In-vivo inhibition of neutral endopeptidase 1 results in higher absorbed tumor doses of [177Lu]Lu-PP-F11N in humans: the lumed phase 0b study

BACKGROUND

A new generation of radiolabeled minigastrin analogs delivers low radiation doses to kidneys and are considered relatively stable due to less enzymatic degradation. Nevertheless, relatively low tumor radiation doses in patients indicate limited stability in humans. We aimed at evaluating the effect of sacubitril, an inhibitor of the neutral endopeptidase 1, on the stability and absorbed doses to tumors and organs by the cholecystokinin-2 receptor agonist [177Lu]Lu-PP-F11N in patients. In this prospective phase 0 study eight consecutive patients with advanced medullary thyroid carcinoma and a current somatostatin receptor subtype 2 PET/CT scan were included. Patients received two short infusions of ~ 1 GBq [177Lu]Lu-PP-F11N in an interval of ~ 4 weeks with and without Entresto® pretreatment in an open-label, randomized cross-over order. Entresto® was given at a single oral dose, containing 48.6 mg sacubitril. Adverse events were graded and quantitative SPECT/CT and blood sampling were performed. Absorbed doses to tumors and relevant organs were calculated.

RESULTS

Pretreatment with Entresto® showed no additional toxicity and increased the stability of [177Lu]Lu-PP-FF11N in blood significantly (p < 0.001). Median tumor-absorbed doses were 2.6-fold higher after Entresto® pretreatment (0.74 vs. 0.28 Gy/GBq, P = 0.03). At the same time, an increase of absorbed doses to stomach, kidneys and bone marrow was observed, resulting in a tumor-to-organ absorbed dose ratio not significantly different with and without Entresto®.

CONCLUSIONS

Premedication with Entresto® results in a relevant stabilization of [177Lu]Lu-PP-FF11N and consecutively increases radiation doses in tumors and organs. Trial registration clinicaltrails.gov, NCT03647657. Registered 20 August 2018.

Radiolabeled Somatostatin Receptor Antagonist Versus Agonist for Peptide Receptor Radionuclide Therapy in Patients with Therapy-Resistant Meningioma: PROMENADE Phase 0 Study

Our primary aim was to compare the therapeutic index (tumor-to-bone marrow and tumor-to-kidney absorbed-dose ratios) of the new radiolabeled somatostatin receptor antagonist [177Lu]Lu-DOTA-JR11 with the established radiolabeled somatostatin receptor agonist [177Lu]Lu-DOTATOC in the same patients with progressive, standard therapy-refractory meningioma. Methods: In this prospective, single-center, open-label phase 0 study (NCT04997317), 6 consecutive patients were included: 3 men and 3 women (mean age, 63.5 y). Patients received 6.9-7.3 GBq (standard injected radioactivity) of [177Lu]Lu-DOTATOC followed by 3.3-4.9 GBq (2 GBq/m2 × body surface area) of [177Lu]Lu-DOTA-JR11 at an interval of 10 ± 1 wk. In total, 1 [177Lu]Lu-DOTATOC and 2-3 [177Lu]Lu-DOTA-JR11 treatment cycles were performed. Quantitative SPECT/CT was done at approximately 24, 48, and 168 h after injection of both radiopharmaceuticals to calculate meningioma and organ absorbed doses as well as tumor-to-organ absorbed-dose ratios (3-dimensional segmentation approach for meningioma, kidneys, liver, bone marrow, and spleen). Results: The median of the meningioma absorbed dose of 1 treatment cycle was 3.4 Gy (range, 0.8-10.2 Gy) for [177Lu]Lu-DOTATOC and 11.5 Gy (range, 4.7-22.7 Gy) for [177Lu]Lu-DOTA-JR11. The median bone marrow and kidney absorbed doses after 1 treatment cycle were 0.11 Gy (range, 0.05-0.17 Gy) and 2.7 Gy (range, 1.3-5.3 Gy) for [177Lu]Lu-DOTATOC and 0.29 Gy (range, 0.16-0.39 Gy) and 3.3 Gy (range, 1.6-5.9 Gy) for [177Lu]Lu-DOTA-JR11, resulting in a 1.4 (range, 0.9-1.9) times higher median tumor-to-bone marrow absorbed-dose ratio and a 2.9 (range, 2.0-4.8) times higher median tumor-to-kidney absorbed-dose ratio with [177Lu]Lu-DOTA-JR11. According to the Common Terminology Criteria for Adverse Events version 5.0, 2 patients developed reversible grade 2 lymphopenia after 1 cycle of [177Lu]Lu-DOTATOC. Afterward, 2 patients developed reversible grade 3 lymphopenia and 1 patient developed reversible grade 3 lymphopenia and neutropenia after 2-3 cycles of [177Lu]Lu-DOTA-JR11. No grade 4 or 5 adverse events were observed at 15 mo or more after the start of therapy. The disease control rate was 83% (95% CI, 53%-100%) at 12 mo or more after inclusion. Conclusion: Treatment with 1 cycle of [177Lu]Lu-DOTA-JR11 showed 2.2-5.7 times higher meningioma absorbed doses and a favorable therapeutic index compared with [177Lu]Lu-DOTATOC after injection of 1.4-2.1 times lower activities. The first efficacy results demonstrated a high disease control rate with an acceptable safety profile in the standard therapy for refractory meningioma patients. Therefore, larger studies with [177Lu]Lu-DOTA-JR11 are warranted in meningioma patients.

Appendicolith appendicitis: should we be operating sooner? A retrospective cohort study

INTRODUCTION

Evidence suggests that delaying an appendicectomy for up to 24 hours does not increase the risk of complicated appendicitis. Appendicoliths are a risk factor for perforation. No study has explored the temporal relationship between appendicolith presence and time to perforation. In this retrospective cohort study, we hypothesise that the presence of an appendicolith confirmed on preoperative computerised tomography scan (pCT) leads to a shorter time to complicated appendicitis.

METHODS

We undertook a retrospective single-centre study of patients admitted between 2018 and 2020. Inclusion criteria included: age ≥18 years, appendicitis confirmed on histopathology following an operation and a pCT scan. Complicated appendicitis was defined intraoperatively as an appendicular abscess, gangrenous or perforated appendix.

RESULTS

Some 310 patients were included in the study. Forty-five per cent presented with complicated appendicitis (n = 138). Appendicoliths were present in 79 (25.5%) patients. Multivariate logistic regression identified an appendicolith as a significant risk factor for perforation (odds ratio 3.50, 95% confidence interval [CI] 1.16-10.59; p = 0.027). Within the first 12 hours of admission, patients with an appendicolith accounted for a significantly greater proportion of those with complicated appendicitis intraoperatively compared with those without (56.7% vs 43.3%, respectively; p = 0.003). Within 12 hours of admission, those with an appendicolith were 2.05 times more likely to suffer from complicated appendicitis than those without (95% CI 1.28-3.29).

CONCLUSIONS

Patients with an appendicolith appendicitis should be considered for an early appendicectomy. Future large-scale multicentre prospective studies are required to explore this further, perhaps informing future guidelines.

Early response monitoring during [177Lu]Lu-PSMA I&T therapy with quantitated SPECT/CT predicts overall survival of mCRPC patients: subgroup analysis of a Swiss-wide prospective registry study

PURPOSE

To assess early tumor response with quantitated SPECT/CT and to correlate it with clinical outcome in metastatic castration-resistant prostate cancer (mCRPC) patients treated with 177Lutetium-PSMA I&T therapy.

