A Novel Sentinel Lymph Node Approach in Oral Squamous Cell Carcinoma.

BACKGROUND: Occult metastases are common in patients with oral squamous cell carcinoma (OSCC) which is why elective neck dissection, adjuvant radiotherapy or watchful waiting have been treatment options after surgical removal of the primary tumour. Sentinel lymph node biopsy (SLNB) has lately emerged as a novel possibility in treatment planning. OBJECTIVES: To establish a reliable and clinically useful protocol for SLNB in staging/elective neck dissection in oral cancer. METHODS: Fourteen consecutive patients with T1-T2 N0 oral cancer were enrolled when scheduled for elective neck dissection. RESULTS: This study outlines various techniques for improving SLNB in head and neck cancer. After evaluation, a combination of techniques was found to constitute a reliable, clinically adaptable work concept. The suggested procedure starts with the pre-surgical injection of radioactive technetium 99Tcm carried on tilmanocept (Lymphoseek ®) at the tumour site. The radioactivity in the lymph node is then visualized preoperatively with Single Photon Emission Computed Tomography (SPECT/CT). Intraoperatively, indocyanine green (ICG) is injected and a sentinel node is visualized with near-infrared light. To support the sentinel node detection, the surgeon uses a hand-held gamma detection probe. This approach results in a reproducible and reliable detection of sentinel nodes. CONCLUSION: This paper presents a novel protocol for the identification of the sentinel node in the head and neck region. The protocol additionally enables the use of flow cytometry analysis of resected lymph nodes.

Impact of the proline residue on ligand binding of neurotensin receptor†2 (NTS2)-selective peptide-peptoid hybrids.

To investigate the binding mode and structure-activity relationships (SARs) of selective neurotensin receptor 2 (NTS2) ligands, novel peptide-peptoid hybrids that simulate the function of the endogenous ligand were developed. Starting from our recently described NTS2 ligands of type 1, structural variants of type 2 and the metabolically stable analogues 3 a,b were developed. Replacement of the proline unit by a collection of structural surrogates and evaluation of the respective molecular probes for NTS2 affinity and selectivity indicated similar SARs as described for NT(8-13) derivatives bound to the subtype NTS1. Peptide-peptoid hybrids 2 d, 3 a,b showed substantial NTS2 binding affinity (Ki =8.1-16 nM) and 2400-8600-fold selectivity over NTS1. The thiazolidine derivative 3 b showed metabolic stability over 32 h in a serum degradation assay. In an inositol phosphate accumulation assay, the neurotensin mimetics 3 a and 3 b displayed an inhibition of constitutive activity exceeding 1.7-2.0 times the activity of NT(8-13). The fluorinated derivative 3 a could afford attractive opportunities to detect NTS2 by (19) F magnetic resonance imaging.

Development of a metabolically stable neurotensin receptor†2 (NTS2) ligand.

Subtype-selective neurotensin receptor 2 (NTS2) ligands can be used as molecular probes to investigate the physiological role of neurotensinergic systems and serve as lead compounds to initiate the development of drugs for the treatment of tonic pain. Starting from our recently described NTS2 ligand 1, structural variants of type 2 were synthesized to further improve binding affinity and selectivity to gain metabolic stability. The peptide-peptoid hybrid 2 b showed excellent NTS2 binding affinity (K(i) =2.8 nM) and 22 000-fold selectivity over NTS1, as well as metabolic stability over 32 h in a serum degradation assay. Employing a MAPK-driven luciferase reporter gene assay and an IP accumulation assay, the neurotensin mimetic 2 b displayed respective inhibitions of constitutive activity exceeding 4.3- and 3.9-fold that of the inverse agonist activity of the endogenous ligand neurotensin.

Discovery of highly potent and neurotensin receptor 2 selective neurotensin mimetics.

The neurotensin receptor subtype 2 (NTS2) is involved in the modulation of tonic pain sensitivity and psychiatric diseases and is, therefore, regarded as a highly attractive pharmacological target protein. Aiming to discover NTS2 selective ligands, we herein describe the identification of screening hits and the chemical synthesis of structural variants leading to the highly potent and NTS2 selective peptide-peptoid hybrids of type 3. The neurotensin mimetics 3a and 3e-g incorporating an N-(4-hydroxyphenethyl)glycine substructure exhibit single digit nanomolar affinity (K(i) = 4.3-8.8 nM) and 1900-12000 fold selectivity over the neurotensin receptor subtype 1 (NTS1). According to functional experiments, the test compounds 3a and 3e-g displayed an inhibition of constitutive mitogen-activated protein kinase (MAPK) activity exceeding 2.6-4.6 times the inverse agonist activity of the endogenous ligand neurotensin.