Automated radiolabeling and handling of 177 Lu- and 225 Ac-PSMA-617 using a robotic pipettor

While automated modules for F-18 and C-11 radiosyntheses are standardized with features such as multiple reactors, vacuum connection and semi-preparative HPLC, labeling and processing of compounds with radiometals such as Zr-89, Lu-177 and Ac-225 often do not require complex manipulations and are frequently performed manually by a radiochemist. These procedures typically involve transferring solutions to and from vials using pipettes followed by heating of the reaction mixture, and do not require all the features found in most commercial automated synthesis units marketed as F-18 or C-11 modules. Here we present an efficient automated method for performing radiosyntheses involving radiometals by adapting a commercially available robotic pipettor originally developed for high-throughput processing of biological samples. While a robotic pipettor is less costly than a radiosynthesis module, it holds many similar advantages over manual radiosynthesis such as minimization of operator error, lower operator exposure rates, and abbreviated synthesis times, among others. To demonstrate the feasibility of using the OpenTrons OT-2 robotic pipettor to perform automated radiosyntheses, we radiolabeled and formulated 177 Lu-PSMA-617 and 225 Ac-PSMA-617 on the system. The OT-2 was then used to help streamline the quality control process for both products, further minimizing manual handling by and exposure to the radiochemist.

Preclinical Development of PNT6555, a Boronic Acid-Based, Fibroblast Activation Protein-α (FAP)-Targeted Radiotheranostic for Imaging and Treatment of FAP-Positive Tumors

The overexpression of fibroblast activation protein-α (FAP) in solid cancers relative to levels in normal tissues has led to its recognition as a target for delivering agents directly to tumors. Radiolabeled quinoline-based FAP ligands have established clinical feasibility for tumor imaging, but their therapeutic potential is limited due to suboptimal tumor retention, which has prompted the search for alternative pharmacophores. One such pharmacophore is the boronic acid derivative N-(pyridine-4-carbonyl)-d-Ala-boroPro, a potent and selective FAP inhibitor (FAPI). In this study, the diagnostic and therapeutic (theranostic) potential of N-(pyridine-4-carbonyl)-d-Ala-boroPro-based metal-chelating DOTA-FAPIs was evaluated. Methods: Three DOTA-FAPIs, PNT6555, PNT6952, and PNT6522, were synthesized and characterized with respect to potency and selectivity toward soluble and cell membrane FAP; cellular uptake of the Lu-chelated analogs; biodistribution and pharmacokinetics in mice xenografted with human embryonic kidney cell-derived tumors expressing mouse FAP; the diagnostic potential of 68Ga-chelated DOTA-FAPIs by direct organ assay and small-animal PET; the antitumor activity of 177Lu-, 225Ac-, or 161Tb-chelated analogs using human embryonic kidney cell-derived tumors expressing mouse FAP; and the tumor-selective delivery of 177Lu-chelated DOTA-FAPIs via direct organ assay and SPECT. Results: DOTA-FAPIs and their natGa and natLu chelates exhibited potent inhibition of human and mouse sources of FAP and greatly reduced activity toward closely related prolyl endopeptidase and dipeptidyl peptidase 4. 68Ga-PNT6555 and 68Ga-PNT6952 showed rapid renal clearance and continuous accumulation in tumors, resulting in tumor-selective exposure at 60 min after administration. 177Lu-PNT6555 was distinguished from 177Lu-PNT6952 and 177Lu-PNT6522 by significantly higher tumor accumulation over 168 h. In therapeutic studies, all 3 177Lu-DOTA-FAPIs exhibited significant antitumor activity at well-tolerated doses, with 177Lu-PNT6555 producing the greatest tumor growth delay and animal survival. 225Ac-PNT6555 and 161Tb-PNT6555 were similarly efficacious, producing 80% and 100% survival at optimal doses, respectively. Conclusion: PNT6555 has potential for clinical translation as a theranostic agent in FAP-positive cancer.

Radiosynthesis and Early Evaluation of a Positron Emission Tomography Imaging Probe [18F]AGAL Targeting Alpha-Galactosidase A Enzyme for Fabry Disease

Success of gene therapy relies on the durable expression and activity of transgene in target tissues. In vivo molecular imaging approaches using positron emission tomography (PET) can non-invasively measure magnitude, location, and durability of transgene expression via direct transgene or indirect reporter gene imaging in target tissues, providing the most proximal PK/PD biomarker for gene therapy trials. Herein, we report the radiosynthesis of a novel PET tracer [18F]AGAL, targeting alpha galactosidase A (α-GAL), a lysosomal enzyme deficient in Fabry disease, and evaluation of its selectivity, specificity, and pharmacokinetic properties in vitro. [18F]AGAL was synthesized via a Cu-catalyzed click reaction between fluorinated pentyne and an aziridine-based galactopyranose precursor with a high yield of 110 mCi, high radiochemical purity of >97% and molar activity of 6 Ci/µmol. The fluorinated AGAL probe showed high α-GAL affinity with IC50 of 30 nM, high pharmacological selectivity (≥50% inhibition on >160 proteins), and suitable pharmacokinetic properties (moderate to low clearance and stability in plasma across species). In vivo [18F]AGAL PET imaging in mice showed high uptake in peripheral organs with rapid renal clearance. These promising results encourage further development of this PET tracer for in vivo imaging of α-GAL expression in target tissues affected by Fabry disease.