METHODS

Single-center, observational study, part of the prospective Swiss national cancer registry study investigating the safety and efficacy of [177Lu]Lu-PSMA I&T (EKNZ: 2021-01271) in mCRPC patients treated with at least two cycles of [177Lu]Lu-PSMA I&T 6-weekly. After the first and second cycle quantitated SPECT/CT (Symbia Intevo, Siemens) was acquired 48 h after injection (three fields of view from head to thigh, 5 s/frame) and reconstructed using xQuant® (48i, 1 s, 10-mm Gauss). Image analysis: The PSMA-positive total tumor volumes (TTV) were semi-automatically delineated using a SUV threshold of 3 with MIMencore® (version 7.1.3, Medical Image Merge Software Inc.). Changes in TTV, highest tumor SUVmax, and total tumor SUVmean between cycles 1 and 2 were calculated and grouped into a) stable or decrease and b) increase. Serum PSA levels were assessed at each therapy cycle and at follow-up until progression or death. Changes in TTV, PSA, SUVmax, and SUVmean were correlated with PSA-progression-free survival (PSA-PFS) and the overall survival (OS) using the Kaplan-Meier methodology (log-rank test).

RESULTS

Between 07/2020 and 04/2022, 111 patients were screened and 73 finally included in the data analysis. The median follow-up was 8.9 months (range 1.4-26.6 months). Stable or decreased TTV at cycle 2 was associated with longer OS (hazard ratio (HR) 0.28, 95% confidence interval (CI) 0.09-0.86, p < 0.01). Similar, stable, or decreased PSA was associated with longer OS (HR 0.21; CI 0.07-0.62, p < 0.01) and PSA-PFS (HR 0.34; 95% CI 0.16-0.72, p < 0.01). Combining TTV and PSA will result in an augmented prognostic value for OS (HR 0.09; CI 0.01-0.63; p < 0.01) and for PSA-PFS (HR 0.11; CI 0.02-0.68; p < 0.01). A reduction of SUVmax or SUVmean was not prognostically relevant, neither for OS (p 0.88 and 0.7) nor for PSA-PFS (p 0.73 and 0.62, respectively).

CONCLUSION

Six weeks after initiating [177Lu]Lu-PSMA I&T, TTV and serum PSA appear to be good prognosticators for OS. Combined together, TTV + PSA change demonstrates augmented prognostic value and can better predict PSA-PFS. Larger studies using TTV change prospectively as an early-response biomarker are warranted for implementing management change towards a more personalized clinical practice.

CUDC-907, a dual PI3K/histone deacetylase inhibitor, increases meta-iodobenzylguanidine uptake (123/131I-mIBG) in vitro and in vivo: a promising candidate for advancing theranostics in neuroendocrine tumors

BACKGROUND

Neuroblastoma (NB) and pheochromocytoma/paraganglioma (PHEO/PGL) are neuroendocrine tumors. Imaging of these neoplasms is performed by scintigraphy after injection of radiolabeled meta-iodobenzylguanidine (mIBG), a norepinephrine analog taken up by tumoral cells through monoamine transporters. The pharmacological induction of these transporters is a promising approach to improve the imaging and therapy (theranostics) of these tumors.

METHODS

Transporters involved in mIBG internalization were identified by using transfected Human Embryonic Kidney (HEK) cells. Histone deacetylase inhibitors (HDACi) and inhibitors of the PI3K/AKT/mTOR pathway were tested in cell lines to study their effect on mIBG internalization. Studies in xenografted mice were performed to assess the effect of the most promising HDACi on 123I-mIBG uptake.

RESULTS

Transfected HEK cells demonstrated that the norepinephrine and dopamine transporter (NET and DAT) avidly internalizes mIBG. Sodium-4-phenylbutyrate (an HDACi), CUDC-907 (a dual HDACi and PI3K inhibitor), BGT226 (a PI3K inhibitor) and VS-5584 and rapamycin (two inhibitors of mTOR) increased mIBG internalization in a neuroblastoma cell line (IGR-NB8) by 2.9-, 2.1-, 2.5-, 1.5- and 1.3-fold, respectively, compared with untreated cells. CUDC-907 also increased mIBG internalization in two other NB cell lines and in one PHEO cell line. We demonstrated that mIBG internalization occurs primarily through the NET. In xenografted mice with IGR-NB8 cells, oral treatment with 5 mg/kg of CUDC-907 increased the tumor uptake of 123I-mIBG by 2.3- and 1.9-fold at 4 and 24 h post-injection, respectively, compared to the untreated group.

CONCLUSIONS

Upregulation of the NET by CUDC-907 lead to a better internalization of mIBG in vitro and in vivo.

Head-to-head comparison of different classes of FAP radioligands designed to increase tumor residence time: monomer, dimer, albumin binders, and small molecules vs peptides

PURPOSE

Fibroblast activation protein-α (FAP)-targeting radioligands have recently demonstrated high diagnostic potential. However, their therapeutic value is impaired by the short tumor residence time. Several strategies have been tested to overcome this limitation, but a head-to-head comparison has never been done. With the aim to identify strengths and limitations of the suggested strategies, we compared the monomer FAPI-46 versus (a) its dimer (FAPI-46-F1D), (b) two albumin binders conjugates (FAPI-46-Ibu (ibuprofen) and FAPI-46-EB (Evans Blue)), and (c) cyclic peptide FAP-2286.

METHODS

177Lu-labeled ligands were evaluated in vitro in cell lines with low (HT-1080.hFAP) and high (HEK-293.hFAP) humanFAP expression. SPECT/CT imaging and biodistribution studies were conducted in HT-1080.hFAP and HEK-293.hFAP xenografts. The areas under the curve (AUC) of the tumor uptake and tumor-to-critical-organs ratios and the absorbed doses were estimated.

RESULTS

Radioligands showed IC50 in the picomolar range. Striking differences were observed in vivo regarding tumor uptake, residence, specificity, and total body distribution. All [177Lu]Lu-FAPI-46-based radioligands showed similar uptake between the two tumor models. [177Lu]Lu-FAP-2286 showed higher uptake in HEK-293.hFAP and the least background. The AUC of the tumor uptake and absorbed dose was higher for [177Lu]Lu-FAPI-46-F1D and the two albumin binder conjugates, [177Lu]Lu-FAPI-46-Ibu and [177Lu]Lu-FAPI-46-EB, in HT1080.hFAP xenografts and for [177Lu]Lu-FAPI-46-EB and [177Lu]Lu-FAP-2286 in HEK293.hFAP xenografts. The tumor-to-critical-organs AUC values and the absorbed doses were in favor of [177Lu]Lu-FAP-2286, but tumor-to-kidneys.

CONCLUSION

The study indicated dimerization and cyclic peptide structures as promising strategies for prolonging tumor residence time, sparing healthy tissues. Albumin binding strategy outcome depended on the albumin binding moiety. The peptide showed advantages in terms of tumor-to-background ratios, besides tumor-to-kidneys, but its tumor uptake was FAP expression-dependent.

