Search

Click chemistry, and in particular copper-free click reactions, have gained growing interest for radiolabeling purposes in the field of radiopharmaceutical sciences. [99mTc][Tc(CO)3(H2O)3]+ is an excellent starting complex for radiolabeling of biomolecules under mild conditions. A new chelator, investigated for the copper-free strain-promoted cycloaddition, was synthesized containing the 2,2’-dipicolylamine (DPA) moiety for the 99mTc-tricarbonyl core and compared with a chelator based on activated esters for conventional radiolabeling. For the copper-free click labeling procedure, a DPA containing 4,8-diazacyclononyne moiety was prepared from a sulfonyl-modified diamide (four steps, 64% yield) ensued by the Nicholas reaction with butyne-1,3-diol. The 99mTc-DPA-DACN-complex was prepared with a radiochemical conversion (RCC) of 89% after 30 min. The following SPAAC reaction with an azide-functionalized PSMA molecule was performed within 4 hours to obtain the PSMA (prostate-specific membrane antigen) targeting 99mTc-complex with 79% RCC and without side products. For comparison, a second DPA-chelator based on a tetrafluorophenyl (TFP) ester was prepared (three steps, 64% yield) and was successfully radiolabeled with [[99mTc]Tc(CO)3(H2O)3]+ in 89% RCC after 20 min and >99% radiochemical purity after separation using an RP18 cartridge. The subsequent conjugation of an amine-functionalized PSMA targeting molecule was performed with 23% RCC after 150 min. Two other unknown side products were observed indicating hydrolysis of the TFP ester during the labeling. All nonradioactive Re(CO)3 complexes were synthesized from (Et4N)2[ReBr3(CO)3] (91% yield for the natRe-DPA-TFP ester, 76% yield for the natRe-DPA-DACN) and characterized to confirm the identity of the 99mTc-complexes.

Lung cancer (LC) is a common type of cancer, which is a leading cause of death around the world. There is an urgency for the development of new drugs that could diagnose the LC in the early stages and in a precise manner. In this direction, the development of nanoparticles radiolabeled with the diagnostic radioisotopes represent an important advance in the field of cancer imaging. In this study were developed PLA/PVA/Atezolizumab nano particles which were radiolabeled with 99mTc (Technetium-99m). The radiolabeled nanoparticles were evaluated in both: in-vitro (L-929 and A-549) as in-vivo (mice). The results showed no cytotoxicity effect in the healthy cells (L-929) and cytotoxicity effect in the tumor cells (A-549). The biodistribution assay demonstrated that 99mTc-PLA/PVA/Atezolizumab could reach the tumor site 14-folds higher than the nonparticulate atezolizumab. In conclusion, 99mTc-PLA/PVA/Atezolizumab nanoparticles showed to be a new drug which is able to precisely image the lung tumor, and it must be considered for clinical trials., Scientific and Technological Research Council of Turkey [TUBITAK-220/S/361]; T.R. Prime Ministry State Planning Organization Foun-dation Grant [09DPT001], This study was supported by The Scientific and Technological Research Council of Turkey (TUBITAK-220/S/361) within the scope of the PhD thesis of Meliha Ekinci. The authors would like to acknowledge the support of T.R. Prime Ministry State Planning Organization Foun-dation Grant Project Number: 09DPT001 for TLC Scanner.

Prostate-specific membrane antigen (PSMA) is a well-validated prostate cancer marker but reported PSMA-targeted tracers derived from the Lys-urea-Glu pharmacophore including the clinically validated [99mTc]Tc-EDDA/HYNIC-iPSMA have high off-target uptake in kidneys, spleen, and salivary glands. In this study, we synthesized and evaluated three novel 99mTc-labeled PSMA-targeted tracers and investigated if the tracers derived from the Lys-urea-Aad pharmacophore could have minimized uptake in off-target organs/tissues. In vitro competition binding assays showed that compared with HYNIC-iPSMA, the three novel ligands had slightly weaker PSMA binding affinity (average Ki = 3.11 vs. 8.96–11.6 nM). Imaging and ex vivo biodistribution studies in LNCaP tumor-bearing mice showed that [99mTc]Tc-EDDA/HYNIC-iPSMA and the three novel tracers successfully visualized LNCaP tumor xenografts in SPECT images and were excreted mainly via the renal pathway. The average tumor uptake at 1 h post-injection varied from 5.40 to 18.8%ID/g, and the tracers derived from the Lys-urea-Aad pharmacophore had much lower uptake in the spleen and salivary glands. Compared with the clinical tracer [99mTc]Tc-EDDA/HYNIC-iPSMA, the Lys-urea-Aad-derived [99mTc]Tc-EDDA-KL01127 had lower background uptake and superior tumor-to-background contrast ratios and is therefore promising for clinical translation to detect prostate cancer lesions with SPECT.

Low-energy electrons (Auger electrons) can be produced via the interaction of photons with gold atoms in gold nanorods (AuNRs). These electrons are similar to those emitted during the decay of technetium-99m (99mTc), a radioactive nuclide widely used for diagnostics in nuclear medicine. Auger and internal conversion (IC) electron emitters appropriately targeted to the DNA of tumors cells may, therefore, represent a new radiotherapeutic approach. 99mTc radiopharmaceuticals, which are used for diagnosis, could indeed be used in theragnostic fields when loaded on AuNRs and delivered to a tumor site. This work aims to provide a proof of concept (i) to evaluate AuNRs as carriers of 99mTc-based radiopharmaceuticals, and (ii) to evaluate the efficacy of Auger electrons emitted by photon-irradiated AuNRs in inducing radio-induced damage in T98G cells, thus mimicking the effect of Auger electrons emitted during the decay of 99mTc used in clinical settings. Data are presented on AuNRs’ chemical characterization (with an aspect ratio of 3.2 and Surface Plasmon Resonance bands at 520 and 680 nm) and the loading of pharmaceuticals (after 99mTc decay) on their surface. Spectroscopic characterizations, such as UV-Vis and synchrotron radiation-induced X-ray photoelectron (SR-XPS) spectroscopies, were performed to investigate the drug–AuNR interaction. Finally, preliminary radiobiological data on cell killing with AuNRs are presented.

Previous Phase I clinical evaluations of the radiolabelled scaffold proteins [99mTc]Tc-ADAPT6 and DARPin [99mTc]Tc-(HE)3-G3 in breast cancer patients have demonstrated their safety and indicated their capability to discriminate between HER2-positive and HER2-negative tumours. The objective of this study was to compare the imaging of HER2-positive tumours in the same patients using [99mTc]Tc-ADAPT6 and [99mTc]Tc-(HE)3-G3. Eleven treatment-naïve female patients (26–65 years) with HER2-positive primary and metastatic breast cancer were included in the study. Each patient was intravenously injected with [99mTc]Tc-ADAPT6, followed by an [99mTc]Tc-(HE)3-G3 injection 3–4 days later and chest SPECT/CT was performed. All primary tumours were clearly visualized using both tracers. The uptake of [99mTc]Tc-ADAPT6 in primary tumours (SUVmax = 4.7 ± 2.1) was significantly higher (p < 0.005) than the uptake of [99mTc]Tc-(HE)3-G3 (SUVmax = 3.5 ± 1.7). There was no significant difference in primary tumour-to-contralateral site values for [99mTc]Tc-ADAPT6 (15.2 ± 7.4) and [99mTc]Tc-(HE)3-G3 (19.6 ± 12.4). All known lymph node metastases were visualized using both tracers. The uptake of [99mTc]Tc-ADAPT6 in all extrahepatic soft tissue lesions was significantly (p < 0.0004) higher than the uptake of [99mTc]Tc-(HE)3-G3. In conclusion, [99mTc]Tc-ADAPT6 and [99mTc]Tc-(HE)3-G3 are suitable for the visualization of HER2-positive breast cancer. At the selected time points, [99mTc]Tc-ADAPT6 has a significantly higher uptake in soft tissue lesions, which might be an advantage for the visualization of small metastases.

To develop novel tumor imaging agents with high tumor uptake and excellent tumor/non-target ratios, a glucose derivative containing cyclohexane (CNMCHDG) was synthesized and labeled with Tc-99m. [99mTc]Tc-CNMCHDG was prepared by a kit formulation that was straightforward to operate and fast. Without purification, [99mTc]Tc-CNMCHDG had a high radiochemical purity of over 95% and great in vitro stability and hydrophilicity (log P = −3.65 ± 0.10). In vitro cellular uptake studies showed that the uptake of [99mTc]Tc-CNMCHDG was significantly inhibited by pre-treatment with D-glucose and increased by pre-treatment with insulin. Preliminary cellular studies have demonstrated that the mechanism by which the complex enters into cells may be related to GLUTs. The results of biodistribution and SPECT imaging studies displayed high tumor uptake and good retention of [99mTc]Tc-CNMCHDG in A549 tumor-bearing mice (4.42 ± 0.36%ID/g at 120 min post-injection). Moreover, [99mTc]Tc-CNMCHDG exhibited excellent tumor-to-non-target ratios and a clean imaging background and is a potential candidate for clinical transformation.

