N-Terminal Stabilization of Radiolabeled Neurotensin Analogues for Improved Tumor Uptake.

Peptide-based radiopharmaceuticals targeting neurotensin-receptor-1 (NTS) are mainly stabilized using chemical modifications at the NT[8-13] sequence, thus increasing the stability and the uptake of the corresponding radionuclide-macrocycle-linker-bioconjugate. We postulate that the introduction of the linker at the -term part induces additional cleavage sites that can be further stabilized to achieve a prolonged uptake. Double (JMV 7259 and JMV 7222) and triple-stabilized neurotensin analogues (JMV 7258 and JMV 7490) were synthesized, radiolabeled, and evaluated on HT-29 cells (NTS).

Design and Synthesis of Ga-Labeled Peptide-Based Heterodimers for Dual Targeting of NTS and GRPR.

Tumor heterogeneity remains one of the main obstacles for cancer diagnosis and treatment. The simultaneous targeting of several cancer biomarkers is an appealing approach for improved diagnostic procedures. Neurotensin receptor 1 (NTS) and Gastrin-Releasing Peptide Receptor (GRPR) are both G-protein coupled receptors with complementary profile of expression in several cancer types.

Rational design of NT-PSMA heterobivalent probes for prostate cancer theranostics.

Targeting the prostate-specific membrane antigen (PSMA) with radiopharmaceuticals for imaging and/or therapy has demonstrated significant advancement in the management of prostate cancer patients. However, PSMA targeting remains unsuccessful in prostate cancers with low expression of PSMA, which account for 15% of cases. The neurotensin receptor-1 (NTS) has been highlighted as a suitable oncotarget for imaging and therapy of PSMA-negative prostate cancer lesions.

Development of Radiopharmaceuticals for NPY Receptor-5 (Y5) Nuclear Imaging in Tumors by Synthesis of Specific Agonists and Investigation of Their Binding Mode.

The neuropeptide-Y (NPY) family acts through four G protein-coupled receptor subtypes in humans, namely, Y, Y, Y, and Y. A growing body of evidence suggest the involvement of the NPY system in several cancers, notably the Y subtype, thus acting as a relevant target for the development of radiopharmaceuticals for imaging or targeted radionuclide therapy (TRT). Here, the [cPP(1-7),NPY(19-23),Ala,Aib,Gln]hPP scaffold, further referred to as sYago, was modified with a DOTA chelator and radiolabeled with Ga and In and investigated and using the MCF-7 model.

Theranostics of Primary Prostate Cancer: Beyond PSMA and GRP-R.

Unlabelled: The imaging of Prostate-Specific Membrane Antigen (PSMA) is now widely used at the initial staging of prostate cancers in patients with a high metastatic risk. However, its ability to detect low-grade tumor lesions is not optimal.

Methods: First, we prospectively performed neurotensin receptor-1 (NTS) IHC in a series of patients receiving both [Ga]Ga-PSMA-617 and [Ga]Ga-RM2 before prostatectomy.

Design, Synthesis, and Biological Evaluation of the First Radio-Metalated Neurotensin Analogue Targeting Neurotensin Receptor 2.

Neurotensin receptor 2 (NTS) is a well-known mediator of central opioid-independent analgesia. Seminal studies have highlighted NTS overexpression in a variety of tumors including prostate cancer, pancreas adenocarcinoma, and breast cancer. Herein, we describe the first radiometalated neurotensin analogue targeting NTS.

Comparison of Ga-PSMA-617 PET/CT and Ga-RM2 PET/CT in Patients with Localized Prostate Cancer Who Are Candidates for Radical Prostatectomy: A Prospective, Single-Arm, Single-Center, Phase II Study.

Considering the wide range of therapeutic options for localized prostate cancer (e.g., active surveillance, radiation-beam therapy, focal therapy, and radical prostatectomy), accurate assessment of the aggressiveness and localization of primary prostate cancer lesions is essential for treatment decision making.

