Non-target Tissues Research Articles

Investigation of mutagenicity of styrene in tumor target and non-target tissues of transgenic Big Blue® mice.

Styrene has been shown to induce lung tumors in mice, but not in rats. The current study investigated the potential role of genotoxicity as an initial key event in the mode of action for styrene-induced lung tumors in mice. Transgenic male B6C3F1 Big Blue® mice were treated by oral gavage for 28 consecutive days with 0 (corn oil), 75, 150, or 300 mg/kg/day of styrene. The 300 mg/kg/day represented the tumorigenic dose in the oral gavage carcinogenicity study conducted in B6C3F1 mice. Following a 28-day expression period, mutant frequencies were assessed at the cII locus of the transgene in the tumor target (lung) and non-target tissues (liver, glandular stomach, and duodenum). Mice treated with N-ethyl-N-nitrosourea (40 mg/kg/day) by oral gavage on Days 1, 2, and 3 of the study and sacrificed on Day 56 served as the positive control group. Genomic DNA was extracted from the selected tissues, processed for the recovery of the transgene into infectious phage, plated onto Escherichia coli strain G1250, and incubated at 37°C for titer determination or at 24°C for the selection of mutant plaques. There were no treatment-related increases in mutant frequency in any of the tissues. The positive control group had a significant increase in the frequency of cII mutants assuring the adequacy of the experimental conditions to detect induced mutations. To conclude, mutagenicity is not considered a plausible initial key event in the mode of action for styrene-induced mouse lung tumors as these data support that styrene is not an in vivo mutagen.

Site-Specific Modification of Native IgGs with Flexible Drug-Load.

Homogeneous, site-specifically conjugated antibodies have shown to result in antibody-drug conjugates (ADCs) with improved efficacy and tolerability compared to stochastically conjugated ADCs. However, precisely controlling the drug load as well as attaching multiple payload moieties to the antibody remains challenging. Here, we demonstrate the simple and direct modification of native IgG-antibodies at the residue glutamine 295 (Q295) without the need for any protein engineering with flexible drug-to-antibody ratios of one or multiple payloads. The conjugation is enabled through short, positively charged lysine containing peptides and native, commercially available microbial transglutaminase. In proof-of-concept studies, HER2-targeting ADCs based on trastuzumab were generated with drug-to-antibody ratios (DARs) of 2 and 4 of the same or different payloads using orthogonal conjugation chemistries. Quantitative biodistribution studies performed with 111In-radiolabeled conjugates showed high tumour uptake and low accumulation of radioactivity in non-targeted tissues. A single dose study of trastuzumab conjugated to the highly potent payload α-Amanitin demonstrated complete and long-lasting tumour remission and was well-tolerated at all dose levels tested.

In vitro and in vivo study of 221Fr and 213Bi progeny release from the 225Ac-labelled TiO2 nanoparticles

BackgroundTargeted alpha therapy (TAT) is an effective option for cancer treatment. To maximize its efficacy and minimize side effects, carriers must deliver radionuclides to target tissues. Most of the nuclides used in TAT decay via the alpha cascade, producing several radioactive daughter nuclei with sufficient energy to escape from the original carrier. Therefore, studying these daughter atoms is crucial in the search for new carriers. Nanoparticles have potential as carriers due to their structure, which can prevent the escape of daughter atoms and reduce radiation exposure to non-target tissues. This work focuses on determining the released activity of 221Fr and 213Bi resulting from the decay of 225Ac labelled TiO2 nanoparticles. ResultsLabelling of TiO2 nanoparticles has shown high sorption rates of 225Ac and its progeny, 221Fr and 213Bi, with over 92 % of activities sorbed on the nanoparticle surface for all measured radionuclides. However, in the quasi-dynamic in vitro system, the released activity of 221Fr and 213Bi is strongly dependent on the nanoparticles concentration, ranging from 15 % for a concentration of 1 mg/mL to approximately 50 % for a nanoparticle concentration of 10 μg/mL in saline solution. The released activities of 213Bi were lower, with a maximum value of around 20 % for concentrations of 0.05, 0.025, and 0.01 mg/mL. The leakage of 225Ac and its progeny was tested in various biological matrices. Minimal released activity was measured in saline at around 10 % after 48 h, while the maximum activity was measured in blood serum and plasma at 20 %. The amount of 225Ac released into the media was minimal (<3 %). The in vitro results were confirmed in a healthy mouse model. The difference in %ID/g was clearly visible immediately after dissection and again after 6 h when 213Bi reached equilibrium with 225Ac. ConclusionThe study verified the potential release of 225Ac progeny from the labelled TiO2 nanoparticles. Experiments were performed to determine the dependence of released activity on nanoparticle concentration and the biological environment. The results demonstrated the high stability of the prepared 225Ac@TiO2 NPs and the potential release of progeny over time. In vivo studies confirmed our hypothesis. The data obtained suggest that the daughter atoms can escape from the original carrier and follow their own biological pathways in the organism.

