A phase 1 safety and bioimaging trial of antibody DS-8895a against EphA2 in patients with advanced or metastatic EphA2 positive cancers.

Ephrin type-A 2 (EphA2) is a transmembrane receptor expressed in epithelial cancers. We report on a phase I dose escalation and biodistribution study of DS-8895a, an anti-EphA2 antibody, in patients with advanced EphA2 positive cancers. DS-8895a was administered at 1, 3, 10 or 20 mg/kg every 2 weeks to determine safety, pharmacokinetics and anti-tumor efficacy. All patients underwent 89Zr trace-labelled infusion of DS-8895a (89Zr-DS-8995a) positron emission tomography imaging to determine the biodistribution of DS-8895a, and correlate findings with EphA2 expression, receptor saturation and response. Nine patients were enrolled on study. Of patients enrolled, seven patients received at least one infusion of DS-8895a: four patients received 1 mg/kg dose (Cohort 1) and three patients received 3 mg/kg dose (Cohort 2). Median age was 67.0 years (range 52-81), majority male (71%), and median number of prior systemic therapies was three (range 0-8). The primary cancer diagnosis was colorectal cancer (two patients) and one patient each had gastric, head and neck, high-grade serous adenocarcinoma, lung, and pancreatic cancers. No dose-limiting toxicities or treatment-related adverse events reported. The best response for the patients in Cohort 1 was stable disease and in Cohort 2 was progressive disease. 89Zr-DS-8895a demonstrated no normal tissue uptake and specific low-grade uptake in most tumours. DS-8895a had limited therapeutic efficacy at doses evaluated and 89Zr-DS-8895a demonstrated low tumour uptake. The biodistribution data from this study were key in halting further development of DS-8895a, highlighting the importance of biodistribution studies in drug development. (Trial registration: ClinicalTrials.gov Identifier NCT02252211).

Physiological and transcriptomic effects of hexafluoropropylene oxide dimer acid in Caenorhabditis elegans during development.

Per- and polyfluoroalkyl substances (PFAS) are chemicals resistant to degradation. While such a feature is desirable in consumer and industrial products, some PFAS, including perfluorooctanoic acid (PFOA), are toxic and bioaccumulate. Hexafluoropropylene oxide dimer acid (HFPO-DA), an emerging PFAS developed to replace PFOA, has not been extensively studied. To evaluate the potential toxicity of HFPO-DA with a cost- and time-efficient approach, we exposed C. elegans larvae for 48 h to 4 × 10-9-4 g/L HFPO-DA in liquid media and measured developmental, behavioral, locomotor, and transcriptional effects at various exposure levels. Worms exposed to 1.5-4 g/L HFPO-DA were developmentally delayed, and progeny production was significantly delayed (p < 0.05) in worms exposed to 2-4 g/L HFPO-DA. Statistically significant differential gene expression was identified in all fourteen HFPO-DA exposure groups ranging from 1.25 × 10-5 to 4 g/L, except for 6.25 × 10-5 g/L. Among 10298 analyzed genes, 2624 differentially expressed genes (DEGs) were identified in the developmentally delayed 4 g/L group only, and 78 genes were differentially expressed in at least one of the thirteen groups testing 1.25 × 10-5-2 g/L HFPO-DA exposures. Genes encoding for detoxification enzymes including cytochrome P450 and UDP glucuronosyltransferases were upregulated in 0.25-4 g/L acute exposure groups. DEGs were also identified in lower exposure level groups, though they did not share biological functions except for six ribosomal protein-coding genes. While our transcriptional data is inconclusive to infer mechanisms of toxicity, the significant gene expression differences at 1.25 × 10-5 g/L, the lowest concentration tested for transcriptional changes, calls for further targeted analyses of low-dose HFPO-DA exposure effects.

Radiolabelling and preclinical characterization of 89Zr-Df-radiolabelled bispecific anti-PD-L1/TGF-ßRII fusion protein bintrafusp alfa.