Development of a New Class of CXCR4-Targeting Radioligands Based on the Endogenous Antagonist EPI-X4 for Oncological Applications

The peptide fragment of human serum albumin that was identified as an inhibitor of C-X-C motif chemokine receptor 4 (CXCR4), termed EPI-X4, was investigated as a scaffold for the development of CXCR4-targeting radio-theragnostics. Derivatives of its truncated version JM#21 (ILRWSRKLPCVS) were conjugated to 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) and tested in Jurkat and Ghost-CXCR4 cells. Ligand-1, -2, -5, -6, -7, -8, and -9 were selected for radiolabeling. Molecular modeling indicated that ¹⁷⁷Lu-DOTA incorporation C-terminally did not interfere with the CXCR4 binding. Lipophilicity, in vitro plasma stability, and cellular uptake hinted ¹⁷⁷Lu-7 as superior. In Jurkat xenografts, all radioligands showed >90% washout from the body within an hour, with the exception of ¹⁷⁷Lu-7 and ¹⁷⁷Lu-9. ¹⁷⁷Lu-7 demonstrated best CXCR4-tumor targeting. Ex vivo biodistribution and single-photon emission computed tomography (SPECT)/positron emission tomography (PET)/CT imaging of ¹⁷⁷Lu-7/⁶⁸Ga-7 showed the same distribution profile for both radioligands, characterized by very low uptake in all nontargeted organs except the kidneys. The data support the feasibility of CXCR4-targeting with EPI-X4-based radioligands and designate ligand-7 as a lead candidate for further optimization.

Development of the 99mTc-Labelled SST2 Antagonist TECANT-1 for a First-in-Man Multicentre Clinical Study

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.

Radiolabeled Somatostatin Analogs-A Continuously Evolving Class of Radiopharmaceuticals

Somatostatin receptors (SSTs) are recognized as favorable molecular targets in neuroendocrine tumors (NETs) and neuroendocrine neoplasms (NENs), with subtype 2 (SST₂) being the predominantly and most frequently expressed. PET/CT imaging with ⁶⁸Ga-labeled SST agonists, e.g., ⁶⁸Ga-DOTA-TOC (SomaKit TOC^®) or ⁶⁸Ga-DOTA-TATE (NETSPOT^®), plays an important role in staging and restaging these tumors and can identify patients who qualify and would potentially benefit from peptide receptor radionuclide therapy (PRRT) with the therapeutic counterparts ¹⁷⁷Lu-DOTA-TOC or ¹⁷⁷Lu-DOTA-TATE (Lutathera^®). This is an important feature of SST targeting, as it allows a personalized treatment approach (theranostic approach). Today, new developments hold promise for enhancing diagnostic accuracy and therapeutic efficacy. Among them, the use of SST₂ antagonists, such as JR11 and LM3, has shown certain advantages in improving image sensitivity and tumor radiation dose, and there is evidence that they may find application in other oncological indications beyond NETs and NENs. In addition, PRRT performed with more cytotoxic α-emitters, such as ²²⁵Ac, or β^- and Auger electrons, such as ¹⁶¹Tb, presents higher efficacy. It remains to be seen if any of these new developments will overpower the established radiolabeled SST analogs and PRRT with β^--emitters.

Theranostics in neuroendocrine tumors: an overview of current approaches and future challenges

Neuroendocrine neoplasms (NENs) comprise a heterogeneous group of tumors, mainly localized in the gastrointestinal system. What characterizes NENs is the expression of hormone receptors on the tumor cell surface, making them accessible for diagnostic and therapeutic approaches (theranostics) using radiolabelled peptides. Somatostatin receptors subtype-two (SST2) play an important role in NENs since they are overexpressed and homogeneously distributed at the surface of the majority of NENs. Accordingly, targeting SST2 for diagnostic and therapeutic purposes has been established. Current research aims at upregulating its expression by epigenetic treatment or improving its targeting via use of alternative radioligands. In addition, recent data suggest a future role of SST antagonists as a diagnostic tool and a potential therapeutic option. Another promising target is the glucagon-like peptide-1 (GLP-1) receptor. Targeting GLP-1R using exendin-4 (GLP-1 analogue) has a high sensitivity for the localization of the often SST2-negative sporadic insulinomas and insulinomas in the context of multiple endocrine neoplasia type-1. Further options for patients with insufficient expression of SST2 involve metaiodobenzylguanidine (MIBG) and the molecular target C-X-C motif chemokine receptor-4 (CXCR4), which have been evaluated for potential theranostic approach in symptomatic NENs or dedifferentiated tumors. Recently, new targets such as the glucose-dependent insulinotropic polypeptide receptor (GIPR) and the fibroblast activation protein (FAP) have been identified in NENs. Finally, minigastrin - a ligand targeting the cholecystokinin-2 (CCK2) receptors in medullary thyroid carcinoma and foregut neuroendocrine tumors - may improve future management of these diseases with currently limited therapeutic options. This review summarises the current approaches and future challenges of diagnostic and therapeutic evaluations in neuroendocrine neoplasms.

Radiolabeled Peptides for Cancer Imaging and Therapy: From Bench-to-Bedside

Radiolabeled peptides can deliver radiation selectively to tumors via targeting peptide receptors that are overexpressed on the surface of cancer cells. The radiation is used either for detection (imaging) or for destruction (therapy) of these tumors. The Division of Radiopharmaceutical Chemistry at the University Hospital Basel has conducted pioneering work on the development of peptide-based radiopharmaceuticals. Our research covers the entire spectrum of such developments, from bench-to-bedside, and it is illustrated in this article by selective cases.

Glucagon-like Peptide-1 Receptor as Emerging Target: Will It Make It to the Clinic?

The glucagon-like peptide-1 receptor (GLP-1R) is an emerging target due to its high expression in benign insulinomas as well as in islet cell hypertrophia/hyperplasia (nesidioblastosis) and pancreatic β-cells. In 2008, occult insulinomas were localized for the first time in men using the metabolically stable radiolabeled glucagon-like peptide-1 (GLP-1) agonist [Lys⁴⁰(Ahx-DTPA-¹¹¹In)NH₂]-exendin-4 (¹¹¹In-DTPA-exendin-4). Afterward, several radiopharmaceuticals for GLP-1R PET/CT imaging were synthesized and evaluated, for example, [Nle¹⁴,Lys⁴⁰(Ahx-DOTA-⁶⁸Ga)NH₂]-exendin-4 (⁶⁸Ga-DOTA-exendin-4), [Cys⁴⁰(MAL-NOTA-⁶⁸Ga)NH₂]-exendin-4 (⁶⁸Ga-NOTA-exendin-4), and [Lys⁴⁰(NODAGA-⁶⁸Ga)NH₂]-exendin-4 (⁶⁸Ga-NODAGA-exendin-4). Several prospective comparison studies provided evidence that GLP-1R PET/CT is significantly more sensitive than contrast-enhanced MRI (ceMRI), contrast-enhanced CT (ceCT), GLP-1R SPECT/CT, somatostatin receptor PET/CT, and SPECT/CT in the detection of benign insulinomas, and insulinomas in the context of multiple endocrine neoplasia type 1. As a result, the European Neuroendocrine Tumor Society guidelines recommend GLP-1R imaging or selective intraarterial calcium stimulation and venous sampling (ASVS) in patients for whom there is a clinical suspicion of having an insulinoma but who have a negative ceMRI/ceCT or negative endoscopic ultrasound. Furthermore, there is growing evidence that GLP-1R PET/CT can visualize and localize adult nesidioblastosis. This is clinically relevant as the distinction between focal and diffuse nesidioblastosis is critical in directing a therapeutic strategy in these patients. Prospective studies have proven the clinical relevance of GLP-1R imaging as it is often the only imaging modality able to localize the insulinoma or nesidioblastosis. It is therefore likely that this noninvasive imaging modality will replace the invasive localization of insulinomas using ASVS. More experimental indications for GLP-1R imaging include the diagnosis of an insulinoma/nesidioblastosis in patients with postprandial hypoglycemia after bariatric bypass surgery and monitoring β-cells in patients with brittle type 1 diabetes after islet-cell transplantation. We believe that these indications and possibly future indications will bring GLP-1R imaging to the clinic.

