HER2 is a well-established target for antibody-based drug delivery. Single-domain antibodies (sdAbs) offer advantages over monoclonal antibodies, including faster clearance, higher antigen-binding affinity, and improved tumor penetration. This study investigates the biodistribution of HER2-targeting sdAbs (with and without HIS-tag) labeled with 68Ga and their therapeutic efficacy radiolabeled with 177Lu, in HER2-positive xenograft. Mice received 10 MBq of 68Ga-labeled HIS-tagged sdAb and underwent PET/CT scans immediately and three hours post-injection. The following day, untagged radioactive sdAb was administered and scanned similarly. Controls were co-injected with an excess of unlabeled sdAb. For therapy study, mice received either four weekly injections or a single dose of 177Lu-labeled sdAb (without HIS-tag). Radiotracers were synthesized with high radiochemical purity (> 99.8%). PET/CT imaging revealed specific tumor accumulation and low background, except in excretory organs. Co-injection of unlabeled sdAbs reduced tumor uptake, confirming tracer specificity. 177Lu-labeled sdAb therapy prolonged median survival by 34 d (single dose) and 26 d (fractionated therapy) versus respective control group treated with unlabeled sdAb. The fractionated therapy group exhibited significantly lower tumor volumes and did not exceed 200% of the initial tumor volume. 68Ga-labeled sdAbs enabled high-contrast PET imaging and 177Lu-labeled sdAbs, particularly in fractionated regimens, effectively delayed tumor progression and were well tolerated, supporting further clinical translation.

The authors wish to replace the ‘Author Contributions’ statement and the affiliation for Jochen Maurer of this article [...]

Background Triple-negative breast cancer (TNBC) lacks biomarkers for targeted therapy. Auger emitters display the best therapeutic effect, if delivered directly into the nucleus proximal to DNA. The nuclear protein Poly (ADP-ribose)-Polymerase 1 (PARP1) is a suitable target against which few inhibitors (PARPi) are clinically approved for treatment of breast cancer with germline BRCA mutation (BRCA mut ). In this study, a theranostic approach was investigated in a TNBC xenografted mouse model by radiolabelling a close derivative of a PARPi Olaparib (termed PARPi-01) with the Auger emitters 123/125 I. Methods TNBC cell line MDA-MB-231 was subcutaneously implanted in female NOD/SCID mice. At a tumour size of ~ 500mm 3 , [ 123 I]PARPi-01 was administered intravenously, and SPECT/CT images were obtained at 4 h or 24 h post injection (p.i). A therapy study was performed with [ 125 I]PARPi-01 in 4 doses (10 MBq/dose, 10 days apart). Tumour growth was monitored by CT scans longitudinally once per week. Upon reaching study endpoint, tissues were harvested and stained with TUNEL assay for detection of apoptosis induction. Results SPECT/CT images showed rapid hepatobiliary tracer clearance at 4 h post injection (p.i.). Retention in thyroid at 24 h p.i. suggested tracer deiodination in vivo. The tumour and liver uptake were 0.2%ID/g and 2.5%ID/g, respectively. The tumour: blood ratio was 1.3. Endogenous therapy induced a significant delay in tumour growth (doubling time increased from 8.3 to 14.2 days), but no significant survival advantage. Significantly higher apoptosis ratio was observed in [ 125 I]PARPi-01 treated tumour tissues. No radiotoxicity was detected in the liver and thyroid. Conclusion Considering the radio-cytotoxic effect in the tumour tissue and a delay on tumour doubling time, [ 125 I]PARPi-01 presents a potential radiotherapeutics for treatment of TNBC. Improvements to overcome the suboptimal pharmacokinetics are necessary for its potential clinical application.