PURPOSE: Τhis study aimed to optimize the 89Zr-radiolabelling of bintrafusp alfa investigational drug product and controls, and perform the in vitro and in vivo characterization of 89Zr-Df-bintrafusp alfa and 89Zr-Df-control radioconjugates. METHODS: Bintrafusp alfa (anti-PD-L1 human IgG1 antibody fused to TGF-ß receptor II (TGF-ßRII), avelumab (anti-PD-L1 human IgG1 control antibody), isotype control (mutated inactive anti-PD-L1 IgG1 control antibody), and trap control (mutated inactive anti-PD-L1 human IgG1 fused to active TGF-ßRII) were chelated with p-isothiocyanatobenzyl-desferrioxamine (Df). After radiolabelling with zirconium-89 (89Zr), radioconjugates were assessed for radiochemical purity, immunoreactivity, antigen binding affinity, and serum stability in vitro. In vivo biodistribution and imaging studies were performed with PET/CT to identify and quantitate 89Zr-Df-bintrafusp alfa tumour uptake in a PD-L1/TGF-ß-positive murine breast cancer model (EMT-6). Specificity of 89Zr-Df-bintrafusp alfa was assessed via a combined biodistribution and imaging experiment in the presence of competing cold bintrafusp alfa (1 mg/kg). RESULTS: Nanomolar affinities for PD-L1 were achieved with 89Zr-Df-bintrafusp alfa and 89Zr-avelumab. Biodistribution and imaging studies in PD-L1- and TGF-ß-positive EMT-6 tumour-bearing BALB/c mice demonstrated the biologic similarity of 89Zr-Df-bintrafusp alfa and 89Zr-avelumab indicating the in vivo distribution pattern of bintrafusp alfa is driven by its PD-L1 binding arm. Competition study with 1 mg of unlabelled bintrafusp alfa or avelumab co-administered with trace dose of 89Zr-labelled bintrafusp alfa demonstrated the impact of dose and specificity of PD-L1 targeting in vivo. CONCLUSION: Molecular imaging of 89Zr-Df-bintrafusp alfa biodistribution was achievable and allows non-invasive quantitation of tumour uptake of 89Zr-Df-bintrafusp alfa, suitable for use in bioimaging clinical trials in cancer patients.

L-Tyrosine Confers Residualizing Properties to a d-Amino Acid-Rich Residualizing Peptide for Radioiodination of Internalizing Antibodies.

PURPOSE: The aims of the study were to develop and evaluate a novel residualizing peptide for labeling internalizing antibodies with (124)I to support clinical development using immuno-positron emission tomography (PET). METHODS: The anti-epidermal growth factor receptor antibody ch806 was radiolabeled directly or indirectly with isotopes and various residualizing peptides. Azido-derivatized radiolabeled peptides were conjugated to dibenzylcyclooctyne-derivatized ch806 antibody via click chemistry. The radiochemical purities, antigen-expressing U87MG.de2-7 human glioblastoma cell-binding properties, and targeting of xenografts at 72 hours post injection of all radioconjugates were compared. Biodistribution of (124)I-PEG4-tptddYddtpt-ch806 and immuno-PET imaging were evaluated in tumor-bearing mice. RESULTS: Biodistribution studies using xenografts at 72 hours post injection showed that (131)I-PEG4-tptddYddtpt-ch806 tumor uptake was similar to (111)In-CHX-A″-DTPA-ch806. (125)I-PEG4-tptddyddtpt-ch806 showed a lower tumor uptake value but higher than directly labeled (125)I-ch806. (124)I-PEG4-tptddYddtpt-ch806 was produced at 23% labeling efficiency, 98% radiochemical purity, 25.9 MBq/mg specific activity, and 64% cell binding in the presence of antigen excess. Tumor uptake for (124)I-PEG4-tptddYddtpt-ch806 was similar to (111)In-CHX-A″-DTPA-ch806. High-resolution immuno-PET/magnetic resonance imaging of tumors showed good correlation with biodistribution data. CONCLUSIONS: The mixed d/l-enantiomeric peptide, dThr-dPro-dThr-dAsp-dAsp-Tyr-dAsp-dAsp-dThr-dPro-dThr, is suitable for radiolabeling antibodies with radiohalogens such as (124)I for high-resolution immuno-PET imaging of tumors and for evaluation in early-phase clinical trials.

Diffusion-weighted MRI, 11C-choline PET and 18F-fluorodeoxyglucose PET for predicting the Gleason score in prostate carcinoma.