Brain volume loss after cranial irradiation: a controlled comparison study between photon vs proton radiotherapy for WHO grade 2-3 gliomas.

Radiation therapy (RT) is an integral treatment component in patients with glioma but associated with neurotoxicity. Proton RT (PRT), as compared with photon RT (XRT), reduces excess radiation to nontarget tissue. We used a retrospective method to evaluate brain imaging metrics of neurotoxicity after treatment with PRT and XRT for glioma. We analyzed brain volume change in thirty-four patients with WHO grade 2-3 gliomas treated with either PRT (n = 17) or XRT (n = 17). Both groups were carefully matched by demographic/clinical criteria and assessed longitudinally for two years post-radiotherapy. Brain volume change was measured as ventricular volume expansion in the tumor free hemisphere (contralateral to RT target) as a proxy indicator of brain volume loss. We further assessed the impact of volumetric changes on cognition in PRT patients, who completed neuropsychological testing as part of an outcome study. We found significant ventricular volume increases in the contralesional hemisphere in both groups at two years post-RT (F(1, 31) = 18.45, p < 0.000, partial η2 = 0.373), with greater volume change observed in XRT (26.55%) vs. PRT (12.03%) (M = 12.03%, SD = 16.26; F(1,31) = 4.26, p = 0.048, partial η2 = 0.121). Although, there was no group-level change on any cognitive test in PRT treated patients, individual changes on cognitive screening, working memory, processing speed and visual memory tasks correlated with contralesional brain volume loss. This study suggests progressive brain volume loss following cranial irradiation, with greater severity after XRT vs. PRT. Radiation-induced brain volume loss appears to be associated with measurable cognitive changes on an individual level. Prospective studies are warranted to validate these findings and their impacts on long-term cognitive function and quality of life. An improved understanding of the structural and functional consequences of cranial radiation is essential to develop neuroprotective strategies.

Novel astatine (211At)-labelled prostate-specific membrane antigen ligand with a neopentyl-glycol structure: evaluation of stability, efficacy, and safety using a prostate cancer xenograft model.

Prostate-specific membrane antigen (PSMA)-targeted alpha therapy is considered a promising alternative treatment for metastatic castration-resistant prostate cancer (mCRPC). Though astatine-211 (211At) is potentially useful alpha-emitter producible by cyclotrons, its clinical application has been limited by instability and a tendency to deastatination in vivo. To overcome these challenges, we developed [211At]At-NpG-PSMA, a novel PSMA ligand with a neopentyl-glycol structure that enhances in vivo stability against deastatination. This study aimed to evaluate the stability, anti-tumour effect, and safety of [211At]At-NpG-PSMA in mice. Xenograft models were prepared by subcutaneous transplantation of PSMA-positive PC-3 PIP cells into BALB/c nu/nu mice. [211At]At-NpG-PSMA was administered to assess biodistribution, and the anti-tumour effect was evaluated at doses of 0.32, 1.00 and 1.93 MBq in comparison with saline. Histopathological examinations were performed to evaluate damage to normal organs. [211At]At-NpG-PSMA demonstrated high tumour uptake (42.0 ± 13.1%ID/g at 3h) with minimal uptake in non-target tissues, including thyroid, stomach and salivary grands (0.28 ± 0.20%ID, 0.71 ± 0.12%ID/g and 0.88 ± 0.10%ID/g at 3h, respectively). A dose-dependent anti-tumour effect was observed, with tumour volumes increasing by 796.0 ± 437.6% in the control versus 161.0 ± 213.4%, -76.4 ± 19.2% and - 59.5 ± 41.6% in the 0.32, 1.00 and 1.93 MBq groups, respectively, by day 15. Mild renal tubule regeneration was noted in the 1.00 MBq group. [211At]At-NpG-PSMA demonstrated significant stability in vivo and anti-tumour effects with minimal side effects, indicating its potential as a new therapeutic drug for PSMA-targeted alpha therapy in mCRPC.

Synergistic Anticancer Effects by Enhancing the G-Quadruplex Binding of Nickel(II) Salphen Complexes through Coupling with S-Doped Carbon Nanodots.