Consensus on molecular imaging and theranostics in neuroendocrine neoplasms

Nuclear medicine plays an increasingly important role in the management neuroendocrine neoplasms (NEN). Somatostatin analogue (SSA)-based positron emission tomography/computed tomography (PET/CT) and peptide receptor radionuclide therapy (PRRT) have been used in clinical trials and approved by the European Medicines Agency (EMA) and the US Food and Drug Administration (FDA). European Association of Nuclear Medicine (EANM) Focus 3 performed a multidisciplinary Delphi process to deliver a balanced perspective on molecular imaging and radionuclide therapy in well-differentiated neuroendocrine tumours (NETs). NETs form in cells that interact with the nervous system or in glands that produce hormones. These cells, called neuroendocrine cells, can be found throughout the body, but NETs are most often found in the abdomen, especially in the gastrointestinal tract. These tumours may also be found in the lungs, pancreas and adrenal glands. In addition to being rare, NETs are also complex and may be difficult to diagnose. Most NETs are non-functioning; however, a minority present with symptoms related to hypersecretion of bioactive compounds. NETs often do not cause symptoms early in the disease process. When diagnosed, substantial number of patients are already found to have metastatic disease. Several societies' guidelines address Neuroendocrine neoplasms (NENs) management; however, many issues are still debated, due to both the difficulty in acquiring strong clinical evidence in a rare and heterogeneous disease and the different availability of diagnostic and therapeutic options across countries. EANM Focus 3 reached consensus on employing ⁶⁸gallium-labelled somatostatin analogue ([⁶⁸Ga]Ga-DOTA-SSA)-based PET/CT with diagnostic CT or magnetic resonance imaging (MRI) for unknown primary NET detection, metastatic NET, NET staging/restaging, suspected extra-adrenal pheochromocytoma/paraganglioma and suspected paraganglioma. Consensus was reached on employing ¹⁸fluorine-fluoro-2-deoxyglucose ([¹⁸F]FDG) PET/CT in neuroendocrine carcinoma, G3 NET and in G1-2 NET with mismatched lesions (CT-positive/[⁶⁸Ga]Ga-DOTA-SSA-negative). Peptide receptor radionuclide therapy (PRRT) was recommended for second line treatment for gastrointestinal NET with [⁶⁸Ga]Ga-DOTA-SSA uptake in all lesions, in G1/G2 NET at disease progression, and in a subset of G3 NET provided all lesions are positive at [¹⁸F]FDG and [⁶⁸Ga]Ga-DOTA-SSA. PRRT rechallenge may be used for in patients with stable disease for at least 1 year after therapy completion. An international consensus is not only a prelude to a more standardised management across countries but also serves as a guide for the direction to follow when designing new research studies.

In vitro effect of some nucleoside reverse transcriptase inhibitors against HSV-1 replication

OBJECTIVE

The current study was designed to investigate the effects of some nucleoside reverse transcriptase inhibitors (NRTIs) on HSV-1 infection.

MATERIALS AND METHODS

Initially, the SwissTargetPrediction server was used to predict the interactions between HSV-1 thymidine kinase and acyclovir, stavudine, zidovudine, didanosine, and entecavir. The effect of each component on Vero cell viability was assessed by the MTT assay. After treatment, the cell supernatants were collected, and HSV-1 replication was analyzed by quantitative real-time PCR.

RESULTS

The qPCR results revealed that viral titers were reduced 41, 40, 19, 44, and 31-fold in the presence of acyclovir, zidovudine, stavudine, didanosine, and entecavir, respectively.

CONCLUSIONS

Our findings indicate that NRTIs significantly reduce HSV-1 replication in cell culture.

Selection of the First 99mTc-Labelled Somatostatin Receptor Subtype 2 Antagonist for Clinical Translation-Preclinical Assessment of Two Optimized Candidates

Recently, radiolabelled antagonists targeting somatostatin receptors subtype 2 (SST2) in neuroendocrine neoplasms demonstrated certain superior properties over agonists. Within the ERA-PerMED project "TECANT" two 99mTc-Tetramine (N4)-derivatized SST2 antagonists (TECANT-1 and TECANT-2) were studied for the selection of the best candidate for clinical translation. Receptor-affinity, internalization and dissociation studies were performed in human embryonic kidney-293 (HEK293) cells transfected with the human SST2 (HEK-SST2). Log D, protein binding and stability in human serum were assessed. Biodistribution and SPECT/CT studies were carried out in nude mice bearing HEK-SST2 xenografts, together with dosimetric estimations from mouse-to-man. [99mTc]Tc-TECANT-1 showed higher hydrophilicity and lower protein binding than [99mTc]-TECANT-2, while stability was comparable. Both radiotracers revealed similar binding affinity, while [99mTc]Tc-TECANT-1 had higher cellular uptake (>50%, at 2 h/37 °C) and lower dissociation rate (<30%, at 2 h/37 °C). In vivo, [99mTc]Tc-TECANT-1 showed lower blood values, kidney and muscles uptake, whereas tumour uptake was comparable to [99mTc]Tc-TECANT-2. SPECT/CT imaging confirmed the biodistribution results, providing the best tumour-to-background image contrast for [99mTc]Tc-TECANT-1 at 4 h post-injection (p.i.). The estimated radiation dose amounted to approximately 6 µSv/MBq for both radiotracers. This preclinical study provided the basis of selection of [99mTc]Tc-TECANT-1 for clinical translation of the first 99mTc-based SST2 antagonist.

High Expression of FAP in Colorectal Cancer Is Associated With Angiogenesis and Immunoregulation Processes

Fibroblast activation protein α (FAP) plays an important role in tissue remodeling and helps tumor cells invade surrounding tissue. We sought to investigate FAP as a prognostic molecular marker in colorectal cancer (CRC) using immunohistochemical and transcriptomic data. FAP expression and clinicopathological information were obtained from The Cancer Genome Atlas data set. The association of FAP expression and tissue cellular heterogeneity landscape was explored using the xCell method. We evaluated FAP protein expression in a cohort of 92 CRCs and 19 non-tumoral tissues. We observed that FAP was upregulated in tumors both at the mRNA and protein levels, and its expression was associated with advanced stages, poor survival, and consensus molecular subtype 4. FAP expression was also associated with angiogenesis and collagen degradation. We observed an enrichment in immune-cell process-related genes associated with FAP overexpression. Colorectal cancers with high FAP expression display an inflamed phenotype enriched for macrophages and monocytes. Those tumors showed enrichment for regulatory T cell populations and depletion of TH1 and natural killer T cells, pointing to an immunosuppressive environment. Colorectal cancers with high levels of stromal FAP are associated with aggressive disease progression and survival. Our results suggest that FAP plays additional roles in tumor progression such as modulation of angiogenesis and immunoregulation in the tumor microenvironment.

Innovative imaging of insulinoma: the end of sampling? A review

Receptors for the incretin glucagon-like peptide-1 (GLP-1R) have been found overexpressed in selected types of human tumors and may, therefore, play an increasingly important role in endocrine gastrointestinal tumor management. In particular, virtually all benign insulinomas express GLP-1R in high density. Targeting GLP-1R with indium-111, technetium-99m or gallium-68-labeled exendin-4 offers a new approach that permits the successful localization of small benign insulinomas. It is likely that this new non-invasive technique has the potential to replace the invasive localization of insulinomas by selective arterial stimulation and venous sampling. In contrast to benign insulinomas, malignant insulin-secreting neuroendocrine tumors express GLP-1R in only one-third of the cases, while they more often express the somatostatin subtype 2 receptors. Importantly, one of the two receptors appears to be always overexpressed. In special cases of endogenous hyperinsulinemic hypoglycemia (EHH), that is, in the context of MEN-1 or adult nesidioblastosis GLP-1R imaging is useful whereas in postprandial hypoglycemia in the context of bariatric surgery, GLP-1R imaging is probably not helpful. This review focuses on the potential use of GLP-1R imaging in the differential diagnosis of EHH.