Τhe Epidermal Growth Factor Receptor tyrosine kinase inhibitor (EGFR-TKI) 6-amino-4-[(3-bromophenyl) amino]quinazoline was derivatized with 6-bromohexanoyl-chloride and coupled with the tridentate chelating agents N-(2-pyridylmethyl) aminoethyl acetic acid (PAMA) and L(+)-cysteine bearing the donor atom set NNO and SNO, respectively. The rhenium precursors ReBr(CO)5 and fac-[NEt4]2[ReBr3(CO)3] were used for the preparation of the Re complexes fac-[Re(NNO)(CO)3] (5a) and fac-[Re(SNO)(CO)3] (7a) which were characterized by NMR and IR spectroscopies. Subsequently, the new potential EGFR inhibitors were labeled with the fac-[99mTc(CO)3]+ core in high yield and radiochemical purity (>90%) by ligand exchange reaction using the fac-[99mTc][Tc(OH2)3(CO)3]+ precursor. The radiolabeled complexes were characterized by comparative HPLC analysis with the analogous rhenium (Re) complexes as references. In vitro studies in the A431 cell lines showed that both ligands and Re complexes inhibit A431 cell growth. Complex 5a demonstrated the highest potency (IC50 = 8.85 ± 2.62 μM) and was further assessed for its capacity to inhibit EGFR autophosphorylation, presenting an IC50 value of 26.11 nM. Biodistribution studies of the 99mTc complexes in healthy mice showed high in vivo stability for both complexes and fast blood and soft tissue clearance with excretion occurring via the hepatobiliary system.

Gastrin-releasing peptide receptors (GRPRs) are overexpressed in the majority of primary prostate tumors and in prostatic lymph node and bone metastases. Several GRPR antagonists were developed for SPECT and PET imaging of prostate cancer. We previously reported a preclinical evaluation of the GRPR antagonist [99mTc]Tc-maSSS-PEG2-RM26 (based on [D-Phe6, Sta13, Leu14-NH2]BBN(6-14)) which bound to GRPR with high affinity and had a favorable biodistribution profile in tumor-bearing animal models. In this study, we aimed to prepare and test kits for prospective use in an early-phase clinical study. The kits were prepared to allow for a one-pot single-step radiolabeling with technetium-99m pertechnetate. The kit vials were tested for sterility and labeling efficacy. The radiolabeled by using the kit GRPR antagonist was evaluated in vitro for binding specificity to GRPR on PC-3 cells (GRPR-positive). In vivo, the toxicity of the kit constituents was evaluated in rats. The labeling efficacy of the kits stored at 4 °C was monitored for 18 months. The biological properties of [99mTc]Tc-maSSS-PEG2-RM26, which were obtained after this period, were examined both in vitro and in vivo. The one-pot (gluconic acid, ethylenediaminetetraacetic acid, stannous chloride, and maSSS-PEG2-RM26) single-step radiolabeling with technetium-99m was successful with high radiochemical yields (>97%) and high molar activities (16–24 MBq/nmol). The radiolabeled peptide maintained its binding properties to GRPR. The kit constituents were sterile and non-toxic when tested in living subjects. In conclusion, the prepared kit is considered safe in animal models and can be further evaluated for use in clinics. Title in Web of Science: The GRPR Antagonist [Tc-99m]Tc-maSSS-PEG(2)-RM26 towards Phase I Clinical Trial: Kit Preparation, Characterization and Toxicity

This study aimed to develop a single photo emission computed tomography/fluorescence (SPECT/FL) bimodal imaging probe to image blood cells. Hyperbranched polyglycerol (HPG) was synthesized by anionic ring-opening polymerization. Succinic anhydride was used to functionalize HPG. Then, indocyanine green (ICG) was bound to HPG, with a 73.59% binding yield. Deferoxamine (DFO) was subsequently bound to ICG-HPG, and DFO-ICG-HPG was radiolabeled with technetium-99m, with 100% yield. The molecular weight of HPG in this study was found to be 6.8 kDa. In in vitro studies, the radiolabeled nanoconjugates remained stable even after 6 h (last timepoint when stability was assessed), and when the nanoconjugates were applied to K562 chronic myeloid leukemia cells, the highest cell viability was observed at a concentration of 5 mu g/mL and binding efficiency increased over time, reaching 30% at 6 h (last timepoint when binding efficiency was assessed). The results support the feasibility of the developed probe to image blood cells, which would be useful for applications such as detecting internal bleeding. [GRAPHICS] ., Ege University Research Fund [2018 FBE 006]; NIH/NCI Cancer Support Grant [P30 CA008748], This work was financially supported by Ege University Research Fund (2018 FBE 006) and partially presented at HEZARFEN International Congress of Science, Mathematics, and Engineering Sciences held in Izmir/Turkey on November 8-10, 2019. Dr. Omer Aras was partially supported through the NIH/NCI Cancer Support Grant P30 CA008748.

Objective(s): Myocardial infarction caused by ischemia of heart tissue is the main reason for death worldwide; therefore, early detection can reduce mortality and treatment costs. Erythropoietin (EPO) has protection effects on ischemic tissue due to nonhematopoietic peptide (pHBSP; ARA-290) which is derived from the B-subunit of EPO. Materials and Methods: We designed and synthesized a modified DOTA-(Lys-Dabcyl6, Phe7)-ARA-290 using Fmoc solid-phase peptide synthesis strategies. To improve serum stability, Fmoc-Lys-(Dabcyl)-OH as lipophilic amino acid was synthesized along with Fmoc-Phe-OH which then were substituted with Arg6 and Ala7, respectively; they were then investigated for the ability to detect ischemic cardiac imaging. DOTA-(Lys-Dabcyl6,Phe7)-ARA-290 was labeled with technetium 99m, and its radiochemical purity (RCP), stability in the presence of human serum and, specific bind to hypoxic H9c2 cells were evaluated. In vivo studies for biodistribution and SPECT scintigraphy were checked in a normal and cardiac ischemia rat model. Results: Radiolabeling purity was obtained more than 96% by ITLC, and in vitro stability of the radiopeptide up to 6 hr was 85%. The binding of 99mTc-ARA-290 to hypoxic cells was remarkably higher than normoxic cells (3 times higher than normoxic cells at 1 hr). Biodistribution and SPECT imaging on the cardiac ischemic model showed that radiopeptide considerably accumulated in the ischemic region (cardiac ischemic-to-lung rate = 3.65 ID/g % at 0.5 hr).Conclusion: The results of studies, in vitro and in vivo, indicated that 99mTc-DOTA-(Lys-Dabcyl6,Phe7)-ARA-290 could be an appropriate candidate for early diagnosis of cardiac ischemia.

Nanoparticles are frequently used as targeting delivery systems for therapeutic and diagnostic radiopharmaceuticals. Polyethylene oxide-polyacrylic acid (PEO-PAAc) nanogel was prepared via γ-radiation-induced polymerization. Variable factors affecting nanoparticles size were investigated. The nanogel was radiolabeled with the imaging radioisotope 99m Tc and finally conjugated with folic acid to target folate receptor actively. PEO-PAAc-folic acid gel was characterized by dynamic light scattering (DLS) and atomic force microscopy (AFM). Biodistribution was studied in normal mice and solid tumor-bearing mice via intravenous and intratumor injections of the radiolabeled PEO-PAAc-folic acid nanogel. Results of biodistribution showed high selective uptake of the prepared complex in tumor muscle compared with normal muscle for both intravenous and intratumor injections. The T/NT ratio was found to be 6.186 and 294.5 for intravenous and intratumor injections, respectively. Consequently, 99m Tc-PEO-PAAc-folic acid complex could be a promising agent for cancer diagnostic imaging.

Background and Design: Psoriasis is a common chronic inflammatory skin disease believed to affect renal functions. Glomerular filtration rate (GFR) is the most important indicator used to assess renal functions. The present study aims to measure the renal function of psoriasis patients via the technetium-99m diethylenetriamine pentaacetate (Tc-99m DTPA) method and compare the values obtained with those determined through indirect measurement methods, such as the modification of diet in renal disease (MDRD) and chronic kidney disease epidemiology collaboration (CKD-EPI), considering the effects of systemic treatments and comorbidities. Materials and Methods: Eighty-seven patients diagnosed with chronic plaque-type psoriasis vulgaris were included in this study. The patients’ demographic characteristics, disease duration, psoriasis area and severity index score, drugs received for psoriasis treatment, comorbidities, and drugs received for comorbidity treatment were noted. Estimated GFRs were also calculated using the MDRD and CKD-EPI formulas. Results: Tc-99m DTPA values were affected only by age. As the patient age increased, a significant decrease in GFR measured with Tc-99m DTPA (r=0.289, p

Introduction. Overexpression of Her2/neu is detected in 15–20 % of patients with breast cancer and associated with an aggressive form of disease and low overall and disease-free survival rates. Currently, immunohistochemical studies (IHC) and methods of in situ hybridization are used to assess Her2/neu status. One of significant drawbacks of this detection is the impossibility of simultaneous assessment of the receptor status of the primary tumor and metastatic sites. The increasing popularity of radionuclide methods using recombinant proteins as a targeting module have already demonstrated their effectiveness in solving this question at the initial stages of clinical research.The purpose of this study is to demonstrate a clinical case of assessing the extent of breast cancer in a patient with overexpression of Her2/neu using a radiopharmaceutical based on targeted protein molecules labeled with technetium-99m.Description of the clinical case. A patient diagnosed with stage IIIA right breast cancer (T2N2M0), multicentric growth and metastases in right axillary and subclavian lymph nodes at the diagnostic stage was injected intravenously with 99mTc-ADAPT6 radiopharmaceutical. The drug was prepared in the Department of Nuclear Medicine of Research Cancer Institute (Tomsk) immediately before its administration. Planar scintigraphy and singlephoton emission tomography of the chest organs were performed 2 hours after injection of 99mTc-ADAPT6 radiopharmaceutical. In addition to the previously described tumors, 3 foci of hyperfixation of the tracer in the projection of the 5th rib on the right along the middle-clavicular line, as well as in the projection of the 8 and 9 thoracic vertebrae (Th VIII, IX) were found. Computed tomography of the chest organs and bone scintigraphy with 99mTc-pyrophosphate showed no metastases in the 5th rib on the right and Th VIII, IX. Magnetic resonance imaging of the thoracic spine revealed 2 metastatic foci in Th VIII, IX. Planar scintigraphy with 99mTc-pyrophosphate and CT performed 6 months after injection of 99mTc-ADAPT6 revealed previously described foci in the projection of the thoracic spine (Th VIII, IX) and 5 ribs on the right along the mid-clavicular line. Conclusion. The results demonstrated during the study suggest that 99mTc-ADAPT6 is a promising tracer for molecular imaging of tumor foci with overexpression of the Her2/neu receptor in breast cancer patients.