In recent decades, researchers have focused on developing less toxic and more precise cancer therapies. Carbon nanodots (CDs) are among the most promising technologies due to their high biocompatibility, tunable fluorescence, and ability to facilitate photothermal and photodynamic therapy. This study explores the synthesis and characterization of two CDs conjugated with Salphen metal complexes, namely, CDs-PEG-M1 and CDs-PEG-M2, through Sonogashira coupling. Their interaction with G-quadruplex DNA structures (G4s), motifs largely involved in cancer development, was evaluated using various spectroscopic techniques. The results indicate that CDs-PEG-M1 exhibits greater effectiveness in stabilizing G4 structures compared to the metal complex alone or nonfunctionalized CDs. This enhanced stabilization suggests that CDs-PEG-M1 could reduce the concentration of the metal complex needed for potential antitumor applications, thereby minimizing side effects on nontarget tissues. When tested on breast cancer models (MDA-MB-231 as a triple-negative model and MCF-7 as a HER-2 positive model) and on a healthy cell line (HDFa), the CDs-PEG-M1 conjugate reduced cell viability in a concentration- and time-dependent manner, showing greater potency and selectivity against cancer cells compared to virgin CDs and the free M1 complex. This synergistic anticancer effect, driven by the interaction with G4 structures and reactive oxygen species production, underscores the potential of CDs-PEG-M1 as a targeted nanotheranostic tool.

9267 Targeting IGF-I to Growth Plate Cartilage Augments Therapeutic Effects on Skeletal Growth and Reduces Hypoglycemic Effects in Mice

Abstract Disclosure: K. Tailor: None. T. Stowe: None. J. Ree: None. B. Ventura: None. J. Deursen: None. R. O'Brien: None. J. Baron: None. J. Lui: None. Recombinant human growth hormone (GH) is commonly used to treat short stature in children but has limited efficacy in severe, non-GH-deficient conditions, such as skeletal dysplasias, and has adverse off-target effects. Because short stature is the result of reduced growth plate chondrogenesis, we hypothesized that targeting chondrogenic growth factors specifically to the growth plate might augment the therapeutic skeletal effect while diminishing adverse effects on non-target tissues. Toward this end, we previously developed fusion proteins conjugating insulin-like growth factor-1 (IGF-1) with a single-chain human monoclonal antibody fragment (ScFv) targeting matrillin-3 (1), a protein specifically expressed in cartilage matrix, and demonstrated increased on-target therapeutic efficacy at the growth plate and decreased off-target effects in a GH-deficient (lit) mouse model (2). In the current study, we established a second GH-deficiency model by administration of a GH antagonist, pegvisomant (PEG), in C57BL/6 wild-type male mice. Alternate-day injection of pegvisomant at 40 mg/kg for 7 days reduced body weight, serum IGF-1 levels, and growth plate height in mice. Using this model, we found that once-daily SQ administration of cartilage-targeted IGF-I (named CV1574-1) for five days increased body weight and growth plate height greater than an equimolar dose of IGF-I itself administered twice daily. Hypoglycemia is an adverse effect of recombinant IGF-1 treatment. Therefore, we also monitored blood glucose levels after a single SQ injection of CV1574-1 and found that this fusion protein showed a reduced hypoglycemic effect compared to injection of IGF-I itself. Lastly, to gain mechanistic insight into the role of matrillin-3 targeting on therapeutic efficacy, we assessed the ability of CV1574-1 to induce pAKT signaling in vitro. Transient exposure to CV1574-1 caused more prolonged induction of pAKT signal in wild-type rat chondrosarcoma (RCS) cells compared to matrillin-3-knockout RCS cells, suggesting that matrillin-3 targeting extends the duration of IGF-1 receptor activation. To summarize, the current findings demonstrate that CV1574-1, a fusion protein that targets IGF-1 to cartilage, improves efficacy at the growth plate, reduces hypoglycemic effects, and, in vitro, prolongs receptor activation. Our study provides further evidence that cartilage-targeted therapy has the potential to provide new pharmacological approaches for the treatment of childhood linear growth disorders, including skeletal dysplasias and growth failure due to systemic disease. Reference:(1) Cheung et al. Pharma Res 2015, 32(7):2439-49.(2) Lui et al. Molecular Therapy 2019, 27(3):673-680 Presentation: 6/3/2024

7237 Targeting IGF-I to Growth Plate Cartilage Augments Therapeutic Effects on Skeletal Growth and Reduces Hypoglycemic Effects in Mice