Content Analysis of Feedback Journals for New Nurses From Preceptor Nurses Using Text Network Analysis

This study aimed to identify keywords, core topic areas, and subthemes by analyzing feedback journals written by preceptor nurses to new nurses during the preceptorship period and to derive implications through word clustering. A total of 143 preceptor nurses' feedback journals for new nurses from March 2020 to January 2021 were converted into a database using Microsoft Office Excel. Text network analysis was performed using the NetMiner 4.4.3 program. After data preprocessing, simple frequency, degree centrality, closeness centrality, betweenness centrality, and community modularity were analyzed. In the feedback journals, the most central words were "study," "medication," "practice," "nursing," "method," "need," and "effort," whereas frustration, "new nurses" had low centrality. Five subthemes were derived: (1) learning necessity to strengthen new nurses' competency, (2) independence of new nurses, (3) emphasis on accuracy in nursing skills, (4) difficulties in understanding the nursing tasks expected of new nurses, and (5) basic competency of new nurses. The results of this study highlighted the experiences of new nurses and allowed for an assessment of journal feedback content provided by preceptor nurses. As such, the study provides basic data to develop a standardized education and competency empowerment program for preceptor nurses.

Capturing New Nurses' Experiences and Supporting Critical Thinking: Text Network Analysis of Critical Reflective Journals

This study analyzed the contents of critical reflective journals written by new nurses during their orientations using a text network. This study aimed to find ways to reduce turnover and improve clinical field adaptability among new nurses. The authors analyzed the content of reflective journals written by 143 new nurses from March 2020 to January 2021. Text network analysis was performed using the NetMiner 4.4.3 program. After data preprocessing, frequency of occurrence, degree centrality, closeness centrality, betweenness centrality, and eigenvector community were analyzed. In total, 453 words were extracted and refined, and words with high simple frequency and centrality were "incompetence," "preparation," "explanation," "injection," "time," "examination," and "first try." "Medication" had the highest frequency of occurrence, and "incompetence" was the most important keyword in the centrality analysis. In addition, component analysis and eigenvector community analysis revealed three sub-theme groups: (1) basic nursing skills required for new nurses, (2) insufficient competency, and (3) explanation of nursing work. Significantly, this study is the first to use the text network method to analyze the subjective experiences of the critical reflective journals of new nurses. In conclusion, changes are needed to improve the education system for new nurses and promote efficient sharing of nursing tasks.

Radiometallation and photo-triggered release of ready-to-inject radiopharmaceuticals from the solid phase

The efficient, large-scale synthesis of radiometallated radiopharmaceuticals represents an emerging clinical need which, to date, is inherently limited by time consuming, sequential procedures to conduct isotope separation, radiochemical labeling and purification prior to formulation for injection into the patient. In this work, we demonstrate that a solid-phase based, concerted separation and radiosynthesis strategy followed by photochemical release of radiotracer in biocompatible solvents can be employed to prepare ready-to-inject, clinical grade radiopharmaceuticals. Optimization of resin base, resin loading, and radiochemical labeling capacity are demonstrated with ⁶⁷Ga and ⁶⁴Cu radioisotopes using a short model peptide sequence and further validated using two peptide-based radiopharmaceuticals with clinical relevance, targeting the gastrin-releasing peptide and the prostate specific membrane antigen. We also demonstrate that the solid-phase approach enables separation of non-radioactive carrier ions Zn²⁺ and Ni²⁺ present at 10⁵-fold excess over ⁶⁷Ga and ⁶⁴Cu by taking advantage of the superior Ga³⁺ and Cu²⁺ binding affinity of the solid-phase appended, chelator-functionalized peptide. Finally, a proof of concept radiolabeling and subsequent preclinical PET-CT study with the clinically employed positron emitter ⁶⁸Ga successfully exemplifies that Solid Phase Radiometallation Photorelease (SPRP) allows the streamlined preparation of radiometallated radiopharmaceuticals by concerted, selective radiometal ion capture, radiolabeling and photorelease.

Landscape of prostate-specific membrane antigen heterogeneity and regulation in AR-positive and AR-negative metastatic prostate cancer

Tumor expression of prostate-specific membrane antigen (PSMA) is lost in 15-20% of men with castration-resistant prostate cancer (CRPC), yet the underlying mechanisms remain poorly defined. In androgen receptor (AR)-positive CRPC, we observed lower PSMA expression in liver lesions versus other sites, suggesting a role of the microenvironment in modulating PSMA. PSMA suppression was associated with promoter histone 3 lysine 27 methylation and higher levels of neutral amino acid transporters, correlating with 18F-fluciclovine uptake on positron emission tomography imaging. While PSMA is regulated by AR, we identified a subset of AR-negative CRPC with high PSMA. HOXB13 and AR co-occupancy at the PSMA enhancer and knockout models point to HOXB13 as an upstream regulator of PSMA in AR-positive and AR-negative prostate cancer. These data demonstrate how PSMA expression is differentially regulated across metastatic lesions and in the context of the AR, which may inform selection for PSMA-targeted therapies and development of complementary biomarkers.