OBJECTIVES: To evaluate the accuracy of transrectal ultrasound-guided (TRUS) biopsy, diffusion-weighted (DW) magnetic resonance imaging (MRI), (11)C-choline (CHOL) positron emission tomography (PET), and (18)F-fluorodeoxyglucose (FDG) PET in predicting the prostatectomy Gleason risk (GR). METHODS: The study included 21 patients who underwent TRUS biopsy and multi-technique imaging before radical prostatectomy. Values from five different tests (TRUS biopsy, DW MRI, CHOL PET, FDG PET, and combined DW MRI/CHOL PET) were correlated with the prostatectomy GR using Spearman's ρ. Tests that were found to have significant correlations were used to classify patients into GR groups. RESULTS: The following tests had significant correlations with prostatectomy GR: TRUS biopsy (ρ = 0.617, P = 0.003), DW MRI (ρ = -0.601, P = 0.004), and combined DW MRI/CHOL PET (ρ = -0.623, P = 0.003). CHOL PET alone and FDG PET only had weak correlations. The correct GR classification rates were 67% with TRUS biopsy, 67% with DW MRI, and 76% with combined DW MRI/CHOL PET. CONCLUSIONS: DW MRI and combined DW MRI/CHOL PET have significant correlations and high rates of correct classification of the prostatectomy GR, the strength and accuracy of which are comparable with TRUS biopsy. KEY POINTS: • Accurate determination of the Gleason score is essential for prostate cancer management. • DW MRI ± CHOL PET correlated significantly with prostatectomy Gleason score. • These correlations are similar to that between TRUS biopsy and prostatectomy.

An Anti-VEGF-B Antibody Reduces Abnormal Tumor Vasculature and Enhances the Effects of Chemotherapy.

The vascular endothelial growth factors (VEGFs) and their receptors (VEGFRs) are key regulators of blood vessel formation, including in tumors, where their deregulated function can promote the production of aberrant, leaky blood vessels, supporting tumor development. Here we investigated the VEGFR1 ligand VEGF-B, which we demonstrate to be expressed in tumor cells and in tumor stroma and vasculature across a range of tumor types. We examined the anti-VEGF-B-specific monoclonal antibody 2H10 in preclinical xenograft models of breast and colorectal cancer, in comparison with the anti-VEGF-A antibody bevacizumab. Similar to bevacizumab, 2H10 therapy was associated with changes in tumor blood vessels and intra-tumoral diffusion consistent with normalization of the tumor vasculature. Accordingly, treatment resulted in partial inhibition of tumor growth, and significantly improved the response to chemotherapy. Our studies indicate the importance of VEGF-B in tumor growth, and the potential of specific anti-VEGF-B treatment to inhibit tumor development, alone or in combination with established chemotherapies.

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.

Toxicity assessment of hexafluoropropylene oxide-dimer acid on morphology, heart physiology, and gene expression during zebrafish (Danio rerio) development.

Hexafluoropropylene oxide-dimer acid (HFPO-DA) is one of the emerging replacements for the "forever" carcinogenic and toxic long-chain PFAS. HFPO-DA is a polymerization aid used for manufacturing fluoropolymers, whose global distribution and undetermined toxic properties are a concern regarding human and ecological health. To assess embryotoxic potential, zebrafish embryos were exposed to HFPO-DA at concentrations of 0.5-20,000 mg/L at 24-, 48-, and 72-h post-fertilization (hpf). Heart rate increased significantly in embryos exposed to 2 mg/L and 10 mg/L HFPO-DA across all time points. Spinal deformities and edema phenotypes were evident among embryos exposed to 1000-16,000 mg/L HFPO-DA at 72 hpf. A median lethal concentration (LC50) was derived as 7651 mg/L at 72 hpf. Shallow RNA sequencing analysis of 9465 transcripts identified 38 consistently differentially expressed genes at 0.5 mg/L, 1 mg/L, 2 mg/L, and 10 mg/L HFPO-DA exposures. Notably, seven downregulated genes were associated with visual response, and seven upregulated genes were expressed in or regulated the cardiovascular system. This study identifies biological targets and molecular pathways affected during animal development by an emerging, potentially problematic, and ubiquitous industrial chemical.

Locomotion and brain gene expression exhibit sex-specific non-monotonic dose-response to HFPO-DA during Drosophila melanogaster lifespan.