Abstract Disclosure: K. Tailor: None. T. Stowe: None. J. Ree: None. B. Ventura: None. J. Deursen: None. R. O'Brien: None. J. Baron: None. J. Lui: None. Recombinant human growth hormone (GH) is commonly used to treat short stature in children but has limited efficacy in severe, non-GH-deficient conditions, such as skeletal dysplasias, and has adverse off-target effects. Because short stature is the result of reduced growth plate chondrogenesis, we hypothesized that targeting chondrogenic growth factors specifically to the growth plate might augment the therapeutic skeletal effect while diminishing adverse effects on non-target tissues. Toward this end, we previously developed fusion proteins conjugating insulin-like growth factor-1 (IGF-1) with a single-chain human monoclonal antibody fragment (ScFv) targeting matrillin-3 (1), a protein specifically expressed in cartilage matrix, and demonstrated increased on-target therapeutic efficacy at the growth plate and decreased off-target effects in a GH-deficient (lit) mouse model (2). In the current study, we established a second GH-deficiency model by administration of a GH antagonist, pegvisomant (PEG), in C57BL/6 wild-type male mice. Alternate-day injection of pegvisomant at 40 mg/kg for 7 days reduced body weight, serum IGF-1 levels, and growth plate height in mice. Using this model, we found that once-daily SQ administration of cartilage-targeted IGF-I (named CV1574-1) for five days increased body weight and growth plate height greater than an equimolar dose of IGF-I itself administered twice daily. Hypoglycemia is an adverse effect of recombinant IGF-1 treatment. Therefore, we also monitored blood glucose levels after a single SQ injection of CV1574-1 and found that this fusion protein showed a reduced hypoglycemic effect compared to injection of IGF-I itself. Lastly, to gain mechanistic insight into the role of matrillin-3 targeting on therapeutic efficacy, we assessed the ability of CV1574-1 to induce pAKT signaling in vitro. Transient exposure to CV1574-1 caused more prolonged induction of pAKT signal in wild-type rat chondrosarcoma (RCS) cells compared to matrillin-3-knockout RCS cells, suggesting that matrillin-3 targeting extends the duration of IGF-1 receptor activation. To summarize, the current findings demonstrate that CV1574-1, a fusion protein that targets IGF-1 to cartilage, improves efficacy at the growth plate, reduces hypoglycemic effects, and, in vitro, prolongs receptor activation. Our study provides further evidence that cartilage-targeted therapy has the potential to provide new pharmacological approaches for the treatment of childhood linear growth disorders, including skeletal dysplasias and growth failure due to systemic disease. Reference:(1) Cheung et al. Pharma Res 2015, 32(7):2439-49.(2) Lui et al. Molecular Therapy 2019, 27(3):673-680 Presentation: 6/3/2024

Novel Drug Delivery Systems: An effective platform for Enhanced Therapy

Modern developments in drug pharmacokinetic and Pharmacodynamics behavior make developing the optimal drug delivery method more rational. It is already clear that future success in medication delivery research will mostly come from interdisciplinary collaborations. Pharmaceutical businesses stand to gain enormous commercial potential and advance human disease treatment by employing better drug delivery methods to make therapeutic agents safer and more effective. It is already apparent that multidisciplinary efforts will mostly be responsible for future success in drug delivery research. Any therapeutic agent that can be made safer and more effective while using an enhanced drug delivery method represents a step forward in the treatment of human diseases as well as significant marketing potential for pharmaceutical companies. The best drug delivery systems, based on the etiology and physiological requirements of the body, deliver a predefined dose of medication to the intended site at the appropriate time and place. The speed at which a medication reaches its intended location cannot be controlled by conventional pharmaceutical dosage forms. Novel drug delivery systems (NDDS) are carriers that maintain the drug concentration in the therapeutic range for longer periods of time and may also deliver the content to the targeted site if desired and as needed, because higher doses often cause serious side effects during treatment. Because of this, therapeutic dosages for drug dispersion in non-target tissue and bodily fluids may be far higher than those needed in target cells.

Novel 99mTc-Labeled Mannose Derivative as a Highly Promising Single Photon Emission Computed Tomography Probe for Tumor Imaging.

18F-2-fluoro-2-deoxy-d-glucose ([18F]FDG) has been the most used positron emission tomography imaging agent for clinical applications. Single photon emission computed tomography (SPECT) imaging is cheaper and used more widely for diagnostic use, but there is no SPECT tumor imaging agent for clinical applications comparable to [18F]FDG. Mannose is a C2 epimer of glucose and can also be transported into tumor cells via glucose transporters (GLUTs). To develop a novel SPECT tumor imaging agent with satisfactory tumor uptake and tumor/nontarget ratios, here a mannose derivative (CN7DM) was synthesized and radiolabeled with technetium-99m to prepare [99mTc]Tc-CN7DM. The six-coordinated structure of [99mTc]Tc-CN7DM was confirmed by the corresponding rhenium compound (Re-CN7DM). [99mTc]Tc-CN7DM was transported into cancer cells via GLUTs and may be trapped in the cancer cells by electrostatic attraction. The probe exhibited high uptake in tumors and low uptake in nontarget tissues in mice bearing different tumors, indicating that [99mTc]Tc-CN7DM exhibited promising potential for SPECT tumor imaging and warranted further clinical investigation.

Interstitial dual-mode ultrasound with a 3-mm MR-compatible catheter for image-guided HIFU and directional in-vitro tissue ablations.