68Ga-Exendin-4 PET/CT Detects Insulinomas in Patients With Endogenous Hyperinsulinemic Hypoglycemia in MEN-1

CONTEXT

Surgical intervention is advised in patients with multiple endocrine neoplasia type-1 (MEN-1) and nonfunctioning pancreatic neuroendocrine tumors (PanNETs) with a size ≥20 mm. Functioning PanNETs, such as in patients with endogenous hyperinsulinemic hypoglycemia (EHH) due to (one or multiple) insulinomas, should be treated surgically independent of size. Preoperative localization of insulinomas is critical for surgery.

OBJECTIVE

To evaluate the feasibility and sensitivity of 68Ga-DOTA-exendin-4 positron emission tomography (PET)/CT in the detection of clinically relevant lesions in patients with MEN-1 and EHH in combination with MRI.

DESIGN

Post hoc subgroup analysis of a larger prospective imaging study with 52 patients with EHH.

PATIENTS

Six of 52 consecutive patients with EHH and genetically proven MEN-1 mutation were included.

INTERVENTIONS

All patients received one 68Ga-DOTA-exendin-4 PET/CT and one MRI scan within 3 to 4 days. Thereafter, surgery was performed based on all imaging results.

MAIN OUTCOME MEASURES

Lesion-based sensitivity of PET/CT and MRI for detection of clinically relevant lesions was calculated. Readers were unaware of other results. The reference standard was surgery with histology and treatment outcome. True positive (i.e., clinically relevant lesions) was defined as PanNETs ≥20 mm or insulinoma.

RESULTS

In six patients, 37 PanNETs were confirmed by histopathology. Sensitivity (95% CI) in the detection of clinically relevant lesions for combined PET/CT plus MRI, MRI, and PET/CT was 92.3% (64% to 99.8%), 38.5% (13.9% to 68.4%), and 84.6% (54.6% to 98.1%), respectively (P = 0.014 for the comparison of PET/CT plus MRI vs MRI). Postsurgery, EHH resolved in all patients.

CONCLUSION

68Ga-DOTA-exendin-4 PET/CT is feasible in patients with MEN-1 and EHH. The combination with MRI is superior to MRI alone in the detection of insulinomas and may guide the surgical strategy.

Design and development of the theranostic pair 177 Lu-OPS201/68 Ga-OPS202 for targeting somatostatin receptor expressing tumors

Radiolabeled somatostatin receptor (sstr) antagonists have shown superiority in different preclinical and clinical settings compared with the well-established and clinically used agonists for targeting sstr-expressing tumors, with regard to pharmacokinetics, tumor uptake, and retention. The theranostic pair ¹⁷⁷ Lu-OPS201/⁶⁸ Ga-OPS202, based on the sstr2 antagonist JR11 (Cpa-c[d-Cys-Aph(Hor)-d-Aph(Cbm)-Lys-Thr-Cys]-d-Tyr-NH₂ ), is the most advanced pair of the antagonist family in terms of preclinical development and is currently under clinical evaluation. OPS201 and OPS202 share the same amino acid sequence (JR11) but feature different conjugated chelators needed for radiolabeling, DOTA for OPS201 and NODAGA for OPS202. In this review, the design and development of the peptidic analog, JR11, and the selection of chelators and radiometals that led to ¹⁷⁷ Lu-OPS201/⁶⁸ Ga-OPS202 are discussed. Furthermore, the preclinical evaluation of both radiolabeled analogs from bench to bedside and the clinical trials involving the theranostic pair are presented.

New Developments in Peptide Receptor Radionuclide Therapy

Peptide Receptor Radionuclide Therapy (PRRT) is an established treatment for non-operable or metastatic neuroendocrine neoplasms that express highly and frequently somatostatin receptors. More generally, PRRT is an attractive therapy option for delivering cytotoxic radiation to tumor cells through specific binding of a radiolabeled peptide to a molecular target. The development of imaging companions gave rise to the concept of radiotheranostics, important for in vivo tumor detection, characterization, staging but also, and more importantly, for individual patient selection and treatment. The success of somatostatin receptor targeting paved the way for the clinical translation of other peptide-based radiopharmaceuticals targeting, e.g. the receptors Cholecystokinin 2, Gastrin Releasing Peptide (GRPR), Neurokinin-1 and C-X-C motif chemokine 4 (CXCR4). While historically the Auger emitter 111In and the high-energy β- emitter 90Y were used, the vast majority of PRRT are currently performed with the medium-energy β- emitter 177Lu, while α emitters are increasingly studied in various clinical applications.

The tetraamine chelator outperforms HYNIC in a new technetium-99m-labelled somatostatin receptor 2 antagonist

Background

Somatostatin receptor targeting radiopeptides are successfully being used to image, stage, and monitor patients with neuroendocrine tumours. They are exclusively agonists that internalise upon binding to the relevant receptor. According to recent reports, antagonists may be preferable to agonists. To date, ^99mTc-labelled somatostatin receptor antagonists have attracted little attention. Here, we report on a new somatostatin receptor subtype 2 (sst2) antagonist, SS-01 (p-Cl-Phe-cyclo(D-Cys-Tyr-D-Trp-Lys-Thr-Cys)D-Tyr-NH₂), with the aim of developing ^99mTc-labelled ligands for SPECT/CT imaging. SS-01 was prepared using Fmoc solid-phase synthesis and subsequently coupled to the chelators 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), 6-carboxy-1,4,8,11-tetraazaundecane (N4), and 6-hydrazinonicotinic acid (HYNIC) to form the corresponding peptide-chelator conjugates SS-03, SS-04, and SS-05, respectively. SS-04 and SS-05 were radiolabelled with ^99mTc and SS-03 with ¹⁷⁷Lu. Binding affinity and antagonistic properties were determined using autoradiography and immunofluorescence microscopy. Biodistribution and small animal SPECT/CT studies were performed on mice bearing HEK293-rsst2 xenografts.

Results

The conjugates showed low nanomolar sst2 affinity and antagonistic properties. ¹⁷⁷Lu-DOTA-SS-01 (¹⁷⁷Lu-SS-03) and ^99mTc-N4-SS-01 (^99mTc-SS-04) demonstrated high cell binding and low internalisation, whereas ^99mTc-HYNIC/edda-SS-01 (^99mTc-SS-05) showed practically no cellular uptake in vitro. The ^99mTc-SS-04 demonstrated impressive tumour uptake at early time points, with 47% injected activity per gram tumour (%IA/g) at 1 h post-injection. The tumour uptake persisted after 4 h and was 32.5 %IA/g at 24 h. The uptake in all other organs decreased much more rapidly leading to high tumour-to-normal organ ratios, which was reflected in high-contrast SPECT/CT images.

Conclusions

These data indicate a very promising ^99mTc-labelled sst2-targeting antagonist. The results demonstrate high sensitivity of the ^99mTc-labelling strategy, which was shown to strongly influence the receptor affinity, contrary to corresponding agonists. ^99mTc-SS-04 exhibits excellent pharmacokinetics and imaging properties and appears to be a suitable candidate for SPECT/CT clinical translation.

Electronic supplementary material

The online version of this article (10.1186/s13550-018-0428-y) contains supplementary material, which is available to authorized users.