BACKGROUND: Legacy per- and polyfluoroalkyl substances (PFAS), known for their environmental persistence and bio-accumulative properties, have been phased out in the U.S. due to public health concerns. A newer polymerization aid used in the manufacture of some fluoropolymers, hexafluoropropylene oxide-dimer acid (HFPO-DA), has lower reported bioaccumulation and toxicity, but is a potential neurotoxicant implicated in dopaminergic neurodegeneration. OBJECTIVE: We investigated HFPO-DA's bio-accumulative potential and sex-specific effects on lifespan, locomotion, and brain gene expression in fruit flies. METHODS: We quantified bioaccumulation of HFPO-DA in fruit flies exposed to 8.7 × 104 µg/L of HFPO-DA in the fly media for 14 days via UHPLC-MS. Long-term effect on lifespan was determined by exposing both sexes to 8.7 × 102 - 8.7 × 105 µg/L of HFPO-DA in media. Locomotion was measured following 3, 7, and 14 days of exposures at 8.7 × 101 - 8.7 × 105 µg/L of HFPO-DA in media, and high-throughput 3'-end RNA-sequencing was used to quantify gene expression in fly brains across the same time points. RESULTS: Bioaccumulation of HFPO-DA in fruit flies was not detected. HFPO-DA-induced effects on lifespan, locomotion, and brain gene expression, and lowest adverse effect level (LOAEL) showed sexually dimorphic patterns. Locomotion scores significantly decreased in at least one dose at all time points for females and only at 3-day exposure for males, while brain gene expression exhibited non-monotonic dose-response. Differentially expressed genes correlated to locomotion scores revealed sex-specific numbers of positively and negatively correlated genes per functional category. CONCLUSION: Although HFPO-DA effects on locomotion and survival were significant at doses higher than the US EPA reference dose, the brain transcriptomic profiling reveals sex-specific changes and neurological molecular targets; gene enrichments highlight disproportionately affected categories, including immune response: female-specific co-upregulation suggests potential neuroinflammation. Consistent sex-specific exposure effects necessitate blocking for sex in experimental design during HFPO-DA risk assessment.

Preclinical radiolabeling, in vivo biodistribution and positron emission tomography of a novel pyrrolobenzodiazepine (PBD)-based antibody drug conjugate targeting ASCT2.

INTRODUCTION: Anti-ASCT2 antibody drug conjugate (ADC) MEDI7247 has been under development as a potential anti-cancer therapy for patients with selected relapsed/refractory hematological malignancies and advanced solid tumors by MedImmune. Although promising efficacy was observed in the clinic, pharmacokinetic (PK) analyses observed low exposure of MEDI7247 in phase I hematological patients. To investigate the biodistribution properties of MEDI7247, MEDI7247 and control antibodies were radiolabeled with zirconium-89 and in vitro and in vivo properties characterized. METHODS: MEDI7247 (human anti-ASCT2 antibody conjugated with pyrrolobenzodiazepine (PBD)) and MEDI7519 (MEDI7247 without PBD drug conjugate) and an isotype control antibody drug conjugate construct were conjugated with p-isothiocyanatobenzyl-deferoxamine (Df) and radiolabeled with zirconium-89. In vitro studies included determining the radiochemical purity, protein integrity, immunoreactivity (Lindmo analysis), apparent antigen binding affinity for ASCT2-positive cells by Scatchard analysis and serum stability of the radiolabeled immunoconjugates. In vivo studies included biodistribution and PET/MRI imaging studies of the radiolabeled immunoconjugates in an ASCT2-positive tumor model, HT-29 colorectal carcinoma xenografts. RESULTS: Conditions for the Df-conjugation and radiolabeling of antibody constructs were determined to produce active radioimmunoconjugates. In vivo biodistribution and whole body PET/MRI imaging studies of [89Zr]Zr-Df-MEDI7519 and [89Zr]Zr-Df-MEDI7247 radioimmunoconjugates in HT-29 colon carcinoma xenografts in BALB/c nude mice demonstrated specific tumor localization. However, more rapid blood clearance and non-specific localization in liver was observed for [89Zr]Zr-Df-MEDI7247 and [89Zr]Zr-Df-MEDI7519 compared to isotype control ADC. Except for liver and bone, other normal tissues demonstrated clearance reflecting the blood clearance for all three constructs and no other abnormal tissue uptake. CONCLUSIONS AND ADVANCES IN KNOWLEDGE: Preclinical biodistribution analyses of [89Zr]Zr-Df-MEDI7247 and [89Zr]Zr-Df-MEDI7519 showed the biodistribution pattern of anti-ASCT2 ADC MEDI7247 was similar to parental MEDI7519, and both antibodies showed specific tumor uptake compared to an isotype control ADC. This study highlights an important role nuclear medicine imaging techniques can play in early preclinical assessment of drug specificity as part of the drug development pipeline.

Subacute ischemic stroke is associated with focal 11C PiB positron emission tomography retention but not with global neocortical Aß deposition.