Non-invasive radionuclide molecular visualization of human epidermal growth factor receptor type 2 (HER2) can provide stratification of patients for HER2-targeting therapy. This method can also enable monitoring of the response to such therapies, thereby making treatment personalized and more efficient. Clinical evaluation in a phase I study demonstrated that injections of two scaffold protein-based imaging probes, [99mTc]Tc-(HE)3-G3 and [99mTc]Tc-ADAPT6, are safe, well-tolerated and cause a low level of radioactivity in healthy tissue. The goal of this preclinical study was to select the best probe for stratification of patients and response monitoring. Biodistribution of both tracers was compared in mice bearing SKOV-3 xenografts with high HER2 expression or MDA-MB-468 xenografts with very low expression. Changes in accumulation of the probes in SKOV-3 tumors 24 h after injection of trastuzumab were evaluated. Both [99mTc]Tc-ADAPT6 and [99mTc]Tc-(HE)3-G3 permitted high contrast imaging of HER2-expressing tumors and a clear discrimination between tumors with high and low HER2 expression. However, [99mTc]Tc-ADAPT6 has better preconditions for higher sensitivity and specificity of stratification. On the other hand, [99mTc]Tc-(HE)3-G3 is capable of detecting the decrease of HER2 expression on response to trastuzumab therapy only 24 h after injection of the loading dose. This indicates that the [99mTc]Tc-(HE)3-G3 tracer would be better for monitoring early response to such treatment. The results of this study should be considered in planning of further clinical development of HER2 imaging probes.

Radioembolization (RE) with glass microspheres (MS) loaded with Yttrium-90 (90Y) has been used to treat tumors in the liver with some reported success. However, assessing absorbed doses (AD) in the planning tumor volume (PTV) and normal liver volume (NLV) is a key problem to address in RE. In clinical practice, the computation of 90Y activity to be administered follows the manufacturer’s recommendations, which do not consider the specific characteristics of MS deposition in each patient’s liver. Our main aim is to develop a methodology to estimate the optimal activity for each patient treatment. It uses the absorbed dose distribution (ADD) derived from the Technetium-99m (99mTc)-labeled macroaggregated albumin (MAA) obtained from pre-treatment planning single-photon emission computed tomography (SPECT) images. Post-treatment positron emission tomography (PET) images of the 90Y-MS distribution were used to estimate the ADD for treatment verification. Sixteen RE treatments were retrospectively selected. The agreement between the estimated mean AD based on the planning imaging and real post-treatment mean AD was good in PTV with an intraclass correlation coefficient (ICC) of 0.79 and excellent in NLV (ICC = 0.97). The optimization of 90Y activity using pre-defined clinical AD thresholds (80 Gy in PTV) imposed on the PTV and NLV voxels showed remarkably high agreement (ICC = 0.96, p < 0.001) in eleven out of the sixteen RE treatments between SPECT-MAA-based and PET-MS-based optimal activity estimates. In conclusion, under well-controlled conditions, pre-treatment SPECT-MAA imaging predicts well the treatment of ADD. In addition, SPECT-MAA imaging can be used to optimize the 90Y-MS activity to be administered to the liver.

Non-invasive radionuclide molecular visualization of human epidermal growth factor receptor type 2 (HER2) can provide stratification of patients for HER2-targeting therapy. This method can also enable monitoring of the response to such therapies, thereby making treatment personalized and more efficient. Clinical evaluation in a phase I study demonstrated that injections of two scaffold protein-based imaging probes, [99mTc]Tc-(HE)3-G3 and [99mTc]Tc-ADAPT6, are safe, well-tolerated and cause a low level of radioactivity in healthy tissue. The goal of this preclinical study was to select the best probe for stratification of patients and response monitoring. Biodistribution of both tracers was compared in mice bearing SKOV-3 xenografts with high HER2 expression or MDA-MB-468 xenografts with very low expression. Changes in accumulation of the probes in SKOV-3 tumors 24 h after injection of trastuzumab were evaluated. Both [99mTc]Tc-ADAPT6 and [99mTc]Tc-(HE)3-G3 permitted high contrast imaging of HER2-expressing tumors and a clear discrimination between tumors with high and low HER2 expression. However, [99mTc]Tc-ADAPT6 has better preconditions for higher sensitivity and specificity of stratification. On the other hand, [99mTc]Tc-(HE)3-G3 is capable of detecting the decrease of HER2 expression on response to trastuzumab therapy only 24 h after injection of the loading dose. This indicates that the [99mTc]Tc-(HE)3-G3 tracer would be better for monitoring early response to such treatment. The results of this study should be considered in planning of further clinical development of HER2 imaging probes. Title in Web of Science: Direct In Vivo Comparison of Tc-99m-Labeled Scaffold Proteins, DARPin G3 and ADAPT6, for Visualization of HER2 Expression and Monitoring of Early Response for Trastuzumab Therapy

Objective: To determine the normal value of thyroid Technetium-99m uptake value in a single centre Pakistani population. Study Design: Cross-sectional study. Place and Duration of Study: Nuclear Medical Centre, Armed Forces Institute of Pathology, Rawalpindi, from Feb 2019 to Apr 2020. Methodology: A total of 90 patients who presented to Nuclear Medical Centre for parathyroid dual radiopharmaceutical scintigraphy were included in study and selected by non-probability consecutive sampling technique. Thyroid uptake studies were calculated via gamma camera acquisition. Pre injection counts were taken from the Technetium-99m pertechnetate filled syringe, thyroid counts were taken from the anterior thyroid image 20 minutes post injection and to look for any residual radiopharmaceutical counts of the empty syringe were also taken. Results: Out of total of 90 patients, 32 (35.6%) were male while 58 (64.4%) were female with male to female ratio of 1:2. The mean age was 38.4 ± 12.7. Mean Thyroid Stimulating Hormone values were 1.6 ± 0.8 and mean T4 values were 11.9 ± 3.5. The 5th-95th percentile range was 0.4-2.2% and median was 1.2%. The interquartile range was calculated to be 0.9-1.5%. Conclusion: Normal value of thyroid Technetium-99m uptake value in a single centre Pakistani population values varies significantly as compared to global figures i.e. 0.3-4.5% and is different than the one used in our own department i.e. 0.5-2.0%.

The aim of this study was to estimate and subsequently measure the occupational radiation exposure for all personnel involved in producing, administering, or performing imaging or surgery with [99mTc]Tc-PSMA-I&S, which has been introduced for identification of tumor-positive lymph nodes during salvage prostate cancer surgery. Methods: The effective dose was estimated and subsequently measured with electronic personal dosimeters for the following procedures and personnel: labeling and quality control by the radiopharmacy technologist, syringe preparation by the nuclear medicine laboratory technologist, patient administration by the nuclear medicine physician, patient imaging by the nuclear medicine imaging technologist, and robot-assisted laparoscopic salvage lymph node dissection attended by an anesthesiology technologist, scrub nurse, surgical nurse, and surgeon. The dose rate of the patient was measured immediately after administration of [99mTc]Tc-PSMA-I&S, after imaging, and after surgery. Results: The estimated dose per procedure ranged from 1.59 × 10-10 μSv (imaging technologist) to 9.74 μSv (scrub nurse). The measured effective dose ranged from 0 to 5 μSv for all personnel during a single procedure with [99mTc]Tc-PSMA-I&S. The highest effective dose was received by the scrub nurse (3.2 ± 1.3 μSv), whereas the lowest dose was measured for the surgical nurse (0.2 ± 0.5 μSv). If a single scrub nurse were to perform as many as 100 procedures with [99mTc]Tc-PSMA-I&S in a year, the total effective dose would be 320 μSv/y. Immediately after administration, the dose rate at 50 cm from the patient was 18.5 ± 1.6 μSv/h, which dropped to 1.8 ± 0.3 μSv/h after imaging the following day, reducing even further to 0.56 ± 0.33 μSv/h after surgery. Conclusion: The effective dose for personnel involved in handling [99mTc]Tc-PSMA-I&S is comparable to that of other 99mTc-radiopharmaceuticals and therefore safe for imaging and radioguided surgery.

Purpose: To prepare technetium-99m (99mTc)-labelled nanogel loaded with 5-fluorouracil (5-FU) containing synthesized gallic acid-stearylamine (GA-SA) conjugate in order to reduce its systemic toxicity and provide site-specific delivery to skin lesions. Methods: Lipid nanocarrier-based 1 % (w/w) 5-FU nanogel containing GA-SA conjugate was successfully formulated. Parameters that included pH, viscosity and entrapment efficiency were measured. Furthermore, 1 % (w/w) 5-FU nanogel and 1 % (w/w) 5-FU commercial formulations were radiolabelled with 99mTc. The radiolabelled 99mTc-5-FU nanogel and commercial formulations were subjected to successive preclinical assessments with respect to radiochemical stability, biodistribution, and gamma scintigraphy in BALB/c mice, and pharmacokinetic studies in New Zealand albino rabbits. Results: The entrapment efficiency of 5-FU in the nanogel preparation was 82.12 ± 1.2 %. The 5-FU nanogel formulation exhibited excellent radiolabelling efficiency (> 93 %) and high stability. Skin/blood localization ratios of 274.93 and 167.89 were obtained for topical radiolabelled drug-loaded 5-FU nanogel formulation and 5-FU commercial formulation, respectively, after 1 h of administration. Gamma scintigraphy and biodistribution studies showed that topically administered 99mTc-5-FU nanogel was distributed mostly in skin, when compared to marketed 5-FU formulation. Pharmacokinetic studies revealed low maximum activity in the blood (Cmax = 34.20 µg/mL), with low intensity (AUC) for topically administered 99mTc-5-FU nanogel formulation. Conclusion: 5-FU nanogel enhances specific delivery of 5-FU at targeted sites and decreases its toxicity in tissues distant from the site of application. The results suggest that nanogel loaded with 5-FU containing synthesized GA-SA conjugate is a novel effective approach for the treatment of skin lesions.