Abstract 3303: Pre-clinical characterization of the novel FAP targeting ligand PNT6555 for imaging and therapy of cancer

Background: Fibroblast Activation Protein-α (FAP) is a transmembrane glycoprotein highly expressed on activated fibroblasts. It is a constitutively active 170 kDa serine protease and a member of the dipeptide peptidase (DPP) family, sharing ~50% homology with DPPIV. FAP expression is only rarely expressed in normal adult tissues and is overexpressed in many epithelial cancers through upregulation on cancer-associated fibroblasts present in the stroma of various types of tumor. POINT BioPharma is developing PNT6555, which comprises a DOTA chelator linked to a FAP-targeting moiety, for imaging and therapeutic applications.

Methods: PNT6555 and its radiometal chelates were evaluated for potency, selectivity, biodistribution and efficacy using biochemical and cellular assays as well as imaging, biodistribution and efficacy studies in tumor bearing mice.

Results: PNT6555 and its gallium (natGa-PNT6555) and lutetium (natLu-PNT6555) chelates showed potent activity in FAP inhibition assays using human, mouse, and rat sources of FAP. PNT6555, natLu-PNT6555 and natGa-PNT6555 also showed significantly reduced potency when tested against PREP and DPPIV, two closely related homologous proteins. In vivo time-course biodistribution studies (by PET-imaging) with 68Ga-PNT6555 showed rapid clearance of 68Ga-PNT6555 from blood through the kidneys and urinary tract, with rising 68Ga-PNT6555 activity observed in the tumor through 60 minutes. At 60 minutes, the tumor was the only site of significant retained activity (>10 %ID/g). In vivo biodistribution studies (by SPECT imaging and direct organ assay) with 177Lu-PNT6555 showed rapid renal clearance into the bladder. After 24 hours, the tumor was the only tissue with significant activity retention. Direct organ assay showed little 177Lu-PNT6555 accumulation and retention in normal tissues with a high level of tumor retention observed out to 168h (>10 %ID/g). Therapeutic studies, using a single dose of 177Lu-PNT6555 or 225Ac-PNT6555, were completed in pre-clinical mouse models of cancer. In the HEK-mFAP model, significant dose responsive efficacy was observed in mice treated with either 177Lu-PNT6555 or 225Ac-PNT6555, with no apparent weight loss observed at all tested dose levels. Several mice experienced long-term survival >100 days at multiple of the tested dose levels.

Conclusions: PNT6555, and its radiometal chelates, are potent and specific inhibitors of FAP. 68Ga/177Lu-PNT6555 showed rapid and prolonged uptake into FAP expressing tumors with limited uptake or retention observed in normal tissues. 177Lu/225Ac-PNT6555 showed compelling efficacy in pre-clinical tumor models that expressed FAP. Clinical studies with imaging and therapeutic chelates of PNT6555 are warranted.

Citation Format: Robin M. Hallett, Sarah E. Poplawski, Mark H. Dornan, Shin Hye Ahn, Shuang Pan, Wu Wengen, Liu Yuxin, David G. Sanford, Valerie S. Hergott, Quang-De Nguyen, Anthony P. Belanger, Jack H. Lai, William Bachovchin, Joe A. McCann. Pre-clinical characterization of the novel FAP targeting ligand PNT6555 for imaging and therapy of cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3303.

Short-term outcomes of a multicentre randomized clinical trial comparing laparoscopic pylorus-preserving gastrectomy with laparoscopic distal gastrectomy for gastric cancer (the KLASS-04 trial)

BACKGROUND

There remain concerns about the safety and functional benefit of laparoscopic pylorus-preserving gastrectomy (LPPG) compared with laparoscopic distal gastrectomy (LDG). This study evaluated short-term outcomes of a randomized clinical trial (RCT) comparing LPPG with LDG for gastric cancer.

METHODS

The Korean Laparoendoscopic Gastrointestinal Surgery Study (KLASS)-04 trial was an investigator-initiated, open-label, parallel-assigned, superiority, multicentre RCT in Korea. Patients with cT1N0M0 cancer located in the middle third of the stomach at least 5 cm from the pylorus were randomized to undergo LPPG or LDG. Participants, care givers and those assessing the outcomes were not blinded to group assignment. Outcomes were 30-day postoperative morbidity rate and death at 90 days.

RESULTS

Some 256 patients from nine institutions were randomized (LPPG 129 patients, LDG 127 patients) between July 2015 and July 2017 and outcomes for 253 patients were analysed. Postoperative complications within 30 days were seen in 19.3 and 15.5 per cent in the LPPG and LDG groups respectively (P = 0·419). Postoperative pyloric stenosis was observed in nine (7.2 per cent) and two (1·5 per cent) patients in the LPPG and LDG groups (P = 0·026) respectively. In multivariable analysis higher BMI was a risk factor for postoperative complications (odds ratio 1·17, 95 per cent c.i. 1·04 to 1·32; P = 0·011). Death at 90 days was zero in both groups.