Targeting of the Cholecystokinin-2 Receptor with the Minigastrin Analog 177Lu-DOTA-PP-F11N: Does the Use of Protease Inhibitors Further Improve In Vivo Distribution?

Patients with metastatic medullary thyroid cancer (MTC) have limited systemic treatment options. The use of radiolabeled gastrin analogs targeting the cholecystokinin-2 receptor (CCK2R) is an attractive approach. However, their therapeutic efficacy is presumably decreased by their enzymatic degradation in vivo. We aimed to investigate whether the chemically stabilized analog ¹⁷⁷Lu-DOTA-PP-F11N (¹⁷⁷Lu-DOTA-(dGlu)₆-Ala-Tyr-Gly-Trp-Nle-Asp-Phe-NH₂) performs better than reference analogs with varying in vivo stability, namely ¹⁷⁷Lu-DOTA-MG11 (¹⁷⁷Lu-DOTA-dGlu-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH₂) and ¹⁷⁷Lu-DOTA-PP-F11 (¹⁷⁷Lu-DOTA-(dGlu)₆-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH₂), and whether the use of protease inhibitors further improves CCKR2 targeting. First human data on ¹⁷⁷Lu-DOTA-PP-F11N are also reported. Methods: In vitro stability of all analogs was assessed against a panel of extra- and intracellular endoproteases, whereas their in vitro evaluation was performed using the human MTC MZ-CRC-1 and the transfected A431-CCK2R(+) cell lines. Biodistribution without and with the protease inhibitors phosphoramidon and thiorphan was assessed 4 h after injection in MZ-CRC-1 and A431-CCK2R(+) dual xenografts. Autoradiography of ¹⁷⁷Lu-DOTA-PP-F11N (without and with phosphoramidon) and NanoSPECT/CT were performed. SPECT/CT images of ¹⁷⁷Lu-DOTA-PP-F11N in a metastatic MTC patient were also acquired. Results: ^natLu-DOTA-PP-F11N is less of a substrate for neprilysins than the other analogs, whereas intracellular cysteine proteases, such as cathepsin-L, might be involved in the degradation of gastrin analogs. The uptake of all radiotracers was higher in MZ-CRC-1 tumors than in A431-CCK2R(+), apparently because of the higher number of binding sites on MZ-CRC-1 cells. ¹⁷⁷Lu-DOTA-PP-F11N had the same biodistribution as ¹⁷⁷Lu-DOTA-PP-F11; however, uptake in the MZ-CRC-1 tumors was almost double (20.7 ± 1.71 vs. 11.2 ± 2.94 %IA [percentage injected activity]/g, P = 0.0002). Coadministration of phosphoramidon or thiorphan increases ¹⁷⁷Lu-DOTA-MG11 uptake significantly in the CCK2R(+) tumors and stomach. Less profound was the effect on ¹⁷⁷Lu-DOTA-PP-F11, whereas no influence or even reduction was observed for ¹⁷⁷Lu-DOTA-PP-F11N (20.7 ± 1.71 vs. 15.6 ± 3.80 [with phosphoramidon] %IA/g, P < 0.05 in MZ-CRC-1 tumors). The first clinical data show high ¹⁷⁷Lu-DOTA-PP-F11N accumulation in tumors, stomach, kidneys, and colon. Conclusion: The performance of ¹⁷⁷Lu-DOTA-PP-F11N without protease inhibitors is as good as the performance of ¹⁷⁷Lu-DOTA-MG11 in the presence of inhibitors. The human application of single compounds without unessential additives is preferable. Preliminary clinical data spotlight the stomach as a potential dose-limiting organ besides the kidneys.

The somatostatin receptor 2 antagonist 64Cu-NODAGA-JR11 outperforms 64Cu-DOTA-TATE in a mouse xenograft model

Copper-64 is an attractive radionuclide for PET imaging and is frequently used in clinical applications. The aim of this study was to perform a side-by-side comparison of the in vitro and in vivo performance of 64Cu-NODAGA-JR11 (NODAGA = 1,4,7-triazacyclononane,1-glutaric acid,4,7-acetic acid, JR11 = p-Cl-Phe-cyclo(D-Cys-Aph(Hor)-D-Aph(cbm)-Lys-Thr-Cys)D-Tyr-NH2), a somatostatin receptor 2 antagonist, with the clinically used sst2 agonist 64Cu-DOTA-TATE ((TATE = D-Phe-cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)Thr). In vitro studies demonstrated Kd values of 5.7±0.95 nM (Bmax = 4.1±0.18 nM) for the antagonist 64/natCu-NODAGA-JR11 and 20.1±4.4. nM (Bmax = 0.48±0.18 nM) for the agonist 64/natCu-DOTA-TATE. Cell uptake studies showed the expected differences between agonists and antagonists. Whereas 64Cu-DOTA-TATE (the agonist) showed very effective internalization in the cell culture assay (with 50% internalized at 4 hours post-peptide addition under the given experimental conditions), 64Cu-NODAGA-JR11 (the antagonist) showed little internalization but strong receptor-mediated uptake at the cell membrane. Biodistribution studies of 64Cu-NODAGA-JR11 showed rapid blood clearance and tumor uptake with increasing tumor-to-relevant organ ratios within the first 4 hours and in some cases, 24 hours, respectively. The tumor washout was slow or non-existent in the first 4 hours, whereas the kidney washout was very efficient, leading to high and increasing tumor-to-kidney ratios over time. Specificity of tumor uptake was proven by co-injection of high excess of non-radiolabeled peptide, which led to >80% tumor blocking. 64Cu-DOTA-TATE showed less favorable pharmacokinetics, with the exception of lower kidney uptake. Blood clearance was distinctly slower and persistent higher blood values were found at 24 hours. Uptake in the liver and lung was relatively high and also persistent. The tumor uptake was specific and similar to that of 64Cu-NODAGA-JR11 at 1 h, but release from the tumor was very fast, particularly between 4 and 24 hours. Tumor-to-normal organ ratios were distinctly lower after 1 hour. This is indicative of insufficient in vivo stability. PET studies of 64Cu-NODAGA-JR11 reflected the biodistribution data with nicely delineated tumor and low background. 64Cu-NODAGA-JR11 shows promising pharmacokinetic properties for further translation into the clinic.

New Gastrin Releasing Peptide Receptor-Directed [99mTc]Demobesin 1 Mimics: Synthesis and Comparative Evaluation

We have previously reported on the gastrin releasing peptide receptor (GRPR) antagonist [^99mTc]1, ([^99mTc]demobesin 1, ^99mTc-[N₄'-diglycolate-dPhe⁶,Leu-NHEt¹³]BBN(6-13)). [^99mTc]1 has shown superior biological profile compared to analogous agonist-based ^99mTc-radioligands. We herein present a small library of [^99mTc]1 mimics generated after structural modifications in (a) the linker ([^99mTc]2, [^99mTc]3, [^99mTc]4), (b) the peptide chain ([^99mTc]5, [^99mTc]6), and (c) the C-terminus ([^99mTc]7 or [^99mTc]8). The effects of above modifications on the biological properties of analogs were studied in PC-3 cells and tumor-bearing SCID mice. All analogs showed subnanomolar affinity for the human GRPR, while most receptor-affine 4 and 8 behaved as potent GRPR antagonists in a functional internalization assay. In mice bearing PC-3 tumors, [^99mTc]1-[^99mTc]6 exhibited GRPR-specific tumor uptake, rapidly clearing from normal tissues. [^99mTc]4 displayed the highest tumor uptake (28.8 ± 4.1%ID/g at 1 h pi), which remained high even after 24 h pi (16.3 ± 1.8%ID/g), well surpassing that of [^99mTc]1 (5.4 ± 0.7%ID/g at 24 h pi).