Current radiolabeled gastrin-releasing peptide receptor (GRPR) ligands usually suffer from high accumulation in GRPR-positive organs (pancreas, stomach), limiting tumor-to-background contrast in the abdomen. In novel N4-bombesin derivatives this was addressed by substitutions at the Gln7-Trp8 site within the MJ9 peptide (H-Pip5-phe6-Gln7-Trp8-Ala9-Val10-Gly11-His12-Sta13-Leu14-NH2) either by homoserine (Hse7), β-(3-benzothienyl) alanine (Bta8) or α-methyl tryptophan (α-Me-Trp8), with the aim of optimizing pharmacokinetics. We prepared and characterized the peptide conjugates 6-carboxy-1,4,8,11-tetraazaundecane (N4)-asp-MJ9, N4-asp-[Bta8]MJ9, N4-[Hse7]MJ9 and N4-[α-Me-Trp8]MJ9, and evaluated these compounds in vitro (GRPR affinity via IC50,inverse; internalization; lipophilicity via logD7.4) and in vivo (biodistribution and μSPECT/CT studies at 1 h post injection (p.i.) in PC-3 tumor-bearing CB17-SCID mice). 99mTc-labeling resulted in radiochemical yields (RCYs) > 95%. All 99mTc-labeled MJ9 analogues showed comparable or higher GRPR affinity than the external reference [99mTc]Tc-Demobesin 4. Receptor-bound fractions were noticeably higher than that of the reference. Despite a slightly enhanced lipophilicity, all novel MJ9 derivatives revealed improved in vivo pharmacokinetics compared to the reference. The Bta8-modified ligand revealed the most favorable tumor-to-abdomen contrast at 1 h p.i. Substitutions at the Gln7-Trp8 site within GRPR ligands hold great potential to modify pharmacokinetics for improved imaging.

Objective: The development of new radiopharmaceuticals capable of specifically imaging cancer is an important research area. For this reason, the aim of this study is to investigate cell binding of novel developed nanoradiopharmaceutical ([99mTc]Tc-nab-PTX) on HT-29 cell line (human colorectal adenocarcinoma cells).Material and Method: In this study, nab-PTX was labeled with [99mTc]Tc, and labeling efficiency and in vitro stability were investigated by radioactive thin layer chromatography (RTLC). Then, cell incorporation of [99mTc]Tc-nab-PTX was performed using HT-29 cell line.Result and Discussion: According to obtained results, nab-PTX was labeled with high radiochemical purity (>99%). The [99mTc]Tc-nab-PTX was found to be stable in saline for 6-h, and in cell medium up to 2-h. It was determined that [99mTc]Tc-nab-PTX had a greater cell binding activity on HT-29 cells than R/H-[99mTc]NaTcO4 at 30 min. The results were found to be promising for future in vivo studies with [99mTc]Tc-nab-PTX., Amaç: Spesifik olarak kanseri görüntüleyebilen yeni radyofarmasötiklerin geliştirilmesi önemli bir araştırma alanıdır. Bu nedenle bu çalışmanın amacı, yeni geliştirilen nanoradyofarmasötiğin ([99mTc]Tc-nab-PTX) HT-29 hücre hattına (insan kolorektal adenokarsinom hücreleri) hücre bağlanmasını araştırmaktır.Materyal ve Metot: Bu çalışmada, nab-PTX [99mTc]Tc ile işaretlenmiş ve işaretleme etkinliği ve in vitro stabilitesi radyoaktif ince tabaka kromatografisi (RTLC) ile araştırılmıştır. Daha sonra, [99mTc]Tc-nab-PTX'in hücre bağlanması, HT-29 hücre hattı kullanılarak gerçekleştirilmiştir.Sonuç ve Tartışma: Elde edilen sonuçlara göre, nab-PTX yüksek radyokimyasal saflıkla (>%99) radyoişaretlenmiştir. [99mTc]Tc-nab-PTX'in oda sıcaklığında 6 saate kadar ve hücre ortamında 2 saate kadar stabil olduğu bulunmuştur. [99mTc]Tc-nab-PTX'in HT-29 hücreleri üzerinde 30. dakikada R/H-[99mTc]NaTcO4'ten daha yüksek bir hücre bağlama aktivitesine sahip olduğu belirlenmiştir. Sonuçların [99mTc]Tc-nab-PTX ile gelecek in vivo çalışmalar için umut verici olduğu bulunmuştur.

Epidermal growth factor receptors (EGFR) of tyrosine kinase (TK) have shown high expression levels in most cancers and are considered a promising target for cancer diagnosis and therapy. Expanding the investigation for novel targeted radiopharmaceuticals, an EGFR inhibitor such as 4-aminoquinazoline derivatives along with a radionuclide such as technetium-99m (99mTc) could be ideal. Thus, we report herein the synthesis, characterization, and biological evaluation of new “4 + 1” mixed-ligand ReIII- and 99mTcIII-complexes of the general formula [99mTc][Tc(NS3)(CN-R)] bearing tris(2-mercaptoethyl)-amine (NS3) as the tetradentate tripodal ligand and a series of isocyanide derivatives (CN-R) of tyrosine kinase inhibitor (3-bromophenyl)quinazoline-4,6-diamine as the monodentate ligand. The quinazoline isocyanide derivatives 4a-d were prepared in two steps and reacted with the [Re(NS3)PMe2Ph] precursor leading to the final complexes 5a-d in high yield. All compounds were characterized by elemental analysis, IR, and NMR spectroscopies. In vitro studies, for their potency to inhibit the cell growth, using intact A431 cells indicate that the quinazoline derivatives 4a-d and the Re complexes 5a-d significantly inhibit the A431 cell growth. In addition, the EGFR autophosphorylation study of complex 5b shows an IC50 value in the nanomolar range. The corresponding “4 + 1” 99mTc-complexes 6a-d were prepared by employing the [99mTc]TcEDTA intermediate and the appropriate monodentate 4a-d in a two-step synthetic procedure with a radiochemical yield (RCY) from 63 to 77 % and a radiochemical purity (RCP) > 99 % after HPLC purification. Their structures have been established by HPLC comparative studies using the well-characterized Re-complexes 5a-d as reference. All 99mTc-complexes remain stable for at least 6 h, and their logD7.4 values confirmed their anticipated lipophilic character. Biodistribution studies in healthy Swiss albino mice of 99mTc-complexes showed hepatobiliary excretion and initial fast blood clearance. Complex 6b was also tested in Albino SCID mice bearing A431 tumors and showed rapid tumor uptake at 5 min (2.80 % ID/g) with a moderate tumor/muscle ratio (2.06) at 4 h p.i. The results encourage further investigation for this type of 99mTc-complexes as single-photon emission computed tomography (SPECT) radio agents for imaging tumors overexpressing EGFR. © 2022 Elsevier Ltd

Recently, the applicability of somatostatin receptor-targeted (SSTR-t) radiotracers for post-ischemic myocardial inflammation imaging has been shown using PET. Currently, there are no studies which demonstrate ability of SPECT and technetium-99m SSTR-t radiotracers to detect inflammation, which appears in response to acute myocardial infarction (AMI). A case of 51-year-old male with acute anterior myocardial infarction (AMI) with ST elevation has been presented. This patient on 7th day after AMI onset underwent SPECT/CT (by cardiac cadmium-zinc-telluride gamma-camera) with 99mTc-Tectrotide, cardiac MRI with gadolinium and, on 9th day after AMI, myocardial perfusion scintigraphy (MPS) at rest. Clear myocardial uptake of 99mTc-Tectrotide, predominantly in apical and intermediate anterior wall of left ventricle was detected. The uptake matched with areas of hypoperfusion (by SPECT) and myocardial injury (by MRI). This case demonstrated the applicability of technetium-99m-labeled SSTR-t radiotracers for post-infarction inflammation imaging. Currently assumed, that SSTR-t radiotracers reflect an increased number of activated macrophages infiltrating infarcted myocardium, which is not possible using any other imaging technique. Thus, potentially, SSTR scintigraphy may be useful for diagnosis and monitoring of myocardial post-infarction inflammation as well as for anti-inflammatory image-guide therapy assessment.

Background. The main purpose of the Her2/neu status determination in clinical practice is to determine the indications for the appointment of targeted therapy. The main methods for detecting the Her2/neu status are the immunohistochemical method (IHC) and the fluorescence in situ hybridization (FISH); however, despite their widespread use, they have a number of significant disadvantages. Over the past few years, radionuclide diagnostics using a new class of alternative scaffold proteins that meet all the requirements for optimal delivery of radionuclides to tumor cells has become widespread. Aim. To study the possibility of clinical use of a radiopharmaceutical based on technetium-99m-labeled target molecules for the diagnosis of breast cancer with the Her2/neu overexpression in humans. Materials and methods. The study included 11 patients with breast cancer (T1–4N0–2M0) before systemic therapy: 5 with Her2/neu overexpression; expression of the marker was not detected in 6. In all cases, morphologicaland immunohistochemical studies were performed. In case of Her2/neu 2+, FISH analysis was performed. The radiopharmaceutical was prepared immediately before administration, after which it was slowly injected intravenously into the patient. Scintigraphic studies in the “WholeBody” mode and SPECT of the chest organs were performed 2, 4, 6 and 24 hours after injection. Results. Radiochemical yield, radiochemical purity and activity before administration were (80 ± 4)%, (98 ± 1)% and (434 ± 19.5) MBq, respectively. The greatest uptake by normal organs was observed at a time interval of 6 hours in the kidneys and at a moderate activity in the liver and lungs at the same time interval. The organ with the highest absorbed dose was the kidneys; significant accumulation was also detected in the adrenal glands, gallbladder, liver, pancreas and spleen. The smallest accu mulation of the studied drug was observed in the brain (0.001 ± 0.000) mGy and skin (0.001 ± 0.000) mGy. The effective dose was (0.009 ± 0.002) mGy. The difference between tumors with positive and negative Her2-neu expression was found at all time points. In this case, the best indicator was determined after 2 hours of drug injection (р < 0.05). Conclusion. Based on the results obtained, it can be indicated that the investigated radiopharmaceutical can be considered as a new additional method for the diagnosis of Her2-positive breast tumors.