Current interstitial techniques of tumor ablation face challenges that ultrasound technologies could meet. The ablation radius and directionality of the ultrasound beam could improve the efficiency and precision. Here, a 9-gauge MR-compatible dual-mode ultrasound catheter prototype was experimentally evaluated for Ultrasound Image-guided High Intensity Focused Ultrasound (USgHIFU) conformal ablations. The prototype consisted of 64 piezocomposite linear array elements and was driven by an open research programmable dual-mode ultrasound platform. After verifying the US-image guidance capabilities of the prototype, the HIFU output performances (dynamic focusing and HIFU intensities) were quantitatively characterized, together with the associated 3D HIFU-induced thermal heating in tissue phantoms (using MR thermometry). Finally, the ability to produce robustly HIFU-induced thermal ablations in in-vitro liver was studied experimentally and compared to numerical modeling. Investigations of several HIFU dynamic focusing allowed overcoming the challenges of miniaturizing the device: mono-focal focusing maximized deep energy deposition, while multi-focal strategies eliminated grating lobes. The linear-array design of the prototype made it possible to produce interstitial ultrasound images of tissue and tumor mimics in situ. Multi-focal pressure fields were generated without grating lobes and transducer surface intensities reached up to Isapa = 14 W·cm-2. Seventeen elementary thermal ablations were performed in vitro. Rotation of the catheter proved the directionality of ablation, sparing non-targeted tissue. This experimental proof of concept demonstrates the feasibility of treating volumes comparable to those of primary solid tumors with a miniaturized USgHIFU catheter whose dimensions are close to those of tools traditionally used in interventional radiology, while offering new functionalities.

Innovative nano-shielding for minimizing stray radiation dose in external radiation therapy: A promising approach to enhance patient safety

This study investigates the effectiveness of novel nanocomposite shielding materials in reducing out-of-field radiation doses during radiation therapy, employing Geant4 Monte Carlo (MC) simulations alongside an anthropomorphic female phantom. The research focuses on two radiation modalities: 6 MV beams with and without flattening filters. Utilizing the Geant4 MC code, detailed simulations of a Varian Clinac 2100C/D linear accelerator and an ICRP-145 mesh-type human phantom were conducted to estimate the doses to out-of-field organs from unintended secondary radiation. This involved simulating a comprehensive linac model, including all relevant beam-line components, and assessing the shielding effects of three different nanocomposites doped with metal nanoparticles at various thicknesses. The nanocomposites, comprising Polytetrafluoroethylene (PTFE), with PtO2, IrO2, and Bi2O3 nanoparticles, were evaluated for their potential to reduce patient organ doses from stray photon doses. The results showed that these materials could significantly lower radiation exposure to non-target tissues.

Reduction of Postradiation Therapy Urinary Toxicity Via Intrafractional Megavoltage-Kilovoltage Prostate Location Monitoring

We hypothesized that an in-house developed system using megavoltage and kilovoltage image guidance (MKIG) to ensure correct prostate positioning during stereotactic body radiation therapy (SBRT) could potentially avoid unwanted doses to nontarget tissues, leading to reduced toxicities. We built a 3-dimensional MKIG platform that accurately tracks prostate implanted fiducials in real time and clinically translated the system to replace a commercial approach, intrafraction motion review (IMR), which only tracks fiducials in the 2-dimensional kilovoltage views. From 2017 to 2019, 150 patients with prostate cancer were treated with SBRT and monitored using MKIG. The motion trace of the fiducials alerts therapists to interrupt and reposition the prostate when displacement exceeds a 1.5 mm threshold. A comparison cohort of 121 patients was treated with the same dose regimen and treatment technique but managed by IMR. Statistics of intrafractional patient shifts and delivery time were collected to evaluate the workflow efficacy. The incidence of grade ≥2 urinary toxicities was analyzed to assess clinical complications. The median follow-up time was 3.7 years (0.2-8.2 years). MKIG treatments had more treatment shifts (1.09 vs 0.28) and a longer average delivery time per fraction (579 ± 205 seconds vs 357 ± 117 seconds) than IMR treatments. Three-quarters (75%) of shifts resulting from MKIG were ≤3 mm, versus 51% in IMR, indicating that MKIG detected and corrected smaller deviations. The incidence of grade ≥2 urinary toxicity was lower in the MKIG than the IMR cohort: 10.7% versus 19.8% (P = .047). On multivariate analysis of late urinary toxicity, only high (>7) preradiation therapy international prostate symptom score (P < .043) and the use of MKIG were selected (P < .029). Automated and quantitative MKIG introduced minimal workflow impact and was superior to IMR in localizing the prostate during SBRT, which correlated with a clinically significant reduction in late urinary toxicity. Further clinical testing using randomized trials will be required to validate the impact on outcomes.

