segments increased with plaque content and was due to specific LOX-1 binding. In vivo SPECT/CT imaging 160 min after injection in atherosclerotic mice confirmed specific targeting of LOX-1-expressing aortic plaques.

Conclusions

The LOX-sdAb specifically targets LOX-1-expressing atherosclerotic plaques within hours after injection. The possibility to image LOX-1 rapidly after administration combined with the favourable biodistribution of a sdAb are beneficial for molecular phenotyping of atherosclerotic plaques and the generation of a future prognostic tracer.

     

Tiotropium Respimat<Superscript>®</Superscript> Versus HandiHaler<Superscript>®</Superscript>: Comparison of Bronchodilator Efficacy of Various Doses in Clinical Trials

Introduction

The long-acting muscarinic antagonist tiotropium bromide is approved in many countries as maintenance therapy for chronic obstructive pulmonary disease (COPD). Tiotropium is available as a dry-powder formulation delivered via HandiHaler^® (18 μg once daily) and is now also approved as an aqueous solution delivered via the Respimat^® Soft Mist? Inhaler (5 μg once daily, 2 puffs of 2.5 µg). Several studies have compared the efficacy of tiotropium HandiHaler (18 μg once daily) with different doses of Respimat. We aimed to compare available bronchodilator efficacy data of once-daily Respimat 1.25, 2.5, 5, 10, 20 µg, and HandiHaler 18 µg to investigate which dose of tiotropium delivered by Respimat is the closest match to tiotropium HandiHaler.

Methods

Evaluation of six clinical trials (duration from 3 weeks to 2–3 years) that included lung function measures (trough forced expiratory volume in 1 s and trough forced vital capacity) as key outcomes.

Results

In the six trials, bronchodilator efficacy of Respimat 5 μg and HandiHaler 18 μg was similar; however, reduced bronchodilator efficacy was observed with lower doses of Respimat (1.25 and 2.5 μg).

Conclusion

These findings support the use of the marketed once-daily dose of Respimat 5 μg for the maintenance treatment of patients with COPD.

Funding

Boehringer Ingelheim.

     

Integrin αvβ3 as a PET Imaging Biomarker for Osteoclast Number in Mouse Models of Negative and Positive Osteoclast Regulation

Purpose

The goal of this study was to determine the specificity of ⁶⁴Cu-CB-TE2A-c(RGDyK) (⁶⁴Cu-RGD) for osteoclast-related diseases, such as Paget's disease or rheumatoid arthritis.

Procedures

C57BL/6 mice were treated systemically with osteoprotegerin (OPG) for 15?days or RANKL for 11?days to suppress and stimulate osteoclastogenesis, respectively. The mice were then imaged by positron emission tomography/computed tomography using ⁶⁴Cu-RGD, followed by determination of serum TRAP5b and bone histology. Standard uptake values were determined to quantify ⁶⁴Cu-RGD in bones and other tissues.

Results

Mice treated with OPG showed decreased bone uptake of ⁶⁴Cu-RGD at 1, 2, and 24?h post-injection of the tracer (p?<?0.01 for all time points) compared to vehicle controls, which correlated with a post-treatment decrease in serum TRAP5b. In contrast, mice treated with RANKL showed significantly increased bone uptake at 2?h post-injection of ⁶⁴Cu-RGD (p?<?0.05) compared to the vehicle control group, corresponding to increased serum TRAP5b and OC numbers as determined by bone histology.

Conclusions

These data demonstrate that ⁶⁴Cu-RGD localizes to areas in bone with increased osteoclast numbers and support the use of ⁶⁴Cu-RGD as an imaging biomarker for osteoclast number that could be used to monitor osteoclast-related pathologies and their treatments.     

Day-to-Day Test–Retest Variability of CBF,CMRO<Subscript>2</Subscript>, and OEF Measurements Using Dynamic <Superscript>15</Superscript>O PET Studies

Purpose  

We assessed test–retest variability of cerebral blood flow (CBF), cerebral blood volume (CBV), cerebral metabolic rate of oxygen (CMRO₂), and oxygen extraction fraction (OEF) measurements derived from dynamic ¹⁵O positron emission tomography (PET) scans.     

Fully Automated Preparation and Conjugation of <Emphasis Type=Italic>N</Emphasis>-Succinimidyl 4-[<Superscript>18</Superscript>F]Fluorobenzoate ([<Superscript>18</Superscript>F]SFB) with RGD Peptide Using a GE FASTlab™ Synthesizer

Purpose  

The aim of this work was to automate the radiosynthesis of [¹⁸F]SFB, a widely used reagent for the labeling of biomolecules with ¹⁸F on a new generation commercial synthesis module (FASTLab™, GE Healthcare).     