Nodular regenerative hyperplasia (NRH) of the liver may lead to noncirrhotic portal hypertension with subsequent development of portosystemic shunts. While extrahepatic and macrovascular shunts are readily visualized with imaging or endoscopy, there is no standard technique to detect intrahepatic microvascular portosystemic shunting and quantitatively assess shunt burden. We present a case of a 53-year-old female with suspected NRH and hepatopulmonary syndrome with inconclusive liver biopsies and absent portosystemic shunts per abdominal imaging. A percutaneous transportal infusion of Technetium-99m labeled macroaggregated albumin (99mTc-MAA) successfully identified intrahepatic microvascular portosystemic shunting and quantified a lung shunt fraction of more than 30%. NRH was subsequently confirmed with a surgical wedge biopsy and the patient was successfuly treated with a liver transplant. Transportal 99mTc-MAA could be used to both identify and quantify otherwise occult microvascular portosystemic shunts in patients with clinical sequelae of portal hypertension.

Although 99mTc is not an ideal Auger electron (AE) emitter for Targeted Radionuclide Therapy (TRT) due to its relatively low Auger electron yield, it can be considered a readily available “model” radionuclide useful to validate the design of new classes of AE-emitting radioconjugates. With this in mind, we performed a detailed study of the radiobiological effects and mechanisms of cell death induced by the dual-targeted radioconjugates 99mTc-TPP-BBN and 99mTc-AO-BBN (TPP = triphenylphosphonium; AO = acridine orange; BBN = bombesin derivative) in human prostate cancer PC3 cells. 99mTc-TPP-BBN and 99mTc-AO-BBN caused a remarkably high reduction of the survival of PC3 cells when compared with the single-targeted congener 99mTc-BBN, leading to an augmented formation of γH2AX foci and micronuclei. 99mTc-TPP-BBN also caused a reduction of the mtDNA copy number, although it enhanced the ATP production by PC3 cells. These differences can be attributed to the augmented uptake of 99mTc-TPP-BBN in the mitochondria and enhanced uptake of 99mTc-AO-BBN in the nucleus, allowing the irradiation of these radiosensitive organelles with the short path-length AEs emitted by 99mTc. In particular, the results obtained for 99mTc-TPP-BBN reinforce the relevance of targeting the mitochondria to promote stronger radiobiological effects by AE-emitting radioconjugates.

Tumor microenvironment fibroblasts overexpress the fibroblast activation protein (FAP). We recently reported the preclinical evaluation of [99mTc]Tc-iFAP as a new SPECT radioligand capable of detecting FAP. This research aimed to evaluate the kinetic and dosimetric profile of [99mTc]Tc-iFAP in healthy volunteers, and to assess the radioligand uptake by different solid tumors in three cancer patients. [99mTc]Tc-iFAP was obtained from lyophilized formulations prepared under GMP conditions with >98% radiochemical purity. Whole-body scans of six healthy subjects were obtained at 0.5, 2, 4, and 24 h after [99mTc]Tc-iFAP (740 MBq) administration. A 2D-planar/3D-SPECT hybrid activity quantitation method was used to fit the biokinetic models of the source organs (volume of interest: VOI) as exponential functions (A(t)VOI). The total nuclear transformations (N) that occurred in the source organs were calculated from the mathematical integration (0,∞) of A(t)VOI. The OLINDA code was used to estimate the radiation doses. Three treatment-naive patients (breast, lung, and cervical cancer) with a prior [18F]FDG PET/CT scan underwent whole-body, chest, and abdominal SPECT/CT scanning after [99mTc]Tc-iFAP (740 MBq) administration. Both imaging methods were compared visually and quantitatively. Oncological diagnoses were performed histopathologically. The results showed favorable [99mTc]Tc-iFAP biodistribution and kinetics due to rapid blood activity removal (t1/2α = 2.22 min and t1/2β = 90 min) and mainly renal clearance. The mean radiation equivalent doses were 5.2 ± 0.8 mSv for the kidney and 1.7 ± 0.3 mSv for the liver after administration of 740 MBq. The effective dose was 2.3 ± 0.4 mSv/740 MBq. [99mTc]Tc-iFAP demonstrated high and reliable uptake in the primary tumor lesions and lymph node metastases in patients with breast, cervical, and lung cancer, which correlated with that detected by [18F]FDG PET/CT. The tumor microenvironment molecular imaging from cancer patients obtained in this research validates the performance of additional clinical studies to determine the utility of [99mTc]Tc-iFAP in the diagnosis and prognosis of different types of solid tumors.

Patients who underwentQuantitative assessment of myocardial radiotracer activity with CPA or VOI have high diagnostic accuracy for ATTR-CM. Both measures are potential non-invasive markers to follow progression of disease or response to therapy.Las imágenes deLa evaluación cuantitativa de la actividad del radiotrazador en miocárdico con CPA o VOI tiene una alta certeza diagnóstica para ATTR-CM. Ambas medidas son potenciales marcadores no invasivos para seguir la progresión de la enfermedad o la respuesta a terapia.背景:L’imagerie au 99mTc-pyrophosphate est devenue une méthode non invasive importante pour le diagnostic de l’amyloidose cardiaque à transthyrétine (ATTR-CM). La quantification de l’activité du 99mTc-pyrophosphate sur les images SPECT, pourrait être un marqueur de l’intensité de la maladie. Dans cette étude, nous avons évalué la précision diagnostique et la signification clinique de la quantification au 99mTc-pyrophosphate. MéTHODES ET RéSULTATS: Les patients ayant bénéficié d’une imagerie au 99mTc-pyrophosphate pour suspicion d’ATTR-CM ont été inclus. Nous avons calculé l’activité (CPA) et le volume (VOI) du 99mTc-pyrophosphate (CPA) au niveau du myocarde sur les images SPECT en rapport à l’activité sanguine au niveau de la cavité ventriculaire gauche. La précision du test a été évaluée en utilisant la surface (AUC) sous la courbe ROC. Au total, 124 patients ont été étudiés (âge moyen de 73,9 ± 11,4). Quarante trois de ces patients (34.7%) furent diagnostiqués positivement pour l’ ATTR-CM. La précision diagnostique de la CPA s’est révélée la plus élevée (AUC 0,996, IC à 95% 0,987 - 1,00), et s’est avérée significativement plus élevée que le score de Perugini (AUC 0,952, p = 0,016). Chez les patients avec ATTR-CM, la CPA est associée à une fraction d’éjection ventriculaire gauche réduite (odds ratio ajusté de 1,28, p = 0,035) et une augmentation d’ hospitalisation pour insuffisance cardiaque (hazard ratio ajusté de 1,29, p = 0,006).L’évaluation quantitative de l’activité du 99mTc-pyrophosphate est d’une grande précision diagnostique pour l’ ATTR-CM. Les mesures CAP et VOI sont des marqueurs non invasifs potentiels pour le suivi de la progression de la maladie ou réponse au traitement.

Thalidomide is a sedative drug discovered at the end of the 50s, it showed high anticancer activity so attempts were made to synthesize thalidomide analogs that had fewer side effects than the parent compound. DPDQA showed higher anticancer activities than thalidomide. Labeling of a DPDQA with 99mTc using Na2S2O4 as reducing agent was performed. The dependence of the radiolabeling yield on the concentrations of DPDQA and reducing agent, pH of the reaction mixture, reaction time, and reaction temperature was studied. Bio-distribution studies in mice with tumor induced in the right thigh were carried out. The tumor infected thigh/contralateral thigh uptake ratio (T/NT) was evaluated. The time for the maximum accumulation of the 99mTc–DPDQA in the tumor site was evaluated after administration of the compound.

Objective To determine the frequency of pyramidal lobe remnants after total thyroidectomy (TT) and the effect on stimulated thyroglobulin (Tg). Methods The study included 1740 differentiated thyroid cancer (DTC) patients who were followed up by our center. The department database was searched to identify DTC patients with residual pyramidal lobe after TT. All postoperative technetium-99m pertechnetate thyroid scintigraphy images were re-evaluated for pyramidal lobe residue. Serum stimulated Tg and thyroid stimulating hormone (TSH) levels measured within the first 6 months after TT were retrieved from the database. Results Pyramidal lobe residue was detected in 10.4% of the patients who underwent TT. Evidence of the pyramidal lobe was present on preoperative ultrasonography in 1.6% of the patients with residual pyramidal lobe. Stimulated Tg in patients with pyramidal lobe residue was significantly higher than that in patients without residue (P = .01). Endogenous stimulated TSH in patients with residual pyramidal lobe was significantly lower than that in patients without residue (P = .036). In 5.7% of patients with pyramidal lobe residue, a TSH level of >30 mIU/L was not achieved, which was a significantly higher rate than that in patients without pyramidal lobe residue (P = .034) and is the level required for maximum radioiodine uptake. Conclusion Pyramidal lobe residue was found in almost 10% of DTC patients. The pyramidal lobe is often missed on preoperative ultrasonography. Residual pyramidal lobe increased stimulated Tg and decreased endogenous stimulated TSH. Residual pyramidal lobe may complicate the follow-up of DTC patients.