Tissue Radiologic and Pathologic Response to Biphasic Pulsed Electric Field Technology in a Porcine Model

PurposeTo evaluate the radiologic, pathologic, and safety characteristics of a commercially available pulsed electric field (PEF) ablation system in a porcine model. Materials and MethodsMonopolar biphasic PEF ablation was delivered to the liver, kidney, and longissimus dorsi muscle through a single needle via a percutaneous or open approach with the Aliya System (Galvanize Therapeutics, Redwood City, California). Six animals were ablated and evaluated in 2 cohorts (Day 3 and Day 28). Muscle, kidney, and liver were ablated in each animal. Intraprocedural cone-beam computed tomography (CT), follow-up weekly CT, blood serology, gross pathology, and histopathology were performed to characterize the radiographic evolution and tissue response. ResultsThere were no adverse events and no findings of electrocardiographic abnormalities, and serologic values returned to baseline by Day 28. Ablation zones were visible on unenhanced CT images during follow-up. Most identified zones became radiographically smaller over time, with some fully resolved by Day 28. The relative decrease in gross ablation zone diameter in the liver and skeletal muscle was 20% and 26%, respectively, whereas kidney sites grew in diameter by 22%. Ablation sites were focal and contained within the intended target tissue without extension to nontarget tissues or collateral structures. ConclusionsThe biphasic PEF system evaluated here resulted in a safe and predictable ablation response, with preservation of structural tissues in an animal model, offering an alternative to thermal ablative modalities, particularly near critical structures.

Radiosynthesis and Preclinical Evaluation of 18F-Labeled Estradiol Derivatives with Different Lipophilicity for PET Imaging of Breast Cancer.

About 75% of breast tumors show an overexpression of the estradiol receptor (ER), making it a valuable target for tumor diagnosis and therapy. To date, 16α-[18F]fluoroestradiol (FES) is the only FDA-approved imaging probe for the positron emission tomography (PET) imaging of ER-positive (ER+) breast cancer. However, FES has the drawback of a high retention in the liver. Therefore, the aim of this study was the development and preclinical evaluation of estradiol (E2) derivatives with different lipophilicity. Three 18F-labeled prosthetic groups (two glycosyl and one PEG azide) were chosen for conjugation with ethinyl estradiol (EE) by 18F-CuAAC (Cu-catalyzed azide-alkyne cycloaddition). The cellular uptake in ER+ MCF-7 tumor cells was highest for the less hydrophilic derivative (18F-TA-Glyco-EE). In nude mice bearing different breast tumors (ER+ MCF-7 and T47D versus ER- MDA-MB-231), 18F-TA-Glyco-EE revealed a high uptake in the liver (13%ID/g, 30 min p.i.), which decreased over 90 min to 1.2%ID/g, indicating fast hepatobiliary clearance. The statistically significant difference of 18F-TA-Glyco-EE uptake in T47D compared to MDA-MB-231 tumors at 60-90 min p.i. indicated ER-specific uptake, whereas in vivo PET imaging did not provide evidence for specific uptake of 18F-TA-Glyco-EE in MCF-7 tumors, probably due to ER occupation by E2 after E2-dependent MCF-7 tumor growth in mice. However, in vitro autoradiography revealed a high specific binding of 18F-TA-Glyco-EE to ER+ tumor slices. We conclude that 18F-TA-Glyco-EE, with its increased hydrophilicity after deacetylation in the blood and thus rapid washout from non-target tissues, may be a viable alternative to FES for the PET imaging of breast cancer.

A simulation study on the effect of penetration of gold nanoparticles in the cytoplasm of healthy eye organs on dose enhancement of brachytherapy

Purpose Special properties and recent advances in the synthesis and biomolecular functionalization of gold nanoparticles (GNPs) have led to the evolution of their use in biomedical applications such as photon radiotherapy. Simulation-based studies on the effect of various parameters that govern the dose enhancement due to utilizing GNPs have facilitated the progress of knowledge in this field. Due to their flexibility and easier accessibility compared with experimental works, simulations have the potential to be considered for pre-clinical tests and, therefore, should be close to the realistic conditions as much as possible. Materials and methods To this aim, the present work investigates the effect of the presence of GNPs that are accumulated in the cytoplasm of the constituent cells in healthy tissues of a human eye phantom, inspired by the published experimental results which report that non-target tissues also receive the drugs containing GNPs. The GNPs’ concentrations are assumed to decrease by moving from the tumor toward the depth of the phantom through a suggested pattern. The MCNPX Monte Carlo code is used for the simulations. Results The results show that for four concentrations tested, the dose enhancement factor in the shallower layer reaches 6, and decreases to 1.2 in the last layer. The dose enhancements are also examined for critical structures of the iris, cornea, sclera, and lens, showing maximum deviations of about 3 to 200% compared with the absence of GNPs in the healthy tissue. Considering the reported doses to the lens by clinical institutions, the effect of penetration of GNPs to deep layers on treatment time is also investigated. Conclusions The results show that the penetration of GNPs from the tumor toward healthy tissues strongly controls the dose enhancement over the various eye structures and emphasizes the importance of modeling the GNPs’ distribution in the medium on the overall dose enhancement. Considering the current challenges in the clinical use of GNPs, more effort needs to be made to reach an effective endpoint in treatment.