Neural stem cells (NSCs) present attractive natural drug delivery systems (DDSs). Their migratory potential enables crossing of the blood-brain barrier and efficient and selective accumulation near malignant cells. Here, we present the potential of NSCs as DDSs for nucleoside analogue conjugated nanogels (NGs). Two different approaches were investigated: the intracellular loading and extracellular cell surface decoration with NGs. For both designs, the tumor-specific migratory potentials of NSCs remained unchanged; however, the intracellular loading showed a shorter NG retention. The cell surface decoration protocol yielded a high loading capacity of 100% after 1 h and a prolonged drug retention. A redox-sensitive linker between NGs and the nucleoside analogue 5-ethynyl-2 '-deoxycytidine (EdC) allowed a tumor environment-specific drug release and its efficient and preferential incorporation into the DNA of the tumor cells. Interestingly, the tumor-trafficking potentials of NSCs were significantly potentiated by irradiation of tumor cells. In conclusion, this study indicates the potentials of cell surface-decorated NSCs as DDSs for tumor specific release, cellular uptake, and incorporation of EdC into DNA.

Ziel/Aim Targeting the HER2 employing monoclonal antibodies for direct therapeutic approach as well as vehicles for specific drug delivery, with payloads such as chemotherapeutic agents, radiopharmaceuticals or radionuclides, has been investigated in depth in the last years. Several single-domain antibodies (sdAbs), also called nanobodies, have been investigated as targeting carriers for non-invasive techniques for molecular imaging, as they offer the advantages of a more accurate determination of the HER2 status and have been shown to be safe and suitable for cancer diagnosis and treatment. The technetium labeled single domain antibody RAD201, has been shown to be safe for use in breast cancer imaging with reasonable radiation doses, favorable biodistribution, and imaging characteristics.

[F-18]FTC-146 was introduced as a very potent and selective sigma-1 receptor radioligand, which has shown promising application as an imaging agent for neuropathic pain with positron emission tomography. In line with a multi-laboratory project on animal welfare, we chose this radioligand to investigate its potential for detecting neuropathic pain and tissue damage in tumor-bearing animals. However, the radiochemical yield (RCY) of around 4-7% was not satisfactory to us, and efforts were made to improve it. Herein, we describe an improved approach for the radiosynthesis of [F-18]FTC-146 resulting in a RCY, which is sevenfold higher than that previously reported. A tosylate precursor was synthesized and radio-fluorination experiments were performed via aliphatic nucleophilic substitution reactions using either K[F-18]F-Kryptofix (R) 222 (K-2.2.2)-carbonate system or tetra-n-butylammonium [F-18]fluoride ([F-18]TBAF). Several parameters affecting the radiolabeling reaction such as solvent, F-18-fluorination agent with the corresponding amount of base, labeling time, and temperature were investigated. Best labeling reaction conditions were found to be [F-18]TBAF and acetonitrile as solvent at 100 & DEG;C. The new protocol was then translated to an automated procedure using a FX2 N synthesis module. Finally, the radiotracer reproducibly obtained with RCYs of 41.7 +/- 4.4% in high radiochemical purity (> 98%) and molar activities up to 171 GBq/mu mol.

PARP1 inhibitors (PARPi) are currently approved for BRCAmut metastatic breast cancer, but they have shown limited response in triple negative breast cancer (TNBC) patients. Combination of an Auger emitter with PARPis enables PARP inhibition and DNA strand break induction simultaneously. This will enhance cytotoxicity and additionally allow a theranostic approach. This study presents the radiosynthesis of the Auger emitter [125I] coupled olaparib derivative: [125I]-PARPi-01, and its therapeutic evaluation in a panel of TNBC cell lines. Specificity was tested by a blocking assay. DNA strand break induction was analysed by γH2AX immunofluorescence staining. Cell cycle analysis and apoptosis assays were studied using flow cytometry in TNBC cell lines (BRCAwt/mut). Anchorage independent growth potential was evaluated using soft agar assay. [125I]-PARPi-01 showed PARP1-specificity and higher cytotoxicity than olaparib in TNBC cell lines irrespective of BRCA their status. Cell lines harbouring DNA repair deficiency showed response to [125I]-PARPi-01 monotherapy. Combined treatment with Dox-NP further enhanced therapeutic efficiency in metastatic resistant BRCAwt cell lines. The clonogenic survival was significantly reduced after treatment with [125I]-PARPi-01 in all TNBC lines investigated. Therapeutic efficacy was further enhanced after combined treatment with chemotherapeutics. [125I]-PARPi-01 is a promising radiotherapeutic agent for low radiation dosages, and mono/combined therapies of TNBC.