CONCLUSION

Postoperative complications and mortality was comparable in patients undergoing LPPG and LDG. Registration number: NCT02595086 (http://www.clinicaltrials.gov).

Enhanced wound healing using a 3D printed VEGF-mimicking peptide incorporated hydrogel patch in a pig model

There is a need for effective wound healing through rapid wound closure, reduction of scar formation, and acceleration of angiogenesis. Hydrogel is widely used in tissue engineering, but it is not an ideal solution because of its low vascularization capability and poor mechanical properties. In this study, gelatin methacrylate (GelMA) was tested as a viable option with tunable physical properties. GelMA hydrogel incorporating a vascular endothelial growth factor (VEGF) mimicking peptide was successfully printed using a three-dimensional (3D) bio-printer owing to the shear-thinning properties of hydrogel inks. The 3D structure of the hydrogel patch had high porosity and water absorption properties. Furthermore, the bioactive characterization was confirmed by cell culture with mouse fibroblasts cell lines (NIH 3T3) and human umbilical vein endothelial cells. VEGF peptide, which is slowly released from hydrogel patches, can promote cell viability, proliferation, and tubular structure formation. In addition, a pig skin wound model was used to evaluate the wound-healing efficacy of GelMA-VEGF hydrogel patches; the results suggest that the GelMA-VEGF hydrogel patch can be used for wound dressing.

Relationship Between Sexual Function and Pelvic Floor and Hip Muscle Strength in Women With Stress Urinary Incontinence

INTRODUCTION

The pelvic floor muscle (PFM) could affect female sexual functions. The hip muscles are morphologically and functionally linked to PFM and are important elements of female sexual attraction.

AIM

To determine the relationship between female sexual function and hip muscle strength and PFM functions in women with stress urinary incontinence (SUI).

METHODS

A total of 42 women with SUI were recruited in this study. Female sexual function was measured using the pelvic organ prolapse urinary incontinence sexual function questionnaire (PISQ). PFM functions were measured using a perineometer. Hip muscle strength was measured using a Smart KEMA tension sensor. The relationship between female sexual function and PFM function and hip muscle strength was assessed using Pearson correlation coefficients and multiple regression analyses with forward selection.

MAIN OUTCOME MEASURES

PISQ score, PFM functions (strength and endurance), and strength of hip extensor, abductor, and adductor were the main outcome measures.

RESULTS

For the behavioral/emotive domain in the PISQ, hip extensor strength (r = 0.452), PFM strength (r = 0.441), PFM endurance (r = 0.362), and hip adductor strength (r = 0.324) were significantly correlated and hip extensor strength emerged in multiple regression. For the physical domain in the PISQ, hip abductor strength (r = 0.417), PFM endurance (r = 0.356), hip adductor strength (r = 0.332), and PFM strength (r = 0.322) were significantly correlated and hip abductor strength entered in multiple regression. For partner-related domain in the PISQ, hip adductor (r = 0.386) and abductor strength (r = 0.314) were significantly correlated and hip adductor strength appeared in multiple regression. For the PISQ total score, hip extensor strength (r = 0.484), PFM endurance (r = 0.470), hip adductor strength (r = 0.424), hip abductor strength (r = 0.393), and PFM strength (r = 0.387) were significantly correlated and hip extensor strength and PFM endurance emerged in multiple regression.

CONCLUSION

The female sexual function could be related to not only PFM functions but also hip muscle strength in women with SUI. Hwang UJ, Lee MS, Jung SH, Ahn SH, Kwon OY. Relationship Between Sexual Function and Pelvic Floor and Hip Muscle Strength in Women With Stress Urinary Incontinence. Sex Med 2021;9:100325.

Homologous Structural, Chemical, and Biological Behavior of Sc and Lu Complexes of the Picaga Bifunctional Chelator: Toward Development of Matched Theranostic Pairs for Radiopharmaceutical Applications

The radioactive isotopes scandium-44/47 and lutetium-177 are gaining relevance for radioimaging and radiotherapy, resulting in a surge of studies on their coordination chemistry and subsequent applications. Although the trivalent ions of these elements are considered close homologues, dissimilar chemical behavior is observed when they are complexed by large ligand architectures due to discrepancies between Lu(III) and Sc(III) ions with respect to size, chemical hardness, and Lewis acidity. Here, we demonstrate that Lu and Sc complexes of 1,4-bis(methoxycarbonyl)-7-[(6-carboxypyridin-2-yl)methyl]-1,4,7-triazacyclononane (H₃mpatcn) and its corresponding bioconjugate picaga-DUPA can be employed to promote analogous structural features and, subsequently, biological properties for coordination complexes of these ions. The close homology was evidenced using potentiometric methods, computational modeling, variable temperature mass spectrometry, and pair distribution function analysis of X-ray scattering data. Radiochemical labeling, in vitro stability, and biodistribution studies with Sc-47 and Lu-177 indicate that the 7-coordinate ligand environment of the bifunctional picaga ligand is compatible with biological applications and the future investigation of β-emitting, picaga-chelated Sc and Lu isotopes for radiotherapy.