We studied an original radiolabeled complex of antimicrobial peptides UBI29-41 and UBI18-35, ubiquicidin derivatives, for distinguishing between bacterial and aseptic inflammation. For radiolabeling of the peptides with technetium-99m, a bifunctional chelating agent succinimide-1-yl 6-(bis(pyridin-2-ylmethyl)amino)hexanoate was used. The obtained complexes 99mТс-DPAH-UBI29-41 and 99mТс-DPAH-UBI18-35 had radiolabeling yield >80% and radiochemical purity >96%. Accumulation of the complexes in the focus of bacterial inflammation in bone structures and the absence of this complex in the site of aseptic inflammation was confirmed in a rat model of traumatic osteomyelitis by single-photon emission computed tomography.

Polyvinylpyrrolidone (PVP) is a biopolymer compound that has been widely used in pharmaceutical and medical applications, especially as a tablet binder and solubilizing agents for injections. In th...

The research objective is to design intranasal (IN) brain targeted CLZ-loaded polymeric nanomicellar systems (PNMS) aiming to improve central systemic CLZ bioavailability. Direct equilibrium method was used to prepare CLZ-PNMS using two hydrophobic poloxamines; Tetronic® 904 (T904) and Tetronic® 701 (T701) and one hydrophilic poloxamer; Synperonic® PE/F127 (F127). Optimization is based on higher percent transmittance, solubilizing efficiency, and in vitro release after 24 h with smaller particle size was achieved using Design-Expert® software. The optimized formula was further evaluated via TEM, ex vivo nasal permeation in addition to in vivo biodistribution using radiolabeling technique of the optimized formula by Technetium-99m (99mTc). The optimized formula M5 has small size (217 nm) with relative high percentage of transmittance (97.72%) and high solubilization efficacy of 60.15-fold following 92.79% of CLZ released after 24 h. Ex vivo nasal permeation showed higher flux of 36.62 μg/cm2.h compared to 7.324 μg/cm2.h for CLZ suspension with no histological irritation. In vivo biodistribution results showed higher values of radioactivity percentage of the labeled optimized formula (99mTc–M5) in brain and brain/blood ratio following IN administration of 99mTc–M5 complex which were greater than their corresponding values following intravenous route. It is obvious that nasal delivery of CLZ-PNMS could be a promising way to improve central systemic CLZ bioavailability.

Broad availability and cost-effectiveness of 99Mo/99mTc generators worldwide support the use, and thus the development, of novel 99mTc-labelled radiopharmaceuticals. In recent years, preclinical and clinical developments for neuroendocrine neoplasms patient management focused on somatostatin receptor subtype 2 (SST2) antagonists, mainly due to their superiority in SST2-tumour targeting and improved diagnostic sensitivity over agonists. The goal of this work was to provide a reliable method for facile preparation of a 99mTc-labelled SST2 antagonist, [99mTc]Tc-TECANT-1, in a hospital radiopharmacy setting, suitable for a multi-centre clinical trial. To ensure successful and reproducible on-site preparation of the radiopharmaceutical for human use shortly before administration, a freeze-dried three-vial kit was developed. The final composition of the kit was established based on the radiolabelling results obtained during the optimisation process, in which variables such as precursor content, pH and buffer, as well as kit formulations, were tested. Finally, the prepared GMP-grade batches met all predefined specification parameters together with long-term kit stability and stability of the product [99mTc]Tc-TECANT-1. Furthermore, the selected precursor content complies with micro-dosing, based on an extended single-dose toxicity study, where histopathology NOEL was established at 0.5 mg/kg BW, being more than 1000 times higher than the planned human dose of 20 µg. In conclusion, [99mTc]Tc-TECANT-1 is suitable to be advanced into a first-in-human clinical trial. Nasl. z nasl. zaslona. Opis vira z dne 9. 3. 2023. Št. članka: 885. Bibliografija: str. 15-16. Abstract. ERA PerMed, Novel 99mTc-labelled somatostatin receptor antagonists in the diagnostic algorithm of neuroendocrine neoplasms—a feasibility study” (TECANT), TECANT Austrian Science Fund FWF National Centre for Research and Development Jagiellonian University Medical College National Centre for Nuclear Research, MIZS (Ministry of Education, Science and Sport), Razvoj inovativnega, z gama sevalcem tehnecijem-99m označenega antagonista somatostatinskih receptorjev za diagnostiko nevroendokrinih novotvorb - raziskava izvedljivosti, TECANT

Many radioactive PSMA inhibitory substances have already been developed for PET diagnostics and therapy of prostate cancer. Because PET radionuclides and instrumentation may not be available, technetium-99 m labelled tracers can be considered as a diagnostic alternative. A suitable tracer is [99mTc]Tc-PSMA-I&S, primarily developed for radio-guided surgery, which has been identified for diagnostics of prostate cancer. However, there is no commercial kit approved for the preparation of [99mTc]Tc-PSMA-I&S on the market. This work presents an automated process for the synthesis of [99mTc]Tc-PSMA-I&S concerning good manufacturing practice (GMP). We used a Scintomics GRP 4 V module, with the SCC software package for programming sequences for this development. The optimum reaction conditions were evaluated in preliminary experiments. The pH of the reaction solution was found to be crucial for the radiochemical yield and radiochemical purity. The validation of [99mTc]Tc-PSMA-I&S (n = 3) achieved a stable radiochemical yield of 58.7 ± 1.5% and stable radiochemical purities of 93.0 ± 0.3%. The amount of free [99mTc]TcO4− in the solution and reduced hydrolysed [99mTc]TcO2 was

Most important quality attributes of any radiopharmaceutical (RPh) are its radiochemical purity (RCP) or content of radiochemical impurities (RCIs) that have to comply with respective norms and limits. However, at present, there is no unified approach to validation of analytical methods in the context of highly radioactive samples.The aim of the study was to develop an approach to validation of methods for determination of RCI content in RPhs.Materials and methods: the authors determined the content of RCIs in a radiopharmaceutical formulation containing a complex of technetium-99m and methylenediphosphonic acid by the radiometric method after isolation of impurities from the main compound by thin-layer chromatography using silica gel and methyl ethyl ketone (for sodium pertechnetate determination) and silica gel and 13.6% sodium acetate solution (for determination of hydrolysed reduced technetium-99m). The radioactivity was registered by a chromatogram scanner with a detector of gamma-rays with energies from 0.05 to 1.5 MeV.Results: the paper analyses existing official approaches to validation of analytical procedures and compares them with the results of experimental studies described in available publications. It assesses the validation parameters for compliance with the acceptance criteria set forth in the current regulations and substantiates selectivity of chromatographic determination of impurities under the selected test conditions. Coefficients of variation for repeatability, reproducibility, and accuracy did not exceed 4.5, 2.8, and 8.9%, respectively, given the relative error of not more than 10.5%. The study demonstrated signal linearity for the 10-fold dilution of the standardised sodium pertechnetate solution, it also demonstrated correspondence between the applied and detected radioactivity when performing the test in the impurity content range of 0.5–5%. The validation procedure was associated with significant radiation burden for the personnel of the quality control laboratory.Conclusions: the authors suggested a methodological approach to validation of methods for determination of RCI content in technetium-99m-based RPhs. This approach may be used in the development of a guideline on validation of analytical methods for RCP/RCI determination in RPhs, or for introduction of relevant sections into existing documents.

In the 1980s, 201Tl scintigraphy helped to introduce noninvasive assessment of myocardial perfusion as an important clinical tool for the detection and management of coronary artery disease (CAD). Monovalent cations such as 201Tl exhibit pharmacokinetics that are very suitable for the assessment of

Introduction. Skin cancers came first in Russia in numbers of oncological diseases. Melanoma, making up only a small part of these cases, leads to the most serious consequences. The nuclear medicine methods application is necessary at the stages of clarifying the diagnosis, searching for remote metastases and the treatment monitoring. The work is devoted to one of the stages of the radiopharmaceutical development for the diagnostics of malignant melanoma and its metastases based on the synthetic analog of α-melanocyte stimulating hormone (SAH) and radionuclide Tc-99m.Aim. The selection of optimal conditions for the preparation of the SAH ∙ 99mTc complex and the study of the using possibility it as a diagnostic tool in in vitro experiments.Materials and methods. Experimental work was carried out to optimize the conditions for obtaining the complex compound SAH ∙ 99mTc. The binding and internalization of this compound by B16-F0 melanoma cells has been studied.Results and discussion. The results of labeling SAH with a 99mTc radionuclide under a wide range of conditions were obtained both by the direct method and using the intermediate complex. The target compound rapidly binds to B16-F0 melanoma cells. The degree of internalization is more than 85 %.Conclusion. Based on the results of chemical experiments and data from in vitro experiments, optimal conditions for obtaining a complex compound SAH ∙ 99mTc with a radiochemical yield of more than 90 % were found. The mechanism of binding of this compound to malignant melanoma cells has been established.