Radiosynthesis and Initial <Emphasis Type="Italic">In Vitro</Emphasis> Evaluation of [<Superscript>18</Superscript>F]F-PEG<Subscript>6</Subscript>-IPQA—A Novel PET Radiotracer for Imaging EGFR Expression-Activity in Lung Carcinomas

Introduction  

Epidermal growth factor receptor (EGFR)-targeted therapies with antibodies and small molecular EGFR kinase inhibitors have shown poor efficacy in unselected populations of patients with advanced non-small cell lung carcinomas (NSCLC). In contrast, patients with overexpression of EGFR and activating mutations in EGFR kinase domain demonstrated improved responses to EGFR kinase inhibitors. Therefore, we have developed a novel radiotracer, [¹⁸F]F-PEG₆-IPQA for PET imaging of EGFR expression-activity in NSCLC, and have described its radiosynthesis and in vitro evaluation in two NSCLC cell lines with wild-type and L858R active mutant EGFR.     

3′-Deoxy-3′-[<Superscript>18</Superscript>F]Fluorothymidine Uptake Is Related to Thymidine Phosphorylase Expression in Various Experimental Tumor Models

Purpose

We recently reported that high thymidine phosphorylase (TP) expression is accompanied by low tumor thymidine concentration and high 3′-deoxy-3′-[¹⁸F]fluorothymidine ([¹⁸F]FLT) uptake in four untreated lung cancer xenografts. Here, we investigated whether this relationship also holds true for a broader range of tumor models.

Procedures

Lysates from n = 15 different tumor models originating from n = 6 institutions were tested for TP and thymidylate synthase (TS) expression using western blots. Results were correlated to [¹⁸F]FLT accumulation in the tumors as determined by positron emission tomography (PET) measurements in the different institutions and to previously published thymidine concentrations.

Results

Expression of TP correlated positively with [¹⁸F]FLT SUV_max (ρ = 0.549, P < 0.05). Furthermore, tumors with high TP levels possessed lower levels of thymidine (ρ = ??0.939, P < 0.001).

Conclusions

In a broad range of tumors, [¹⁸F]FLT uptake as measured by PET is substantially influenced by TP expression and tumor thymidine concentrations. These data strengthen the role of TP as factor confounding [¹⁸F]FLT uptake.

     

Randomized Controlled Trial of Hyalobarrier<Superscript>®</Superscript> Versus No Hyalobarrier<Superscript>®</Superscript> on the Ovulatory Status of Women with Periovarian Adhesions: A Pilot Study

Introduction

Periadnexal adhesions are known to contribute to subfertility. The restoration of the tubo-ovarian anatomy is one the key principles in reproductive surgery, and this involves adhesiolysis. However, adhesion formation/reformation is very common after periovarian adhesiolysis. It is not known if the application of Hyalobarrier^®, an anti-adhesion gel, around the adnexal region postsurgery influences ovulatory status. The study is a pilot randomized controlled trial (RCT) randomizing women into the application of Hyalobarrier^® versus no Hyalobarrier^® at the time of laparoscopy, where postsurgical ovulatory status and pregnancy rates were evaluated.

Methods

This was a pilot RCT where women were recruited from the gynecological and subfertility clinic who were deemed to require an operative laparoscopy. If intraoperatively they were found to have periovarian adhesions, they were randomized into having adhesiolysis with and without usage of Hyalobarrier^®. Demographic details and intraoperative details including the severity, extent, and the ease of use of Hyalobarrier^® were recorded. Prior to the surgery and postoperatively, the participants had their serum hormonal status (day 2 FSH, LH and day 21 progesterone) evaluated. Postoperatively, they underwent a follicular tracking cycle at 3 months.

Results

Fifteen women were randomized into use of Hyalobarrier^® (study group) and 15 into the no Hyalobarrier^® group (control group) between December 2011 and January 2014. There was no difference in the patient characteristics in terms of age, BMI, the number of previous pregnancies, or the extent, site, and severity of adhesions between the two groups. There was no significant difference between the study versus control groups in terms of the hormonal profile (day 2 FSH and day 21 progesterone) before or after surgery. The 3-month postoperative day 10–12 follicular tracking findings and endometrial thickness were similar between the study and control groups. Four women were pregnant in the study group (24%) and one in the control group (7%) cumulatively over 2 years.

Conclusion

The use of Hyalobarrier^® post salpingo-ovariolysis did not influence follicular development as inferred from the results of the day 21 progesterone and folliculogram on day 10–12 3-month postsurgery.

Trial Registration

ISRCTN number, ISRCTN1833588.

Funding

Nordic Pharma.