New freeze-dried kit for diagnosis of bombesin receptor expressing tumors

It has been shown that some primary human tumors and their metastases, including prostate and breast tumors, over-express gastrin-releasing peptide [GRP] receptors. Bombesin is a neuropeptide with a high affinity for these GRP receptors. The purpose of this study was to prepare and evaluate the characteristics of a new Freeze-dried kit, [6-hydrazinopyridine-3-carboxylic acid [HYNIC]]-GABA-Bombesin [7-14] NH[2] designed for the labeling with 99mTc using tricine and EDDA as coligand. Synthesis was performed on a solid phase using a standard Fmoc strategy and HYNIC precursor coupled at the N-terminus. Purified peptide conjugate was labeled with [99m]Tc at 100°C for 10 min. Radiochemical analysis involved ITLC and high-performance liquid chromatography methods. Peptide conjugate stability and affinity to human serum was challenged for 24 hours. The internalization rate was studied in GRP receptor expressing PC-3 cells. Biodistribution of radiopeptide was studied in rats. Radiolabeling was performed at high specific activities, and radiochemical purity was >98%. The stability of radiolabeled peptide in human serum was excellent. In vitro studies showed >14% of activity was specific internalized into PC-3 cells up to 4 h. After injection into rat biodistribution data showed a rapid blood clearance, with renal excretion and specific binding towards GRP receptor-positive tissues such as pancreas [1.15 +/- 0.19% ID/g after 4 h]. [[99m]Tc-HYNIC]-GABA-Bombesin [7-14] NH[2] showed favorable radiochemical and biological characteristics which make our new designed labeled peptide conjugate as a very suitable agent for diagnostic purposes in malignant tumors

Synthesis and evaluation of a new radiolabeled bombesin analogue for diagnosis of GRP receptor expressing tumors

Bombesin [BN], a 14-amino acid neuropeptide, shows high affinity for the human GRP [gastrin releasing peptide] receptors, which are overexpressed by a variety of cancers, including prostate, breast, pancreas, gastrointestinal, and small cell lung cancer. Aim was to prepare [6-hydrazinopyridine-3-carboxylic acid [HYNIC[0], D-Tyr[6], D-Trp[8]] - BN [6-14] NH[2] that could be easily labeled with[99m]Tc and evaluation of its potential as an imaging agent. Synthesis of the peptide amide was carried out onto Rink Amide MB HA [4-Methylbenzhydrylamine] resin. A bifunctional chelating agent [BFCA] was attached to the N terminal peptide in solid-phase. [99m]Tc labeling was performed by addition of sodium pertechnetate to solution that include [HYNIC[0], D-Tyr[6], D-Trp[8]] Bombesin [6-14] NH[2], tricine, ethylenediamine-N,N'-diaeetic acid [EDDA] and SnCl[2]. Radiochemical evaluation was carried out by reverse phase high-performance liquid chromatography [HPLC] and instant thin layer chromatography [ITLC]. In- vitro internalization was tested using human prostate cancer cells [PC-3] with blocked and non-blocked receptors. Biodistribution was determined in rats. [99m]Tc/tricine/EDDA-HYNIC[0], D-Tyr[6], D-Trp[8]] bombesin [6-14] NH[2] was obtained with radiochemical purities >98%. Results of in-vitro studies demonstrated a high stability in serum and suitable internalization. Biodistribution data showed a rapid blood clearance, with renal excretion and specific binding towards GRP receptor-positive tissues such as pancreas. In this study, labeling of this novel conjugate with [99m] Tc easily was performed using coligand. The prepared [99m]Tc-HYNIC-BN conjugate has promising characteristics for the diagnosis of malignant tumors

Synthesis, labeling and quality control of a new neuropeptide Y analogue for diagnosis of breast tumors

Over expression of selected peptide receptors in human tumors has been shown to represent clinically relevant targets for cancer diagnosis and therapy. The aim of this work was to investigate Neuropeptide Y [NPY] as a new radiopharmaceutical for diagnosis of breast cancer. A neuropeptide Y analogues with Y[1] receptor preference and agonistic properties was synthesized by solid phase method. After conjugation with diethylenetriaminepentaacetic acid [DTPA] labeling with [111]In was performed. For labeled peptide, yield of labeling, stability in human serum, receptor binding in cell surface with internalization in SK-N-MC cells, and biodistribution in normal rat were determined. Peptide was synthesized and labeled with more than 95% purity. Radiolabeled peptide was stable in human serum and specifically binds and internalized in the cells with Y1 receptor [4h = 22%]. A rapid clearance from blood pool and urinary with hepatobiliary excretion were observed. Our results showed that this peptide can be considered as a candidate for diagnosis of breast tumors

New peptide based freeze-dried kit [99m] Tc-HYNIC]-UBI 29-41 as a human specific infection imaging agent

Ubiquicidin 29-41 [UBI] is a fragment of the cationic antimicrobial peptide that is present in various species including humans. The purpose of this study was to investigate radiochemical and biological characteristics of [6-hydrazinopyridine-3-carboxylic acid [HYNIC]]-UBI 29-41 designed for the labeling with 99mTc using tricine as coligand. Synthesis was preformed on a solid phase using a standard Fmoc strategy and HYNIC precursor coupled at the N-terminus. Purified peptide conjugate was labeled with 99mTc at 100°C for 10 min. Radiochemical analysis involved ITLC and high-performance liquid chromatography methods. Peptide conjugate stability and affinity to human serum was challenged for 24 hours and its in vitro binding to bacteria was assessed. Biodistribution and accumulation of radiopeptide in staphylococcus aureus infected mice were studied using scintigraphy and ex vivo counting. Radiolabeling was performed at high specific activities, and radiochemical purity was >95%. The stability of radiolabeled peptide in human serum was excellent. In vitro studies showed 70% of radioactivity was bound to bacteria. After injection into mice with a bacterial infection, removing from the circulation occurred mainly by renal clearance and site of infection was rapidly detected within 30 min. Target to nontarget muscle ratio was 2.099 +/- 0.05% at 30 min post injection. [99mTc-HYNIC]-UBI 29-41 showed favorable radiochemical and biological characteristics which permitted detection of the infection with optimal visualization within 30 min