Background: As the treatment approaches of Graves’ disease (GD) and thyroiditis are different, the differential diagnosis is essential. Aim: To assess the diagnostic value of free triiodothyronine (FT3) to free thyroxine (FT4) ratio for differentiation between GD and destructive thyroiditis. Subjects and Methods: The present study was conducted on 100 newly diagnosed thyrotoxicosis patients; 61 with thyroiditis (group 1) and 39 with GD (group 2) and 20 healthy, age-matched subjects representing a control group (Group 3). All participants underwent medical history taking and clinical examination, serum levels of thyroid-stimulating hormone (TSH), FT3, and FT4 were measured, Technetium 99m thyroid Scan was done to all recruited patients. Results: The present results recorded significant increases in FT3, FT4, and decreases in TSH levels in Graves’ disease group than in the thyroiditis group. There was a statistically significant difference between the study groups regarding FT3/FT4 ratio, which was lower in thyroiditis group than in Graves’ disease group (0.21± 0.03 in group 1 vs 0.35±0.18 in group 2, p-value

Fibroblast activation protein (FAP) is expressed in the microenvironment of most human epithelial tumors. 68Ga-labeled FAP inhibitors based on the cyanopyrrolidine structure (FAPI) are currently used for the detection of the tumor microenvironment by PET imaging. This research aimed to design, synthesize and preclinically evaluate a new FAP inhibitor radiopharmaceutical based on the 99mTc-((R)-1-((6-hydrazinylnicotinoyl)-D-alanyl) pyrrolidin-2-yl) boronic acid (99mTc-iFAP) structure for SPECT imaging. Molecular docking for affinity calculations was performed using the AutoDock software. The chemical synthesis was based on a series of coupling reactions of 6-hidrazinylnicotinic acid (HYNIC) and D-alanine to a boronic acid derivative. The iFAP was prepared as a lyophilized formulation based on EDDA/SnCl2 for labeling with 99mTc. The radiochemical purity (R.P.) was verified via ITLC-SG and reversed-phase radio-HPLC. The stability in human serum was evaluated by size-exclusion HPLC. In vitro cell uptake was assessed using N30 stromal endometrial cells (FAP positive) and human fibroblasts (FAP negative). Biodistribution and tumor uptake were determined in Hep-G2 tumor-bearing nude mice, from which images were acquired using a micro-SPECT/CT. The iFAP ligand (Ki = 0.536 nm, AutoDock affinity), characterized by UV-Vis, FT-IR, 1H–NMR and UPLC-mass spectroscopies, was synthesized with a chemical purity of 92%. The 99mTc-iFAP was obtained with a R.P. >98%. In vitro and in vivo studies indicated high radiotracer stability in human serum (>95% at 24 h), specific recognition for FAP, high tumor uptake (7.05 ± 1.13% ID/g at 30 min) and fast kidney elimination. The results found in this research justify additional dosimetric and clinical studies to establish the sensitivity and specificity of the 99mTc-iFAP.

Edelfosine (ET) is a potent antitumor agent but causes severe side effects that have limited its use in clinical practice. For this reason, nanoencapsulation in lipid nanoparticles (LNs) is advantageous as it protects from ET side-effects. Interestingly, previous studies showed the efficacy of LNs containing ET in various types of tumor. In this paper, biodistribution studies of nanoencapsulated ET, administered by three routes (oral, intravenous (IV) and intraperitoneal (IP)), were tested in order to select the optimal route of administration. To do this, ET-LNs were labeled with Technetium-99 m (99mTc) and administered by the oral, IV and IP route in mice. IV admin- istration of the radiolabeled LNs led to fast elimination from the blood circulation and increased accumulation in reticulo-endothelial (RES) organs, while their oral administration could not provide any evidence on their bio- distribution since large radiocomplexes were formed in the presence of gastrointestinal fluids. However, when the LNs were administered by the IP route they could access the systemic circulation and provided more constant blood ET-LN levels compared to the IV route. These findings suggest that the IP route can be used to sustain the level of drug in the blood and avoid accumulation in RES organs.

Background: Recent advances in nanotechnology have offered new hope for cancer detection, prevention, and treatment. Nanomedicine, a term for the application of nanotechnology in medical and health fields, uses nanoparticles for several applications such as imaging, diagnostic, targeted cancer therapy, drug and gene delivery, tissue engineering, and theranostics. Results: Here, we overview the current state-of-the-art of radiolabeled nanoparticles for molecular imaging and radionuclide therapy. Nanostructured radiopharmaceuticals of technetium-99m, copper-64, lutetium-177, and radium-223 are discussed within the scope of this review article. Conclusion: Nanoradiopharmaceuticals may lead to better development of theranostics inspired by ingenious delivery and imaging systems. Cancer nano-theranostics have the potential to lead the way to more specific and individualized cancer treatment., Technology Agency of the Czech Republic [TO01000074, TJ04000129]; Ministry of Education, Youth and Sports [8J20PL016]; FAPERJ: Cientista do Nosso Estado [E-26/200.815/2021]; CNPq: Bolsa de Produtividade [301069/2018-2]; FAPERJ: Rede NanoSaude [E-26/010.000981/2019], Technology Agency of the Czech Republic Grant Nos.: TO01000074, TJ04000129, Ministry of Education, Youth and Sports under Grant No.: 8J20PL016. FAPERJ: Cientista do Nosso Estado (E-26/200.815/2021), Rede NanoSaude (E-26/010.000981/2019) and CNPq: Bolsa de Produtividade (301069/2018-2).

The demand for the use of radioactive isotopes in medicine is increasing with each coming year necessitating the increased output of radionuclide products. One of the most widely spread radionuclides used in medicine is technetium-99m (99mТс) (Feasibility of producing molybdenum-99 2015, NEA 2012, The Supply of Medical Radioisotopes 2015). The very short 99mТс life (6-hour half-life) requires its production directly on the site of medical treatment. This is achieved using molybdenum-technetium generators (Kodina and Krasikova 2014, Technical Reports No. NF-T-5.4. 2013, Technetium-99 Generator 2021) loaded with molybdenum-99 (99Мо), which uninterruptedly decays (half-life of 66 hours) yielding 99mTc. Close attention must be paid in the course of production of molybdenum-technetium generators to radiation safety during transportation of 99Мо on the territory of the manufacturing facility. The main measure for ensuring radiation safety during transportation of 99Мо is the application of special packaging kits. The Karpov Institute of Physical Chemistry JSC uses a wide range of packaging kits of types A and B for transportation of radioactive materials on the territory of the manufacturer with design features providing the required level of radiation safety. In particular, the KL-15 shipping cask loaded/unloaded from the top is used for onsite transportation of 99Мо for charging molybdenum-technetium generators. The maximum permissible activity of 99Мо is not specified in the passport of the KL-15 cask. Planned construction of a radionuclide production shop in accordance with GMP requirements will require the increase of output of target radionuclides by several times. The above considerations necessitated the evaluation of the maximum permissible activity of 99Мо planned to be transported in KL-15 casks. No other type of standard casks can be used because of their outside dimensions prohibiting the unloading of 99Мо inside the “hot” chamber. Calculation and experimental evaluation of permissible 99Мо activity during transportation inside the KL-15 cask was performed. The paper presents the calculated evaluation of the maximum permissible activity of 99Мо in a KL-15 cask to ensure the radiation exposure of personnel of group A working with the cask not exceeding the established level at the enterprise (80 μSv per shift) and not requiring the use of additional measures and means of protection. The results of the work allow us drawing the conclusion that the KL-15 cask ensures the required level of radiation safety with up to 241 Ki of 99Мо loaded in the cask.

Click chemistry, and in particular copper-free click reactions, have gained growing interest in the field of radiopharmaceutical sciences. The 99mTc-tricarbonyl moiety is an excellent precursor for radiolabelling of biomolecules. This master thesis aims at synthesizing two new chelators containing the 2,2’-dipicolylamine (DPA) moiety for 99mTc and investigating the copper-free strain-promoted cycloaddition for the Tc(CO)3-core. The first chelator was based on a tetrafluorophenyl ester and was successfully radiolabeled with [99mTc][Tc(CO)3(H2O)3]+ at 40°C with a a radiochemical conversion (RCC) of 89% after 20 min. The chelator was afforded in a radiochemical purity over 99% after separation using a cartridge. The subsequent conjugation of an amine-functionalized PSMA (prostate-specific membrane antigen) targeting motif was investigated, and the PSMA targeting 99mTc-complex was afforded with an RCC of 23% at 100°C after 150 min. Two other unknown side products were observed. Further in-depth studies are required to optimize the radiolabeling and to identify the formed side-products. For the SPAAC reaction, a 4,8-diazacyclononyne containing the DPA moiety was prepared via the Nicholas reaction. Radiolabeling at 100°C afforded the radiolabeled complex with an RCC of 89% after 30 min. The ensuing SPAAC reaction with an azide-functionalized PSMA motif was studied at three different temperatures. The PSMA targeting 99mTc-complex was afforded selectively at 100°C after 4 hours with an RCC of 89%. No side products were observed. Nonradioactive Re(CO)3-complexes were synthesized and characterized to confirm the 99mTc-complexes. Further modifications of the 4,8-diazacyclononyne could prospectively enable to carry out the radiolabeling under physiological conditions. Continuing in vitro and in vivo experiments are planned.