Purpose Kidney fibrosis leads to a progressive reduction in kidney function ultimately resulting in kidney failure. Diagnostic tools to detect kidney fibrosis are all invasive in nature requiring kidney biopsies with subsequent histological validation. In this retrospective study, the diagnostic value of three different radiotracers for the noninvasive prediction of kidney fibrosis was analyzed, taking into account the glomerular filtration rate (GFR) and the intra-renal parenchymal radiotracer uptake. Methods In 81 patients receiving either one of the following molecular imaging probes, [(68) Ga]Ga-FAPI, [(68) Ga]Ga-PSMA, or [(68) Ga]Ga-DOTATOC, kidney function parameters were correlated with SUVmax and SUVmean of the renal parenchyma and background activity measured in lung parenchyma, myocardium, gluteal muscle, and the abdominal aorta. Patients were clustered according to their grade of chronic kidney disease (CKD), and a regression analysis and one-way ANOVA were conducted in this retrospective analysis. Results We found a negative correlation between GFR and [(68) Ga]Ga-FAPI uptake for both SUVmax and SUVmean values, whereas background activity showed no correlation with GFR. [(68) Ga]Ga-DOTATOC and [(68) Ga]Ga-PSMA did not correlate between CKD stage and intra-renal parenchymal radiotracer uptake. Only [(68) Ga]Ga-PSMA background activity exhibited a positive correlation with GFR suggesting an unspecific binding/retention potentially due to longer circulation times. Conclusion There is a significant negative correlation between renal parenchymal [(68) Ga]Ga-FAPI uptake and GFR, which was not the case for [(68) Ga]Ga-DOTATOC and [(68) Ga]Ga-PSMA. This correlation suggests a specific binding of FAPI rather than a potential unspecific retention in the renal parenchyma, underlining the potential value of [(68) Ga]Ga-FAPI for the noninvasive quantitative evaluation of kidney fibrosis.

Given the high sensitivity and specificity of sodium [18F]Fluoride (Na[18F]F) for vascular calcifications and positive emerging data of vitamin K on vascular health, the aim of this study is to assess the ability of Na[18F]F to monitor therapy and disease progression in a unitary atherosclerotic mouse model. ApoE−/− mice were placed on a Western-type diet for 12-weeks and then split into four groups. The early stage atherosclerosis group received a chow diet for an additional 12-weeks, while the advanced atherosclerosis group continued the Western-type diet. The Menaquinone-7 (MK-7) and Warfarin groups received MK-7 or Warfarin supplementation during the additional 12-weeks, respectively. Control wild type mice were fed a chow diet for 24-weeks. All of the mice were scanned with Na[18F]F using a small animal positron emission tomography (PET)/computed tomography (CT). The Warfarin group presented spotty calcifications on the CT in the proximal aorta. All of the spots corresponded to dense mineralisations on the von Kossa staining. After the control, the MK-7 group had the lowest Na[18F]F uptake. The advanced and Warfarin groups presented the highest uptake in the aortic arch and left ventricle. The advanced stage group did not develop spotty calcifications, however Na[18F]F uptake was still observed, suggesting the presence of micro-calcifications. In a newly applied mouse model, developing spotty calcifications on CT exclusively in the proximal aorta, Na[18F]F seems to efficiently monitor plaque progression and the beneficial effects of vitamin K on cardiovascular disease.

Im vorliegenden Artikel wird verschiedentlich der Begriff „Herstellung“ verwendet. Die Autoren legen Wert auf die Feststellung, dass damit nicht zwingend eine „Herstellung“ im Sinne von § 4 Absatz 14 des Arzneimittelgesetzes (AMG) gemeint ist. Es kann sich vielmehr auch um ein „Präparieren“, „zulassungskonformes Verwenden von Fertigarzneimitteln“ o. ä. handeln. Nicht zwingend sind also Tätigkeiten gemeint, die der Erlaubnispflicht des § 13 Absatz 1 AMG unterliegen.