Towards the first measurement of matter-antimatter gravitational interaction

The AEgIS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy) is a CERN based experiment with the central aim to measure directly the gravitational acceleration of antihydrogen. Antihydrogen atoms will be produced via charge exchange reactions which will consist of Rydberg-excited positronium atoms sent to cooled antiprotons within an electromagnetic trap. The resulting Rydberg antihydrogen atoms will then be horizontally accelerated by an electric field gradient (Stark effect), they will then pass through a moiré deflectometer. The vertical deflection caused by the Earth's gravitational field will test for the first time the Weak Equivalence Principle for antimatter. Detection will be undertaken via a position sensitive detector. Around 103 antihydrogen atoms are needed for the gravitational measurement to be completed. The present status, current achievements and results will be presented, with special attention toward the laser excitation of positronium (Ps) to the n=3 state and the production of Ps atoms in the transmission geometry.

Somatostatin Receptor Antagonists for Imaging and Therapy

Somatostatin receptor (sstr) scintigraphy for imaging and sstr analogs for treatment have been used for more than 20 y. An important improvement in recent years was the introduction of peptide receptor radionuclide therapy with radiolabeled sstr agonists, such as [⁹⁰Y-DOTA⁰,Tyr³]octreotide or [¹⁷⁷Lu-DOTA⁰,Tyr³]octreotide (⁹⁰Y- or ¹⁷⁷Lu-DOTATOC, respectively) and [¹⁷⁷Lu-DOTA⁰,Tyr³]octreotate (¹⁷⁷Lu-DOTATATE). PET/CT with ⁶⁸Ga-labeled sstr agonists, such as ⁶⁸Ga-DOTATOC, ⁶⁸Ga-DOTATATE, and [⁶⁸Ga-DOTA,1-Nal³]octreotide (⁶⁸Ga-DOTANOC), plays an important role in staging and restaging neuroendocrine tumors. Most importantly, sstr scintigraphy and sstr PET/CT can distinguish patients who will qualify for and benefit from peptide receptor radionuclide therapy. This characteristic of sstr targeting is important because it allows a personalized treatment approach (theranostic approach). Until recently, it was thought that internalization of the radiolabeled agonist was mandatory for sstr-mediated imaging and therapy. It was Ginj et al. who proposed in 2006 the paradigm shift that radiolabeled sstr antagonists may perform better than agonists despite the lack of internalization. Despite the rather limited number of head-to-head comparisons of sstr antagonists and agonists, the superiority of sstr antagonists was demonstrated in several cases. From a small library of sstr antagonists, the analog JR11 (Cpa-c[d-Cys-Aph(Hor)-d-Aph(Cbm)-Lys-Thr-Cys]-d-Tyr-NH₂), an antagonist with selectivity for sstr subtype 2, showed the best overall characteristics for sstr subtype 2 targeting and was therefore selected for clinical translation. JR11 is under clinical development as a PET imaging agent when labeled with ⁶⁸Ga (⁶⁸Ga-NODAGA-JR11 or ⁶⁸Ga-OPS202) and as a therapeutic agent when labeled with ¹⁷⁷Lu (¹⁷⁷Lu-DOTA-JR11 or ¹⁷⁷Lu-OPS201). In this article, we discuss the development and current status of radiolabeled sstr antagonists. Evidence based on preclinical work, on quantitative in vivo autoradiography of human tumor slices, and on human data now supports a shift to sstr antagonists.

Crosstalk between E2f1 and c-Myc mediates hepato-protective effect of royal jelly on taxol-induced damages

Previous histopathological studies have shown the hepatotoxicity of paclitaxel (TXL). However, there is little known about the molecular pathway(s) of TXL-induced hepatotoxicity. Therefore, this study aimed to uncover the role of two transcription factors in the TXL-induced hepatotoxicity. Moreover, the hepato-protective effect of royal jelly (RJ) on TXL-induced toxicity was investigated. Wistar rats were divided into control and test groups. The test groups along with TXL received various doses of RJ (0, 50, 100 and 150 mg/kg, body weight). Biochemical hepatic functional assays, histopathological studies and hepatic superoxide dismutase level were determined. Additionally, the expression of E2f1 and cellular-myelocytomatosis (c-Myc) at messenger RNA (mRNA) level in the liver was evaluated. The hepatic functional biomarkers showed a significant ( p < 0.05) elevation in the TXL-received animals, while RJ administration for 28 days resulted in a remarkable reduction in TXL-elevated alkaline phosphatase, alanine transaminase and lactate dehydrogenase levels. The TXL-treated animals showed a significant ( p < 0.05) up-regulation of E2f1 and down-regulation of c-Myc at mRNA level, respectively. RJ lowered the expression of E2f1 while enhanced the expression of c-Myc in a dose-dependent manner. Our data suggest the hepato-protective effects of RJ on TXL-induced toxicity, which may attribute to a clear crosstalk between E2f1 and c-Myc as two regulators of liver growth.

Preoperative Glucagon-like peptide-1 receptor imaging reduces surgical trauma and pancreatic tissue loss in insulinoma patients: a report of three cases

Background

Insulinomas are rare tumors, in the majority of cases best treated by surgical resection. Preoperative localization of insulinoma is challenging. The more precise the preoperative localization the less invasive and safer is the resection. The purpose of the study is to check the impact of a new technique to localize insulinoma on the surgical strategy.

Findings

We present exact preoperative localization with Glucagon-like peptide-1 receptor (GLP-1R) imaging. This allows a more precise resection thereby reducing surgical access trauma, loss of healthy pancreatic tissue and increasing safety and quality of the surgical intervention.

Conclusion

With the help of precise preoperative localization of insulinoma with GLP-1R imaging the surgeon is able to minimize the amount of resected healthy pancreatic tissue. We hypothesize that GLP-1R imaging will become a preoperative diagnostic tool to be used for many patients scheduled for open or laparoscopic insulinoma resection.

Localization of Hidden Insulinomas with ⁶⁸Ga-DOTA-Exendin-4 PET/CT: A Pilot Study

(111)In-DOTA-exendin-4 SPECT/CT has been shown to be highly efficient in the detection of insulinomas. We aimed at determining whether novel PET/CT imaging with [Nle(14),Lys(40)(Ahx-DOTA-(68)Ga)NH2]exendin-4 ((68)Ga-DOTA-exendin-4) is feasible and sensitive in detecting benign insulinomas.

METHODS

(68)Ga-DOTA-exendin-4 PET/CT and (111)In-DOTA-exendin-4 SPECT/CT were performed in a randomized cross-over order on 5 patients with endogenous hyperinsulinemic hypoglycemia. The gold standard for comparison was the histologic diagnosis after surgery.

RESULTS

In 4 patients histologic diagnosis confirmed a benign insulinoma, whereas one patient refused surgery despite a positive (68)Ga-DOTA-exendin-4 PET/CT scan. In 4 of 5 patients, previously performed conventional imaging (CT or MR imaging) was not able to localize the insulinoma. (68)Ga-DOTA-exendin-4 PET/CT correctly identified the insulinoma in 4 of 4 patients, whereas (111)In-DOTA-exendin-4 SPECT/CT correctly identified the insulinoma in only 2 of 4 patients.

CONCLUSION

These preliminary data suggest that the use of (68)Ga-DOTA-exendin-4 PET/CT in detecting hidden insulinomas is feasible.

Does imaging αvβ3 integrin expression with PET detect changes in angiogenesis during bevacizumab therapy?