Site-Specific 89Zr- and 111In-Radiolabeling and In Vivo Evaluation of Glycan-free Antibodies by Azide-Alkyne Cycloaddition with a Non-natural Amino Acid

Antibody-drug conjugates (ADCs) are a class of targeted therapeutics consisting of a monoclonal antibody coupled to a cytotoxic payload. Various bioconjugation methods for producing site-specific ADCs have been reported recently, in efforts to improve immunoreactivity and pharmacokinetics and minimize batch variance-potential issues associated with first-generation ADCs prepared via stochastic peptide coupling of lysines or reduced cysteines. Recently, cell-free protein synthesis of antibodies incorporating para-azidomethyl phenylalanine (pAMF) at specific locations within the protein sequence has emerged as a means to generate antibody-drug conjugates with strictly defined drug-antibody-ratio, leading to ADCs with markedly improved stability, activity, and specificity. The incorporation of pAMF enables the conjugation of payloads functionalized for strain-promoted azide-alkyne cycloaddition. Here, we introduce two dibenzylcyclooctyne-functionalized bifunctional chelators that enable the incorporation of radioisotopes for positron emission tomography with ⁸⁹Zr (t_1/2 = 78.4 h, β⁺ = 395 keV (22%), γ = 897 keV) or single photon emission computed tomography with ¹¹¹In (t_1/2 = 67.3 h, γ = 171 keV (91%), 245 keV (94%)) under physiologically compatible conditions. We show that the corresponding radiolabeled conjugates with site-specifically functionalized antibodies targeting HER2 are amenable to targeted molecular imaging of HER2+ expressing tumor xenografts in mice and exhibit a favorable biodistribution profile in comparison with conventional, glycosylated antibody conjugates generated by stochastic bioconjugation.

Asymptomatic Cerebral Vasoconstriction after Carotid Artery Stenting

BACKGROUND AND PURPOSE

Carotid artery stent placement is widely performed for treatment of carotid stenosis. The purpose of this study is to present our observations on cerebral vasoconstriction in ipsilateral anterior circulation during immediate poststenting angiography in patients with near-total occlusion of the proximal ICA.

MATERIALS AND METHODS

We retrospectively reviewed patient data from December 2008 to December 2018. There were 28 patients with carotid near-total occlusion. Two neuroradiologists reviewed the final cerebral angiographic finding of carotid artery stent placement to evaluate the presence of vasoconstriction or vasodilation.

RESULTS

A total of 28 patients with near-total occlusion (mean ± standard deviation age, 69.0 ± 6.5 years; 92.9% male) were analyzed. Ten patients showed vasoconstriction in the treated territory, and 18 patients did not show vasoconstriction after carotid artery stenting. There were no statistically significant differences in comorbidity, frequency of symptomatic lesions, antiplatelet medication, mean procedure time, and initial NIHSS and baseline modified Rankin scale scores between the 2 groups. However, vasoconstriction is more likely to happen in patients with isolated territory from the contralateral anterior and posterior circulation (66.7% in the isolated territory group and 12.5% in the not-isolated territory group; P < .05). No headache or neurologic deficit was noted in all 10 patients with cerebral vasoconstriction.

CONCLUSIONS

Cerebral vasoconstriction may occur after carotid artery stenting more frequently than expected. It occurs more frequently in patients with near-total occlusion and with isolation of the cerebral circulation. A large-scale study is necessary to assess the clinical implications of cerebral vasoconstriction after carotid artery stenting.

Chelation with a twist: a bifunctional chelator to enable room temperature radiolabeling and targeted PET imaging with scandium-44

Scandium-44 has emerged as an attractive, novel PET radioisotope with ideal emission properties and half-life (t 1/2 = 3.97 h, E mean β+ = 632 keV) well matched to the pharmacokinetics of small molecules, peptides and small biologics. Conjugates of the current gold-standard chelator for 44Sc, 1,4,7,10-tetraaza-cyclododecane-1,4,7,10-tetraacetic acid (DOTA), require heating to achieve radiochemical complexation, limiting application of this isotope in conjunction with temperature-sensitive biologics. To establish Sc(iii) isotopes as broadly applicable tools for nuclear medicine, development of alternative bifunctional chelators is required. To address this need, we characterized the Sc(iii)-chelation properties of the small-cavity triaza-macrocycle-based, picolinate-functionalized chelator H3mpatcn. Spectroscopic and radiochemical studies establish the [Sc(mpatcn)] complex as kinetically inert and appropriate for biological applications. A proof-of-concept bifunctional conjugate targeting the prostate-specific membrane antigen (PSMA), picaga-DUPA, chelates 44Sc to form 44Sc(picaga)-DUPA at room temperature with an apparent molar activity of 60 MBq μmol-1 and formation of inert RRR-Λ and SSS-Δ-twist isomers. Sc(picaga)-DUPA exhibits a K i of 1.6 nM for PSMA, comparable to the 18F-based imaging probe DCFPyL (K i = 1.1 nM) currently in phase 3 clinical trials for imaging prostate cancer. Finally, we successfully employed 44Sc(picaga)-DUPA to image PSMA-expressing tumors in a preclinical mouse model, establishing the picaga bifunctional chelator as an optimal choice for the 44Sc PET nuclide.