Over the past 20 years, 68Ga-labelled radiopharmaceuticals have become an important part in clinical routine. However, the worldwide supply with 68Ge/68Ga generators is limited as well as the number of patient doses per batch of 68Ga radiopharmaceutical. In the recent years, a new technique appeared, making use of the ease of aqueous labelling via chelators as with 68Ga but using 18F instead. This technique takes advantage of the strong coordinative bond between aluminium and fluoride, realized in the aqueous cation [Al18F]2+. Most applications to date make use of one-pot syntheses with free Al(III) ions in the system. In contrast, we investigated the labelling approach split into two steps: generating the Al-bearing precursor in pure form and using this Al compound as a precursor in the labelling step with aqueous [18F]fluoride. Hence, no free Al3+ ions are present in the labelling step. We investigated the impact of parameters: temperature, pH, addition of organic solvent, and reaction time using the model chelator NH2-MPAA-NODA. With optimized parameters we could stably achieve a 80% radiochemical yield exerting a 30-min reaction time at 100 °C. This technique has the potential to become an important approach in radiopharmaceutical syntheses.

Ziel/Aim (Micro-)Calcification is an established hallmark of vulnerable atherosclerotic plaque formation. Given the high sensitivity and specificity of Sodium [18F]Fluoride (Na[18F]F) for vascular calcifications and positive emerging data of vitamin K on vascular health, the aim of this study is to assess the ability of Na[18F]F to monitor therapy and disease progression in a unitary atherosclerotic mouse model.

1463 Background: Gallium labelled radiotracers have gained more impact in clinical PET imaging. Preparing these PET radiotracers on demand by means of kits would allow to increase operating flexibility and the ability to adapt to different hospital structures. In this in vitro study we aimed at investigating the internalization behavior of two different [68Ga]Ga-PSMA-11 preparations - either produced via a traditional synthesizer (Scintomics) at 95°C or with the Telix Kit at room temperature - in PSMA positive and negative cells. The two preparations differ in their isomeric pattern and therefore could potentially behave differently. Methods: LNCaP cells (PSMA+) and PC3 cells (PSMA-) were incubated in triplicate with both preparations of [68Ga]Ga-PSMA-11 (AMNI and scint, 0.5 MBq/well each), with or without a specific inhibitor of PSMA for 15, 30, 45, or 60 min at 37°C and 5% CO2. After stopping cell uptake with cold PBS, cell membrane/surface bound [68Ga]Ga-PSMA-11 as well as the internalized fraction of [68Ga]Ga-PSMA-11 were extracted and counted by a gamma-counter. A linear model was fitted to the data to determine whether the cellular binding and internalization in percent of injected dose/well (%ID/well) of the two different preparations of [68Ga]Ga-PSMA-11 were the same or not. Results: Comparison of the %ID/well showed that cellular binding and internalization of both the Scintomics and Telix (ANMI) Kit preparations of [68Ga]Ga-PSMA-11 was markedly greater in LNCaP cells (top graph) than in PC3 cells (bottom graph). The tests to compare the linear model fitted to the %ID data obtained with the ANMI product to that obtained with the synthesizer across both cell lines showed no P-value of less than 0.05 (Table). Thus, the data is supportive of no difference between the two products in all the sample types across each cell line. Conclusions: [68Ga]Ga-PSMA-11 prepared at room temperature with the Telix Kit has PSMA binding propreties that do not significantly differ from those of the tracer produced at 95C° with a traditional synthesizer. Consequently, the PET imaging characteristics of the tracer prepared with the Telix Kit are not expected to differ from those of the synthesizer prepared tracer.