In recent years, there has been a growing interest in molecular imaging markers of tumor-induced angiogenesis. Several radiolabeled RGD (arginine, glycine, aspartate) peptides have been developed for PET imaging of αvβ3 integrins in the tumor vasculature, but there are only limited data on how angiogenesis inhibitors affect the tumor uptake of these peptides.

METHODS

Changes in (68)Ga-NODAGA-c(RGDfK) peptide uptake were measured using PET during bevacizumab therapy of 2 αvβ3-negative squamous cell carcinoma cell lines (A-431 and FaDu) that induce αvβ3-positive neovasculature when transplanted into nude mice. Tumor uptake of (68)Ga-NODAGA-c(RGDfK) was correlated to microvascular density, vascular morphology, and permeability as well as αvβ3 integrin expression.

RESULTS

Bevacizumab significantly inhibited growth of A-431 tumors and caused a significant reduction in microvascular density and αvβ3 integrin expression within 7 d after start of therapy. Bevacizumab also caused a normalization of blood vessel morphology and decreased tumor necrosis. However, (68)Ga-NODAGA-c(RGDfK) uptake was significantly increased at day 7 of therapy and did not decrease until after 3 wk of treatment. In Fadu xenografts, bevacizumab therapy caused only a minor inhibition of tumor growth and minor changes in (68)Ga-NODAGA-c(RGDfK) uptake.

CONCLUSION

Uptake of radiolabeled RGD peptides is not necessarily decreased by effective antiangiogenic therapy. Early in the course of therapy a decrease in the expression of αvβ3 integrins may not be reflected by a decrease in the uptake of RGD peptides.

Comparison of somatostatin receptor agonist and antagonist for peptide receptor radionuclide therapy: a pilot study

Preclinical and clinical studies have indicated that somatostatin receptor (sst)-expressing tumors demonstrate higher uptake of radiolabeled sst antagonists than of sst agonists. In 4 consecutive patients with advanced neuroendocrine tumors, we evaluated whether treatment with (177)Lu-labeled sst antagonists is feasible.

METHODS

After injection of approximately 1 GBq of (177)Lu-DOTA-[Cpa-c(DCys-Aph(Hor)-DAph(Cbm)-Lys-Thr-Cys)-DTyr-NH2] ((177)Lu-DOTA-JR11) and (177)Lu-DOTATATE, 3-dimensional voxel dosimetry analysis based on SPECT/CT was performed. A higher tumor-to-organ dose ratio for (177)Lu-DOTA-JR11 than for (177)Lu-DOTATATE was the prerequisite for treatment with (177)Lu-DOTA-JR11.

RESULTS

Reversible minor adverse effects of (177)Lu-DOTA-JR11 were observed. (177)Lu-DOTA-JR11 showed a 1.7-10.6 times higher tumor dose than (177)Lu-DOTATATE. At the same time, the tumor-to-kidney and tumor-to-bone marrow dose ratio was 1.1-7.2 times higher. All 4 patients were treated with (177)Lu-DOTA-JR11, resulting in partial remission in 2 patients, stable disease in 1 patient, and mixed response in the other patient.

CONCLUSION

Treatment of neuroendocrine tumors with radiolabeled sst antagonists is clinically feasible and may have a significant impact on peptide receptor radionuclide therapy.

Effect of a home bleaching agent on the fracture toughness of resin composites, using short rod design

STATEMENT OF PROBLEM

Resin composites are brittle materials and their major shortcomings are manifested in their sensitivity to flaws and defects. Although various mechanical properties of resin composites have been described, few studies are available on assessing the effect of bleaching agents on resin composites using the short rod design.

PURPOSE

To place various resin composites into distilled water at 37°C for 21 days and determine the effect of immersion time in distilled water, with and without exposure to 10% carbamide peroxide by employing short rod design fracture toughness test.

MATERIALS AND METHOD

Specimens were prepared from three resin composites; Rok (SDI), Esthet (Dentsply), and Estelite (Tokuyama). For each material, a total of 24 disc-shaped specimens were prepared using a custom-made mould. Specimens were randomly divided into 3 groups of 8 and conditioned in 37°C distilled water for either 24 hours, or 21 days. 21 day specimens were tested both with and without applying bleaching agent; Polanight (SDI). Study group specimens were bleached for 21 days, 2 hours a day. The specimens were loaded using a universal testing machine with a crosshead speed of 0.5 mm per minute. The maximum load at specimen failure was recorded and the KIc (MPa. M (0.5)) was calculated.

RESULTS

Statistical analysis using two-way ANOVA showed a significant relationship between material and time (p< 0.05).Tukey's test showed that after 24 h of immersion in distilled water, Rok revealed the highest KIc followed by Esthet and Estelite. The bleaching agent significantly improved the fracture toughness values of Esthet while it decreased that of Estelite.

CONCLUSION

The fracture toughness of the resin composites was affected by the bleaching agent and distilled water. In comparison with Rok and Estelite, fracture toughness of Esthet was increased due to aging and application of bleaching agent.

Radiopharmaceutical development of radiolabelled peptides

Receptor targeting with radiolabelled peptides has become very important in nuclear medicine and oncology in the past few years. The overexpression of many peptide receptors in numerous cancers, compared to their relatively low density in physiological organs, represents the molecular basis for in vivo imaging and targeted radionuclide therapy with radiolabelled peptide-based probes. The prototypes are analogs of somatostatin which are routinely used in the clinic. More recent developments include somatostatin analogs with a broader receptor subtype profile or with antagonistic properties. Many other peptide families such as bombesin, cholecystokinin/gastrin, glucagon-like peptide-1 (GLP-1)/exendin, arginine-glycine-aspartic acid (RGD) etc. have been explored during the last few years and quite a number of potential radiolabelled probes have been derived from them. On the other hand, a variety of strategies and optimized protocols for efficient labelling of peptides with clinically relevant radionuclides such as (99m)Tc, M(3+) radiometals ((111)In, (86/90)Y, (177)Lu, (67/68)Ga), (64/67)Cu, (18)F or radioisotopes of iodine have been developed. The labelling approaches include direct labelling, the use of bifunctional chelators or prosthetic groups. The choice of the labelling approach is driven by the nature and the chemical properties of the radionuclide. Additionally, chemical strategies, including modification of the amino acid sequence and introduction of linkers/spacers with different characteristics, have been explored for the improvement of the overall performance of the radiopeptides, e.g. metabolic stability and pharmacokinetics. Herein, we discuss the development of peptides as radiopharmaceuticals starting from the choice of the labelling method and the conditions to the design and optimization of the peptide probe, as well as some recent developments, focusing on a selected list of peptide families, including somatostatin, bombesin, cholecystokinin/gastrin, GLP-1/exendin and RGD.

Radiolabeled peptides: valuable tools for the detection and treatment of cancer

Human cancer cells overexpress many peptide receptors as molecular targets. Radiolabeled peptides that bind with high affinity and specificity to the receptors on tumor cells hold great potential for both diagnostic imaging and targeted radionuclide therapy. The advantage of solid-phase peptide synthesis, the availability of different chelating agents and prosthetic groups and bioconjugation techniques permit the facile preparation of a wide variety of peptide-based targeting molecules with diverse biological and tumor targeting properties. Some of these peptides, including somatostatin, bombesin, vasoactive intestinal peptide, gastrin, neurotensin, exendin and RGD are currently under investigation. It is anticipated that in the near future many of these peptides may find applications in nuclear oncology. This article presents recent developments in the field of small peptides, and their applications in the diagnosis and treatment of cancer.