61Cu-PSMA-Targeted PET for Prostate Cancer: From Radiotracer Development to First-in-Human Imaging.

The demand for PET tracers that target prostate-specific membrane antigen (PSMA) continues to increase. Meeting this demand with approved 68Ga- and 18F-labeled PSMA tracers is challenging outside of major urban centers. This is because the short physical half-life of these radionuclides makes it necessary to produce them near their sites of usage. To overcome this challenge, we propose cyclotron-produced 61Cu for labeling PSMA PET tracers. 61Cu can be produced on a large scale, and its 3.33-h half-life allows shipping over considerably longer distances than possible for 68Ga and 18F. Production of true theranostic twins using 61Cu and the β--emitter 67Cu is also feasible. Methods: PSMA-I&T (DOTAGA-(l-y)fk(sub-KuE)) and its derivative in which the DOTAGA chelator was replaced by NODAGA (NODAGA-(l-y)fk(sub-KuE)), herein reported as DOTAGA-PSMA-I&T and NODAGA-PSMA-I&T, respectively, were labeled with 61Cu and compared with [68Ga]Ga-DOTAGA-PSMA-I&T, [68Ga]Ga-NODAGA-PSMA-I&T, [68Ga]Ga-PSMA-11, and [18F]PSMA-1007. In vitro (lipophilicity, affinity, cellular uptake, and distribution) and invivo (PET/CT, biodistribution, and stability) studies were performed in LNCaP cells and xenografts. Human dosimetry estimates were calculated for [61Cu]Cu-NODAGA-PSMA-I&T. First-in-human imaging with [61Cu]Cu-NODAGA-PSMA-I&T was performed in a patient with metastatic prostate cancer. Results: [61Cu]Cu-DOTAGA-PSMA-I&T and [61Cu]Cu-NODAGA-PSMA-I&T were synthesized with radiochemical purity of more than 97%, at an apparent molar activity of 24 MBq/nmol, without purification after labeling. In vitro, natural Cu (natCu)-DOTAGA-PSMA-I&T and natCu-NODAGA-PSMA-I&T showed high affinity for PSMA (inhibitory concentration of 50%, 11.2 ± 2.3 and 9.3 ± 1.8 nM, respectively), although lower than the reference natGa-PSMA-11 (inhibitory concentration of 50%, 2.4 ± 0.4 nM). Their cellular uptake and distribution were comparable to those of [68Ga]Ga-PSMA-11. In vivo, [61Cu]Cu-NODAGA-PSMA-I&T showed significantly lower uptake in nontargeted tissues than [61Cu]Cu-DOTAGA-PSMA-I&T and higher tumor uptake (14.0 ± 5.0 percentage injected activity per gram of tissue [%IA/g]) than [61Cu]Cu-DOTAGA-PSMA-I&T (6.06 ± 0.25 %IA/g, P = 0.0059), [68Ga]Ga-PSMA-11 (10.2 ± 1.5 %IA/g, P = 0.0972), and [18F]PSMA-1007 (9.70 ± 2.57 %IA/g, P = 0.080) at 1 h after injection. Tumor uptake was also higher for [61Cu]Cu-NODAGA-PSMA-I&T at 4 h after injection (10.7 ± 3.3 %IA/g) than for [61Cu]Cu-DOTAGA-PSMA-I&T (4.88 ± 0.63 %IA/g, P = 0.0014) and [18F]PSMA-1007 (6.28 ± 2.19 %IA/g, P = 0.0145). Tumor-to-nontumor ratios of [61Cu]Cu-NODAGA-PSMA-I&T were superior to those of [61Cu]Cu-DOTAGA-PSMA-I&T and comparable to those of [68Ga]Ga-PSMA-11 and [18F]PSMA-1007 at 1 h after injection and increased significantly between 1 and 4 h after injection in most cases. Human dosimetry estimates for [61Cu]Cu-NODAGA-PSMA-I&T were similar to the ones reported for 18F-PSMA ligands. First-in-human imaging demonstrated multifocal osseous and hepatic metastases. Conclusion: [61Cu]Cu-NODAGA-PSMA-I&T is a promising PSMA radiotracer that compares favorably with [68Ga]Ga-PSMA-11 and [18F]PSMA-1007, while allowing delayed imaging.