Ga-Radiolabeling and Pharmacological Characterization of a Kit-Based Formulation of the Gastrin-Releasing Peptide Receptor (GRP-R) Antagonist RM2 for Convenient Preparation of [Ga]Ga-RM2.

Background: [Ga]Ga-RM2 is a potent Gastrin-Releasing Peptide-receptor (GRP-R) antagonist for imaging prostate cancer and breast cancer, currently under clinical evaluation in several specialized centers around the world. Targeted radionuclide therapy of GRP-R-expressing tumors is also being investigated. We here report the characteristics of a kit-based formulation of RM2 that should ease the development of GRP-R imaging and make it available to more institutions and patients.

Striatal and cerebellar vesicular acetylcholine transporter expression is disrupted in human DYT1 dystonia.

Early-onset torsion dystonia (TOR1A/DYT1) is a devastating hereditary motor disorder whose pathophysiology remains unclear. Studies in transgenic mice suggested abnormal cholinergic transmission in the putamen, but this has not yet been demonstrated in humans. The role of the cerebellum in the pathophysiology of the disease has also been highlighted but the involvement of the intrinsic cerebellar cholinergic system is unknown.

Silicon-Containing Neurotensin Analogues as Radiopharmaceuticals for NTS-Positive Tumors Imaging.

Several independent studies have demonstrated the overexpression of NTS in various malignancies, which make this receptor of interest for imaging and therapy. To date, radiolabeled neurotensin analogues suffer from low plasmatic stability and thus insufficient availability for high uptake in tumors. We report the development of Ga-radiolabeled neurotensin analogues with improved radiopharmaceutical properties through the introduction of the silicon-containing amino acid trimethylsilylalanine (TMSAla).

Design, synthesis, and biological evaluation of a multifunctional neuropeptide-Y conjugate for selective nuclear delivery of radiolanthanides.

Background: Targeting G protein-coupled receptors on the surface of cancer cells with peptide ligands is a promising concept for the selective tumor delivery of therapeutically active cargos, including radiometals for targeted radionuclide therapy (TRT). Recently, the radiolanthanide terbium-161 (Tb) gained significant interest for TRT application, since it decays with medium-energy β-radiation but also emits a significant amount of conversion and Auger electrons with short tissue penetration range. The therapeutic efficiency of radiometals emitting Auger electrons, like Tb, can therefore be highly boosted by an additional subcellular delivery into the nucleus, in order to facilitate maximum dose deposition to the DNA.

Combining 3'-Deoxy-3'-[18F] fluorothymidine and MRI increases the sensitivity of glioma volume detection.

Objective: 3'-Deoxy-3'-[18F] fluorothymidine (18F-FLT) is a marker of cell proliferation and displays a high tumor-to-background ratio in brain tumor lesions. We determined whether combining 18F-FLT PET and MRI study improves the detection of tumoral tissue compared to MRI alone and whether 18F-FLT uptake has a prognostic value by studying its association with histopathological features.

Methods: Thirteen patients with a supratentorial malignant glioma were recruited and scheduled for surgery.

68Ga-PSMA-617 Compared With 68Ga-RM2 and 18F-FCholine PET/CT for the Initial Staging of High-Risk Prostate Cancer.

Ga-labeled prostate-specific membrane antigen inhibitors and Ga-labeled gastrin-releasing peptide receptor antagonists showed interesting results for staging biochemically recurrent prostate cancer. In this case, Ga-prostate-specific membrane antigen-617 PET/CT, Ga-RM2 PET/CT, and F-choline PET/CT were performed in a patient (66-year-old man, prostate-specific antigen = 6.7 ng/mL) with biopsy-proven Gleason 9 (5 + 4) prostate cancer, candidate for radical prostatectomy and lymph node dissection.

Comparison of the radiolabeled PSMA-inhibitor In-PSMA-617 and the radiolabeled GRP-R antagonist In-RM2 in primary prostate cancer samples.