BACKGROUND AND PURPOSE: Conflicting evidence exists as to whether focal cerebral ischemia contributes to cerebral amyloid deposition. We aimed to look at Aß deposits, detected by N-methyl-2-(4'-methylaminophenyl)-6-hydroxybenzothiazole (PiB) positron emission tomography, in patients with recent ischemic stroke. Specifically, we hypothesized that patients with recent ischemic stroke have higher local and neocortical PiB positron emission tomography retention and that this may be associated with major vascular risk factors. METHODS: Ischemic stroke patients were studied using PiB positron emission tomography within 30 days and compared to age-matched controls. Distribution volume ratio maps were created using Logan graphical analysis with the cerebellar cortex as a reference. RESULTS: Among the 21 ischemic stroke patients (median age, 76 years; interquartile range, 68-77), the ipsilateral peri-infarct region PiB retention was higher compared to the contralateral mirror region, with a PiB distribution volume ratio difference of 0.29 (95% CI, 0.2-0.44; P=0.001) at median 10 (interquartile range, 7-14) days after stroke. Two patients also had higher PiB retention within the infarct compared to the contralateral side. There was no difference in the neocortical PiB retention elsewhere in the brain among ischemic stroke patients compared with 22 age-matched normal controls (P=0.22). Among the risk factors in the ischemic stroke patients, diabetes was associated with a higher neocortical PiB retention (Spearman Rho=0.48; 95% CI, 0.28-0.72). CONCLUSIONS: PiB retention was higher in the peri-infarct region among patients with recent ischemic stroke. This did not translate into a higher global neocortical PiB retention except possibly in patients with diabetes. The cause of the focal PiB retention is uncertain and requires further investigation.

18F-THK523: a novel in vivo tau imaging ligand for Alzheimer's disease.

While considerable effort has focused on developing positron emission tomography ß-amyloid imaging radiotracers for the early diagnosis of Alzheimer's disease, no radiotracer is available for the non-invasive quantification of tau. In this study, we detail the characterization of (18)F-THK523 as a novel tau imaging radiotracer. In vitro binding studies demonstrated that (18)F-THK523 binds with higher affinity to a greater number of binding sites on recombinant tau (K18Δ280K) compared with ß-amyloid(1-42) fibrils. Autoradiographic and histofluorescence analysis of human hippocampal serial sections with Alzheimer's disease exhibited positive THK523 binding that co-localized with immunoreactive tau pathology, but failed to highlight ß-amyloid plaques. Micro-positron emission tomography analysis demonstrated significantly higher retention of (18)F-THK523 (48%; P < 0.007) in tau transgenic mice brains compared with their wild-type littermates or APP/PS1 mice. The preclinical examination of THK523 has demonstrated its high affinity and selectivity for tau pathology both in vitro and in vivo, indicating that (18)F-THK523 fulfils ligand criteria for human imaging trials.

Cerebral ß-amyloid detected by Pittsburgh compound B positron emission topography predisposes to recombinant tissue plasminogen activator-related hemorrhage.

Cerebral amyloid angiopathy (CAA) may be an important predisposing factor for the hemorrhagic complications of recombinant tissue-type plasminogen activator (rt-PA) therapy. We studied patients treated within 3 hours of onset of ischemic stroke with rt-PA using positron emission tomography to compare Pittsburgh compound B (PiB) (a cerebral ß-amyloid ligand) retention in those with and without parenchymal hemorrhage (PH) and normal controls. Neocortical PiB retention was higher among patients with PH compared with patients without PH and normal controls, suggesting underlying CAA as a predisposing factor for rt-PA-related hemorrhage. This finding may provide an impetus for the development of a more practical rapid pretreatment screening technique.

Reevaluate how to evaluate: Systemic assessment biases affect students' confidence in college upper-division biology laboratory courses.

Grades influence students' confidence and decisions to complete STEM degrees and pursue relevant careers. What affects students' confidence and performance in college upper-division biology laboratory courses and how relevant are evaluation methods to career success? STEM laboratory courses are an excellent model to address these issues because of the hybrid environment, combining traditional lecture course format and the practical application of knowledge. We surveyed 567 students in two upper-division laboratory molecular biology courses at a major research university to compare course-content self-assessment, students' predicted grades, and actual grades received. By analyzing students' confidence and correlating them to grades assigned by the instructor, we identified biases including student and Instructor Assistant (IA) gender, IA experience, and academic quarter. Considering the systemic effect of identified biases, a correlation (R2  = 0.37, p < 0.01) between predicted and actual grades, and weak but statistically significant correlation (R2  = 0.10, p < 0.01) between students' comprehensive course-content self-assessment and their predicted grade are not surprising. Our analysis suggests that students' quantifiable self-assessment, a relatively simple and data-rich resource, helps identify evaluation bias. If administered periodically throughout the course, these assessments can help mitigate biases, improve student learning, evaluation, and retention in STEM fields.