Trivalent metal complex geometry of the substrate governs cathepsin B enzymatic cleavage rate

The identity of the trivalent metal ion controls the rate of the enzymatic cleavage of a series of metal-complexed cathepsin B substrates. Increasing the distance between the metal complex and the enzyme cleavage site diminishes this effect.

Imaging Triage of Patients with Late-Window (6-24 Hours) Acute Ischemic Stroke: A Comparative Study Using Multiphase CT Angiography versus CT Perfusion

BACKGROUND AND PURPOSE

The role of collateral imaging in selecting patients for endovascular thrombectomy beyond 6 hours from onset has not been established. To assess the comparative utility of collateral imaging using multiphase CTA in selecting late window patients for EVT.

MATERIALS AND METHODS

We used data from a prospective multicenter observational study in which all patients underwent imaging with multiphase CT angiography as well as CTP. Two blinded reviewers evaluated patients' eligibility for endovascular thrombectomy using published collateral imaging (multiphase CTA) criteria compared with CTP using the selection criteria of the Clinical Mismatch in the Triage of Wake Up and Late Presenting Strokes Undergoing Neurointervention with Trevo (DAWN) and Endovascular Therapy Following Imaging Evaluation for Ischemic Stroke 3 (DEFUSE-3) trials. CTP images were processed using automated commercial software. The outcomes of patients eligible for endovascular thrombectomy according to multiphase CTA, DAWN, or DEFUSE-3 criteria were compared using multivariable logistic regression modeling. Model characteristics were compared using the C-statistic for the receiver operating characteristic curve, the Akaike information criterion, and the Bayesian information criterion.

RESULTS

Eighty-six patients presented beyond 6 hours from onset/last known well (median, 9.6 hours; interquartile range, 4.1 hours). Thirty-five patients (40.7%) received endovascular thrombectomy, of whom good functional outcome (90-day mRS, 0-2) was achieved in 16/35 (47%). Collateral-based imaging paradigms significantly modified the treatment effect of endovascular thrombectomy on 90-day mRS 0-2 (P _interaction = .007). The multiphase CTA-based regression model best fit the data for the 90-day outcome (C-statistic, 0.86; 95% CI, 0.77-0.94) and was associated with the least information loss (Akaike information criterion, 95.7; Bayesian information criterion, 114.9) compared with CTP-based models.

CONCLUSIONS

The collateral-based imaging paradigm using multiphase CTA compares well with CTP in selecting patients for endovascular thrombectomy in the late time window.

Theranostic Gallium Siderophore Ciprofloxacin Conjugate with Broad Spectrum Antibiotic Potency

Pathogenic bacteria scavenge ferric iron from the host for survival and proliferation using small-molecular chelators, siderophores. Here, we introduce and assess the gallium(III) complex of ciprofloxacin-functionalized desferrichrome (D2) as a potential therapeutic for bacterial infection using an in vitro assay and radiochemical, tracer-based approach. Ga-D2 exhibits a minimum inhibitory concentration of 0.23 μM in Escherichia coli, in line with the parent fluoroquinolone antibiotic. Competitive and mutant strain assays show that Ga-D2 relies on FhuA-mediated transport for internalization. Ga-D2 is potent against Pseudomonas aeruginosa (3.8 μM), Staphylococcus aureus (0.94 μM), and Klebsiella pneumoniae (12.5 μM), while Fe-D2 is inactive in these strains. Radiochemical experiments with E. coli reveal that ⁶⁷Ga-D2 is taken up more efficiently than ⁶⁷Ga-citrate. In naive mice, ⁶⁷Ga-D2 clears renally and is excreted 13% intact in the urine. These pharmacokinetic and bacterial growth inhibitory properties qualify Ga-D2 for future investigations as a diagnosis and treatment tool for infection.

Association of blood n-3 fatty acid with bone mass and bone marrow TRAP-5b in the elderly with and without hip fracture

The plasma n-3 fatty acid level was 26.2% lower in patients with osteoporotic hip fracture than in those with osteoarthritis. In all patients, n-3 fatty acid was positively associated with bone mineral density and inversely associated with tartrate-resistant acid phosphatase-5b level in bone marrow aspirates, reflecting the bone microenvironment.

INTRODUCTION

Despite the potential beneficial role of n-3 fatty acid (FA) on bone metabolism, the specific mechanisms underlying these effects in humans remain unclear. Here, we assessed whether the plasma n-3 level, as an objective indicator of its status, is associated with osteoporosis-related phenotypes and bone-related markers in human bone marrow (BM) samples.

METHODS

This was a case-control and cross-sectional study conducted in a clinical unit. n-3 FA in the blood and bone biochemical markers in the BM aspirates were measured by gas chromatography/mass spectrometry and immunoassay, respectively. BM fluids were collected from 72 patients who underwent hip surgery because of either osteoporotic hip fracture (HF; n = 28) or osteoarthritis (n = 44).