Background Personalized molecular radiotherapy based on theragnostics requires accurate quantification of the amount of radiopharmaceutical activity administered to patients both in diagnostic and therapeutic applications. This international multi-center study aims to investigate the clinical measurement accuracy of radionuclide calibrators for 7 radionuclides used in theragnostics: 99m Tc, 111 In, 123 I, 124 I, 131 I, 177 Lu, and 90 Y. Methods In total, 32 radionuclide calibrators from 8 hospitals located in the Netherlands, Belgium, and Germany were tested. For each radionuclide, a set of four samples comprising two clinical containers (10-mL glass vial and 3-mL syringe) with two filling volumes were measured. The reference value of each sample was determined by two certified radioactivity calibration centers (SCK CEN and JRC) using two secondary standard ionization chambers. The deviation in measured activity with respect to the reference value was determined for each radionuclide and each measurement geometry. In addition, the combined systematic deviation of activity measurements in a theragnostic setting was evaluated for 5 clinically relevant theragnostic pairs: 131 I/ 123 I, 131 I/ 124 I, 177 Lu/ 111 In, 90 Y/ 99m Tc, and 90 Y/ 111 In. Results For 99m Tc, 131 I, and 177 Lu, a small minority of measurements were not within ± 5% range from the reference activity (percentage of measurements not within range: 99m Tc, 6%; 131 I, 14%; 177 Lu, 24%) and almost none were outside ± 10% range. However, for 111 In, 123 I, 124 I, and 90 Y, more than half of all measurements were not accurate within ± 5% range ( 111 In, 51%; 123 I, 83%; 124 I, 63%; 90 Y, 61%) and not all were within ± 10% margin ( 111 In, 22%; 123 I, 35%; 124 I, 15%; 90 Y, 25%). A large variability in measurement accuracy was observed between radionuclide calibrator systems, type of sample container (vial vs syringe), and source-geometry calibration/correction settings used. Consequently, we observed large combined deviations (percentage deviation > ± 10%) for the investigated theragnostic pairs, in particular for 90 Y/ 111 In, 131 I/ 123 I, and 90 Y/ 99m Tc. Conclusions Our study shows that substantial over- or underestimation of therapeutic patient doses is likely to occur in a theragnostic setting due to errors in the assessment of radioactivity with radionuclide calibrators. These findings underline the importance of thorough validation of radionuclide calibrator systems for each clinically relevant radionuclide and sample geometry.

Ziel/Aim Poly ADP-ribose polymerase (PARP) inhibition is based on the concept of synthetic lethality where simultaneous loss of two complementary proteins (BRCA mutation and PARP inhibition) leads to cell death. Clinically, PARP inhibitors (PARPi) are approved for ovarian and breast cancer patients harboring germline BRCA mutation (BRCAmut). In this study, a theranostic approach was investigated by tagging Iod-123/125 to the backbone of the PARPi, Olaparib (Iod-123/125-PARPi-01).

BACKGROUND:Lumbar disc herniation is often associated with an inflammatory process. In this context, inflammation has been considered a key factor in the modulation of pain. Here, we present a case of inflammatory activity directly documented in a patient with a lumbar disc herniation.CASE DESCRIPTION:A 49-year-old male presented with progressive low back pain and left-sided S1 radiculopathy, without a focal neurological deficit. The lumbar MR revealed a prominent herniated disc at the L5-S1 level, with compression of the left S1 root. The patient underwent a L5-S1 discectomy using a standard interlaminar approach. Although initially he was pain free, he required three additional operations to address recurrent pain complaints. As research indicates that local inflammation contributes to neuropathic pain, we had the patient undergoes single-photon emission computed tomography (SPECT) imaging using technetium-99m-labeled-infliximab (an anti-tumor necrosis factor [TNF]-alpha monoclonal antibody) before a proposed fourth operation. The SPECT study documented a strong signal at the site of the herniated disc, thus confirming the diagnosis of a pro-inflammatory process involving the S1 nerve root. Nine months after the fourth operation, the patient was pain free. Of interest, the second SPECT study in the now asymptomatic patient demonstrated no detectable/ residual signal at the operative/disc site.CONCLUSION:Absence of a SPECT TNF-alpha signal in a pain-free patient following a lumbar discectomy correlates with the reduction/resolution of the local preoperative inflammatory response.