First clinical study of a pegylated diabody 124I-labeled PEG-AVP0458 in patients with tumor-associated glycoprotein 72 positive cancers.

Through protein engineering and a novel pegylation strategy, a diabody specific to tumor-associated glycoprotein 72 (TAG-72) (PEG-AVP0458) has been created to optimize pharmacokinetics and bioavailability to tumor. We report the preclinical and clinical translation of PEG-AVP0458 to a first-in-human clinical trial of a diabody. Methods: Clinical translation followed characterization of PEG-AVP0458 drug product and preclinical biodistribution and imaging assessments of Iodine-124 trace labeled PEG-AVP0458 (124I-PEG-AVP0458). The primary study objective of the first-in-human study was the safety of a single protein dose of 1.0 or 10 mg/m2 124I-PEG-AVP0458 in patients with TAG-72 positive relapsed/ metastatic prostate or ovarian cancer. Secondary study objectives were evaluation of the biodistribution, tumor uptake, pharmacokinetics and immunogenicity. Patients were infused with a single-dose of 124I labeled PEG-AVP0458 (3-5 mCi (111-185 MBq) for positron emission tomography (PET) imaging, performed sequentially over a one-week period. Safety, pharmacokinetics, biodistribution, and immunogenicity were assessed up to 28 days after infusion. Results: PEG-AVP0458 was radiolabeled with 124I and shown to retain high TAG-72 affinity and excellent targeting of TAG-72 positive xenografts by biodistribution analysis and PET imaging. In the first-in-human trial, no adverse events or toxicity attributable to 124I-PEG-AVP0458 were observed. Imaging was evaluable in 5 patients, with rapid and highly specific targeting of tumor and minimal normal organ uptake, leading to high tumor:blood ratios. Serum concentration values of 124I-PEG-AVP0458 showed consistent values between patients, and there was no significant difference in T½α and T½ß between dose levels with mean (± SD) results of T½α = 5.10 ± 4.58 hours, T½ß = 46.19 ± 13.06 hours. Conclusions: These data demonstrates the safety and feasibility of using pegylated diabodies for selective tumor imaging and potential delivery of therapeutic payloads in cancer patients.

Radiation dosimetry of beta-amyloid tracers 11C-PiB and 18F-BAY94-9172.

UNLABELLED: Beta-amyloid (Abeta) imaging has great potential to aid in the diagnosis of Alzheimer disease and the development of therapeutics. The radiation dosimetry of Abeta radioligands may influence their application; therefore, we calculated and compared the effective doses (EDs) of 11C-PiB and a new 18F-labeled ligand, 18F-BAY94-9172. METHODS: Attenuation-corrected whole-body scans were performed at 0, 15, 30, 45, and 60 min after injection of 350+/-28 MBq (mean+/-SD) of 11C-PiB in 6 subjects and at 0, 20, 60, 120, and 180 min after injection of 319+/-27 MBq of 18F-BAY94-9172 in 3 subjects. Coregistered CT was used to define volumes of interest (VOIs) on the PET images. The source organs were the brain, lungs, liver, kidneys, spleen, and vertebrae. The VOIs for the contents of the gallbladder, urinary bladder, lower large intestine, upper large intestine, and small intestine were also defined. Total activity in each organ at each time point was calculated by use of reference organ volumes. The resultant time-activity curves were fitted with constrained exponential fits, and cumulated activities were determined. A dynamic bladder voiding model was used. The OLINDA/EXM program was used to calculate the whole-body EDs from the acquired data. RESULTS: For 11C-PiB, the highest absorbed doses were in the gallbladder wall (44.80+/-29.30 microGy/MBq), urinary bladder wall (26.30+/-8.50 microGy/MBq), liver (19.88+/-3.58 microGy/MBq), and kidneys (12.92+/-3.37 microGy/MBq). The ED was 5.29+/-0.66 microSv/MBq. For 18F-BAY94-9172, the highest doses were also in the gallbladder wall (132.40+/-43.40 microGy/MBq), urinary bladder wall (24.77+/-7.36 microGy/MBq), and liver (39.07+/-8.31 microGy/MBq). The ED was 14.67+/-1.39 microSv/MBq. CONCLUSION: The estimated organ doses for 11C-PiB were comparable to those reported in earlier research. With the doses used in published studies (300-700 MBq), the EDs would range from 1.6 to 3.7 mSv. The ED of 18F-BAY94-9172 was 30% lower than that of 18F-FDG and, at the published dose of 300 MBq, would yield an ED of 4.4 mSv. The dosimetry of both Abeta radioligands is suitable for clinical and research applications.