RESULTS

After adjusting for confounders, patients with HF had 26.2% lower plasma n-3 levels than those with osteoarthritis (P = 0.006), and each standard deviation increment in plasma n-3 was associated with a multivariate-adjusted odds ratio of 0.40 for osteoporotic HF (P = 0.010). In multivariate analyses including all patients, a higher plasma n-3 level was associated with higher bone mass at the lumbar spine (β = 0.615, P = 0.002) and total femur (β = 0.244, P = 0.045). Interestingly, the plasma n-3 level was inversely associated with the tartrate-resistant acid phosphatase-5b level (β = - 0.633, P = 0.023), but not with the bone-specific alkaline phosphatase level, in BM aspirates.

CONCLUSIONS

These findings provide clinical evidence that n-3 FA is a potential inhibitor of osteoclastogenesis that favors human bone health.

The effects of cortisol and adrenal androgen on bone mass in Asians with and without subclinical hypercortisolism

Analyses using the largest Korean cohort of adrenal incidentaloma (AI) revealed that subtle cortisol excess in premenopausal women and reduced dehydroepiandrosterone-sulfate (DHEA-S) in postmenopausal women and men are associated with bone mineral density (BMD) reduction in Asian patients with subclinical hypercortisolism (SH).

INTRODUCTION

Few studies evaluated bone metabolism in Asians with SH. We investigated associations of cortisol and DHEA-S, an adrenal androgen, with BMD in Asians with AI, with or without SH.

METHODS

We used cross-sectional data of a prospective multicenter study from Korea. We measured BMD, bone turnover markers, cortisol levels after 1-mg dexamethasone suppression test (1-mg DST), DHEA-S, and baseline cortisol to DHEA-S ratio (cort/DHEA-S) in 109 AI patients with SH (18 premenopausal, 38 postmenopausal women, and 53 men) and 686 with non-functional AI (NFAI; 59 premenopausal, 199 postmenopausal women, and 428 men).

RESULTS

Pre- and postmenopausal women, but not men, with SH had lower BMDs at lumbar spine (LS) than those with NFAI (P = 0.008~0.016). Premenopausal women with SH also had lower BMDs at the hip than those with NFAI (P = 0.009~0.012). After adjusting for confounders, cortisol levels after 1-mg DST demonstrated inverse associations with BMDs at all skeletal sites only in premenopausal women (β = - 0.042~- 0.033, P = 0.019~0.040). DHEA-S had positive associations with LS BMD in postmenopausal women (β = 0.096, P = 0.001) and men (β = 0.029, P = 0.038). The cort/DHEA-S had inverse associations with LS BMD in postmenopausal women (β = - 0.081, P = 0.004) and men (β = - 0.029, P = 0.011). These inverse associations of cort/DHEA-S remained significant after adjusting for cortisol levels after 1-mg DST (β = - 0.079~- 0.026, P = 0.006~0.029). In postmenopausal women, the odds ratios of lower BMD by DHEA-S and cort/DHEA-S was 0.26 (95% CI, 0.08-0.82) and 3.40 (95% CI, 1.12-10.33), respectively.

CONCLUSION

Subtle cortisol excess in premenopausal women and reduced DHEA-S in postmenopausal women and men may contribute to BMD reduction in Asians with SH.

Clot Burden Score and Early Ischemia Predict Intracranial Hemorrhage following Endovascular Therapy

BACKGROUND AND PURPOSE

Intracranial hemorrhage is a known complication following endovascular thrombectomy. The radiologic characteristics of a CT scan may assist with hemorrhage risk stratification. We assessed the radiologic predictors of intracranial hemorrhage following endovascular therapy using data from the INTERRSeCT (Identifying New Approaches to Optimize Thrombus Characterization for Predicting Early Recanalization and Reperfusion With IV Alteplase and Other Treatments Using Serial CT Angiography) study.

MATERIALS AND METHODS

Patients undergoing endovascular therapy underwent baseline imaging, postprocedural angiography, and 24-hour follow-up imaging. The primary outcome was any intracranial hemorrhage observed on follow-up imaging. The secondary outcome was symptomatic hemorrhage. We assessed the relationship between hemorrhage occurrence and baseline patient characteristics, clinical course, and imaging factors: baseline ASPECTS, thrombus location, residual flow grade, collateralization, and clot burden score. Multivariable logistic regression with backward selection was used to adjust for relevant covariates.

RESULTS

Of the 199 enrolled patients who met the inclusion criteria, 46 (23%) had an intracranial hemorrhage at 24 hours. On multivariable analysis, postprocedural hemorrhage was associated with pretreatment ASPECTS (OR, 1.56 per point lost; 95% CI, 1.12-2.15), clot burden score (OR, 1.19 per point lost; 95% CI, 1.03-1.38), and ICA thrombus location (OR, 3.10; 95% CI, 1.07-8.91). In post hoc analysis, clot burden scores of ≤3 (sensitivity, 41%; specificity, 82%; OR, 3.12; 95% CI, 1.36-7.15) and pretreatment ASPECTS ≤ 7 (sensitivity, 48%; specificity, 82%; OR, 3.17; 95% CI, 1.35-7.45) robustly predicted hemorrhage. Residual flow grade and collateralization were not associated with hemorrhage occurrence. Symptomatic hemorrhage was observed in 4 patients.