Prostat kanseri ve akabinde görülen kemik metastazları günümüzde çok yaygındır. Bununla birlikte hemen hemen tüm kanserler kemiğe metastaz yapabilmektedir. Yeni ortaya çıkan prostat kanseri vakalarından %4’e yakını her yıl ölümle sonuçlanmaktadır. Prostat kanserinin ve kemik metastazlarının tanı ve tedavisinde otofloresans özellikli 99mTc-C-Fe3O4-SiO2-HPG-NH2-DPAPA ((S)-2,5-bis(bis(fosfonometil)amino)pentanoik asit) konjuge ve 99mTc radyoişaretli hedeflenmiş Süper Paramanyetik Demir Oksit (SPIO) nanopartikülleri hazırlamayı amaçladık. Bu yaklaşım kulağa çok alışıldık gelmese de EDTMP (Quadramet, Cytogen) türevi olan DPAPA molekülünün prostat kanserlerinin kemik metastazlarında birikim için tasarlanmış bir radyofarmasötik olarak geçmişte kullanıldığı bilinmektedir. Bu çalışmanın amacı, prostat kanserine ve akabinde oluşan kemik metastazlarına spesifik alternatif bir teşhis ve tedavi ajanı oluşturmaktır. Bu amaçla prostat kanserine ve kemik metastazlarına spesifik bir molekül olduğu düşünülen EDTMP (etilendiamintetrametilen fosfonat) türevi DPAPA (3,5 bis(difosfoamino)pentanoik asit) molekülüne bağlı demir oksit içerikli nanoparçacık sistemleri üzerinde çalışılmıştır. Bu çalışmada kübik manyetik özellikli nanoparçacıklar sentezlenmiş, (TEOS) SiO2 ile kaplanarak ve HPG (Yüksek yoğunluklu poligliserol) ile modifiye edilmiştir. Daha sonra, kullanılan konjugasyon yöntemi ile bu parçacıklar DPAPA ((S)-2,5-bis(bis(fosfonometil)amino)pentanoik asit) ile konjuge edilmiş ve radyonüklid işaretleme ile in vitro çalışmalar yapılmış, hücre üzerindeki etkinliği test edilmiştir. Sentezlenen molekülün tanı amaçlı kullanılması için SnCl2 indirgeme yöntemi kullanılarak 99mTc ile radyoişaretleme yapılmıştır. HPLC, HPLRC, TLRC ve FTIR analizleri, beklenen moleküler yapıları doğrulamıştır. DLS, SEM, SPM ve TEM görüntüleri, nanoparçacıkların ve nanokonjugatların yapılan modifikasyonlar ve konjugasyonlar sonrasındaki değişimlerini göstermiş ve doğrulamıştır. XPS analizleri ile modifikasyonlar ve katmanların elementel durumu tespit edilmiştir ve nanomalzeminin içerik doğrulanması gerçekleştirilmiştir. ICP-MS analizi ile elementel olarak ppm cinsinden demir miktar tayinleri kantitatif olarak yapılmıştır. VSM analizi ile manyetik özellikleri emu/g cinsinden bulunmuştur ve buna bağlı olarak MR potansiyeli yapılan denemeler ile tespit edilmiştir. Florimetrik analizleri sonucunda otofloresans’a sahip olduğu kanıtlanmıştır. Elde edilen bu sonuç floresans özelliğin izlenebilme potansiyeli açısından önemlidir. PC-3, LNCaP, RWPE-1, K-562 ve Saos-2 hücre hatlarındaki afiniteleri ve sitotoksisiteleri, in vitro hücre kültürü deneyleri kullanılarak belirlenmiştir. Burada sunulan sonuçlar, tasarlanan 99mTc-C-Fe3O4-SiO2-HPG-NH2-DPAPA nanokonjugatı’nın prostat ve kemik kanserine spesifik bir teranostik olduğunu ve bu açıdan faydalı olabilecek bir ilaç sistemi olduğunu göstermektedir., Prostate cancer and subsequent bone metastases are very common today. However, almost all cancers can metastasize to the bone. Approximately 4% of newly emerging prostate cancer cases result in death each year. In the diagnosis and treatment of prostate cancer and bone metastases, 99mTc-C-Fe3O4-SiO2-HPG-NH2- DPAPA ((S)-2,5-bis(bis(phosphonomethyl)amino)pentanoic acid) conjugated and 99mTc radiolabeled targeted super We aimed to prepare paramagnetic iron oxide (SPIO) nanoparticles Although this approach does not sound familiar, it is known that the DPAPA molecule, which is a derivative of EDTMP (Quadramet, Cytogen), has been used in the past as a radiopharmaceutical designed for accumulation in bone metastases of prostate cancers. The aim of this study is to create an alternative diagnostic and therapeutic agent specific for prostate cancer and subsequent bone metastases. For this purpose, nanoparticle systems containing iron oxide attached to the EDTMP (ethylenediaminetetramethylene phosphonate) derivative DPAPA (((S)-2,5- bis(bis(phosphonomethyl)amino)pentanoic acid) molecule, which is thought to be a specific molecule for prostate cancer and bone metastases, were studied. In this study, cubic magnetic nanoparticles were synthesized, coated with (TEOS) SiO2 and modified with HPG (Hyper branched polyglycerol). Then, with the conjugation method used, these particles were conjugated with DPAPA ((S)-2,5- bis(bis(phosphonomethyl)amino)pentanoic acid) and in vitro studies were carried out with radionuclide labeling, its effectiveness on the cell was tested. For the use of the synthesized molecule for diagnostic purposes, the 99mTc reduction method was used. HPLC, HPLRC, TLRC and FT-IR analyzes confirmed the expected molecular structures. DLS, SEM, SPM and TEM images showed and confirmed the changes of nanoparticles and nanoconjugates after modifications and conjugations. XPS analyzes determined the modifications and elemental state of the layers. Quantitative determination of elemental ppm was made by ICP-MS analysis. The magnetic properties were found in emu/g by VSM analysis, and accordingly, the MR potential was determined. It has been proven to have autofluorescence as a result of fluorimetric analysis. This result is important in terms of its fluorescence tracing potential. Their affinity and cytotoxicity in PC-3, LNCaP, RWPE-1, K-562 and Saos- 2 cell lines were determined using in vitro cell culture experiments. The results presented here demonstrate that the designed 99mTc-C-Fe3O4- SiO2-HPG-NH2-DPAPA nanoconjugate is a prostate and bone cancer-specific theranostic and may be a useful drug system in this regard.

Using the nanoprecipitation process, chitosan coated poly lactic-co-glycolic acid (PLGA) based polymeric nanoparticle formulations of two molecular weights were developed as a possible cancer cell diagnostic agent. Photon correlation spectroscopy was used to measure the particle size, distribution [polydispersity index (PDI)], and zeta potential values of developed nanoparticle formulations. The F1 [low molecular weight PLGA (Resomer (R) RG 503 H)] and F2 [high molecular weight PLGA (Resomer (R) RG 504 H)] formulations were then directly labeled with Technetium-99m ([99mTc]Tc) using stannous salts (chloride) as a reducing agent. The radiochemical purity (RP) and in vitro stability in different mediums of the formulations were assessed using ascending radioactive thin layer chromatography (RTLC) method. The cell incorporation of [99mTc]Tc labeled F1 and F2 formulations, as well as Reduced/Hydrolized [99mTc]NaTcO4 (R/H-[99mTc]NaTcO4) in the MCF-7 (breast cancer cell line) cells, was then assessed. The nanoparticles had a middle size of 408.9 +/- 3.626 nm to 421.3 +/- 7.205 nm, a PDI value of 0.310 +/- 0.055 to 0.330 +/- 0.066, and a positive charge of +70.5 +/- 1.4 mV to +75.5 +/- 3.8 mV, according to the characterization results. F1 and F2 formulations were effectively radiolabeled with [99mTc]Tc, and their RP was found to be over 98% in both cases. When compared to [99mTc]Tc-F1 (45.091 +/- 2.254%) and R/H-[99mTc]NaTcO4 (8.527 +/- 0.426%), the incorporation percentages of [99mTc]Tc-F2 (70.756 +/- 3.537%) were shown to be higher in cancer cell lines (breast cancer cells, MCF-7). According to this research, radiolabeled chitosan coated PLGA nanoparticles ([99mTc]Tc-F2) could be suggested as promising cancer detection formulations. However, further investigations, such as biodistribution studies, should be performed.

Negatively charged microspheres (NCMs) are postulated as a new form of treatment for chronic wounds. Despite the efficacy shown at clinical level, more studies are required to demonstrate their safety and local effect. The objective of the work was to confirm the lack of NCM systemic absorption performing a biodistribution study of the NCMs in an open wound rat animal model. To this end, radiolabeling of NCMs with technetium-99 m was optimized and biodistribution studies were performed by in vivo SPEC/CT imaging and ex vivo counting during 24 h after topical administration. The studies were performed on animals treated with a single or repeated dose to study the effect of macrophages during a prolonged treatment. NCM radiolabeling was achieved in a simple, efficient and stable manner with high yield. SPECT/CT images showed that almost all NCMs (about 85 %) remained on the wound for 24 h either after single or multiple administrations. Ex vivo biodistribution studies confirmed that there was no accumulation of NCMs in any organ or tissue except in the wound area, suggesting a lack of absorption. In conclusion, NCMs can be considered safe as local wound treatment since they remain at the administration area., This project was partially supported by the Basque Government (HAZITEK, ZE-2017/00014) and co-funded by the European Regional Development Fund (ERDF).

Fibroblast activation protein (FAP) is expressed in the microenvironment of most human epithelial tumors. 68Ga-labeled FAP inhibitors based on the cyanopyrrolidine structure (FAPI) are currently used for the detection of the tumor microenvironment by PET imaging. This research aimed to design, synthesize and preclinically evaluate a new FAP inhibitor radiopharmaceutical based on the 99mTc-((R)-1-((6-hydrazinylnicotinoyl)-D-alanyl) pyrrolidin-2-yl) boronic acid (99mTc-iFAP) structure for SPECT imaging. Molecular docking for affinity calculations was performed using the AutoDock software. The chemical synthesis was based on a series of coupling reactions of 6-hidrazinylnicotinic acid (HYNIC) and D-alanine to a boronic acid derivative. The iFAP was prepared as a lyophilized formulation based on EDDA/SnCl2 for labeling with 99mTc. The radiochemical purity (R.P.) was verified via ITLC-SG and reversed-phase radio-HPLC. The stability in human serum was evaluated by size-exclusion HPLC. In vitro cell uptake was assessed using N30 stromal endometrial cells (FAP positive) and human fibroblasts (FAP negative). Biodistribution and tumor uptake were determined in Hep-G2 tumor-bearing nude mice, from which images were acquired using a micro-SPECT/CT. The iFAP ligand (Ki = 0.536 nm, AutoDock affinity), characterized by UV-Vis, FT-IR, 1H–NMR and UPLC-mass spectroscopies, was synthesized with a chemical purity of 92%. The 99mTc-iFAP was obtained with a R.P. >98%. In vitro and in vivo studies indicated high radiotracer stability in human serum (>95% at 24 h), specific recognition for FAP, high tumor uptake (7.05 ± 1.13% ID/g at 30 min) and fast kidney elimination. The results found in this research justify additional dosimetric and clinical studies to establish the sensitivity and specificity of the 99mTc-iFAP.