Deletion of intestinal Hdac3 remodels the lipidome of enterocytes and protects mice from diet-induced obesity.

Histone deacetylase 3 (Hdac3) regulates the expression of lipid metabolism genes in multiple tissues, however its role in regulating lipid metabolism in the intestinal epithelium is unknown. Here we demonstrate that intestine-specific deletion of Hdac3 (Hdac3IKO) protects mice from diet induced obesity. Intestinal epithelial cells (IECs) from Hdac3IKO mice display co-ordinate induction of genes and proteins involved in mitochondrial and peroxisomal ß-oxidation, have an increased rate of fatty acid oxidation, and undergo marked remodelling of their lipidome, particularly a reduction in long chain triglycerides. Many HDAC3-regulated fatty oxidation genes are transcriptional targets of the PPAR family of nuclear receptors, Hdac3 deletion enhances their induction by PPAR-agonists, and pharmacological HDAC3 inhibition induces their expression in enterocytes. These findings establish a central role for HDAC3 in co-ordinating PPAR-regulated lipid oxidation in the intestinal epithelium, and identify intestinal HDAC3 as a potential therapeutic target for preventing obesity and related diseases.

Molecular imaging of T cell co-regulator factor B7-H3 with 89Zr-DS-5573a.

B7-H3 is a transmembrane protein widely expressed in a variety of cancers and has been shown to play a role in anti-tumor immunity. This study aims to develop a molecular imaging probe to identify B7-H3 expression in tumors and to develop 89Zr-DS-5573a as a theranostic that could aid patient selection in clinical Phase I studies. Methods: The anti-B7-H3 humanised monoclonal antibody DS-5573a was labeled with zirconium-89 (89Zr-), and assessed for radiochemical purity, immunoreactivity (Lindmo analysis), antigen binding affinity (Scatchard analysis), and serum stability in vitro. In vivo biodistribution and imaging studies were performed with positron emission tomography and magnetic resonance imaging (PET/MRI) studies to identify and quantitate 89Zr-DS-5573a tumor uptake in a B7-H3-positive breast cancer model (MDA-MB-231) and a B7-H3-negative murine colon cancer model (CT26). Imaging and biodistribution studies were also performed in MDA-MB-231 tumor-bearing SCID mice in the absence and presence of therapeutic DS-5573a antibody dose (3 mg/kg DS-5573a). Results:89Zr-DS-5573a showed high and specific binding to B7-H3-expressing MDA-MB-231 cells (immunoreactivity on day 0, 75.0 ± 2.9%), and low binding to B7-H3-negative CT26 cells (immunoreactivity on day 0, 10.85 ± 0.11%) in vitro. 89Zr-DS-5573a demonstrated good serum stability in vitro with 57.2 ± 2.0% of immunoreactivity remaining on day 7. In vivo biodistribution studies showed high uptake of 89Zr-DS-5573a in B7-H3-expressing MDA-MB-231 tumor-bearing mice, achieving 32.32 ± 6.55 %ID/g on day 7 post injection in BALB/c nu/nu mice and 25.76 ± 1.79 %ID/g in SCID mice, with minimal evidence of non-specific uptake in normal tissues, and excellent tumor localization on PET/MRI. In a combined imaging/therapy study, receptor saturation was demonstrated in tumors responding to therapy. Conclusion:89Zr-DS-5573a demonstrates specific and prolonged targeting of B7-H3-expressing tumors in vivo. Saturation of binding sites was demonstrated in tumors responding to DS-5573a therapy. These results indicate that 89Zr-DS-5573a has potential to target B7-H3-expressing tumors in cancer patients. Furthermore 89Zr-DS-5573a has the potential to provide important insights into T cell biology through its specific binding to B7-H3.