CONCLUSIONS

Radiologic factors, early ischemia on CT, and increased CTA clot burden are associated with an increased risk of intracranial hemorrhage in patients undergoing endovascular therapy.

Abstract P3-13-01: Application of supine MRI-based 3D printing breast surgical guide for precision breast-conserving surgery

Background

If the size of the tumor is large, neoadjuvant systemic therapy (NST) is performed to reduce the size of the tumor and to conserve the breast. It is known that magnetic resonance imaging is more accurate than mammography (MMG) or ultrasonography (USG) in determining the area of residual cancer in breast-conserving surgery (BSG) after NST. However, there are some problems when performing BCS using MRI. Because the posture of MRI test is different from the posture at surgery, it is difficult to accurately mark the area of the tumor observed in MRI. Neoadjuvant systemic therapy reduces tumor size and often makes it difficult to detect the original tumor area on preoperative MRI. Even if the tumor is not visible in the image, the cancer cells may remain, so it is important to accurately indicate the extent of the initial tumor and remove it. Until now, however, there has been no way to accurately mark past breast tumors in the breast. We have developed a breast surgical guide (BSG) that can mark a range of tumor directly on the breast using three-dimensional printing technology based on supine MRI. This study analyzed the results of patients who underwent BCS using a 3D printing breast surgical guide (3D-BSG) based on supine MRI.

Methods

This trial was designed as a prospective single-institution cohort study. Our study protocol was approved by the Institutional Review Board of Asan Medical Center, Seoul, Korea (IRB No. 2016-1237). Patients who were expected to undergo BCS after NST were enrolled in this study and supine MRI was performed before and after NST. From MRI images, morphological shapes of breasts and tumors were modeled. The prepared digital model was saved in stereolithography file format and then exported to a 3D printer. 3D-BSG is designed to be able to mark the skin and attach the dye injecting column to mark the around the tumor. The breast tissue was removed with blue dye on the basis of the border. To obtain tumor free margin, intraoperative frozen sections were identified in several cavities and re-excision was performed if tumor positive.

Results

Between January 2016 and May 2017, 50 patients were enrolled in the study. BCS was applied to 40 patients, except for those who were rejected or mastectomy. Complete remission was observed in 15 patients after NST. Four patients had tumor positive on resection margins on frozen biopsy during operation, two with IDC and two with DCIS. Re-excision was performed in these patients and tumor negative margin was confirmed in all patients in the final pathology results. The median size of the long axis of the tumor was 1.7 cm (range, 0.5 to 4.5 cm) and the median size of the long axis of the removed breast tissue was 5.1 cm (range, 2.3 to 8.1 cm). The distance between tumor and resection margin was 1.2 cm (range, 0.1 to 4.8 cm)..

Conclusions

In BCS, the application of the supine MRI based 3D-BSG showed low rates of positive margins. Unlike conventional localization techniques, application of 3D-BSG does not cause pain to the patient, has no radiation exposure, and has no time required for the localization procedure, so it will be helpful for patients in BCS in the future.

Citation Format: Ko B, Kim N, Seo J, Kim H, Gong G, Kim S, Son B, Ahn SH. Application of supine MRI-based 3D printing breast surgical guide for precision breast-conserving surgery [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-13-01.

Abstract P2-14-21: Not presented

This abstract was not presented at the conference.

Citation Format: Lee S, Ahn SH, Lee JW, Chung IY, Ko BS, Kim HJ, Kim J, Shon G, Son BH. Not presented [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-14-21.

Linear Desferrichrome-Linked Silicon-Rhodamine Antibody Conjugate Enables Targeted Multimodal Imaging of HER2 in Vitro and in Vivo

We report the nuclear and optical in vitro and in vivo imaging of SKOV-3 cells by targeting HER2 with a bimodal trastuzumab conjugate. Previously, we have shown that desferrichrome derivatives provide a robust and versatile radiolabeling platform for the radioisotope zirconium-89. Here, we appended silicon-rhodamine functionalized linear desferrichrome to trastuzumab. This construct was radiolabeled and used to image cellular binding and antibody uptake in vitro and in vivo. The robust extinction coefficient of the SiR deep-red emissive fluorophore enables direct quantification of the number of appended chelators and fluorophore molecules per antibody. Subsequent radiolabeling of the multifunctional immunoconjugate with ⁸⁹Zr was achieved with a 64 ± 9% radiochemical yield, while the reference immunoconjugate desferrioxamine (DFO)-trastuzumab exhibited a yield of 84 ± 9%. In vivo PET imaging (24, 48, 72, and 96 h post injection) and biodistribution experiments (96 h post injection) in HER2+ tumor bearing mice revealed no statistically significant difference of the two ⁸⁹Zr-labeled conjugates at each time point evaluated. The bimodal conjugate permitted successful in vivo fluorescence imaging (96 h post injection) and subsequent fluorescence-guided, surgical resection of the tumor mass. This report details the first successful application of a fluorophore-functionalized desferrichrome derivative for targeted imaging, motivating further development and application of this scaffold as a multimodal imaging platform.