Application of 99mTc-Labeled WL12 Peptides as a Tumor PD-L1-Targeted SPECT Imaging Agent: Kit Formulation, Preclinical Evaluation, and Study on the Influence of Coligands.

With the development of PD-1/PD-L1 immune checkpoint inhibitor therapy, the ability to monitor PD-L1 expression in the tumor microenvironment is important for guiding therapy. This study was performed to develop a novel radiotracer with optimal pharmacokinetic properties to reflect PD-L1 expression in vivo via single-photon emission computed tomography (SPECT) imaging. [99mTc]Tc-HYNIC-WL12-tricine/M (M = TPPTS, PDA, ISONIC, 4-PSA) complexes with high radiochemical purity (>97%) and suitable molar activity (from 100.5 GBq/μmol to 300 GBq/μmol) were prepared through a kit preparation process. All 99mTc-labeled HYNIC-WL12 radiotracers displayed good in vitro stability for 4 h. The affinity and specificity of the four radiotracers for PD-L1 were demonstrated both in vitro and in vivo. The results of biodistribution studies displayed that the pharmacokinetics of the 99mTc-HYNIC-conjugated radiotracers were significantly influenced by the coligands of the radiotracers. Among them, [99mTc]Tc-HYNIC-WL12-tricine/ISONIC exhibited the optimal pharmacokinetic properties (t1/2α = 8.55 min, t1/2β = 54.05 min), including the fastest clearance in nontarget tissues, highest tumor-to-background contrast (e.g., tumor-to-muscle ratio, tumor-to-blood ratio: 40.42 ± 1.59, 14.72 ± 2.77 at 4 h p.i., respectively), and the lowest estimated radiation absorbed dose, highlighting its potential as a clinical SPECT imaging probe for tumor PD-L1 detection.

Fabrication and characterization of hydroquinone in liposomal gel for transdermal drug delivery

This study aimed to formulate a gel for hydroquinone dermal therapy using liposomes to maintain the active agents' concentration in the skin's deepest layers. Cholesterol was incorporated to enhance the liposome's bilayer characteristics, increasing microviscosity, membrane stability, and blister rigidity. Various methods for liposome preparation exist, but the film hydration method, being the most common, was utilized here. Results for formulation HL6, which had lower levels of Lecithin Cholesterol and rotation speed, revealed a vesicle size of 180.4 nm, a Zeta potential of -37.5 mV, and an entrapment efficiency of 69.10±1.52%. In-vitro drug release data for formulations F1, F2, and F3 within 30 minutes showed hydroquinone release rates of 97.75±0.28%, 98.92±0.56%, and 94.45±0.36%, respectively. The order of drug release was F2 &gt; F1 &gt; F3, with F2 demonstrating the maximum release rate. The study concludes that liposomal gel is an effective transdermal drug delivery system for therapeutic molecules. Lipid vesicles, such as liposomes, are among the best mechanisms for delivering medications to their intended locations while minimizing their dissemination to non-target tissues. This liposomal gel-based formulation shows significant potential for effectively treating acne by maintaining high concentrations of active agents in the skin's deepest layers and ensuring a controlled and sustained drug release.

Coaxial nanofibrous aerogel featuring porous network-structured channels for ovarian cancer treatment by sustained release of chitosan oligosaccharide

Ovarian cancer, the deadliest gynecological malignancy, primarily treated with chemotherapy. However, systemic chemotherapy often leads to severe toxic side effects and chemoresistance. Drug-loaded aerogels have emerged as a promising method for drug delivery, as they can improve drug solubility and bioavailability, control drug release, and reduce drug distribution in non-targeted tissues, thereby minimizing side effects. In this research, chitosan oligosaccharide (COS)-loaded nanofibers composite chitosan (CS) aerogels (COS-NFs/CS) with a porous network structure were created using nanofiber recombination and freeze-drying techniques. The core layer of the aerogel has a COS loading rate of 60 %, enabling the COS-NFs/CS aerogel to significantly inhibit the migration and proliferation of ovarian cancer cells (resulting in a decrease in the survival rate of ovarian cancer cells to 33.70 % after 48 h). The coaxial fiber's unique shell-core structure and the aerogel's porous network structure enable the COS-NFs/CS aerogels to release COS steadily and slowly over 30 days, effectively reducing the initial burst release of COS. Additionally, the COS-NFs/CS aerogels exhibit good biocompatibility, degradability (only retaining 18.52 % of their weight after 6 weeks of implantation), and promote angiogenesis, thus promoting wound healing post-oophorectomy. In conclusion, COS-NFs/CS aerogels show great potential for application in the treatment of ovarian cancer.