Visual assessment versus quantitative assessment of 11C-PIB PET and 18F-FDG PET for detection of Alzheimer's disease.

UNLABELLED: Amyloid-beta (Abeta) imaging with N-methyl-(11)C-2-(4'-methylamino-phenyl)-6-hydroxy-benzothiazole ((11)C-6-OH-BTA-1; also known as (11)C-PIB) shows a robust increase in cortical binding in Alzheimer's disease (AD). The aim of this study was to explore the clinical potential of Abeta imaging for the diagnosis of AD by comparison of the accuracy of visual reading of (11)C-PIB images with quantitative analysis and (18)F-FDG. METHODS: Fifteen AD patients (age, 71.1 +/- 11.3 y [mean +/- SD]; mini-mental state examination [MMSE], 18.9 +/- 9.3 [mean +/- SD]) and 25 healthy control (HC) subjects (age, 71.9 +/- 6.82 y; MMSE >or= 28) underwent 90-min dynamic (11)C-PIB PET and 20-min static (18)F-FDG PET. (11)C-PIB images, generated from data acquired between 40 and 70 min after injection, and (18)F-FDG images were rated separately by 2 readers as normal, possible AD, or probable AD. Quantitative analyses used the distribution volume ratio (DVR) of frontal cortex, parietotemporal cortex, posterior cingulate, and caudate nucleus for (11)C-PIB and standardized uptake value ratio (SUVR) of parietotemporal cortex and posterior cingulate for (18)F-FDG, using cerebellar cortex as the reference region. Receiver-operating-characteristic (ROC) analysis was performed to compare the accuracy of quantitative measures. To determine the effect of age on diagnostic accuracy, the median age of the AD subjects (74 y) was chosen to separate the cohort into younger (64.4 +/- 5.8 y) and older (78.6 +/- 4.1 y) groups. RESULTS: Visual agreement between readers was excellent for (11)C-PIB (kappa = 0.90) and good for (18)F-FDG (kappa = 0.56). (11)C-PIB was more accurate than (18)F-FDG both on visual reading (accuracy, 90% vs. 70%, P = 0.05) and ROC analysis (95% vs. 83%, P = 0.02). Accuracy declined more with (18)F-FDG than with (11)C-PIB in the older group. CONCLUSION: Visual analysis of (11)C-PIB images appears more accurate than visual reading of (18)F-FDG for identification of AD and has accuracy similar to quantitative analysis of a 90-min dynamic scan. The accuracy of (11)C-PIB PET is limited by cortical binding in some healthy elderly subjects, consistent with postmortem studies of cerebral Abeta. Longitudinal follow-up is required to determine if this represents detection of preclinical AD.

Engineering anti-Lewis-Y hu3S193 antibodies with improved therapeutic ratio for radioimmunotherapy of epithelial cancers.

BACKGROUND: The aim of the study was to explore Fc mutations of a humanised anti-Lewis-Y antibody (IgG1) hu3S193 as a strategy to improve therapeutic ratios for therapeutic payload delivery. METHODS: Four hu3S193 variants (I253A, H310A, H435A and I253A/H310A) were generated via site-directed mutagenesis and radiolabelled with diagnostic isotopes iodine-125 or indium-111. Biodistribution studies in Lewis-Y-positive tumour-bearing mice were used to calculate the dose in tumours and organs for therapeutic isotopes (iodine-131, yttrium-90 and lutetium-177). RESULTS: (111)In-labelled I253A and H435A showed similar slow kinetics (t 1/2ß, 63.2 and 62.2 h, respectively) and a maximum tumour uptake of 33.11 ± 4.05 and 33.69 ± 3.77 percentage injected dose per gramme (%ID/g), respectively. (111)In-labelled I253A/H310A cleared fastest (t 1/2ß, 9.1 h) with the lowest maximum tumour uptake (23.72 ± 0.85 %ID/g). The highest increase in tumour-to-blood area under the curve (AUC) ratio was observed with the metal-labelled mutants ((90)Y and (177)Lu). (177)Lu-CHX-A" DTPA-hu3S193 I253A/H310A (6:1) showed the highest tumour-to-blood AUC ratio compared to wild type (3:1) and other variants and doubling of calculated dose to tumour based on red marrow dose constraints. CONCLUSIONS: These results suggest that hu3S193 Fc can be engineered with improved therapeutic ratios for (90)Y- and (177)Lu-based therapy, with the best candidate being hu3S193 I253A/H310A for (177)Lu-based therapy.