Purpose: Prostate-specific membrane antigen (PSMA) and gastrin-releasing peptide receptor (GRP-R) are expressed in prostate cancer and can be targeted with radiolabeled inhibitors and antagonists. Their performances for the initial characterization of prostatic tumors have been barely evaluated but never compared. We aimed to gather comparative preclinical data of the role of PSMA and GRP-R targeting in prostate cancer.

Comparison of the binding of the gastrin-releasing peptide receptor (GRP-R) antagonist 68Ga-RM2 and 18F-FDG in breast cancer samples.

The Gastrin-Releasing Peptide Receptor (GRPR) is over-expressed in estrogen receptor (ER) positive breast tumors and related metastatic lymph nodes offering the opportunity of imaging and therapy of luminal tumors. 68Ga-RM2 binding and 18F-FDG binding in tumoral zones were measured and compared using tissue micro-imaging with a beta imager on 14 breast cancer samples (10 primaries and 4 associated metastatic lymph nodes). Results were then assessed against ER expression, progesterone receptor (PR) expression, HER2 over-expression or not and Ki-67 expression.

Highly hindered 2-(aryl-di-tert-butylsilyl)-N-methyl-imidazoles: a new tool for the aqueous F- and F-fluorination of biomolecule-based structures.

A new class of silicon-based fluoride acceptors with a C-linked heterocycle as the leaving group was synthesized in one step from commercial chemicals, and linked to biomolecules. The resulting conjugates were efficiently 19F-fluorinated in aqueous mixtures, and switching to 18F-labelling provided nucleoside- and peptide-based bioconjugates with excellent molar activities suitable for biological applications.

Evaluation of (68)Ga-DOTA-TOC PET/CT for the detection of duodenopancreatic neuroendocrine tumors in patients with MEN1.

Context: Somatostatin receptor scintigraphy with (111)In-pentetreotide (SRS) is used to detect duodenopancreatic neuroendocrine tumors (dpNETs) in multiple endocrine neoplasia type 1 (MEN1). However, SRS has limited sensitivity for this purpose. Positron emission tomography/computed tomography (PET/CT) with (68)Ga-DOTA-TOC has a higher rate of sporadic dpNETs detection than SRS but there is little data for dpNETs detection in MEN1.

A phantom-based method to standardize dose-calibrators for new β+-emitters.

Quantitative imaging with PET requires accurate measurements of the amount of radioactivity injected into the patient and the concentration of radioactivity in a given region. Recently, new positron emitters, such as (124)I, (89)Zr, (82)Rb, (68)Ga, and (64)Cu, have emerged to promote PET development, but standards are still largely lacking. Therefore, we propose to validate a simple, robust, and replicable methodology, not requiring the use of any standards, to accurately calibrate a dose-calibrator for any β(+)-emitter.

A new SiF-Dipropargyl glycerol scaffold as a versatile prosthetic group to design dimeric radioligands: synthesis of the [(18) F]BMPPSiF tracer to image serotonin receptors.

A novel SiX-dipropargyl glycerol scaffold (X: H, F, or (18) F) was developed as a versatile prosthetic group that provides technical advantages for the preparation of dimeric radioligands based on silicon fluoride acceptor pre- or post-labeling with fluorine-18. Rapid conjugation with the prosthetic group takes place in microwave-assisted click conjugation under mild conditions. Thus, a bivalent homodimeric SiX-dipropargyl glycerol derivatized radioligand, [(18) F]BMPPSiF, with enhanced affinity was developed by using click conjugation.

Silicon-based chemistry: an original and efficient one-step approach to [18F]-nucleosides and [18F]-oligonucleotides for PET imaging.

Take it eaSi! Nucleosides, dinucleotides, and one oligonucleotide, all modified by click chemistry, have for the first time been directly and very efficiently labeled with (18)F by using a silicon-based, one-step approach that opens the way for the development of a new class of positron emission tomography (PET) tracers (see graphic).